Ecological Status of a Coastal Stream in the sea Port Area of Kribi, Cameroon: Diversity of Benthic Macroinvertebrates and Relationship to Some Physico-Chemical Parameters of the aquatic ecosystem

 Corresponding author: Bisse Ndiva Thérèse Inès Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Ecological Status of a Coastal Stream in the sea Port Area of Kribi, Cameroon: Diversity of Benthic Macroinvertebrates and Relationship to Some Physico-Chemical Parameters of the aquatic ecosystem Thérèse Inès Bisse Ndiva *, Samuel Foto Menbohan, Wilfreid Christiane Noel Betsi, Bolivar Ndourwe Far, Mathias Nwaha, Ulrich Tchouta, Pélagie Ladibe, Larry Nathaniel Lactio and Gideon Ajeagah Aghaindum Laboratory of Hydrobiology and Environment, Faculty of Science, University of Yaounde I, P.O. Box: 812, Yaounde, Cameroon. World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 Publication history: Received on 09 May 2025; revised on 15 June 2025; accepted on 17 June 2025 Article DOI: https://doi.org/10.30574/wjarr.2025.26.3.1721 Abstract A study aimed to assess the ecological status of the water of the Mboro coastal stream, located in the sea port area of Kribi, South Region of Cameroon, through the diversity of benthic macroinvertebrates and some physico-chemical parameters of the water were carried out. Samples were done seasonally using a multi-habitat approach. Physicochemical analyses revealed a relatively high oxygen saturation level (79.88 ± 4.91%), an average temperature of (27.70°C ± 1.66°C), and a slightly basic average pH of (7.20 ± 0.77 UC). The relatively low values of the Organic Pollution Index (IPO) indicate that the water of the Mboro stream are polluted. The biological results show a taxonomic richness of 78 taxa including 9391 individuals. Divided into 2 phyla (Molluscs and Arthropods), 4 classes, 20 orders, and 52 families. The class Gastropods was predominant with 35% relative abundance, dominated by the family of Neritidae (Nerita senegalensis), followed by the class Bivalves with a relative abundance of 33%, supplanted by the family of Mytilidae (Mytilus edulis, Xenostrobus pulex) and Mutelidae (Mutela rostrata). These organisms are pollutant-tolerant and can survive in degraded environments. Their significant presence downstream reflects the advanced deterioration of the water quality in that section of the stream. Thus, the development upstream of pollutant-sensitive groups such as the Baetidae (Ephemeroptera), Veliidae and Gerridae (Heteroptera), and Aeshnidae (Odonata) indicates a habitat of good ecological quality. The Hilsenhoff Biotic Index also revealed a notable deterioration of water quality downstream of this industrial complex. Keywords: Ecological status; Benthic macroinvertebrates; Physico-chemical parameters; Coastal stream; Mboro; Kribi sea port area 1. Introduction A coastal environment is defined as a dual terrestrial and marine fringe, one corresponding to the nearby watershed, the other to the area influenced with telluric inputs [1]. Coastal watercourses, located at the interface between terrestrial and marine ecosystems, play a crucial role in the water cycle, maintaining water quality, and supporting great biological diversity [2]. In Cameroon, watercources are subject to increasingly growing and diverse disturbances on a daily basis due to natural factors and the rapid anthropization of natural environments [3,4]. The impact of such human activities as rapid urbanization, intensive agriculture, industrial pollution, and climate change threatens the health of watercourses, leading to the degradation of water quality, the modification of aquatic populations [5], and consequently, the reduction of biodiversity [6]. Hence, the need for a permanent