Distribution of soft-bottom polychaetes assemblages at different scales in shallow waters of the northern mediterranean Spanish coast

DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST Letzi Graciela Serrano Samaniego Rafael Sardá Borroy Barcelona, June 2012 DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST Doctorate dissertation To obtain the Doctoral Degree in Marine Sciences Marine Sciences Doctoral Program UPC-UB-CSIC Developed in the Marine Engineering Laboratory (Laboratori d'Enginyeria Marítima, LIM/UPC) and in the Center for Advance Studies of Blanes (Centre d’Estudis Avançats de Blanes-CEAB) By Letzi Graciela Serrano Samaniego Dissertation supervisor: Rafael Sardá Borroy, CEAB-CSIC June 2012 Barcelona, Spain To my dear family:  My dearly husband: Carlos I love you. My beloved kids  Carlos  Letzy  Yenia  Kelsy vii DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST TABLE OF CONTENTS Acknowledgements ......................................................................................................... ix Summary ......................................................................................................................... 11 Introduction .................................................................................................................... 12 Polychaetes as a zoological model ................................................................................. 12 Common generalities about Polychaetes ........................................................................ 12 Systematics ..................................................................................................................... 14 Morphology .................................................................................................................... 17 Feeding Strategies .......................................................................................................... 19 The Mediterranean Sea ................................................................................................... 21 Oceanographic features .................................................................................................. 21 Thesis structure ............................................................................................................... 26 References ...................................................................................................................... 30 Chapter 1 ........................................................................................................................ 30 A polychaete-dominated community in the Nw Mediterranean sea, 20 years after cessation of sewage discharges....................................................................................... 30 Abstract ........................................................................................................................... 30 Introduction .................................................................................................................... 31 Material and methods ..................................................................................................... 33 Study site ................................................................................................................................. 33 Sampling and laboratory procedures ....................................................................................... 36 Measurement methods and secondary production estimates .................................................. 37 Computation of indices for the analyzed benthic assemblages ............................................... 39 Results ............................................................................................................................ 40 Sedimentology ......................................................................................................................... 40 Community structure and dynamics ........................................................................................ 42 Secondary production .............................................................................................................. 49 Discussion …………………………………………………………………………51 Chapter 2 ........................................................................................................................ 58 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast).............................................................. 58 Abstract ........................................................................................................................... 58 Introduction .................................................................................................................... 58 Material and methods ..................................................................................................... 61 Study sites ............................................................................................................................... 61 viii The sampling effort ................................................................................................................. 63 Data analysis and assemblage classification ........................................................................... 64 Diversity measures .................................................................................................................. 65 Results ............................................................................................................................ 65 Gulf of Roses study ................................................................................................................. 65 The Littoral surf beach assemblage ......................................................................................... 70 The Littoral fine sand assemblage ........................................................................................... 71 The Littoral sandy mud assemblage ........................................................................................ 73 Discussion ....................................................................................................................... 78 Chapter 3 ........................................................................................................................ 84 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast .................................................................................................................. 84 Abstract ........................................................................................................................... 84 Introduction .................................................................................................................... 84 Material and methods ..................................................................................................... 86 Study area ................................................................................................................................ 86 Sampling and laboratory procedures ....................................................................................... 89 Data analysis ........................................................................................................................... 90 Results ............................................................................................................................ 91 Granulometry .......................................................................................................................... 91 Species richness, abundances and heterogeneity diversity...................................................... 93 Spatial distribution and faunal assemblages ............................................................................ 97 Discussion ..................................................................................................................... 107 Granulometry ........................................................................................................................ 107 Species richness, abundances and heterogeneity diversity.................................................... 107 Spatial distribution and faunal assemblages .......................................................................... 108 Acknowledgements ...................................................................................................... 111 Chapter 4 ...................................................................................................................... 115 Assessment of soft-bottom polychaete assemblages in Littoral Fine Sands (LFS) community based on a mesoscales survey: .................................................................. 115 Abstract ......................................................................................................................... 115 Introduction .................................................................................................................. 115 Material and methods ................................................................................................... 118 Sampling and laboratory procedures ..................................................................................... 118 Data analysis ......................................................................................................................... 123 Results .......................................................................................................................... 124 Assemblage classification ..................................................................................................... 124 Sedimentology ....................................................................................................................... 125 Community structure ............................................................................................................. 127 Trophic composition and estimates of productivity .............................................................. 136 Discussion ..................................................................................................................... 138 Acknowledgements ...................................................................................................... 142 Apendix ........................................................................................................................ 167 ix ACKNOWLEDGEMENTS I am very grateful to the program “Becas de Excelencia Profesional” IFARHUSENACYT research grant of Panama government by allow me develop the doctoral studies in Marine Sciences program (UPC-UB-CSIC). And Universidad Autónoma de Chiriquí and Universidad de Panama by hold my employed during these years. Thanks to my thesis director Rafael Sardà Borroy “Rafa” by the wise advises dedication and valuable helping during all this years and who collaboration was very important for ending this thesis just in time. Rafa without your help it was not possible. Thanks you so much. To Joao Gil for helping to resolve some doubts in the polychaetes identification and bibliography. Also I want to thanks to technician Gustavo Carreras for his helping with some sorting and samples weighed. I am in debt to David March Morla for the valuable helping with all maps. Also was appreciative the bibliography given by Dany Martin. I am very grateful to Genoveva Comas, secretary of the Laboratori d'Enginyeria Marítima, LIM/UPC, by the fast and efficient diligent, and to Conxita Avila, Cruz Palacín, Vicente Gracia and Rafa Sardá again, by the following to thesis ante-project. Also I wish give my grateful to the staff of Center d’Estudis Avançats, Carmela Bosca, Gemma Peña, Ramón Coma, Angel Luque, and Rafa for the helping and bear me through these years. Thanks to Helena Barrios who was library for some years and now David Alenya. Also I want to show my grateful to cleaner ladies Ana, Maricarmen and Emilia by the moment gathered and by their good mood. I am indebted with my friends Chiara Romano, Francesco Pittito, Guillermo de Mendoza, Carlos Rivera and specially to Juan Pablo Lozoya by their helping during these years. Also, thankful to Sergi Taboada and Carlo Tidu by their help and comment. Also thankful to all my Ceab-mate and friends, I do not add more names because I could miss some people, and it is not my intention, but I want to express, all of you will have a placed in my heart. I am glad for all gathered moment, I do not forget them. DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 16 interstitial forms to over 3 m (some Eunicidae, Onuphidae) and may live from a few weeks to several years (Beesley et al. 2000). The number of segments may be few and limited or many and unlimited. New segments develop immediately in front of the pygidium (Pettibone 1982). The polychaete body consists of three basic regions: the presegmental region is derived from the episphere, prototroch and the area surrounding the mouth in the larvae and makes up the prostomium and peristomium (the head) in the adult worm (Beesley et al. 2000). The head consists of the preoral prostomium, which contains the cerebral ganglia and bears the most important sense organs (Day 1967). It may be in the form of a simple lobe or furnished with various appendages, including a pair of ventral palps and frontal dorsal, or occipital antennae; sometimes simple eyespots or a pair of welldeveloped stalked eyes are present (Alciopidae, Polyodontidae). The peristomium, enclosing the ventral mouth, may be formed of one to several fused segments which often lack parapodia and setae and are furnished with a variable number of tentacular or peristomial cirri. The prostomium and peristomium may be more or less fused, and are furnished with a pair of long grooved tentacular palps, ciliated nuchal organs, and a median caruncle extending posteriorly from the prostomium. In the sedentary or tubedwelling forms, the prostomium may be indistinct and more or less hidden by other structures, such as numerous oral tentacles (Terebellidae, Ampharetidae), enlarged flattened setae or paleae (Amphictenidae, Sabellariidae), or an enlarged branchial plume (Sabellidae, Serputidae). Usually, each segment following the peristomium is provided with paired parapodia in the form of fleshy lateral outgrowths bearing bundles of setae. When present, the parapodia are uniramous or biramous (dorsal notopodium and ventral neuropodium), and each is supported by a short rod or aciculum. In the burrowing and sedentary forms, the rami may be in the form of low ridges (tori) provided with rows of acicular hooks or minute setae or uncini. The setae are particularly varied, slender or stout, smooth or dentate, and simple or compound, with basal stems and distal blades of various types. The parapodia may bear accessory structures, such as dorsal and ventral cirri, dorsal scalps (Aphroditacea), flattened lobes or ligules (Nereididae), flattened plates or lamellae (Nephtyidae, Spionidae), or filiform or branched branchiae (Eunicidae). The pygidium, containing the dorsal anus, may be simple or may be provided with cirri or flattened plates (Pettibone 1982). DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 17 The epidermis of the body wall is often furnished with ciliated cells which form ciliated tracts and bands; they may set up currents of water, aiding in respiration, and bringing food-laden water and selected particles for tube construction to the mouth. In addition to the circular and longitudinal muscles of the body wall, there may be oblique and transverse muscles, complicated musculature associated with the tentacles and proboscis, and prominent parapodial and setal muscles. The circular muscle layer may be reduced or absent. Slow crawling movement is carried out by the parapodial muscles, rapid crawling and swimming by the parapodia and by undulations of the body which use the well-developed longitudinal muscle bundles. Burrowing may involve two types of anchors; the penetration anchor is a dilation of the upper part of the body that holds the worm against the burrow when the distal region is elongated by contraction of the circular or transverse muscles; this is followed by dilation of the distal region, forming the terminal anchor, which allows contraction of the longitudinal muscles to move the worm into the substrate. The two types of anchors are applied alternately until burial is complete. Polychaetes with elongate narrow bodies and poorly developed parapodia swim by means of undulations which pass along the body and exert a backward thrust against the water in a complex three-dimensional spiral motion or a lateral sinusoidal movement. Irrigation currents are often produced in burrowing and tube-dwelling polychaetes by muscular means, such as undulations of the body in a dorsoventral plane, or pistonlike swellings which pass up or down the body (Pettibone 1982). Feeding Strategies Fauchald and Jumars (1979) proposed a consistent conceptual framework to test hypotheses on the sympatric occurrence of congeners with limited morphological differentiation. Their polychaete feeding guilds were established based on a set of relations among food particle size and composition, the mechanisms involved in food capture and ingestion, and motility patterns associated with the feeding itself. Secondarily, the ingestion and assimilation efficiencies and the size or volume of the area necessary for the survival of a given organism would be involved. But currently, analyses of polychaete assemblages do not generally use the complete conceptual framework elaborated by them, i.e. (microphagous and microphagous), which in turn can be subdivided in 5 submodes and 12 subgroups formed according to feeding DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 18 morphology of each mode. They were combined with the three components of feeding motility to form 22 feeding guilds that are biologically acceptable. The most used feeding schemes generally divide the fauna into five or six trophic categories (omnivores, herbivores, carnivores, filter feeders, surface deposit feeders and burrowers) (Pagliosa 2005). On the other hand, Beesley et al. (2000) have summarized this strategies with no implication of phylogenetic relationships, but are useful for ecological purposes, they following schema given by (Fauchald and Jumars 1979) as: 1. Raptorial feeding (Carnivorous, Herbivorous and Omnivorous): this group, all macrophagous polychaetes, included polychaetes with eversible muscular ventral or muscular axial pharynx, to seize food items (often with jaws or teeth) like Eunicida and Phyllodocida, the two groups use its jaws to either seize live animals (carnivorous), tear off pieces of algae (herbivorous) or to grasp dead and decaying matter (scavengers). Some of the raptorial groups, such Phyllodocidae, lack jaws and use their eversible pharynx to capture prey. Members of Onuphidae family have burrowing lives mode, emerge to seek their prey where waves break. They have powerful jaws and feed on small to medium-sized invertebrates as well as drift algae. 2. Deposit-feeders (non-selective): the majority of groups using this method have a simple ventral or axial buccal organ. Some arenicolids and maldanids live in relatively permanent burrows or tubes and feed on the continuous raining of sand or mud falling around the burrow. Others, such as orbiniids, which do not have permanent burrows or tubes, move about the sediment, eating it as they tunnel. In sediments the amount of nutritional value varies; shallow-water mud deposits tend to contain high densities of non-selective deposit-feeders. The total organic matter in such areas can be as low as 1-2% and most deposit-feeders have to eat continually. 3. Surface deposit-feeder (selective): some deposit-feeders do not ingest haphazardly, but use their palps or buccal organs to sort organic material from sediment particles of a particular size range, typically the smaller one. As smaller particles have a great surface area to volume ratio than large particles, they carry more food proportionately per weight ingested. Hence, it is more DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 19 efficient to eat smaller particles than a random selection of various-sized particles. Selective deposit-feeders usually live in tubes. 4. Filter feeders: polychaetes filter-feeder, filter suspended particles from the water column. These polychaetes live in some sort of tube. The best known are sabellids serpulids and some chaetopterids. Sabellids and serpulids have elaborate palps in the form of tentacular crowns. A funnel is formed as the crown is expanded out of the tube. On each radiole cilia beat and create a current in the surrounding water. This current passes through the radioles into the funnel, swirls around its base and then passes upwards and outwards. Then food particles are trapped on small brnaches of the radioles, termed pinnules, and carries into groove by cilia. The ciliary current transports the particles towards the base of the radioles where the material is sorted. Small particles are swallowed. But large ones are diverted from the muth and dropped into the awater. Othes species sort the particles into three sizes; mid-sized particles are used in construction of the tube (Beesley et al. 2000). THE MEDITERRANEAN SEA Oceanographic features The Mediterranean Sea is a mid-latitude semi-enclosed sea, or almost isolated oceanic system. Many processes which are essential to the general circulation of the world ocean also occur within the Mediterranean, either identically or analogously (MalanotteRizzoli 2001; Robinson et al. 2001). The Mediterranean Sea (Fig. 1) is a marginal basin connected with the Atlantic Ocean via the Strait of Gibraltar (Astraldi et al. 1999). Therein, The Mediterranean Sea exchanges water, salt, heat, and other properties with the North Atlantic Ocean. The North Atlantic is known to play an important role in the global thermohaline circulation, as the major site of deepand bottom-water formation for the global thermohaline cell (conveyor belt) which encompasses the Atlantic, Southern, Indian, and Pacific Oceans. The salty water of Mediterranean origin may affect water formation processes and variabilities and even the stability of the global DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 20 thermohaline equilibrium state (Robinson et al. 2001). Besides the Mediterranean Sea is formed by two principal sub-basins (the Western and the Eastern Mediterranean) both connected by the Sicily Strait. As the Eastern and the Western Mediterranean, in their turn, enclose several regional seas that are also separated by straits and channels. It constitutes choke points where may observed the exchange of water masses and related properties internally between all the sub-basins and externally between the Mediterranean and the world ocean. The most important strait and channel are: the Corsica and the Balearic Channels, which control the meridional fluxes of the Western Mediterranean Sea; the Sardinia Channel, which forms the eastern boundary of the western Mediterranean basin; the Otranto Strait, through which are conveyed the exchanges between the Adriatic Sea with the rest of Mediterranean; and the Cretan Arc Straits, which is the interface between the Aegean Sea and the Eastern Mediterranean Basin (Astraldi et al. 1999). Thus the Mediterranean circulation is forced by water exchange through the straits, by wind stress, and by buoyancy flux at the surface due to freshwater and heat fluxes (Robinson et al. 2001). The circulation on all the Mediterranean sea have been well explained by Millot (1989); (1999) and Malanotte-Rizzoli (2001). Circulation in the Western Mediterranean follows three main ways: a) An upper thermocline circulation, the ‘Modified Atlantic Water’ MAW name used by Millot (1999) to refer to the surface water all over the Mediterranean Sea, which forms a 100–200 m layer characterized by salinities that increase, due to evaporation and mixing, from ;36.5 at Gibraltar to 38.0–38.3 in the north of the Western Mediterranean Sea, and by a mean temperature, below the mixed layer, of usually 14–15 ºC. b) Other intermediate layer circulation with Levantine Intermediate Water (LIW) pathways. The LIW, which the highest temperature could be 14.5 ºC and 38.7 salinity at 200 m depth along the Sicilian strait, but also a cooler than 14.0 ºC and denser than 0.1, water with approximately the same salinity at the bottom along the Tunisian slope. c) The latest one is considered deep thermohaline circulation with Western Mediterranean dense and deep waters (WMDW) pathways. This water mass DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 21 formed during the winter, mainly in the Gulf of Lions, and generally characterized by values of 12.75–12.80 ºC and 38.44–38.46 salinity content. This water mass (MAW) in the Alboran Sea describes a quasi-permanent anti-cyclonic gyre in the west and a more variable circuit in the eastern Alboran. Further east, the MAW is gathered in the strong meandering Algerian current, whose instabilities lead to the formation of anti-cyclonic eddies (diameter nearly 50-100 km) alongside the Algerian coast. These eddies grow in size; some may detach from the coast and drift into the interior of the Balearic Sea. There is also a quasi-stationary cyclonic path of MAW around the Balearic Sea leading to the formation of the Western Corsican Current west of Corsica. In the Tyrrhenian Sea, another steady cyclonic path of MAW, intrudes into Northern Ligurian Sea, where it joins the Western Corsican Current generating a return south-west ward flow along the Italian, French, and Spanish coasts, towards the Alboran Sea, called the Northern Current. The latest shows strong seasonal variability, becoming more intense and narrower in wintertime when it develops intense meanders, and splits into multiple branches in the southern Balearic Sea. The LIW circulation emerges from the Sicily Straits into the Western Mediterranean in the intermediate layer, 200-600 depth. LIW follows a cyclonic route all around the Tyrrhenian Sea, and splits into two branches at the northern tip of Corsica. One branch enters directly into the Ligurian Sea, the second circulates around Sardinia and Corsica, merges with the previous branch and successively flows cyclonically around the Balearic Sea. This major LIW branch enters the Gulf of Lions, where it plays a crucial role in preconditioning the winter convective cell of WMDW located here. WMDW has been observed to form in the Gulf of Lions basically every year, under winter episodes of cold, dry Mistral wind blowing from France. Here the mixed, ventilating chimney (around 100 km in diameter) can reach 2000 m depth. However, the mean LIW pathway is still controversial. The WMDW follows a circuitous cyclonic route that leads it throughout the Balearic and Tyrrhenian Seas. The deep WMDW flow is obviously affected by topography. In the Tyrrhenian Sea, the WMDW joins the Tyrrhenian Dense Water present in the deep layers. At Gibraltar, upwelling of WMDW occurs, mixing with the overlying LIW, and DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 22 contributing (what it is believed to be a small proportion) to the outflow from Gibraltar into the northern Atlantic. The Mediterranean Sea is a marine biodiversity hot spot. Spatial patterns showed a general decrease in biodiversity from northwestern to southeastern regions following a gradient of production, with some exceptions and caution due to lack of information of the biota along the southern and eastern edges. Biodiversity was also generally higher in coastal areas and continental shelves, and decreases with depth. Temporal trends indicated that overexploitation and habitat loss have been the main human drivers of historical changes in biodiversity. Currently, habitat loss and degradation, followed by fishing impacts, pollution, climate change, eutrophication, and the establishment of alien species are the most important threats to the whole taxonomic groups (Coll et al. 2010). Now, the new Marine Environmental Policy of the European Union, the Marine Strategy Framework Directive (MSFD), aims to achieve a good environmental status (GEnS) and the sustainable use of marine ecosystems, using the ecosystem approach as its basic reference framework (DIRECTIVE_2008/56/EC). This policy contained 11 descriptors have been identified for the achievement of GEnS, following European guidelines on the interpretation and application of the biological diversity descriptor as the first one on the list: “Biological diversity is maintained. The quality and occurrence of habitats and the distribution and abundance of species are in line with prevailing physiographic, geographic and climatic conditions”. When this descriptor is analyzed, the recommended levels of ecological organization for the assessment include species state, habitat/community state, landscape state and, finally, the entire ecosystem state (Cochrane et al. 2010). These authors also recommended a pragmatic, risk-based selection of biodiversity components using surrogates to assess the biodiversity state of a particular region. In addition, the use of the predominant habitat/community types, the ecotypes of the mobile species group, and the species and habitats listed under Community legislation and international conventions was suggested. THESIS STRUCTURE The studies about macrobenthic distribution that includes polychaetes faunal in the Mediterranean Sea were done by (Pérès and Picard 1964) in infralittoral (limit zone DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 23 compatible with seagrasses) and and circalittoral zone (limit zone compatible with photophilic algae). Similarly were important the surveys done by Guille (1970, 1971) in the French Catalonian border and Desbruyères et al. (1972-73) in the Gulf of Roses. Gili et al. (1987), studied several types of bottom between 5-80 m, along Catalonian coast. About polychaetes I can mention the studies by Capaccioni-Azzati (1987); Martin et al. (1990); (Afonso-Carrillo et al. 1992; Pinedo et al. 2000) in Alfaques bay. In Barcelones area (Méndez 1996). Over dynamic aspect of macrofauna (Sardá et al. 1995). And over dynamic of some polychaete species Grémare et al. (1998) on D. arietina and Pinedo et al. (2000) over O. fusiformis. Other surveys dealing aspect that includes polychaetes are those associated with wastewater discard (Ros et al. 1992; Cardell-Corral 1996; Cardell et al. 1999; Serrano et al. 2011) and/or organic enrichment (Méndez et al. 1997). The main objectives of this study are focused on elucidate: 1. How the soft-bottom Polychaete Fauna is distributed and structured in shallow waters alongside the Spanish Northern Mediterranean coast? 2. What are the main soft-bottom Polychaete assemblages found at the Littoral Fine Sands Community in the Spanish Northern Mediterranean coast? 3. What are the conditioning factors that allow the structure and distribution of the Polychaete Fauna in shallow waters? 4. How the Polychaete Fauna vary in a regional scale from the mouth of the Rhone River (France) to the vicinity of the Valencia city (Spain)? The information presented in the following chapters could be considered as a baseline study to assess the state of the coastal zone, taking into account that this region underneath strong human pressures. The thesis is organized taking into account different spatial scales of Polychaetes faunal distribution in shallow waters: a local scale, a sub-regional one, a large regional scale and the last one, analizing a mesoscale distribution. Most of the presented data is based on the Littoral Fine Sands Community (Labrune et al. 2006, 2007); the characteristic community that dominates shallow waters from 10 to 25-30 m in the Nort western DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 24 Mediterranean Sea. All of the analysis carried out in this Thesis are based on samples taken during the framework of different scientific projects (SPIO, MeVaPlaya-II, INTERFASE, REDIT-I, REDIT-II and INDEMARES). The thesis is structured in four chapters detailed below:  Chapter 1: a local scale survey:  A polychaete-dominated community in the NW Mediterranean Sea, 20 years after cessation of sewage discharges. In this chapter, one sampling station surrounded by intense human activities was chosen, off the city of Barcelona. The spatial effects of past wastewater discharges in the region were analyzed by Ros et al. (1992); Méndez (1996); Cardell et al. (1999) on a single station at 20 m depth. After 20 years, after long time cessation of discharges, the station was revisited for assessment. The main goals of this investigation were:  To assess the changes observed in benthic communities during these years.  To calculate the secondary production of this community through time, relating these values to sewage discharges, water quality and sediment improvement.  Chapter 2: a sub-regional spatial scale:  Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast). Alt Empordà case study, was chosen because this area is more pristine, despite of the economic activity generated by leisure activities, which currently is not considerable, but which activity plus the pressures by artisanal and industrial fisheries activities could finally contribute the which degradation of the marine environment due to overfrequentation of visitors. Thus, the polychaete fauna at a large number of stations in the Gulf of Roses and the northern part of the “Cap de Creus” are revisited 30 years after a French oceanographic campaign carried out in 1970-72 using similar methodologies. The main goals of this investigation were: DISTRIBUTION OF SOFT-BOTTOM POLYCHAETES ASSEMBLAGES AT DIFFERENT SCALES IN SHALLOW WATERS OF THE NORTHERN MEDITERRANEAN SPANISH COAST 25  To assess the present status of soft-bottom communities in two areas of the “Cap de Creus” region and to make a long-term comparison with old data obtained for these habitats..  