assessment of their health status using reliable and adequate indicators, such as biological indicators [7,8]. World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1947 The autonomous port of Kribi, linked to natural resources, promotes both economic development and environmental preservation, although it requires sustainable management to avoid pollution and ecosystem degradation. In this context, assessing the ecological status of a coastal watercourse in a port area becomes a priority to ensure its sustainable management and to prevent irreversible degradation. Thus, to assess the quality of these waters, the measurement of physico-chemical variables coupled with the diversity of bioindicators such as benthic macroinvertebrates constitutes the complete and most informative method [9,10]. Benthic macroinvertebrates are, by definition, organisms visible to the naked eye, lacking a skeleton, and spending at least part of their life cycle in water. They are recognized as good indicators of the health of aquatic ecosystems [11] due to their sedentary nature, high diversity, varied life cycles, and variable tolerance to pollution and habitat degradation [12,13]. In Cameroon, these organisms have already been the subject of several studies [14,15,16,17]. Unfortunately, few data are available on the ecological status of watercourses in the coastal area of Kribi. This study was therefore conducted to fill this gap. It aims to determine the biodiversity of benthic macroinvertebrates in the Mboro coastal river in Kribi and to analyze their relationship with certain environmental factors. 2. Material and methods 2.1. Geographical framework of study The coastal city of Kribi, located on the Gulf of Guinea in the South Region of Cameroon, is the capital of the Ocean department. It is located between 2°56'14" N latitude and 9°54'27" E longitude, with an average altitude of 18 m. Kribi is a strategic port city and an important economic center, with key economic activities including fishing, tourism, the timber industry, energy, and the deep-water port. The climate is equatorial with four unevenly distributed seasons: a long dry season (November - March), a short rainy season (April - June), a short dry season (July), and a long rainy season (August - October), with an average monthly rainfall of 239.3 mm [18]. However, field studies have shown that the long dry season actually runs from mid-December to early March, the short rainy season from late March to May, the short dry season from June to July, and the long rainy season from August to November. 2.2. Description of the Study Site and Sampling Stations Mboro is a watercourse located within the area designated for the Kribi deep sea port construction project, called Zone 1. Its source is located in the public utility declaration zone, at the foot of the Mamelles Mountains, only its lower course before the estuary lying outside Zone 1. Sampling was conducted by season (beginning and end of each season) from March 2023 to March 2024 over 12 campaigns. Four sampling stations named Mboro 1 (Mb1), Mboro 2 (Mb2), Mboro 3 (Mb3), and Mboro 4 (Mb4) and they were chosen based on the representativeness of different river sections (crenon, rhithron, potamon), site accessibility, the presence of microhabitats, and proximity to pollution sources (Figure 1). The substrate is composed of mud, sand, and granite (Table 1). As in all of Southern Cameroon, the soils fall into three categories: ferralitic soils found at the top of interfluves and at the base of slopes, hydromorphic soils in the marshy valleys, and soils in the lowlands. The geographical coordinates of these stations are contained in Table 1. Table 1 Some characteristics of the Mboro river