To update the distributional pattern of polychaetes in the area of the “Cap de Creus” analyzing its relationship with the main environmental parameters.  Chapter 3: a regional spatial scale:  Assessment of soft-bottom polychaete sassemblages in the Northern Mediterranean Spanish coast. This chapter benefits from a regional oceanographic campaign carried out by a Spanish-French co-operation financed by the French CNRS, the REDIT-II campaign. In this campaign shallow soft-bottom environments were sampled from the locality of Portbou (Gerona) to the vicinity of the Valencia city. The main goals of this study were:  To describe the regional pool of polychaete species inhabiting shallow soft-bottom environments throughout the observed region.  Chapter 4: a mesoscale analysis:  Chapter 4. Assessment of soft-bottom polychaete assemblages in the Littoral Fine Sand (LFS) community based on a mesoscale survey: from the mouth of the Rhone river (France) to the vicinity of Valencia (Spain). In this later chapter, we are making a comparison between the different soft-bottom polychaete assemblages found through two oceanographic campaigns (REDIT-I and REDIT-II) at shallow waters (10 and 20 m depth) of the Gulf of Lions and the Northern MNediterranean Spanish coast. The main goals of this investigation were:  To describe the distribution patterns of soft-bottom polychaete species throughout the observed region.  To identify the relationship between polychaetes assemblages and its main environmental parameters, as well as to get some biomass and productivity estimates. CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 33 communities inhabiting the coastal region following alleviation of the pressure that organic matter previously exerted on them. In this article, the results obtained during two surveys carried out at the same sampling station, off the city of Barcelona, are presented. These two surveys were separated by twenty years. Additional data on the spatial effects of past wastewater discharges in the region can be seen in Ros & Cardell (1992); Cardell (1996) and Cardell et al. (1999). Data presented in this article will be compared against seasonal data obtained from a reference station included in the MacroBen database (Vanden Berghe et al. 2009) representing the shallow soft-bottom environments along the Catalan coast. By using these results, the main goals of this article were: a) to assess the changes observed in benthic communities during these years, and b) to calculate the secondary production of this community with time, relating these values to sewage discharges, water quality and sediment improvement. MATERIAL AND METHODS Study site The article is based on samples collected from a single sampling site. This sampling station was located off the Barcelona municipal area (NE, Spain) in a soft-bottom environment at a depth of 20 m (Figure 1). Although at that depth, shallow soft-bottom non-vegetated areas from the Western Mediterranean are commonly inhabited by the medium to fine-sand community represented by Spisula subtruncata (sensu Pérès & Picard 1964), in the case of Barcelona, these habitats have been receiving the pressures and effluents from the city for hundreds of years, which in turn have produced a change in their physical and chemical properties. The sampling station was first widely affected by the city’s non-treated effluents, then, in the last century, by the waste water treatment plant facilities installed during the 1970s, and, more recently, by the new updated and modernized Besòs waste water treatment plant. A monthly sampling procedure was carried out at this station in 1987-88. After twenty years, the station was revisited and sampled CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 34 again to detect any changes and to relate those changes with the improvement in the city’s depuration of its waste waters. During the first period of the study (1987-88), sediments off Barcelona city received effluents from different sources. The Besòs treatment plant had primary sludge treatment (half of this was solid suspended material) of over 4.105 m3 day-1, that was sent through a 4 km pipeline from the shore to a depth of 56 m (Figure 1a), with wastewater discharged via an outlet pipe just 600 m long (Ros & Cardell 1992; Cardell 1996; López-Sánchez et al. 1996). In addition, another important untreated sewage discharge flowed mainly through the mouth of the Besòs River (3.105 m3 day-1) (Figure 1d), and the rest of the sewage inputs of the city were depurated in the Bogatell treatment plant (8.104 m3 day-1) that discharged directly on the shoreline (Figure 1b,c). The sampling site was located to the south of these three inputs and received their inflow directly due to the prevailing NE-SW direction of the coastal currents in this geographical area (Font & Miralles 1978). Figure 1. Map of the study area showing the sampling station. CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 35 During the 1990s, the Besòs treatment plant was remodelled with new compact technologies (expanding the biological treatment process) to meet the standards required by the European Union to which Spain was incorporated in 1986. Today, the plant treats the sewage water for an area with a population of 1.6 million inhabitants, comprising the municipalities from Barcelona (75%), Sant Adrià de Besòs, Santa Coloma de Gramanet, Badalona, Montgat and Tiana. It is a very large plant (one of the biggest in the world), with a rated flow of over 6.105 m3 day-1 for an equivalent population of about 3 million inhabitants. The effluent from the new plant flows into the sea at a depth of 45 m through a subsea pipeline 2,900 m long (2.1 m diameter). Previous outlets and the Bogatell plant have been closed and the water flowing through the mouth of the Besòs River has been highly depurated, so the organic enrichment impacts on the benthic habitats living in the area of the sampling station have been drastically reduced. The variability of climatic and hydrographic conditions of the littoral is typical of temperate zones, and the surface seawater temperature has been shown to range between 11-12 ºC and 25-26 ºC (Amengual et al. 1988; Cebrián et al. 1996). The freshwater regime depends on the Besòs River increasing its flow during autumn and spring. It is combined with intermittent heavy discharges (pulses) after storm periods. Planktonic gross primary production peaks during late winter in this area (Estrada 1980; Satta et al. 1996). All these factors mentioned above were important to the understanding of the dynamics and regulation of the biological benthic secondary production. Sampling and laboratory procedures The station was sampled monthly from September 1987 to September 1988 during the course of the SPIO project, and then, after 20 years, the same station was sampled again in June and November 2008. These months were selected as sampling time points as it had been shown (Sardá et al. 1995; 1999) that abundance average are comparable with the annual abundance average of the entire year when monthly sampling is carried out. Sediment samples were collected using 0.1 m² and 0.06 m² Van Veen grabs, respectively. Three grabs were taken for the analysis of benthic infauna and one for CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 36 sedimentological analyses, although in 2008 only a 0.06 m² Van Veen grab was used. The grabs were able to penetrate 30 cm into the sediments. No biogenic structures were seen on the bottom of the grab samples. Samples were immediately sieved on a 500-m mesh and the fauna retained were fixed in 5% formaldehyde. Polychaete species were later identified to the lowest practical taxonomic level and counted. Individual species biomass was determined as dry weight. During the first sampling (1987-88), selected individuals from representative size categories for the most important species were measured through a binocular microscope equipped with a camera lucida and digitizing tablet. They were then dried (24 h at 70 ºC) and their biomass was obtained as dry weight (g·m-2). Using this data, regressions of width vs. dry weight were computed for each major species found and they were used to convert width to biomass (Sardá et al. 1999). In 2008, biomass was obtained as wet weight. For comparison purposes, all the data given in this article are expressed in dry weight using, where necessary, the dry weight (17.6%) from wet weight conversion factor calculated for polychaetes in Rumohr et al. (1987). Organisms were classified into five trophic groups according to the classical literature (Fauchald & Jumars 1979): filter feeders; mixed (filter and surface-deposit feeders); surface-deposit feeders; subsurface-deposit feeders; and carnivores/omnivores. Within different research projects, the structure and dynamics of a shallow soft-bottom macroinfaunal assemblage of the mediumto fine-sand sediment community of Spisula subtruncata was investigated (Sardá et al. 1999). This station has been incorporated into the MacroBen database (Vanden Berghe et al. 2009) as a reference point due to the five year data series obtained there. In this current study, its observed dynamics and parameters were compared against those registered on the Barcelona coast at the sampling site. During 1987-88, the samples obtained for sedimentological analysis were frozen immediately, stored until analyzed, and then defrosted and dried in the laboratory. Metal content was analyzed by flame atomic absorption using a Perking-Elmer 460 spectrophotometer (Palanques & Diaz, 1994). The polychlorinated biphenyl PCB and CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 37 polycyclic aromatic hydrocarbon PAH contents were obtained by gas chromatography. The samples collected in 2008 were sent to an accredited laboratory for metals analysis, whereas PCBs and PAHs were analyzed using standard techniques. Measurement methods and secondary production estimates In 1987-88, secondary production of the two most important contributors for biomass in the assemblage, Capitella capitata and Malacoceros fuliginosus, was studied by conventional direct production estimates. The maximum thoracic width was used as a size estimate in order to measure growth and to identify generations in the populations of both species of polychaetes. Size measurements were carried out through a stereo microscope using a camera lucida and a digitalizing tablet. For the two species, a thoracic width (TW, mm) versus dry weight (DW, mg) regression was calculated to obtain the biomass of the different specimens: C. capitata: DW = 0.32 TW2.57, R2=0.88 M. fuliginosus: DW= 1.22 TW1.35, R2=0.71 Secondary production was estimated by the Hynes method (Hynes & Coleman 1968; Hamilton et al. 1969; Benke 1979) following the formula given by (Menzie 1980): where Nj and Nj+1 are average numbers of individuals of class j and j+1, wj * wj+1 is the geometric mean of the dry weight of two successive size classes, i is the number of size classes and CPI is the cohort production interval. The CPI (a correction for development times shorter or longer than a year) may be inferred from shifts in size distribution throughout the year or from clearly defined emergence periods when independent growth studies under controlled conditions are lacking (Benke 1993). The population dynamics data for both species were used to analyze their cohort production CPI wwNNiP i jjjjj 12 *))(( 1 5.0 11          CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 38 intervals. For these analyses, all organisms of both species were classified into three age classes (recruiters, juvenile, and adults). For C. capitata, the recruiters were considered as the individuals included in the lowest size-class measured for the population (maximum thoracic width less than 200 µm), and, according to Tsutsumi (1990) and Tsutsumi et al. (1990), adults (reproductive organisms) were considered as all the individuals with a maximum thoracic width greater than 500 µm. For Malacoceros fuliginosus, and following the same patterns, recruiters were considered as all the individuals with a maximum thoracic width of less than 300 µm, and adults as those with a thoracic width greater than 1000 µm, according to Day & Wilson (1934) and Guerin (1975). For the remainder of the macroinfaunal species, an approximate estimate of secondary production was obtained by compiling the average monthly standing stock. Increases in biomass which occurred from one sampling date to the next were added together. Production estimates compiled in this fashion yielded similar values to most of the values calculated from empirical models (Sardá, 1997). During samples taken in 2008, and with the purpose of comparing present data with the historical data obtained in 1987-88, secondary production of polychaetes was obtained following a regression model developed by Brey (1990): Log10P = - 0.018 + 1.022 * log10B – 0.016 * log10W where P is the secondary production [g (dry weight) m-2 a-1]; B is the mean biomass of dry weight (g·m-2); and W the mean dry weight (g). The P/B ratio was calculated because it could reflect the metabolism and life cycle of species in a community population. In this case, the following allometric equation was used: P = (B/A)0.73 *A CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 39 where A is the abundance, B is the biomass, B/A is the mean body size and 0.73 is the average exponent of the regression of annual production on body size for macrobenthic invertebrates (Brey 1990; Warwick et al. 2010). Computation of indices for the analyzed benthic assemblages Macroinfaunal data were used for the computation of different univariate indices: Species richness, Shannon-Wiener index (H’), Margalef index (d), and Simpson index (1-λ’). Together with ABC plots, these indices were computed using the Primer© 6 software package (version 6.1.6) (Warwick 1986). Several indices based on ecological groups (measuring disturbance of the benthic community) were also computed: AMBI, M-AMBI (Borja et al. 2000; 2003; Borja & Muxika 2005; Borja & Mader 2008) and PAMBI, and all data were transformed using the square root, fallowing Warwick et al. (2010). All analyses were performed with the AMBI index software (version 4.1) (Borja & Mader 2008). AMBI accounts for the relative abundance of several ecological groups of species (corresponding to different levels of sensitivity/tolerance) in a sample, and ranges between 0 and 6. Low AMBI values are associated with the dominance of sensitive species and thus high quality environments, whereas high AMBI values are associated with the dominance of tolerant species and thus low quality environments. In this study, the PAMBI was also calculated as it has recently been shown to be more robust, besides being ecologically and functionally much more relevant (Warwick et al. 2010). The root-transformed species production data was employed for both study periods. RESULTS Sedimentology The sediment characteristics of the sampled site during the two periods analyzed are shown in Table 1. The content of silt-clay in the sediments decreased from 95% (1987- CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 40 88) to 25% (2008). As a consequence, the granulometrical typology of the sampling station varied from being representative of a clear muddy environment to characterizing a silty-sand enriched environment. In addition, the organic carbon content of the sediments was reduced by half. The cessation of wastewater discharges at shallow depths in the region was mainly responsible for this sedimentological change by the reduction of the flow of suspended solid materials onto the bottoms. CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 41 Table I. Sediment characteristics and pollutant indicators. Sediment Granulometry (%) 1988 2008 Gravel (>2 mm) 0.60 3.22 Very coarse sand (1 > 2 mm) 0.30 Coarse sand (0.71 > 1 mm) 0.26 Medium sand (0.5 > 0.71 mm) 4.80 0.21 Fine sand (0.125 > 0.5 mm) 17.36 Very fine sand (> 0.063 mm < 0.125 mm) 53.50 Silt-clay (< 0.063 mm) 94.50 24.96 Total Organic Carbon (TOC) (C) 2.90 Pollutant Indicators (mg/kg) Cadmium (Cd) 5-10 <1 Copper (Cu) 46-175 210 Chrome (Cr) n.a. 490 Nickel (Ni) n.a. 30 Lead (Pb) 405-521 280 Zinc (Zn) n.a. 540 Mercury (Hg) 4-9 56 Polychlorinated biphenyls (PCBs) 808 <0.07 Polycyclic aromatic hydrocarbons (PAHs) 318 <0.16 (n.a.; data not available) During 1987-88, the analyzed sediments contained a high organic content and were heavily polluted by hazardous metals, PCBs and PAHs (Table I). However, besides the higher rates of organic matter and inorganic pollutants, hypoxia was never observed in the overlying water during the study period. After spending a considerable amount of money on waste water improvement, effluents were treated to a higher degree and the discharge was reduced drastically. However, the analysis carried out in 2008 showed that the sediments were still far from being completely clean and in a normal condition. Although significant improvements were observed in the content of PCBs and PAHs, the sediments were still highly polluted due to their metal content. Local sources, other than the wastewater discharge, were probably responsible for this metal contamination imprint. CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 42 Community structure and dynamics The faunal composition of the benthic samples that were analyzed in the period 1987-88 showed a poorly structured community with a relatively small number of species (Table II). The species found at the sample site included 38 species of polychaetes as the major group of fauna, followed by 10 species of bivalves, and a few cumacean, amphipod and prosobranch individuals. No other faunal groups were observed. Polychaetes were by far the most important group, constituting 99% of the mean annual density (385,261 ind. m-2), and 71% of the mean annual biomass (12.75 g m-2). The mean annual diversity of this altered benthic community, calculated by the different diversity indices computed, was very low (Table III). There was a seasonal pattern in total macroinfaunal abundance and biomass (Figure 2). Abundance increased gradually from September to a maximum during July (750,000 ind. m-2). Following this early summer peak, there was a sharp decrease through the summer. A one-way ANOVA of the abundance data revealed significant seasonal differences (F statistic= 41.57, p<0.01). The seasonality for biomass values was less pronounced than that of abundance (Figure 2). Two main peaks were detected during the year, with an early initial peak during February, and another one in June. These peaks were clearly attributed to the seasonal dynamics of the main contributor species. Table II. Species composition with mean annual macroinfaunal abundance (ind. m-2) and biomass (g dry wt m-2) for the two periods analyzed. 1988 2008 TG SPECIES Abundance ind. m-2 % Biomass g m-2 % Biomass Rank Abundance ind. m-2 % Biomass g m-2 % Biomass Rank SS Capitella capitata 378,101 98.14 10.0273 78.7 1 1,094 13.42 0.0098 1.0 17 S Malacoceros fuliginosus 2,546 0.66 1.7412 13.7 2 - - - - S Spio decoratus 1,684 0.44 0.2158 1.7 4 - - - - C Exogone (Exogone) verugera 851 0.22 0.0080 0.1 11 0.14 0.0002 0.0 SS Mediomastus fragilis 611 0.16 0.2484 1.9 3 1,411 17.30 0.0455 4.9 4 S Pseudopolydora antennata 463 0.12 0.0524 0.4 8 14 0.17 0.0027 0.3 30 C Ophryotrocha hartmanni 422 0.11 0.0039 0.0 847 10.38 0.0043 0.5 28 SS Heteromastus filiformis 83 0.02 0.0548 0.4 7 - - - - S Aonides oxycephala 77 0.02 0.0415 0.3 10 3 0.03 0.0010 0.1 S Dipolydora coeca 68 0.02 0.0081 0.1 203 2.49 0.0134 1.4 12 S Prionospio malmgreni 65 0.02 0.0067 0.1 - - - - C Neanthes caudata 56 0.02 0.0288 0.2 11 - - - - S Poecilochaetus serpens 30 0.01 0.0026 0.0 128 1.57 0.0084 0.9 18 SS Lagis koreni 21 0.01 0.0090 0.1 8 0.10 0.0046 0.5 27 SS Notomastus latericeus 18 0.01 0.0226 0.2 12 611 7.49 0.2769 29.7 1 C Nereididae 15 0.00 0.0037 0.0 - - - - C Podarkeopsis capensis 15 0.00 0.0004 0.0 - - - - CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 49 Table III. Mean annual main community parameters and biotic indices calculated. 1988 Status 2008 Status Abundance (ind. m-2) 385,261 8,158 Biomass (g dry weight m-2) 12.75 0.93 Polychaete species 38 60 Shannon [H’ log2] (bits·ind.-1) 0.19 ± 0.06 3.91 ± 0.13 Margalef index [d] 0.85 ± 0.14 4.00 ± 0.36 Simpson index [1-λ’] 0.04 ± 0.01 0.90 ± 0.01 AMBI (abundance) 5.34 ± 0.14 Heavily disturbed 2.67 ± 0.30 Slightly disturbed PAMBI (productivity) 4.82 ± 0.80 Bad 2.43 ± 0.21 Good M-AMBI (abundance) 0.81 ± 0.07 High 0.95 ± 0.06 High Secondary production Using the Hynes methodology, in 1987-88, the estimated production for Capitella capitata was calculated as 77.8 g dry wt m-2 for the average annual cohort, and with a mean annual biomass of 10.03 g dry wt m-2 this gave the production to mean biomass ratio (P/B) a value of 7.75. The analysis of the evolution of the C. capitata size classes allowed three main generations to be recognized throughout the year (Figure 5). The main recruitment peaks, observed in Figure 4 as the increased percentage presence of recruiters in the populations, were observed in January, March, and July. Following these three peaks of recruitment, the biomass of C. capitata increased to a maximum of approximately 20 g dry wt m-2. Using these shifts in size distribution during the year, the CPI for the C. capitata population (4 months) was estimated as 121.6 days. Consequently, the annual secondary production for the C. capitata population in this community would be 233.5 g dry wt m-2 year-1. CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 50 Figure 5. Main recruitment peaks and biomass values for the two main populations during September 1987 and September 1988. For Malacoceros fuliginosus, the production was estimated as 6.7 g dry wt m-2, with a mean annual biomass of 1.74 g dry wt m-2, which resulted in a production to mean biomass ratio (P/B) of 3.85. The analysis of the variation in the size-structure of the population during the year showed two generations with recruitment peaks in December and March. Following these two peaks of recruitment, the biomass increased to approximately 2 and 4 g dry wt m-2, respectively. Using these shifts in size distribution, CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 51 a CPI of 182.5 days (6 months) was estimated for M. fuliginosus. This calculation yielded an annual secondary production value for the species of 13.4 g dry wt m-2 year-1. In the case of Loripes lacteus, the population cohorts were able to be identified. Following the production of the cohorts through the year, a secondary production value was obtained for L. lacteus of 21.5 g dry wt m-2 y-1, with a mean annual biomass value of 4.11 g dry wt m-2. The P/B ratio obtained in this case would be 5.23. By adding together the increases in biomass that occurred from one sample date to the next, the secondary production of the rest of the macroinfaunal component of the community was estimated as 7.95 g dry wt m-2 year-1. The total secondary production from September 1987 to September 1988 in the entire community was then calculated as 276.3 g dry wt m-2 y-1 (85% from the Capitella capitata complex). The productivity obtained for the period 1987-88 yielded an annual secondary production of 207.7 g dry wt m-2 y-1, which was a little lower than the one obtained by conventional methodologies, whereas, in 2008, this regression model yielded an annual secondary production of only 8.0 g dry wt m-2 year-1. DISCUSSION Wastewater from the Barcelona metropolitan area was discharged for decades through near-shore outfalls off Barcelona itself. Together with the direct effluents discharged by the Besòs River, they were responsible for a profound alteration of the physical and biological composition of the shallow soft-bottom environments. In 1987-88, sediment properties of the benthic assemblage were heavily influenced by the sewage discharges, and high values of organic carbon content and other inorganic pollutants were registered (Amengual et al. 1988). These values were essential for the interpretation of the faunal data. In contrast to the earlier conditions, 20 years after cessation of wastewater discharge at shallow depths, muddy sediments were partially washed by the currents, and the recent sediments showed no PCB and PAH pollutants, although metal contamination was still important. The presence of high values of lead, zinc, copper, and nickel suggested that CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 52 metals were also delivered from other sources rather than only wastewater, such as atmospheric deposition and/or water runoff from the city, as certain metals have become broadly used in several industries and activities, and their concentrations increased accordingly in waters receiving inputs from the land. Therefore, currently, shallow softbottom sediments off Barcelona contain less organic carbon but they are still polluted by dangerous concentrations of hazardous metals. The effects of organic enrichment on benthic dynamics have been widely accepted since the model of Pearson & Rosenberg (1978). At early stages of enrichment, benthic communities tend to increase abundance, biomass and, even, the number of species. However, if enrichment continues, although abundance still increases, biomass and species richness decline (transitional phase) until, finally, at the peak of enrichment, opportunistic species dominate the community, at which point the abundance is very high, biomass increases again and species richness remains very low (polluted phase). In the most extreme cases, with lack of oxygen and the presence of hydrogen sulphide, macrofauna is lost completely. The observations made at the Barcelona station sampled showed a clear move (recovery) from a highly polluted phase to a transitional phase. Nevertheless, twenty years after the removal of the high inputs of wastewater discharges into these shallow soft-bottom environments there were still signs of disturbance, such as the high abundance of some opportunistic species and low biomass values. The effects of the organic enrichment did not alter the foreseen seasonal cycle of density expected for this area. In terms of abundance, as already described for Northwestern Mediterranean soft-bottom shallow habitats (Sardá et al. 1995; 1999), macroinfaunal density increased to a peak in May-June as new recruiters settled into the sediments. Then, a sharp decrease occurred during summer and lower density values were observed through the autumn and winter. In this area, it is generally accepted that autotrophic (mainly phytoplankton) production is the largest organic carbon source for the benthos under normal conditions (Satta et al. 1996). In non-enriched conditions, these shallow sublittoral habitats tend to be structurally complex in species composition, showing sporadic appearances of many species and large recruitments of others that are concentrated in shorter periods of the year. As has been observed in the reference CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 53 station, spring peaks of density normally ranged from 15,000 to 50,000 ind. m-2 (Sardá et al. 1995). The ecological change due to the sewage outfall led to the sediment being colonized by a very low diversity assemblage mainly comprised of three species, where density values were more than one order of magnitude higher than those calculated for non-enriched shallow communities. However, the seasonal cycle of this modified community was similar to the one observed in a non-impacted community, with the exception that, in this case, the largest organic carbon source originated from man-made activities. The biomass of the infaunal community affected by the sewage outfall responded differently to that observed for the abundance. In non-enriched communities of the Western Mediterranean, the seasonal pattern of biomass followed roughly that of abundance and only one very predictable biomass peak was observed (Sardá et al. 1995; 1999). The annual pattern of biomass in this enriched community showed two main peaks of biomass throughout the year, with the Capitella capitata complex being almost entirely responsible for such a seasonal pattern. Mean biomass values of the macrobenthic community decreased by an order of magnitude during these twenty years. In the Northwestern Mediterranean region, shallow, non-vegetated, soft-bottom habitats are, in general, poor in biomass and productivity. Except in the vicinity of large rivers where values up to 18.4 g dry wt m-2 have been recorded (the Gulf of Fos, France; Massé, 1972), in enclosed areas or coastal lagoons (157.2 g dry wt m-2 for the Camargue area, Massé, 1972; 66.0 g dry wt m-2 in the Alfacs Bay, Ebro Delta, Martin et al. 2000) or large cities, as in our case study, where biomass and productivity tend to increase, the rest of the values are, in general, small. Laboratory experiments have shown that, even if food and other environmental conditions are maintained constant, the populations of Capitella capitata can have large temporal oscillations (Chesney & Tenore, 1985; Grémare et al. 1988). It has been proposed that these oscillations would be due to the achievement of the population carrying capacity by over-exploitation of food and spatial resources. Several authors (Chesney & Tenore, 1985; Grémare et al., 1988, 1989) suggested a density-dependent effect for the decrease in the reproductive output of the species due to the lower CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 54 availability of food resources by unit of biomass. In our sampling site, it seems that the population of C. capitata grew until it reached a biomass of approximately 20 g dry wt m-2, when it suddenly crashed. After the crash, the population recovered rapidly, except during the summer time. In summer, even if recruitment of new individuals was still very high, the survival was clearly reduced and the population declined abruptly. There are at least three possible explanations for this: (1) the decline was due to the development of reducing conditions in the sediments (Tsutsumi, 1990), (2) the absence of sufficient food in quantity and quality to maintain an increased metabolic rate in the species (Charles & Amouroux 1995; Grémare et al. 1997, 1998, and (3) other physical disturbances over the sediment. However, no anoxic conditions were observed in the analyzed sediment during the sampled season (Amengual et al. 1988), therefore, the depletion of infauna by the development of reducing conditions in the sediments cannot be an explanation. On the other hand, although the quality of the organic input could be lower in the summer its quantity could not be, as shown by the specific conditions of the studied site. Therefore, the crash in the summer could probably be due to a combination of physical conditions, carrying capacity and food, since mixing processes in the water column are greatly reduced when the temperature is high. Secondary production of the benthic community inhabiting the studied station was drastically reduced by the cessation of wastewater discharges. In 1987-88, direct measurements used to calculate this production yielded accurate results (276.3 g dry wt m-2 y-1), and these values were in agreement with those calculated by Méndez et al. (1997) at a similar station (1991-92). In 2008, the data obtained did not allow us to use such conventional methodologies, although the use of multiple regressions based on pooled biological data has been shown to be useful (Sardá, 1997). Using the methodology developed by Brey (1990), we were able to obtain a production number in 1987-88 (207.7 g dry wt m-2 y-1) not far from that obtained by conventional methodologies, and, moreover, we could compare this data with the one obtained for 2008 (8.0 g dry wt m-2 y-1), demonstrating the drastic reduction in secondary production of this community. CHAPTER 1 A POLYCHAETE-DOMINATED COMMUNITY IN THE NW MEDITERRANEAN SEA, 20 YEARS AFTER CESSATION OF SEWAGE DISCHARGES 55 During these twenty years, a drastic reduction in wastewater discharges into the shallow soft-bottom environments off Barcelona was reported. However, although pulses of organic matter were highly reduced, sediments were still polluted by metals as a consequence of the multiplicity of human activities that leads to metal loading in the marine environment. The recovery process of the benthic community inhabiting these soft-bottom environments is still under debate. Although the organic input decreased, the metal concentration present in the sediments may inhibit its full recovery to normal conditions. Mirroring the decrease in the organic input, secondary production of the macrofaunal community was also sharply reduced. It is a fact that waste water treatment plants today can greatly reduce the organic outputs of these installations. Nevertheless, we should understand that the marine environment can assimilate a certain quantity of domestic wastes without large adverse changes and, as a result, if metal contamination can also be avoided, some increase in coastal productivity by a bioenhancement factor due to lower level waste water discharges could even be positive. Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 58 CHAPTER 2 LONG-TERM COMPARISON OF POLYCHETE ASSEMBLAGES WITHIN SOFTBOTTOMS OFF THE ALT EMPORDÀ (NORTH WESTERN MEDITERRANEAN COAST) ABSTRACT Soft-bottom polychaete species present in 42 stations of the “Cap de Creus” region (Northern Mediterranean Spanish coast) who were previously sampled by French scientists in 1970-72 were revisited using similar methodologies during two oceanographic campaigns, both in 2002 (Bay of Roses) and 2009 (northeastern part of the “Cap de Creus”). Five different polychaete assemblages were identified; (a) a littoral surf beach assemblage, (b) a littoral fine sand assemblage, (c) a littoral sandy mud assemblages, (d) a coastal terrigenous mud assemblage, and (e) a detritic sand assemblage. These assemblages were associated to the different platform communities described by Labrune et al. (2007). In the Bay of Roses, results showed a decrease in the number of species and individuals at the two shallowest assemblages and registered similar numbers for the deepest one. Species such as Owenia fusiformis and Nephthys hombergii were clearly less abundant while other species such as Ditrupa arietina in fine sand sediments and Lumbrineris latreilli in sandy mud sediments clearly have increase their numbers. In the northeastern part of the “Cap de Creus”, the number of species and individuals were similar to those described, by Desbruyères et al. (1972-73); however, assemblage’s composition showed notable differences. INTRODUCTION The structure and organization of soft-bottom macroinvertebrate communities in the Catalan Sea (North western Mediterranean) was deeply investigated decades ago by French researches of the Banyuls-sur-mer Oceanographic Laboratory through several oceanographic campaigns carried out in the late sixtees and early seventees of the last century (Got et al., 1968; Guille, 1970, 1971; Aloïsi & Got, 1972-73; (Desbruyères et Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 65 Gulf of Roses and the classification proposed by Desbruyères et al. (1972-73) was first assessed using two non-parametric MDS based analysis on polychaetes compositions recorded during the present study, and the Desbruyères et al. (1972-73) for the three internal communities of the Bay. These analyses were carried out at the lowest taxonomic level, on square-root transformed abundance data and using the Bray Curtis similarity index. We eliminated rare species (presence in less than 10% of the samples) from our analysis. All these analyses were carried out using the Primer© 6 software package (version 6.1.13) (Warwick 1986). Diversity measures Ecological indicators based on diversity were measured through the use of different univariate indices: Species richness, Shannon-Wiener index (H’), Margalef index (d), and Simpson index (1-λ’) were computed using the Primer© 6 software package (version 6.1.6) (Warwick 1986). RESULTS Gulf of Roses study A total of 3415 individuals belonging to 137 species of Polychaetes and three species of Sipunculida were identified during the present study in the 68 samples analyzed. This number is a little bit smaller if it is compared with the 173 species obtained in the oceanographic campaign of 1970-72. A list of the species obtained in our study is presented in Table 1. Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 66 Table 1. Species list found in the Gulf of Roses study with it abundance and biomass. A B C Density Biomass Density Biomass Density Biomass (ind m-2) (mg m-2) (ind m-2) (mg m-2) (ind m-2) (mg m-2) Scoletoma impatiens 100 80.5 25 14.0 6 95.0 Ditrupa arietina 64 433.5 0 0.0 2 27.9 Chone duneri 54 219.7 0 0.0 25 8.4 Prionospio caspersi 40 4.5 0 0.0 13 2.1 Nephtys hombergii 35 0.0 8 4.8 23 80.5 Myriochele oculata 33 19.3 0 0.0 38 12.4 Paradoneis armata 15 14.4 0 0.0 4 0.8 Exogone verugera 11 2.3 0 0.0 5 0.4 Glycera rouxi 11 69.4 0 0.0 18 736.6 Scoloplos armiger 8 31.0 4 3.9 9 91.4 POLYCHAETA unident. 8 77.6 4 38.7 15 90.9 Glycera capitata 8 52.1 0 0.0 0 0.0 Mediomastus fragilis 7 1.9 0 0.0 27 7.5 Sigalion squamosum 7 17.9 13 18.4 2 0.7 Glycera convoluta 6 11.1 0 0.0 1 14.3 Owenia fusiformis 6 64.9 4 61.7 6 39.7 Goniada maculata 4 2.2 0 0.0 13 26.2 Nereis zonata 3 1.9 0 0.0 0 0.0 Aricidea capensis bansei 3 0.4 0 0.0 0 0.0 Dipolydora flava 3 2.5 0 0.0 2 1.2 Drilonereis filum 3 3.9 0 0.0 4 18.8 Eunice vittata 3 26.0 0 0.0 5 9.7 Lumbrineris latreilli 3 54.0 0 0.0 180 269.4 Magelona mirabilis 3 8.0 0 0.0 2 0.1 Pseudoleiocapitella fauveli 3 0.9 0 0.0 0 0.0 Polydora caeca 3 2.2 0 0.0 3 1.1 Schistomeringos rudolphii 3 0.6 13 1.9 0 0.0 Arabella iricolor 1 24.0 0 0.0 0 0.0 Lumbricomastus sp. 1 10.0 0 0.0 0 0.0 Caulleriella alata 1 0.0 0 0.0 0 0.0 Chaetozone setosa 1 2.7 0 0.0 8 26.0 Chone infundibuliformis 1 50.2 0 0.0 0 0.4 Clymenura clypeata 1 4.1 0 0.0 13 28.5 Eteone longa 1 0.7 0 0.0 1 250.1 Exogone naidina 1 0.2 0 0.0 16 0.6 Marphysa bellii 1 0.9 0 0.0 2 1.3 Melinna palmata 1 0.6 0 0.0 9 21.0 Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 67 Notomastus latericeus 1 6.6 0 0.0 38 190.0 Phyllodoce laminosa 1 9.3 0 0.0 1 7.2 Piromis eruca 1 21.4 0 0.0 6 3.9 Spio filicornis 1 0.0 0 0.0 3 3.1 Syllis cornuta 1 0.1 0 0.0 2 1.1 Phascolion strombi 1 0.8 0 0.0 2 1.6 SIPUNCULIDA unident. 1 13.7 0 0.0 4 39.5 Amaeana trilobata 0 0.0 0 0.0 1 3.7 Amage adspersa 0 0.0 0 0.0 1 0.2 Ampharete acutifrons 0 0.0 0 0.0 2 3.1 Amphicteis gunneri 0 0.0 0 0.0 1 0.2 Amphitrite sp. 0 0.0 0 0.0 1 6.0 Aonides oxycephala 0 0.0 0 0.0 2 4.8 Apelochaeta marioni 0 0.0 0 0.0 44 61.3 Aponuphis fauveli 0 0.0 0 0.0 1 1.3 Aponuphis bilineata 0 0.0 4 8.3 17 84.5 Aricidea assimilis 0 0.0 0 0.0 6 4.2 Aricidea sp. 0 0.0 0 0.0 3 1.2 Aricidea suecica 0 0.0 0 0.0 21 7.1 Armandia cirrhosa 0 0.0 0 0.0 4 28.5 Autolytus sp. 0 0.0 0 0.0 0 0.2 Chone sp. 0 0.0 0 0.0 2 0.6 Cirriformia tentaculata 0 0.0 0 0.0 4 11.1 Cirrophorus furcatus 0 0.0 0 0.0 4 141.6 Cirrophorus branchiatus 0 0.0 0 0.0 0 0.0 Cossura soyeri 0 0.0 0 0.0 16 2.9 Dorvillea rubrovittata 0 0.0 0 0.0 1 16.8 Euchone rosea 0 0.0 0 0.0 9 1.1 Euclymene oerstedii 0 0.0 0 0.0 19 32.7 Euclymene robusta 0 0.0 0 0.0 0 0.3 Euclymene sp. 0 0.0 0 0.0 2 6.1 Eulalia parva 0 0.0 0 0.0 0 0.0 Exogone hebes 0 0.0 0 0.0 0 0.1 Fabriciola sp. 0 0.0 0 0.0 2 0.1 Fauvelopsis adriatica 0 0.0 0 0.0 3 2.7 Glycera sp. 0 0.0 4 6.0 2 0.1 Gyptis rosea 0 0.0 0 0.0 1 0.1 Harmothoe sp. 0 0.0 0 0.0 0 0.7 Heteromastus filiformis 0 0.0 0 0.0 1 11.3 Hyalinoecia tubicola 0 0.0 0 0.0 0 0.5 Laetmonice hystrix 0 0.0 0 0.0 0 0.5 Lanice conchilega 0 0.0 0 0.0 0 0.0 Laonice cirrata 0 0.0 0 0.0 2 3.1 Leanira hystricis 0 0.0 0 0.0 1 97.8 Levinsenia gracilis 0 0.0 0 0.0 41 4.0 Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 68 Lumbrineris sp. 0 0.0 0 0.0 1 0.9 Magelona sp. 0 0.0 0 0.0 1 1.7 Magelona alleni 0 0.0 0 0.0 1 20.1 Magelona filiformis 0 0.0 4 1.7 0 0.0 Magelona minuta 0 0.0 0 0.0 36 5.9 Malacoceros fuliginosus 0 0.0 0 0.0 1 2.9 Micronephtys maryae 0 0.0 0 0.0 3 7.2 Monticellina heterochaeta 0 0.0 0 0.0 25 24.1 Nephtys cirrosa 0 0.0 0 0.0 1 304.7 Nephtys hystricis 0 0.0 13 40.0 12 31.4 Nephtys paradoxa 0 0.0 0 0.0 3 57.4 Nereiphylla sp. 0 0.0 0 0.0 0 0.0 Nerinides cantabra 0 0.0 4 34.7 0 0.2 Nerinides sp. 0 0.0 0 0.0 0 0.6 Notocirrus scoticus 0 0.0 0 0.0 0 53.1 Ophiodromus flexuosus 0 0.0 0 0.0 4 7.1 Orbinia cuvieri 0 0.0 0 0.0 1 3.8 Oriopsis armandi 0 0.0 0 0.0 1 1.5 Paradoneis lyra 0 0.0 0 0.0 4 0.4 Paradoneis sp. 0 0.0 0 0.0 0 2.7 Paralacydonia paradoxa 0 0.0 0 0.0 21 33.1 Parapionosyllis labronica 0 0.0 0 0.0 0 0.1 Paraprionospio pinnata 0 0.0 0 0.0 1 51.9 Pectinaria koreni 0 0.0 0 0.0 1 14.0 Pholoe minuta 0 0.0 0 0.0 0 0.0 Phyllodoce mucosa 0 0.0 0 0.0 1 4.2 Pilargis verrucosa 0 0.0 0 0.0 2 8.0 Pista cristata 0 0.0 0 0.0 2 9.0 Pista maculata 0 0.0 0 0.0 0 0.9 Poecilochaetus serpens 0 0.0 0 0.0 1 5.3 Polycirrus sp. 0 0.0 0 0.0 0 2.6 Praxillella gracilis 0 0.0 0 0.0 5 26.4 Praxillella praetermissa 0 0.0 0 0.0 1 7.6 Praxillella sp. 0 0.0 0 0.0 0 0.2 Prionospio cirrifera 0 0.0 0 0.0 6 1.3 Prionospio malmgreni 0 0.0 0 0.0 41 12.0 Prionospio sp. 0 0.0 0 0.0 2 1.0 Prionospio streenstrupi 0 0.0 0 0.0 1 7.0 Protodorvillea kefersteini 0 0.0 0 0.0 0 0.0 Pseudomalacoceros tridentata 0 0.0 0 0.0 0 0.0 Pseudopolydora antennata 0 0.0 0 0.0 1 8.1 Scolelepis ciliata 0 0.0 0 0.0 0 24.6 Scoletoma emandibulata mabiti 0 0.0 0 0.0 5 13.5 Serpula concharum 0 0.0 0 0.0 2 0.0 Sigambra tentaculata 0 0.0 0 0.0 0 0.0 Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 69 Sphaerodorum gracilis 0 0.0 0 0.0 0 0.1 Sphaerosyllis ovigera 0 0.0 0 0.0 1 0.1 Sphaerosyllis sp. 0 0.0 0 0.0 2 0.3 Sphaerosyllis taylori 0 0.0 0 0.0 0 0.1 Spiochaetopterus costarum 0 0.0 0 0.0 3 2.3 Spiophanes bombyx 0 0.0 0 0.0 1 4.8 Spiophanes kroyeri 0 0.0 0 0.0 5 0.9 Sternaspis scutata 0 0.0 0 0.0 10 806.9 Sthenelais limicola 0 0.0 0 0.0 1 0.0 Syllis gerlachi 0 0.0 0 0.0 0 0.1 Syllis parapari 0 0.0 0 0.0 4 0.8 Terebellides stroemi 0 0.0 0 0.0 1 7.0 Trichobranchus glacialis 0 0.0 0 0.0 1 4.8 Aspidosiphon muelleri 0 0.0 0 0.0 109 784.1 Total 470 1535.8 100 234.0 1050 5018.6 Using the work carried out in 2002, our multivariate classification technique (MDS ordination of the used matrix derived from transformed data of abundances) divided the stations into three groups of similar species composition (see Figure 2 for its cluster representation). These three assemblages included: (A) a littoral surf beach assemblage, (B) a littoral fine sand assemblage, and (C) and a littoral sandy mud assemblage; matching the different sediment types found in the Gulf of Roses. When this cluster is compared with the one obtained in 1972-73, the stations from the two periods, besides some overlapping, tend to differentiate. The correspondence with the sample aggregation in 1970-72 is shown below: (1) The littoral surf-beach assemblage (A) and the Littoral find sand assemblage (B) are in correspondence with the “commonauté des sables fins à Spisula subtruncata”. In 1972-73 both communities were not possible to differentiate. (2) The littoral sandy mud assemblage (C) correspond to the “variation des vases sableuses litorales de la sous-communauté des vases à Nucula sulcata”. The previos “faciès de transition de sables vaseus à Nephthys homergii” seen in the work of 1972-73 was not possible to differentiate from the other samples of the littoral sandy mud assemblage. Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 70 Five of the samples carried out in 2002 were not included in any of these groups (# 18, 23, 3, 6, and 22) being different by themselves or almost defaunated in the case of the shallower ones. A comparison of the results from the 34 stations for the two sampling periods (1972-73 and 2002) showed some trends towards an increase in the number of individuals but decreasing the number of species, especially in the shallowest communities. We could not see this data from biomass because there was not biomass data reported for 1972-73. Table 2 enclosed general data about these three assemblages. Table 2. Main (± standard deviation) benthic parameters from the three assemblages identified in the study. Surf Beach Fine Sand Sandy mud assemblage assemblage assemblage Species number 7,5±0,7 15,8±4,8 Abundance (ind m-2) 100,1±11,8 469,8±250,7 1149,3±936,9 Biomass (mg m-2) 233,5±49,5 782,6±480,6 5025,1±4003,1 Grain size (um) 231,8±32,2 149,3±15,3 32,1±46,5 CaCO3 (%) 16,3±4,2 18,5±2,3 24,5±7,1 Organic matter (% weight) 1,1±0,2 1,1±0,3 2,4±0,9 Sedimentology conditions found in the Gulf of Roses were not too different from those observed in 1972-73. It was characterized by sandy soft-bottom sediments until the depth of around 20 m that they are replace by sandy muds between 20 and 50-60 and later on by muddy habitats. The Littoral surf beach assemblage This assemblage is observed from the surf zone of beaches in which sediments can be moved in and out and organisms are subjected to a high physical energy environment; in our case samples obtained above 10 m depth. In 1972-73, sampled stations obtained Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 71 in this environments could not been separated from the rest of the fine sand community. In 2003, the assemblage only group stations 9 and 11. During the present study we only found 10 species. Total abundances and number of species showed a marked decrease between 1972-73 and 2002 (from 645 to 100 ind. m-2, and from 51 to just 10 species). Table 3 showing a comparison between the two periods. Table 3. Littoral beach-surf assemblage. Individuals per meter square of the most abundant species (between parentheses the species rank). Species (Desbruyères et al. 1972-73) present study data 2002 Owenia fusiformis 93(1) 4(6) Nephtys hombergii 58(2) 8(5) Prionospio cirrifera 53(3) --- Magelona mirabilis 50(4) --- Cirrophorus branchiatus 43(5) --- Scoletoma impatiens 33(6) 25(1) Lumbrineris gracilis 33(7) --- Mediomastus capensis 25(8) --- Nephtys hystricis --- 13(2) Sigalion squamosum --- 13(3) Schistomeringos rudolphi 3 13(4) Magelona filiformis --- 4(7) Scoloplos armiger 15 4(8) Species number 51 10 Number of individuals 645 100 When compared with previous data, observed changes in density were due to the absence of several species that were common in 1972-73 and the drastic decrease in the abundance of Owenia fusiformis. From the species present in the community in 197273, only Scoletoma impatiens seems to be on the same numbers that were obtained in the seventees. Total biomass value for polychaetes was computed as 234 mg dry weight m-2 from which the most important contributors were Owenia fusiformis, Nephthys hystricis, and Nerinides cantabra (see Table 3). The Littoral fine sand assemblage The evaluation of changes for the typical assemblage of the Littoral fine sand community (LFS) in the Gulf of Roses reported and decrease in the number of individuals but maintaining its number of species (from 1316 to 470 ind m-2, and from 43 to 42 species). Most of the changes that we can see in the comparison between 1972- Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 72 73 and 2002 (Table 4) can be related to the decrease in the number of individuals of Owenia fusiformis (however we cannot be sure that this could be due to a seasonal effect, may be recruitment patterns in 1972-73) and the appearance of Ditrupa arietina, which was absent from the community in 1972-73 and reached a density of 64 ind m-2 in 2002. Scoletoma impatiens, as in the previous analyzed assemblage, was the dominant species with similar numbers to which were found in 1972-73. Table 4. Littoral fine sand assemblage. Individuals per meter square of the most abundant species (between parentheses the species rank). Species (Desbruyères et al. 1972-73) Present study data 2002 Owenia fusiformis 648(1) 6 Magelona mirabilis 98(2) 3 Lumbrineris gracilis 90(3) --- Scoletoma impatiens 90(4) 100(1) Clymenura clypeata 60(5) 1 Chaetozone setosa 54(6) 1 Levinsenia gracilis 26(7) Glycera rouxi 22(8) 11(8) Prionospio cirrifera 23 --- Ditrupa arietina --- 64(2) Chone duneri --- 54(3) Prionospio caspersi 17 40(4) Nephtys hombergii 12 35(5) Myriochele oculata 10 33(6) Paradoneis armata 1 15(7) Species number 43 42 Number of individuals 1316 470 The polychete biomass for the entire assemblage averaged 1335,8 mg dry weight m-2. Ditrupa arietina (433,5 mg dry weight m-2) and Chone duneri (219,7 mg dry weight m2) were its main contributors. The case of Ditrupa arietina was really notable because it was absent in 1972-73 and in 2002 it can be considered a clear characteristic species of this community, basically there is not individuals in the other two assemblages that were studied in our campaign. Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 73 The Littoral sandy mud assemblage Most of the samples obtained in the study of the Gulf of Roses got together in a particular cluster. This cluster grouped all samples under the Littoral sandy mud (LSM) assemblage in the Gulf. It was the most numerous in number of species, in abundance as well as in biomass. Curiously enough, total abundances and number of species showed very similar numbers from 1972-73 to 2002 (1054 and 1050 ind m-2, and 112 and 120 respectively). Table 5 is showing a comparison between the two periods. Table 5 Littoral sandy mud assemblage. Individuals per meter square of the most abundant species (between parentheses the species rank). Species (Desbruyères et al. 1972-73) Present study data 2002 Monticellina heterochaeta 183(1) 25 Prionospio cirrifera 109(2) 6 Levinsenia gracilis 70(3) 41(3) Lumbrineris latreilli 63(4) 180(1) Nematonereis unicornis 59(5) --- Prionospio malmgreni 55(6) 41(4) Terebellides stroemi 49(7) 1 Paralacydonia paradoxa 35(8) 21 Chaetozone setosa 31 8 Apelochaeta marioni 044(2) Myriochele oculata 9 38(6) Notomastus latericius 27 38(7) Magelona minuta 14 36(8) Nephtys hystricis 28(8) 23(8) Prionospio caspersi --- 40(5) Sternaspis scutata 8 35(6) Species number 112 120 Number of individuals 1054 1050 The pool of species found in the study of 2012 is similar to the one sampled in 1972-73. However polychaete dominance is in different species been Lumbrineris latreilli the one that contributed most on abundance. Together with other species such as Apelochaeta marioni, Aricidea suecica, Notomastus latericius, Cossura soyeri, Euclymene oerstedii, Levinsenia gracilis, Magelona minuta, Paralacydonia paradoxa, Prionospio malgreni, Sternaspis scutata and Monticellina heterochaeta constituted the most characteristic species in the assemblage. Special attention deserves the presence of the sipunculid Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 74 Aspidosiphon muelleri (109 ind. m-2) which also make habitat for other species as Syllis parapari. Sandy mud areas were rich in species and contained comparatively with the other studied assemblages high infaunal biomass (5018,6 mg dry weight m-2). Six species contributed on average more than 200 mg dry weight m-2, Sternaspis scutata (806,9 dry weight m-2), the sipunculid Aspidosiphon muelleri (784,1 dry weight m-2), Glycera rouxii (736,6 dry weight m-2), Nephthys cirrosa (304,7 dry weight m-2), Lumbrineris latreilli (269,4 dry weight m-2), and Eteone longa (250,0 dry weight m-2). The different stations that in 1972-73 were included in the so called transition facies with Nephthys hombergii converged in 2002 under this sandy mud assemblage. Nephthys hombergii who gave name to this facies move from 80 ind m-2 in 1972-73 to just 8 ind m-2 in 2002 while Magelona mirabilis, the dominant species in the old work (110 ind m-2) was not collected in these samples in 2002. The most important species in the samples of 2002 that revist the old stations were the polychaetes Ditrupa arietina (108 ind m-2), not present in 1972-73 and Scoletoma emandibulata mabiti (18 ind m-2) and two species of Sipunculids, Aspidosiphon muelleri (167 ind m-2) and Phascolion strombi (59 ind m-2). The ecological indicators based on diversity in the assemblages was summary Table 6, it show that diversity in the Gulf of Roses in general was high, even though the evenness in the Littoral beach-surf assemblage indicated that species do not were equal abundant. Chapter 2 Long-term comparison of Polychete assemblages within soft-bottoms off the Alt Empordà (North western Mediterranean coast) 81 The results of the present study show the occurrence of several changes in the composition and structure of soft-bottom polychaete assemblages in the “Cap de Creus”. Main changes are related to the decrease of Owenia fusifromis and the increase of Ditrupa arietina in the area, as well as the reduction in numbers of several species that were used to even describe communities in the seventees, species such as Nephthys hombergii, Scoloplos armiger and Notomastus latericius. Both aspects are clearly observed when we compared this data with the one given in Desbruyères et al. (197273). There is not a clear explanation today about the cause of this change, but due to the regional (mesoscale) importance of these changes, the decrease in fine particles coming to the sea and resuspension mechanisms could be behind this change. Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 84 CHAPTER 3 SPATIAL DISTRIBUTION AND DIVERSITY OF POLYCHAETE FAUNAL IN THE NORTHERN MEDITERRANEAN SPANISH COAST ABSTRACT The spatial distribution, diversity of polychaetes and the relationship between polychaetes assemblages and its main environmental parameters were studied along the North-western Mediterranean portion of coast between the French border and the Valencia City REDIT-II campaign. 59 sampling sites were considered in twenty-two inshore-offshore transects located at depth gradient (10, 20 and 30m) in Littoral Fine Sand. I found maximal and minimal densities and diversities related to other areas of the Mediterranean Sea. The faunal assemblages found in it study were similar to establish in the vicinity of Gulf of Lions and other areas of the Mediterranean Sea, although our results do not reveals linked to granulometric parameters. INTRODUCTION Biological diversity involves a range of different levels of organisation from the genetic variation between individuals and populations, to species diversity, assemblages, habitats, landscapes and biogeographical provinces (Gray 2000). In Mediterranean Sea, the marine diversity range from 4-25% of the world marine species. Within the metazoans, polychaeta is the second highest group in proportion of species records after Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 85 the sponges. Thus, Mediterranean Sea is considered a marine biodiversity hot spot (Coll et al. 2010). However marine biodiversity have obtained a little attention accorded to its terrestrial counterpart. Even though, historically Mediterranean Sea has been thoroughly studied (Bianchi and Morri 2000). On the other side, the global economy, as mainly effect of human activity, is directly (e.g. food, materials) and indirectly (ecosystem services) dependent on biodiversity (Costello et al. 2006), and now the major cause of changes to marine biological diversity, especially in coastal areas (Ellingsen 2001). Currently, following the new European policy, the Marine Strategy Framework (MSFD) (DIRECTIVE_2008/56/EC), the biological diversity at different temporal and spatial scales is a prerequisite as criteria and methodological standards to be evaluated on good environmental status (GEnS) of marine waters. Studies on polychaetes distribution have done in some areas the Spanish Mediterranean coast by several author like Desbruyères et al. (1972-73) in the Catalonian coast. Polychaete distribution and diversity in the Gulf of Lions (Guille 1971; Labrune et al. 2006, 2007). Also information over polychaetes distribution on impacted sites by anthropogenic activities have done also by Ros et al. (1992); Cardell-Corral (1996); Méndez (1996); Cardell et al. (1999) (Serrano et al. 2011) in zone closed to Barcelona. Given that Spain is among the European Countries with the longest coastal zone (Sardá 2001), which includes 4.872 km long, without mention island and northern territories in Africa. Out of these, Mediterranean coast is around the half, 2.058 km long (INE 2008), of Spain whole coast. However the knowing of polychaetes distribution still has several gaps, alongside this coast, being necessary clarify these breaks. Like Coll et al. (2010) showed, polychaetes are one of the most characteristic groups in Mediterranean coastal. It predominance in soft-bottom communities confers to this group a significant importance on the knowing of the mechanisms that control the community dynamics. The main aim of this study is to describe the polychaetes distribution alongside depth gradient in northern costal in Mediterranean Sea. In this context, the specific objectives Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 86 of the present study were (1) to describe the distributional pattern of polychaetes for the region, (2) to identify the relationship between polychaetes assemblages and its main environmental parameters. MATERIAL AND METHODS Study area The Western Mediterranean is characterized by its wide continental shelf, by lower salinity and temperature values as well as by higher primary productivity and chlorophyll a concentration values (Arvanitidis et al. 2002). The study area includes around 1000 km of the Spanish Mediterranean coast, comprising Catalonia 699 km and Valencia 454 km. Both of the two coasts with the highest human pressures (Sarda et al. 2005; Yepes and Medina 2005). It coast have some important river that discharge flow in Mediterranean sea (Ebro and Llobregat) and other less important (Arnau et al. 2004). Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 87 Figure 1. Map of location of the sampling sites and transects alongside the Spanish coast. Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 88 Table 1. Geographic coordinates location from sampling sites, granulometry expressed by D50 (µm) and % of silt-clay. The sampling sites were sampled at three depth (10, 20 and 30 meters) in different transect alongside the coast. Transect Depth (m) D50 (µm) % of siltclay Latitude Longitude 2U 10 222.4 0.9 42º13'41" N 03º07'49" E 2U 20 170.7 3.8 42º13'17" N 03º08'10" E 2U 30 135.3 8.3 42º12'52" N 03º10'13" E 2V 10 150.9 5.8 42º07'24" N 03º08'39" E 2V 20 156.4 3.8 42º07'60" N 03º09'59" E 2V 30 110.1 19.6 42º08'05" N 03º10'34" E 2W 10 162.3 4.8 42º01'13" N 03º12'22" E 2W 20 62.2 50.6 42º01'12" N 03º12'47" E 2W 30 62.0 50.6 42º01'12" N 03º13'19" E 2T 10 263.4 0.0 41º50'22" N 03º06'6" E 2T 20 215.8 4.9 41º50'11" N 03º06'14" E 2T 30 136.1 13.5 41º49'51" N 03º06'18" E 2S 30 160.2 21.4 41º42'29" N 02º55'30" E 2R 10 174.7 1.6 41º40'18" N 02º47'50" E 2R 20 243.3 0.0 41º40'14" N 02º48'3" E 2R 30 622.1 4.9 41º39'54" N 02º48'19" E 2Q 10 529.2 1.3 41º34'34" N 02º34'35" E 2Q 20 597.8 0.4 41º34'23" N 02º34'38" E 2Q 30 72.4 48.4 41º33'38" N 02º35'03" E 2P 10 181.5 3.4 41º28'6" N 02º18'50" E 2P 20 127.4 16.9 41º27'58" N 02º18'37" E 2P 30 106.3 31.5 41º27'38" N 02º18'50" E 2O 10 132.8 8.4 41º17'11" N 02º07'56" E 2O 20 98.1 32.2 41º17'3" N 02º08'1" E 2O 30 26.9 71.8 41º16'51" N 02º08'07" E 2N 10 156.0 1.5 41º14'55" N 01º54'23" E 2N 20 44.8 65.0 41º14'19" N 01º54'42" E 2N 30 27.0 73.2 41º13'16" N 01º55'03" E 2M 10 108.3 6.2 41º12'17" N 01º46'2" E 2M 20 456.9 11.7 41º10'50" N 01º46'1" E 2M 30 471.7 4.2 41º09'49" N 01º45'54" E 2L 10 133.6 5.8 41º10'40" N 01º33'5" E 2L 20 67.2 45.6 41º10'12" N 01º33'38" E 2L 30 48.6 64.4 40º09'45" N 01º33'36" E 2K 10 171.7 0.0 41º06'39" N 01º15'52" E 2K 20 159.9 6.7 41º06'29" N 01º16'7" E 2K 30 39.8 68.2 41º06'11" N 01º16'12" E 2J 20 196.0 25.1 40º52'44" N 00º48'44" E 2J 30 547.7 11.8 40º52'25" N 00º49'16" E 2H 10 80.7 38.4 40º36'2" N 00º49'6" E 2H 20 103.0 24.8 40º35'1" N 00º50'49" E 2H 30 15.1 87.3 40º34'15" N 00º51'20" E 2G 10 27.4 80.6 40º30'44" N 00º34'50" E 2G 20 28.2 82.3 40º29'22" N 00º37'15" E 2G 30 11.9 94.0 40º28'04" N 00º39'17" E Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 89 Transect Depth (m) D50 (µm) % of siltclay Latitude Longitude 2F 20 62.7 50.2 40º20'4" N 00º26'15" E 2F 30 19.4 72.2 40º19'04" N 00º27'52" E 2E 10 127.9 5.2 40º09'30" N 00º12'47" E 2E 20 92.6 33.8 40º09'6" N 00º13'51" E 2E 30 14.3 83.2 40º08'23" N 00º15'34" E 2D 30 24.5 61.3 39º56'23" N 00º05'36" E 2C 20 94.2 22.0 39º48'2" N 00º03'44" W 2C 30 98.2 34.7 39º47'17" N 00º02'30" W 2B 10 132.7 3.3 39º39'54" N 00º11'42" W 2B 20 99.6 15.2 39º39'25" N 00º10'38" W 2B 30 48.8 61.3 39º39'00" N 00º09'48" W 2A 10 n.a. n.a. 39º28'23" N 00º18'30" W 2A 20 165.5 28.6 39º27'50" N 00º16'45" W 2A 30 48.8 59.4 39º27'43" N 00º15'33" W (n.a.) data no aviable Sampling and laboratory procedures Samples were obtained during the course of the REDIT-II (December 1999, on the N.O. Tethys) campaigns, alongside the coast, see Table 1. Geographic coordinates location from sampling sites, granulometry expressed by D50 (µm) and % of silt-clay. The sampling sites were sampled at three depth (10, 20 and 30 meters) in different transect alongside the coast. for detail of geographic coordinates and location. The benthic samples were obtained at 59 stations in 22 inshore-offshore transects (10, 20 and 30 m depths) between the French border and the vicinity of the Valencia city in the area of the North-western Mediterranean coast (Figure 1). Out of these overall sample transects, four of it could not be achieved at 10 m depth (e.g. 2C, 2D, 2F, 2J and 2S) and neither two at 20 m depth (e.g. 2D and 2S), due to technical constraints. Sediment samples were collected using a 0.1 m² van Veen grab. At each site, 3 grabs were taken for the analysis of benthic macrofauna, and 1 for granulometric analyses. Macrofauna samples were immediately sieved on a 1 mm mesh and the fauna retained were fixed in 5% formaldehyde. At the laboratory, samples were sorted and polychaetes were separated from the remaining fauna. Polychaetes species were later identified to the lowest practical taxonomic level and counted. Unidentified species were only taken Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 90 into account when they could not be mistaken for other identified species. Data analyses were carried out on data pooled over the three replicated sampling units (Ellingsen 2001). To examine possible physical habitat characteristics that might be correlated with macrofaunal assemblages, several variables were analyzed for each sampling station. Water depth was recorded from the ship echosounder log at the time of sampling. Granulometric analysis was conducted on fresh sediment using a Malvern® Mastersizer 2000 laser microgranulometer. Data analysis Analysis of polychaetes was performed using as univariate measures of diversity species richness (S), the Shannon-Wiener index (H’) (log base 2) and the reciprocal of Simpson’s index (1-λ’) see (Magurran 2004). Following Peet (1974) and Ellingsen (2002) I calling H’ and 1-λ’as heterogeneity diversity and used labelling of species restricted to a single site ‘uniques’, species occurring at exactly 2 sites only ‘duplicates’, species represented by a single individual ‘singletons’, according to Colwell and Coddington (1994). Also I used multidimensional scaling (MDS) analyses of faunal data. All indices were computed using the Primer© 6 software package (version 6.1.13) (Clarke and Gorley 2006). Assemblages were performed on previously reduced sets of species in order to limit the noise introduced by the rare species. The elimination of these later species from the analysis was based on general presences on samples sites lower than 10%. Polychaetes assemblages were then elucidated by cluster analysis based on the faunal composition (Bray Curtis similarity, average link grouping). Abundances were square-root transformed to limit the influence of the most dominant taxa. The taxa most responsible for similarities within each cluster of stations on one hand, and for dissimilarities between clusters of stations on the other hand were identified using the SIMPER Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 97 Table 3. Pairwise Spearman rank correlations between environmental and biotic variables, including D. arietina with significant (p < 0.01) coefficients in bold face (n for all correlations=59) S N d J' H'(log2) 1-λ' Depth D50 (um) <63% D. arietina S N 0.79 d 0.97 0.64 J' 0.03 -0.42 0.20 H'(log2) 0.80 0.37 0.88 0.58 1-λ' 0.61 0.15 0.72 0.76 0.94 Depth 0.21 0.24 0.17 0.12 0.22 0.16 D50 (µm) 0.07 0.07 0.07 -0.07 0.01 0.01 -0.34 <63% 0.19 0.13 0.18 0.16 0.27 0.20 0.59 -0.80 D. arietina 0.12 0.18 0.07 -0.27 -0.08 -0.11 0.08 0.27 -0.23 Exception abundance (N) and evenness (J'), there were positive correlations among heterogeneity diversity measures. see (Table 3). Also there is a positive correlation between percentage of silt-clay and depth. And finally Spearman rank reveals negative correlations between median grain sizes D50 (µm) and percentage of silt-clay. Spatial distribution and faunal assemblages The MDS analysis shows a main distributional gradient of species linked to depth alongside the coastal area (Figure 4), and ANOSIM (ANOVA one-way) indicated it differences were significative (Global R): 0.406 (p<0.001). Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 98 Figure 4. MDS ordinations for abundance of all replicates at each sampling site. The SIMPER analysis confirmed the species contribution more responsible of this distribution. Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 99 Table 4). Also I plotted how the species were distributed at 3 depths, alongside the coast, as percentage of contribution. Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 100 Table 4. Contribution and cumulative contribution of the species the most responsible for similarity in all depth from Spanish coast NW-Mediterranean Sea based on square root transformed species abundances according to the SIMPER analysis; Av. similarity: (10 m 10%, 20 m 15%, 30 m 14%). Species Av. Abund. (ind-m-2) Contribution % Cumulative contribution % Depth (m) 10 Lumbrineris impatiens 27 25.14 25.14 Owenia fusiformis 102 12.38 37.52 Galathowenia oculata 16 7.69 45.22 Aponuphis bilineata 8 5.94 51.16 Paradoneis armata 10 5.23 56.39 Chone duneri 28 5.16 61.55 Species Av. Abund. (ind-m-2) Contribution % Cumulative contribution % 20 Ditrupa arietina 142 15.36 15.36 Galathowenia oculata 49 11.93 27.29 Notomastus latericeus 48 10.08 37.38 Aponuphis bilineata 34 8.98 46.35 Lumbrineris latreilli 28 7.09 53.44 Monticellina heterochaeta 65 4.67 58.11 Spiophanes bombyx 16 3.79 61.9 Species Av. Abund. (ind-m-2) Contribution % Cumulative contribution % 30 m Lumbrineris gracilis 77 21.13 21.13 Monticellina heterochaeta 37 8.51 28.75 Aponuphis bilineata 39 5.08 33.84 Sternaspis scutata 17 4.79 38.63 Ditrupa arietina 107 4.59 43.22 Notomastus profundus 10 3.91 47.13 Notocirrus scoticus 10 3.83 50.95 Eunereis longissima 23 3.61 54.75 Lumbrineris latreilli 21 3.42 57.98 Scoletoma emandibulata 10 3.05 61.04 The species that more contributed with similarity at 10 m depth were Lumbrineris impatiens, which was widely distributed (82% of sampling station at 10 m depth), however it abundance was low, see Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 101 Table 4. The owenids group Owenia fusiformis and Galathowenia oculata, where O. fusiformis was found in 53% of sampling station, closed to river mouth (e.g. Ter, Bèsos, Lobregat and Mijares) even though the most rivers have low flow (Figure 5). By contrast G. oculata had a minor abundance in the zone, but was found in 71% of sampling sites. Aponuphis bilineata have a low abundances but it was present in 71% of sampling sites. Paradoneis armata only was present in 65% of sampling sites with low abundances, and Chone duneri were present in 71% of sampling sites but it abundance was lower than at 20 m depth (Figure 5). Figure 5. Distributional pattern of polychaetes most important at 10 m depth. At 20 m depth D. arietina was found in 65% of the sampling sites (Figure 6) but it abundances was higher than 10 or 30 m depth and it was mainly found since Gulf of Roses until vicinity of Barcelona, and it again was present near to Ebro delta, but in minor densities. The other species G. oculata and Notomastus latericeus was represented in 95% of sampling station but with less density (Figure 6). A. bilineata was in 85% of sampling sites, but it abundance was higher is we compared with abundance Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 102 found at 10 m depth but similar to found at 30 m depth, although at 30 m only was present in 64% of sampling site (Figure 6). Lumbrineris latreilli was found in 90% of sampling sites at 20 m depth, even though it abundance is similar at 20 and 30 m depth, in the later depth was ubiquity in the vicinity Barcelona to Ebro delta (Figure 7). In the last depth (30 m) Lumbrineris gracilis was the mainly contributor although only was in 55% of sampling sites following by Monticellina heterochaeta which was the most widely distributed (82%) of sampling station but whose densities were moderated is we compared with density of it at 20 m depth. Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 103 Table 4, Figure 7). Figure 6. Distributional pattern of the most important polychaetes at 20 m depth When I plot D. arietina average abundance pattern at all depth, it shows that D. arietina is the main contributor to differences among distribution in soft-bottom littoral zone. And it distribution in the infralittoral zone is most important in the north Spanish coast. Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 104 Figure 7. Distributional pattern of the most important polychaetes at 30 m depth. In a view differences at all depth, shows some inconstancies, the cluster analysis shows that there are 5 assemblages in the zone at 24% of similarity, and (ANOVA R: 0.69 p< 0.001), reveals that there are significative differences among clusters. The cluster 1 was formed by 11 sampling station, all at 10 m depth with D50 (µm) 180.63 ± 117.57 and % silt-clay 4.15 ± 2.50 and it mainly contributors were O. fusiformis, G. oculata, L. impatiens, C. duneri, P. armata and A. bilineata; cluster 2 was shaped by 10 sampling stations northern Tordera river, D50 (µm) 171.55 ± 55.22 and % silt-clay 7.63 ± 8.82, exception was sampling station 2H20 (20 m depth) located near to the mouth of Ebro delta and it mainly contributor was D. arietina (81%) and Av. Abundance 402 ind. m-2 , which showed assemblages with those sampling stations located in gulf of Roses, and also near to Tordera river; the third cluster encircled 11 sampling station at 10 and 20 m depth southern Tarragona with D50 (µm) 100.68 ± 57.13 and % silt-clay 38.29 ± 25.72 which mainly contributors were N. latericeus, L. latreilli, G. oculata, A. bilineata, C. arenicola and C. collaris; the cluster 4 was the biggest of all cluster, it grouping 22 sampling stations between 20 and 30 m depth and D50 (µm) 184.00 ± 204.60, % siltclay 37.33 ± 24.34, mainly before Gulf of Roses it mainly contributors were the lumbrinerids (L. gracilis, L. nonatoi, and L. latreilli), M. dorsobranchialis, N. hombergii, A. bilineata and; and the last cluster 5 only contained 5 sampling stations 30 Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 105 m depth, located southern Barcelona and D50 (µm) 17.52 ± 5.93 and % silt-clay 81.98 ± 9.30, it mainly contributors were S. scutata and L. gracilis see (Figure 9). Figure 8. Presence and average abundance of D. arietina at all depth sampled (10, 20 and 30 m) Chapter 3 Spatial distribution and diversity of polychaete faunal in the northern Mediterranean Spanish coast 106 Figure 9. Dendrogram of cluster analysis alongside the coast. Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 115 CHAPTER 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: From the mouth of the Rhone River (France) to the vicinity of Valencia (Spain) ABSTRACT Forty-four inshore-offshore transects along the North-western Mediterranean portion of coast between the mouth of the Rhône River and the Valencia city were sampled during the REDIT-I campaign (September 1998, [R1]) and the REDIT-II campaign (December 1999, [R2]). The pool of polychaetes species and the distribution pattern of its assemblages on shallow littoral fine sands (10 and 20m stations) were analyzed at this regional scale. Biomass data from the obtained collection was assessed by species and trophic guilds, and here is provided together with estimates about its productivity. INTRODUCTION The assessment of biological diversity at different temporal and spatial scales is a prerequisite when criteria and methodological standards on Good Environmental Status (GEnS) of marine waters need to be evaluated following the Marine Strategy Framework Directive-MSFD (2008/56/EC). For these assessments, the natural characteristics of biodiversity (descriptor 1 of the MSFD), as well as the particular pressures requiring management responses, need to be understand because they change according to different biogeographic regions (Cochrane et al. 2010). Following the recommendations of the MSFD, a suitable set of European ecological assessment areas Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 116 should be defined to analyze habitat/community distribution and condition. This knowledge is basic for cooperation in planning future coastal and marine conservation and uses, as well as for further implementation of the MSFD. Although indicators of GEnS are obliged by the Directive at subnational economic exclusive zone regional scales, it is important to consider the utilization of indicators that give comparable information besides intrinsic variations due to spatial heterogeneity. Selected indicators can vary naturally according to different natural condition factors such as granulometrical configurations due to major currents and/or organic content in sediments due to river inflow or anthropic pressures. Here, we are providing data on a very extended community in the Mediterranean Sea, the Littoral Sand Community (Labrune et al., 2007), both at French and Spanish sublittoral waters to analyze its species composition, community variables, and differences due to geographical location. During 1998 and 1999, French-Spanish cooperation was initiated to assess the biological diversity of shallow soft-bottom benthic macroinfauna in the region of the Gulf of Lions and the Northern Mediterranean Spanish coast. The coast portion between the mouths of the Rhône River to the vicinity of the Valencia city was assessed. The main aim of the present study was to describe the distribution pattern of the pool of species present in this particular region of the North-western Mediterranean Sea. This region comprises around 2000 km of coastal fringe and can be considered by its dimension, its social-ecological importance, and its scientific knowledge, a suitable area to be assessed in the implementation of the MSFD. The Gulf of Lions has been the departure point for the pioneer biological description of soft-bottom communities in the Mediterranean (Picard 1965; Guille 1970, 1971; Massé 1972; Bellan and Bourcier 1984). Recently, the distribution, composition and ecological quality of the benthic macroinfauna in the Gulf of Lions was reassessed (Grémare et al. 1998; Grémare et al. 1998; Labrune et al. 2006; 2006; 2007; Labrune et al. 2008). In these papers, a new terminology for the soft-bottom assemblages observed in the Gulf of Lions: littoral fine sand community (LFS), littoral sandy mud community (LSM), and Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 117 terrigenous coastal mud community (TCM) was introduced, and its correspondence with ancient community classification data (Picard 1965; Guille 1970) indicated. However, besides the additional information given for biodiversity and ecological quality of such environments, no biomass data was included. Despite its importance when functional analyses are taken into consideration, biomass estimates are often absent in macrofaunal studies, nevertheless, biomass data can be related with energy inputs of organic matter, biomass estimates can be used to compute crude measures of production, and biomass changes expressed as trophic guilds can be related with anthropogenic impacts on the marine environment. From all the zoological taxa found in soft-bottom communities, polychaetes are one of the most characteristic groups (Knox 1977). It has been shown that in many cases polychaetes may constitute a good surrogate for describing the distribution of the entire communities (Mackie et al. 1997; Olsgard et al. 2003; Mackie et al. 2005). The predominance of polychaetes in soft-bottom communities confers to this group a significant importance in the understanding of the mechanisms that control the community dynamics, and calls for its inclusion as indicators for GEnS in benthic environments. The main aim of the present study was to describe the pool of polychaete species throughout the observed region in their shallow Littoral Sands providing its basic community data. In addition, a second objective of the paper was to address the suitability of using particular indicators derived of this analysis for the Descriptor 1 of GEnS. In this context, the specific objectives of the present study were (1) to describe the distributional pattern of polychaetes for the region, (2) to identify the relationship between polychaetes assemblages and its main environmental parameters, (3) to include measurements of biomass that could give us indications on the productivity of the are, and (4) to select indicators for GEnS in the Littoral Sand Community. Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 118 MATERIAL AND METHODS Sampling and laboratory procedures Littoral sand benthic samples were obtained at 77 stations in forty-one inshore-offshore transects (10, 20 m depths) between the mouth of the Rhône river and the vicinity of the Valencia city in the area of the North-western Mediterranean coast (Figure 1). Transects were sampled during the course of the REDIT –I (September 1998, from the mouth of the Rhône river to the French-Spanish border on the N.O. Georges Petit) and the REDIT-II (December 1999, from the border to Valencia on the N.O. Tethys) campaigns (Table 1). Eight of the sample transects of the REDIT-I (R1) and REDIT-II (R2) campaigns could not be achieved at 10 m depth (R1O, R1P, R2C, R2D, R2F, R2I, R2J, and R2S) due to technical geo-morphological constraints, while transects R2D, R2I, and R2S were not sampled at 20 m depth for the same reason. Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 119 Table 1. Geographic coordinates location from sampling sites ordered north to south in both coast, granulometry expressed by D50 (µm) and % of silt-clay. The sample sites have 5 digits, the two first ones link campaign (e.g. R1_ Redite I (French coast campaign) or R2_ Redite II (Spanish coast campaign); the third digit corresponds to transects from long coast and are represented by a letter (A-W); and two last one are depth in meters (10 or 20). French coast campaign Spanish coast campaign S. Site Latitude Longitude D50 (µm) % of silt-clay S. Site Latitude Longitude D50 (µm) % of silt-clay R1U10 43º19'55'' N 4º44'56" E 111.5 12.7 R2U10 42º13'41" N 3º07'49" E 222.4 0.9 R1U20 43º19'01'' N 4º44'56" E 79.9 36.1 R2U20 42º13'17" N 3º08'01" E 170.7 3.8 R1T10 43º20'06'' N 4º36'22" E 182.8 1.4 R2V10 42º07'24" N 3º08'39" E 150.9 5.8 R1T20 43º19'26'' N 4º36'11" E 55.0 52.2 R2V20 42º07'60" N 3º09'59" E 156.4 3.8 R1S10 43º26'24'' N 4º29'01" E 47.2 61.4 R2W10 42º01'13" N 3º12'22" E 162.3 4.8 R1S20 43º22'55'' N 4º28'11" E 45.6 61.8 R2W20 42º01'12" N 3º12'47" E 62.2 50.6 R1R10 43º26'16'' N 4º19'26" E 124.7 3.7 R2T10 41º50'22" N 3º06'06" E 263.4 0.0 R1R20 43º24'57'' N 4º18'56" E 49.8 53.5 R2T20 41º50'11" N 3º06'14" E 215.8 4.9 R1Q10 43º27'32'' N 4º09'26" E 145.6 1.5 R2R10 41º40'18" N 2º47'50" E 174.7 1.6 R1Q20 43º26'45'' N 4º09'32" E 108.0 23.0 R2R20 41º40'14" N 2º48'03" E 243.3 0.0 R1P20 43º21'14'' N 3º59'54" E 32.1 77.4 R2Q10 41º34'34" N 2º34'35" E 529.2 1.3 R1O20 43º25'12'' N 3º49'41" E 223.3 1.7 R2Q20 41º34'23" N 2º34'38" E 597.8 0.4 R1N10 43º22'55'' N 3º41'26" E 131.2 6.8 R2P10 41º28'06" N 2º18'50" E 181.5 3.4 R1N20 43º22'22'' N 3º41'44" E 104.0 22.8 R2P20 41º27'58" N 2º18'37" E 127.4 16.9 R1M10 43º16'40'' N 3º31'58" E 192.8 0.0 R2O10 41º17'11" N 2º07'56" E 132.8 8.4 R1M20 43º16'19'' N 3º32'24" E 132.9 14.6 R2O20 41º17'03" N 2º08'01" E 98.1 32.2 R1L10 43º15'39'' N 3º21'49" E 133.7 1.9 R2N10 41º14'55" N 1º54'23" E 156.0 1.5 R1L20 43º13'55'' N 3º23'11" E 100.2 20.9 R2N20 41º14'19" N 1º54'42" E 44.8 65.0 Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 120 French coast campaign Spanish coast campaign S. Site Latitude Longitude D50 (µm) % of silt-clay S. Site Latitude Longitude D50 (µm) % of silt-clay R1K10 43º11'9'' N 3º13'26" E 158.0 0.0 R2M10 41º12'17" N 1º46'02" E 108.3 6.2 R1K20 43º10'33'' N 3º13'56" E 78.9 37.0 R2M20 41º10'50" N 1º46'01" E 456.9 11.7 R1J10 43º07'08'' N 3º09'10" E 167.7 0.0 R2L10 41º10'40" N 1º33'05" E 133.6 5.8 R1J20 43º06'57'' N 3º09'26" E 125.9 15.1 R2L20 41º10'12" N 1º33'38" E 67.2 45.6 R1I10 43º00'03'' N 3º04'28" E 161.8 1.7 R2K10 41º06'39" N 1º15'52" E 171.7 0.0 R1I20 43º00'03'' N 3º04'55" E 77.5 42.1 R2K20 41º06'29" N 1º16'07" E 159.9 6.7 R1H10 42º55'55'' N 3º03'40" E 157.9 6.0 R2J20 40º52'44" N 0º48'44" E 196.0 25.1 R1H20 42º55'55'' N 3º04'30" E 125.3 9.5 R2H10 40º36'02" N 0º49'06" E 80.7 38.4 R1G10 42º50'56'' N 3º03'26" E 189.3 2.6 R2H20 40º35'01" N 0º50'49" E 103.0 24.8 R1G20 42º50'56'' N 3º03'54" E 97.4 23.8 R2G10 40º30'44" N 0º34'50" E 27.4 80.6 R1F10 42º46'44'' N 3º02'54" E 217.2 2.4 R2G20 40º29'22" N 0º37'15" E 28.2 82.3 R1F20 42º46'44'' N 3º03'21" E 147.8 10.8 R2F20 40º20'04" N 0º26'15" E 62.7 50.2 R1E10 42º43'22'' N 3º02'50" E 211.7 3.2 R2E10 40º09'30" N 0º12'47" E 127.9 5.2 R1E20 42º43'26'' N 3º03'12" E 200.3 4.4 R2E20 40º09'06" N 0º13'51" E 92.6 33.8 R1D10 42º41'27'' N 3º02'50" E 182.6 4.2 R2C20 39º48'02" N 0º03'44" W 94.2 22.0 R1D20 42º41'27'' N 3º03'14" E 163.4 8.8 R2B10 39º39'54" N 0º11'42" W 132.7 3.3 R1C10 42º39'03'' N 3º02'42" E 177.4 1.6 R2B20 39º39'25" N 0º10'38" W 99.6 15.2 R1C20 42º39'03'' N 3º03'14" E 153.5 6.8 R2A10 39º28'23" N 0º18'30" W n.a. n.a. R1B10 42º35'20'' N 3º03'04" E 160.7 4.6 R2A20 39º27'50" N 0º16'45" W 165.5 28.6 R1B20 42º35'20'' N 3º03'41" E 91.1 25.4 R1A10 42º33'25'' N 3º03'13" E 148.1 7.2 R1A20 42º33'25'' N 3º04'08" E 278.2 3.4 (n.a.) data no aviable Chapter 4 121 Figure 1. Map of the zone study. The blue circle belongs to sampling stations from Gulf of Lions and red circles from Spain coast. Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 122 Sediment samples were collected using a 0.1 m² van Veen grab. At each sampled site, 3 grabs were taken for the analysis of benthic macrofauna, and 1 for granulometric and organic content analyses. Macrofauna samples were immediately sieved on a 1 mm mesh and the fauna retained were fixed in 5% formaldehyde. At the laboratory, samples were sorted and polychaetes were separated from the remaining fauna. Polychaete species were later identified to the lowest practical taxonomic level and counted. Unidentified species were only taken into account when they could not be mistaken for other identified species. Data analyses were carried out on data pooled over the three replicated sampling units (Ellingsen 2001). Individual polychaete species biomass was determined as wet weight to avoid destruction of the collected material except for two nominal species Ditrupa arietina and Owenia fusiformis. For these two species I used regressions of width vs. dry weight to convert it width measurements to biomass following Sardá et al. (1999). Then for D. arietina the regression used is: DWDa = 0.4522 (dDa) 3.992 where DWDa is dry weight of D. arietina in mg and (dDa) is diameter aperture of it tube in mm. For Owenia fusiformis the regression is: DWOf = 0.8434 (wtOf) 2.177 where DWOf is dry weight of O. fusiformis in mg and (wtOf) is the maximum width of the tube in mm. A binocular microscope equipped with a camera lucida and digitizing tablet was used for all measurements. For comparative purposes data given in this paper are expressed in dry weight using the conversion factor of dry weight = 17,6% of wet weight calculated for polychaetes (Rumohr et al. 1987). Each species was attributed to a feeding guild: (F) filter feeders; (M) mixed (filter and surface-deposit feeders); (S) Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 123 surface-deposit feeders; (SS) subsurface-deposit feeders; and (C) carnivores/omnivores, using information in (Fauchald and Jumars 1979; Dauvin and Ibanez 1986). To examine possible physical habitat characteristics that might be correlated with macrofaunal assemblages, several variables were analyzed for each sampling station. Water depth was recorded from the ship echosounder log at the time of sampling. Granulometric analysis was conducted on fresh sediment using a Malvern® Mastersizer 2000 laser microgranulometer. Data analysis Analysis of biological data for the classification of polychaetes assemblages was performed on previously reduced sets of species in order to limit the noise introduced by the not so common species (i.e. those presented at least in 8 of 77 sample sites). The elimination of these later species from the analysis was based on general presences on samples sites lower than 10%. Polychaetes assemblages were then elucidated by cluster analysis based on the faunal composition (Bray Curtis similarity, average link grouping). Abundances were square-root transformed to limit the influence of the most dominant taxa. The taxa most responsible for similarities within each cluster of stations on one hand, and for dissimilarities between clusters of stations on the other hand were identified using the SIMPER procedure. All these analyses were carried out using the Primer© 6 software package (version 6.1.13) (Warwick 1986). The relationships between polychaetes distribution and environmental parameters were first assessed by testing for significant correlation between the similarity matrices of polychaetes abundance and (1) depth, (2) silt-clay content using Mantel tests. Production estimates were obtained based on is biomass data. In order to rank the most important polychaetes contributors to the productivity of the region, we estimated its secondary production using the allometric equation developed by (Brey 1990; Warwick et al. 2010): P = (B/A)0.73 *A Chapter 4 130 The sampling station the highest richness was R2A20 (72 ssp.) located near Valencia port in Spain and the lowest was R1U10 (4 ssp.) located near the Rhone river (Figure 4b). The most abundant sampling station was R1J20 (5103 ± 3451 ind. m-2) which the most contributor was D. arietina (4770 ± 3163 ind. m-2) and the lowest R1T10 (43 ind. m-2) (Figure 4-c). The highest D. arietina biomass was found in R1Q20 (11.88 ± 7.46 g dry wt. m-2) (Figure 5-b) and the highest O. fusiformis biomass (6.37 ± 3.53 g dry wt. m2) was found in R1L10 (Figure 5-a). The biggest cluster observed in the analysis grouped 66 stations and it has two subclusters that we named 1-A and 1-B. The sub-cluster 1-A has 45 stations, principally located to the Gulf of Lions and out of these 6 were north zone Spain coast, exception R2E10 which was located southern in Torre Nostra (Valencia). The sub-cluster 1-B has 21 stations; most of these principally located at 20 m deep from Spain coast a few of them at 10 m deep (R2G10, R2H10, R2L10 AND R2A10). This cluster 1 contained 69 species that were considered constant, accessories or accidentals. Average mean sand grain size composition for both clusters is 170 and 155 µm respectively for sub-cluster 1-A and 1-B respectively. The main difference between both subclusters is the large densities observed for the two most abundant species (Ditrupa arietina and Owenia fusiformis) in subcluster 1-A when compared with subcluster 1-B. This caused that the averages abundances of all species in these two subclusters totaled 911 ind. m-2 and 835 ind. m-2, respectively. The species composition for the most abundant species can be seen in Table 4. Chapter 4 131 Figure 5. Biomass plot in dry weight gm2. a) O. fusiformis biomass. b). D. arietina biomass c) Biomass of all species found. Chapter 4 132 The second cluster (2) has eight stations all of these from the Spanish coast (R2B10, R2K10, R2M10, R2Q10, R2R10, R2T10, R2U10 and R2V10). Only there were 3 stations left from these clusters, R1T10 and R1U10 which had very low taxa (Labrune et al. 2007) in the Gulf of Lions, and another one (R2O10) was located near Llobregat mouth river in Spain coast. In this case, this cluster contained only 33 species that were considered constant, accessories or accidentals. These samples contain a significant larger amount of grain size in its sediment composition averaging 226 µm. The species composition for the most abundant species can be seen in Table 3. The diversity in general was moderately to low, it ranked between H’ 0.45 to 4.76 bits.ind-2, in addition J’ indicated that species were unbalanced distributed. Exceptions were some sampling station, where the highest diversity was obtained from 20 m deep in Spain coast within sub-cluster 1-B. On the other hand almost the lowest from Gulf of Lions (France coast) (Figure 4-a). Average values and standard deviations of the different computed univariate indices [average abundance, Shannon-Wiener index (H’), Margalef index (d), and Simpson index (1-λ’)] of diversity within each cluster and subcluster are shown in Table 2. Table 2. Data of diversity and dominance in the zone. Av. Abund. (ind.m-2) d H'(log2) 1-λ' Cluster 1 887 ± 796 4 ± 2 3 ± 1 1 ± 0 Sub-cluster 1-A 911 ± 843 3 ± 1 2.4 ± 1 0.6 ± 0.2 Sub-cluster 1-B 835 ± 700 6 ± 2 4.2 ± 0.6 1 ± 0.1 Cluster 2 199 ± 68 3 ± 1 3 ± 1 1 ± 0 Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 133 Table 3. Contribution and cumulative contribution of the species the most responsible for similarity in the Principal Cluster from Mediterranean coast based on square root transformed species abundances according to the SIMPER analysis; Av. similarity: (Cluster 1: 20 %; Cluster 2: 22 %). Species Av. Abund. Av. Biom. Contribution % Cumulative contribution % Cluster 1 (ind-m-2) (dry wt m2) Ditrupa arietina 306 0.425 31 31 Owenia fusiformis 151 0.398 19 50 Hyalinoecia bilineata 33 0.025 8 58 Lumbrineris latreilli 25 0.024 6 64 Nephtys hombergii 18 0.030 5 68 Galathowenia oculata 23 0.003 5 73 Chone duneri 21 0.012 4 77 Glycera unicornis 12 0.020 3 81 Lumbrineris impatiens 15 0.006 2 83 Spiophanes bombyx 8 0.004 2 84 Notomastus latericeus 20 0.035 2 86 Nephtys cirrosa 5 0.005 1 87 Monticellina heterochaeta 21 0.003 1 88 Glycinde nordmanni 3 0.003 1 89 Anobothrus gracilis 5 0.003 1 89 Eunice vittata 5 0.005 1 90 Melinna palmata 5 0.004 1 91 Species Av. Abund. Av. Biom. Contribution % Cumulative contribution % Cluster 2 (ind-m-2) (dry wt m2) Lumbrineris impatiens 38 0.015 33 33 Paradoneis armata 13 0.001 9 42 Nephtys cirrosa 8 0.007 8 52 Ditrupa arietina 30 0.031 8 59 Magelona mirabilis 9 0.004 7 66 Sigalion mathildae 4 0.001 5 72 Hyalinoecia bilineata 6 0.01 4 76 Glycera alba 7 0 4 80 Scoloplos (Scoloplos) armiger 2 0 3 83 Clymenura clypeata 5 0 3 86 Chone duneri 5 0 2 88 Chaetozone setosa 1 0 1 89 Prionospio fallax 2 0 1 91 Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 134 Table 4. Contribution and cumulative contribution of the species the most responsible for similarity in sub-cluster 1-A and sub-cluster 1-B from Mediterranean Sea based on square root transformed species abundances according to the SIMPER analysis; Av. similarity: (sub-cluster1A: 28 %; sub-cluster 1-B: 18 %). Species Av. Abund. (ind-m2) Av. Biom. (dry wt m2) Contributio n % Cumulative contribution % Subcluste r 1-A Ditrupa arietina 428 0.608 38 38 Owenia fusiformis 217 0.576 26 65 Hyalinoecia bilineata 33 0.024 5 70 Chone duneri 27 0.017 5 75 Nephtys hombergii 17 0.034 5 80 Glycera unicornis 15 0.016 4 83 Lumbrineris latreilli 22 0.029 3 86 Lumbrineris impatiens 21 0.007 3 89 Galathowenia oculata 12 0.001 2 91 Species Av. Abund. (ind-m2) Av. Biom. (dry wt m2) Contribution % Cumulative contribution % Subcluster 1-B Notomastus latericeus 62 0.060 15 15 Galathowenia oculata 47 0.007 12 26 Lumbrineris latreilli 31 0.010 11 37 Hyalinoecia bilineata 32 0.031 9 46 Monticellina heterochaeta 63 0.007 5 51 Mediomastus fragilis 42 0.004 4 54 Ditrupa arietina 46 0.032 3 57 Spiophanes bombyx 11 0.005 3 60 Chone collaris 8 0.000 2 62 Owenia fusiformis 9 0.015 2 65 Nephtys hombergii 21 0.020 2 67 Eunice vittata 8 0.006 2 69 Melinna palmata 9 0.004 1 70 Pseudopolydora paucibranchiata 17 0.000 1 72 Spiochaetopterus costarum 9 0.005 1 73 Clymenura clypeata 8 0.003 1 74 Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 135 Lumbrineris nonatoi 14 0.005 1 75 Phyllodoce lineata 4 0.006 1 76 Scoloplos (Scoloplos) armiger 6 0.000 1 77 Glycera unicornis 7 0.003 1 78 Exogone (Exogone) verugera 7 0.000 1 79 Pista cristata 4 0.005 1 80 Lumbrineris gracilis 14 0.006 1 81 Euchone 4 0.000 1 82 Chone duneri 10 0.000 1 82 Aricidea (Aricidea) pseudoarticulata 19 0.009 1 83 Chone arenicola 4 0.001 1 84 Praxillella affinis 7 0.003 1 84 Euclymene robusta 8 0.001 1 85 Glycera alba 7 0.004 1 86 Eunereis longissima 7 0.017 1 86 Magelona minuta 12 0.000 1 87 Euclymene oerstedi 10 0.004 1 87 Spio filicornis 4 0.000 1 88 Chone acustica 10 0.001 1 89 Scoletoma emandibulata mabiti 6 0.006 1 89 Paranaitis kosteriensis 3 0.001 1 90 Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 136 Trophic composition and estimates of productivity Based on species feeding guild, the trophic group distribution for the polychaetes species found can be observed in the graphic bars of (Figure 6-a.b). The proportions of (F) filter feeders, (S) surface-deposit feeders and (SS) subsurface-deposit feeders was more or less comparable in both clusters if we see the presence of O. fusiformis (M) and D. arietina (F) separately, then we can see these later two species are clearly responsible when all data is totaled. Regarding cluster 1 Figure 6-a), the filter-feeder group was the most important one, it was richer in abundance (35%) and biomass (36%) and its most important contributor was D. arietina (65% of the entire F group). This group was followed by the mixed group (M), in this case the percentage of presence also was also lower (6%) than others group, and abundance (23%) and biomass (35%), its main contributor was O. fusiformis (82% of the entire M group). Conversely, the cluster 2 (Figure 6-b) had the same pattern corresponding to species number of carnivores/omnivores (C) group; but the mainly difference was linking with abundance (48%) and biomass (54%) because them were in agreement to species number. However, the (M) group had poor species number (9%), abundance (5%) and biomass (2%). The mainly different were in the proportions about (C) and (M) group i.e., even though in both of cluster carnivores/omnivores (C) group look alike in presence (38% in cluster 1, 40% in cluster 2) it abundance and biomass was less important in cluster 1 (20 and 18% respectively) than cluster 2 (48 and 54% respectively), while (M) group had a presence (6% in cluster 1, 9% in cluster 2) it abundance and biomass was more important in cluster 1 (23 and 35% respectively) than cluster 2 (5 and 2% respectively). Chapter 4 137 Figure 6. Trophic guild distribution in both clusters. a) Cluster 1. b) Cluster 2. The mean secondary production in the whole zone was computed as (5.73 g dry wt. m2y-1). It was clearly highest in Cluster 1 (6.59 g dry wt. m-2y-1) than in Cluster 2 (0.10 g dry wt. m-2y-1). By trophic group in overall zone the (F) group was the most productive (4.24 g dry wt. m-2y-1), it was following by (M) group (3.71 g dry wt. m-2y-1), (C) group (2.03 g dry wt. m-2y-1), the other two group were SS (0.75 g dry wt. m-2y-1) and S group (0.65 g dry wt. m-2y-1). Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 138 DISCUSSION Along the littoral sands analyzed from the mouth of the Rhône River to the vicinity of Valencia City, three natural species assemblages were distinguished related to grain size and the increased presence of two polychete species (D. arietina and O. fusiformis). The three assemblages found in this study, belong to the Littoral Fine Sands community (LFS) according to Labrune et al. (2007). Littoral sands of the North-western Mediterranean are mostly occupied by the LFS community due to the predominant presence of fine to medium sediments in its soft-bottom infralittoral (Wentworth 1922). In specific places where coarse sand sediments are dominant, near rocky shores as the Cap de Creus (Sardá et al. 2012) or highly dynamic deltas as the Tordera one (Sardá et al. 1999), the LFS community is replace by the Littoral Coarse Sands community (LCS). LFS and LCS are the two basic communities that can be described. Even though Mediterranean has been considered an oligotrophic Sea (Margalef 1985) due to negative balance with Atlantic sea, Atlantic sea obtains nutrient inputs from deep water of Mediterranean while it lasted receives poor nutrient surfaces water from Atlantic sea (Lloret et al. 2001; Salat et al. 2011). For this reason, local events such as wind-driven mixing and river discharges can have an important role on its local fertilization (Estrada 1996; Estrada et al. 1999). In the North-western Mediterranean, there are only small freshwater discharges caused by episodic stormy rain flow through otherwise dry rivers. However, long stretches of coastline are fertilized only by the discharge of mostly treated but nutrient-rich urban and industrial effluents. Exceptions to this rule are estuarine areas receiving the discharges of the large rivers, Rhone and Ebro collecting the runoff from snow-covered mountain ranges (Alps, Pyrenees) and wastewater from large cities and intensive agricultural and industrial activities (Cruzado et al. 2002). The linkage between river runoff (Salen-Picard and Arlhac 2002; SalenPicard et al. 2003; Darnaude et al. 2004; Hermand et al. 2008) or wastewater discharges Chapter 4 ASSESSMENT OF SOFT-BOTTOM POLYCHAETE ASSEMBLAGES IN LITTORAL FINE SANDS (LFS) COMMUNITY BASED ON A MESOSCALES SURVEY: FROM THE MOUTH OF THE RHONE RIVER (FRANCE) TO THE VICINITY OF VALENCIA (SPAIN) 139 (Cardell et al. 1999; Serrano et al. 2011) on macroinfaunal assemblages and coastal fishery yields trough trophic webs has also been well recorded. Those processes also could help to maintain mostly well sorted fine sand bottom like found by (Guille 1970; Desbruyères et al. 1972-73; Labrune et al. 2007) and found in this study alongside the Mediterranean French and the Northern Mediterranean Spanish coast, because almost sampling sites had mainly fine sand. Palanques Palanques et al. (2009) point out that the maximum near-bottom sediment fluxes are associated with storm events and strong wind-induced currents, as well as sediment resuspension is mainly produced on the inner shelf by the action of waves, especially during storms in the Ebro delta river as well as Ulses et al. (2008) reported in Gulf of Lions. Even though Arnau et al. (2004), shows us that flood events lead to the formation of sediment plumes off river mouths which play a major role in the overall water and sediment discharge and, consequently, in the development of prodeltaic bodies and their fine-grained extensions alongshore, towards the continental shelf, and beyond. The three assemblages found for the LFS community in this work can be distinguished by the disproportionate presence of two polychaete species and its average grain size. A small proportion of stations were isolated by a higher grain size due to shallower depths in open environments. Most of the other stations (10 and 20 m) were located in fine sands sediments but, in this case, some of them, were highly influenced by the large presence of individuals of two species (D. arietina and O. fusiformis). Large densities of single polychaete species in soft-bottom environments are frequent in two basic conditions; in the response of assemblages to stressors such as organic enrichment (e.g. Capitella capitata in the Barcelona region, Cardell et al., 1999), or in recruitment periods (Sardá et al., 1999). In the North-western Mediterranean, recruitment periods for soft-bottom polychaetes species take place in late winter-early spring while in the periods sampled during this study no recruits are seen in the bottoms. This could be an indication that such high numbers of these two species are as a response of some type of pressure. The presence in high numbers of these two species reduced deeply the diversity of the assemblage in which this occurs. 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