sampling stations Code Longitude Latitude Humain action MB1 E 9°52'21.74412'' N 2°43'48.378'' No action identified MB2 E 9°52'22.18476'' N 2°43'48.52344'' Fishing, swimming, washing dishes and laundry MB3 E 9°52'18.73272'' N 2°43'50.69388'' fishing, swimming, washing dishes and laundry MB4 E 9°52'17.59548'' N 2°43'51.93516'' Swimming, presence of pirogues World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1948 Figure 1 Hydrographic map of the Mboro river showing the sampling stations. Open Street Map (OSM) 2.3. Measurement of physico-chemical parameters Physicochemical parameters were measured both in the field and in the laboratory following the recommendations of [19]. Temperature, pH, dissolved oxygen content, electrical conductivity, and salinity were measured in situ using a thermometer and a multiparameter of the HANNA HI 98130 brand respectively. In the laboratory, orthophosphates, the forms of nitrogen, were measured with a WAHTECH spectrophotometer, the alkalinity by volumetry from water samples taken in the field using the 1000 mL polyethylene vials, double-capped. The organic load of the waters was assessed by measuring the Organic Pollution Index (OPI) Table 2 and 3. Table 2 Limits of the OPI classes [20] Parameters Classes Classes NH4+ (mg/L) NO2- (µg/L) PO43- (µg/L) 5 < 0,1 ≤ 5 ≤ 15 4 0.1 - 0,9 6 – 10 16 – 75 2 2.5 – 6 51 – 150 251 -900 1 > 6 > 150 > 900 Table 3 Interpretation of the class average [20] Class average level of organic pollution 5.0 – 4.6 Nul 4.5 – 4.0 Low 3.9 – 3.0 Moderate 2.9 – 2.0 Strong 1.9 – 1.0 Very Strong World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1949 2.4. Measurement of biological variables Regarding biology, benthic macroinvertebrates were sampled using the multihabitat approach [21]. Using a squareshaped cutter of 30 cm on each side equipped with a conical net of 500 μm mesh opening and 50 cm deep, about twenty dips were made over an area of 3m2. The organisms caught in the net were collected using a pair of fine forceps and fixed with 10% formalin in polyethylene bottles. In the laboratory, the organisms were thoroughly rinsed with tap water to remove formalin and preserve in pill boxes containing 70 °C alcohol. They were then identified under a binocular magnifying glass using appropriate keys and books. Organic water pollution was assessed using the Hilsenhoff index (FBI) Table 4. The data analysis was done using Excel 2016, Spss 20.0 and XLSTAT version 2018. Table 4 Interprétation grid for Hilsenhoff Biotic Index (FBI) (1988) Hilsenhoff scale Water quality class 0.00 to 3.75 Excellent : no organic pollution 3.76 to 4.25 Very good: slight organic pollution possible 4.26 to 5.00 Good: Likely to be organic pollution 5.01 to 5.75 Average: fairly substantial organic pollution 5.76 to 6.50 Somewhat poor: substantial organic pollution 6.51 to 7.25 Poor: substantial organic pollution 7.26 to 10.00 Poor: substantial organic pollution grave 3. Results 3.1. Physicochemical parameters 3.1.1. Temperature The water temperature varies from 25.6 °C to 30.8 °C with an average value of 27.70 ± 1.66 °C (Figure 2). The KruskalWallis test showed significant differences over time (p ˂0.05). Figure 2 Spatio-temporal variation in the water temperature of the Mboro watercourse during the study period 3.1.2. pH The pH values of the waters vary from 6.50 CU (Mb2, LDS) to 8.25 CU (Mb4, LRS) for an average of 7.35 ± 0.44 CU. The Kruskal-Wallis test revealed no significant spatiotemporal differences (p > 0.05) (Figure 3). World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1950 Figure 3 Spatio-temporal variation of the pH of the Mboro watercourse during the study period 3.1.3. Dissolved Oxygen The maximum dissolved oxygen saturation rate of the water (Figure 4) is obtained at station Mb4 (92.40%) in SDS and the minimum rate at station Mb1 (66%) in SRS. Significant differences were observed between stations (p <0.05). Figure 4 Spatio-temporal variation in dissolved oxygen concentrations in waters of the Mboro stream during the study 3.1.4. Electrical Conductivity The electrical conductivity of the water has a minimum value of 35.70 µS/cm at the Mb2 station LDS and a maximum value of 34600 µS/cm at the Mb4 station in Lds (Figure 5). Spatially, the Kruskal-Wallis test revealed significant differences between station (p<0.05). Figure 5 Spatio-temporal variation in the electrical conductivity of the waters of the Mboro stream during the study period World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1951 3.1.5. Salinity Water salinity values range from 0 ppt (Mb1, Mb2, Mb3) to 2.27 ppt (Mb 4) (Figure 6). The Kruskal Wallis test showed significant differences from one season to another (p <0.05). Figure 6 Spatio-temporal variation of the salinity of the Mboro stream waters during the study period 3.1.6. Alkalinity The alkalinity values of the waters vary from 11 mg/L in SDS (Mb2 and Mb3 stations) to 91.33 mg/L in LDS (Mb4 station). The Kruskal-Wallis test revealed significant differences between seasons (p <0.05) (Figure 7). Figure 7 Spatio-temporal variation in the alkalinity of the Mboro stream waters during the study period 3.2. Organic Pollution Index (OPI) The calculation of the organic pollution index (IPO) shows values that vary between 2 indicating high pollution (all stations in the long rainy season) and 3.69 indicating moderate pollution (stations Mb1 and Mb4 in the short dry season) (Figure 8). World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1952 Figure 8 Spatio-seasonal variation of the Organic Pollution Index (OPI) during the study period 3.3. Biological parameters 3.3.1. Taxonomic richness and abundance of benthic macroinvertebrates The benthic macroinvertebrate population belongs to 02 phyla (Molluscs and Arthropods), 04 classes (Insects, Malacostracae, Gastropods and bivalves), 20 orders, 52 families and 78 genera/species for a total of 9391 individuals (Table 5). Table 5 Benthic macroinvertebrates sampled at the various stations of the Mboro stream during the study period Phyla Classes Orders Families Genera Species Mb 1 Mb 2 Mb 3 Mb 4 Total Arthrop ods Insects Heteroptera Veliidae Velia sp Velia sp 99 101 146 0 346 Microvelia sp Microvelia sp 39 7 25 0 71 Mesoveliida e Mesovelia sp Mesovelia sp 14 0 0 0 14 Gerridae Hynesionella omer-cooperi Hynesionella omer-cooperi 32 11 0 0 43 Gerris sp Gerris sp 228 84 76 0 388 Cylindrostethus quadrivittatus Cylindrostethus quadrivittatus 2 0 0 0 2 Naucoridae Laccocoris sp Laccocoris sp 6 0 0 0 6 Naucoris Naucoris 3 3 0 0 6 Belostomid ae Belostoma Belostoma cordofana 3 0 0 0 3 Sphaerodema Sphaerodema 27 0 0 0 27 Nepinae Laccotrephes Laccotrephes alter 0 2 0 0 2 Hydrometri dae Hydrometra sp Hydrometra sp 1 0 0 0 1 Nepidae Nepa Nepa seurati berg 10 0 0 0 10 World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1953 Ranatra Ranatra linearis 6 7 0 0 13 Notonectid ae Notonecta sp Notonecta sp 3 0 0 0 3 Anisops Anisops 4 2 0 0 6 Pleasp Plea sp 1 0 0 0 1 Ephemeropter a Baetidae Baetis Baetis 34 0 0 0 34 Coleoptera Haliplidae Haliplus natalensis Haliplus natalensis 5 0 0 0 5 Hydrophilid ae Hydrochara Hydrochara 3 0 0 0 3 hydrophilus hydrophilus 8 0 0 0 8 Dytiscidae Hydaticus flavolineatus Boheman Hydaticus flavolineatus Boheman 16 0 0 0 16 Laccophilus Laccophilus 3 0 0 0 3 Odonata Aeshnidae Anaciaeschna Anaciaeschna 30 0 0 0 30 Aeshna Aeshna 72 0 0 0 72 Boyeria irene Boyeria irene 32 0 0 0 32 Gomphidae Gomphus Gomphus 10 0 0 0 10 Libellulidae Libellula Libellula 40 0 0 0 40 Orthetrum Orthetrum 25 0 0 0 25 Sympetrum Sympetrum 60 0 0 0 60 Coenagrion idae Coenagrio proparte Coenagrio proparte 12 0 0 0 12 Calopterygi dae Calopteryx Calopteryx 1 0 0 0 1 Hydrophilid ae Enochrus Enochrus 1 0 0 0 1 Corduliidae Cordulia Cordulia 1 0 0 0 1 Diptera Dasyhelein ae Dasyhelea sp Dasyhelea sp. 17 0 0 0 17 Chironomid ae Chironomus Chironomus 40 10 0 0 50 Chironomini Chironomini 68 35 0 0 103 Tanytarsini Tanytarsini 0 10 0 0 10 Orthoptera Gryllotalpid ae Neocurtilla Neocurtilla 0 3 0 0 3 Malacostr aceae Decapoda Palaemonid ae Macrobrachiu m Macrobrachium vollenovenii 20 190 437 0 647 Macrobrachium macrobrachion 0 31 10 0 41 Macrobrachium niloticus 0 0 2 0 2 Atyidae Atya Atya africana 0 0 32 0 32 World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1954 Caridina Caridina africana 0 0 0 0 0 Sesarmidae Perisesarma sp Perisesarma sp 0 0 309 323 632 Potamidae Potamonaute Potamonaute ecorssei 0 16 26 30 72 Paguridae Pagurus Pagurus 0 0 0 18 18 Mollusc s Gastropod s Neogastropod a Volutiddae Cymbium Cymbium glans 0 0 2 0 2 Muricidae Stramonita Stramonita 0 0 1 0 1 Murex Murex sp 0 0 0 1 1 Caenogastrop oda Paludomid ae Cleopatra Cleopatra sp 0 0 0 306 306 Thiaridae Melanoïdes Melanoïdes tuberculata 0 0 0 10 10 Hemisinida e Pachymelania Pachymelania aurita 0 0 0 2 2 Pachymelania fusca 0 0 0 1 1 Melanopsid ae Melanopsis Melanopsis praemorsa 0 0 0 32 32 Sorbeoconcha Pachycilida e Potadoma Potadoma sp 0 0 0 3 3 Potadoma bicarinata 0 0 0 2 2 Cycloneritida Neritidae Nerita Nerita senegalensis 0 0 0 1228 1228 Neritina Neritina afra 0 0 0 607 607 Neritina nattalensis 0 0 1 0 1 Neritina tiassalensis 0 0 0 4 4 Nerit a iris 0 0 0 133 133 Theodoxus Theodoxus fluviatilis 0 0 0 2 2 Littorinimorp ha Cypraeidae Cypraea Cypraea 0 0 3 0 3 Littorinidae Echinolittorina Echinolittorina reticulata 0 0 0 834 834 Littoraria Littoraria angulifera 0 0 0 2 2 Strombidae Lobatus Lobatus gigas 0 0 2 0 2 Hydrobiida e Tomichia Tomichia producta 0 2 0 0 2 Potamidida e Pirenella Pirenella conica 0 0 0 64 64 Systellommato phora Onchidiidae Onchidella Onchidella 0 0 0 18 18 World Journal of Advanced Research and Reviews, 2025, 26(03), 1946-1961 1961 [28] Dzavi J, Foto M, Mboye B, Nwaha M, Biram in Ngon Spatiotemporal Variations of Benthic Macroinvertebratesin Some Tropical Forest Streams of Nyong Catchment (Cameroon). 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[35] Messoé, Acha Y, Ajeagah A, Abundance dynamics of odonates in the course Nyamessamba water receiving the influential agro-industrial Société des Hévéas du Cameroon-HEVECAM (Nieté – South Cameroon). Cameroon Journal of Biological and Biochemical Sciences, 30(2): 134-144 2022. [36] Mary N, The Biotic Index of New Caledonia (IBNC) and the Biosedimentary (IBS). Methodological and Technical Guide, 78 p 2015. [37] Fisher S, Gray L, Grimm N, Busch D, Temporal succession in a Desert stream ecosystem following flash flooding. Ecol. Monogr., 52, 93–110. [CrossRef] 1982. [38] Dajoz R, Précis d'Écologie, 7th ed.; Dunod: Paris, France; p. 615 2000. Authors short biography Thérèse Inès Bisse Ndiva is a PhD student in hydrobiology and environment at the University of Yaounde I, Faculty of Science, Laboratory of Hydrobiology and Environment, Cameroon. Holder of a master's degree in hydrobiology and environment (specializing in Benthic Macroinvertebrates) in 2021, she devotes her research to benthic macroinvertebrate communities as indicators of the ecological quality of freshwater environments. Her thesis focuses on the environmental factors of some rivers in the South Region of Cameroon (Kribi) and the structure of the Benthic Macroinvertebrate population, combining bioecological analyses and multivariate statistical approaches.