Testate amoebae as a potential tracer of organic matter dislodged from peat extraction areas

This is a self-archived version of an original article. This version may differ from the original in pagination and typographic details. Author(s): Title: Year: Version: Copyright: Rights: Rights url: Please cite the original version: CC BY 4.0 https://creativecommons.org/licenses/by/4.0/ Testate amoebae as a potential tracer of organic matter dislodged from peat extraction areas © Boreal Environment Research Publishing Board, 2020 Published version Daza Secco, Emmanuela; Haimi, Jari; Vähäkuopus, Tuija; Ojala, Antti; Valpola, Samu; Meissnner, Kristian Daza Secco, E., Haimi, J., Vähäkuopus, T., Ojala, A., Valpola, S., & Meissnner, K. (2020). Testate amoebae as a potential tracer of organic matter dislodged from peat extraction areas. Boreal Environment Research, 25, 19-37. http://www.borenv.net/BER/archive/pdfs/ber25/ber25-019037.pdf 2020 BOREAL ENVIRONMENT RESEARCH 25: 19–37 © 2020 ISSN 1797-2469 (online) Helsinki 25 March 2020 Editor in charge of this article: Johanna Mattila Testate amoebae as a potential tracer of organic matter dislodged from peat extraction areas Emmanuela Daza Secco1)2), Jari Haimi1), Tuija Vähäkuopus3), Antti Ojala4), Samu Valpola3) and Kristian Meissner2)* 1) University of Jyväskylä, Department of Biological and Environmental Science. Survontie 9C, 40500 Jyväskylä, Finland 2) Finnish Environment Institute. Survontie 9A, 40500 Jyväskylä, Finland (*corresponding author’s e-mail: [email protected]) 3) Geological Survey of Finland, P.O. Box 97, 67101 Kokkola, Finland 4) Geological Survey of Finland, P.O. Box 96, 02151, Espoo, Finland Received 9 May 2019, final version received 21 Feb. 2020, accepted 5 Feb. 2020 Daza Secco E., Haimi J., Vähäkuopus T., Ojala A., Valpola S. & Meissner K. 2020: Testate amoebae as a potential tracer of organic matter dislodged from peat extraction areas. Boreal Env. Res. 25: 19–37. In the boreal zone, surface waters mostly receive external organic matter (OM) from surrounding peatlands. The lake’s biological communities may respond to changes in OM inputs caused by anthropogenic activities in the catchment. Testate amoebae (TA) possess an outer shell that preserves well in lake sediments and are commonly used in paleo-environmental studies. Additionally, they fall into the size range of particles transported from peatlands to lakes, making them potential particle tracers. Here, we compared TA communities of current and pre-peat extraction sediments from lakes receiving OM only from peat extraction areas (impact lakes) with lakes receiving OM from peatlands under other uses (control lakes). We found no differences between control and impact lakes, neither between current and pre-peat extraction. In conclusion, there is either no significant increase in the amount of organic matter discharge from peatland areas, or dislodged testate amoeba are retained in areas upstream of the lakes. Introduction In peatlands, net primary production exceeds the rate of decomposition, leading to accumulation of organic matter as peat. Hence, the role of peatlands is highly important in the carbon cycle, as net sinks of atmospheric CO2 (Gorham 1995). Similarly to other ecosystems, peatlands have been subject to significant anthropogenic impacts for different purposes, such as drainage for forestry and agriculture (Coulson et al. 1990) and commercial peat harvesting (Kløve 1998, Pavey et al. 2007). In Finland, the original area covered by peatlands was ca. 104 000 km2, equalling 30% of the total land area and of which, currently ca. 59 000 km2 have been drained mostly for forestry and agriculture (Turunen 2008), and ca. 650 km2 for active peat extraction (Väyrynen 2008). Peat erosion and its subsequent transport from the extraction field downstream to water systems is one of the main environmental problems of peat extraction (Kløve 1998). The eroded peat is transported to rivers and lakes where it accumulates causing eutrophication and increased sedimentation and oxygen consumption (Sallantaus 1984, Nieminen et al. 2010). 20 Daza Secco et al. • BOREAL ENV. RES. Vol. 25 In many boreal surface waters, the major source of organic matter are peatlands in their catchment areas (Clark et al. 2008). Increased leaching of organic matter due to anthropogenic activities influence nutrient cycling and photochemical processes (Stevenson 1994), mainly due to increases in colour, dissolved organic carbon concentrations (DOC), suspended solids (Kondelin 2006) and increased concentration of total nitrogen and phosphorus (Nieminen et al. 2017). In turn, these are expected to affect the biological communities of the downstream water bodies (e.g., Laine et al. 1995, Solomon et al. 2016). However, while environmental changes due to peat drainage for forestry and peat extraction in surface waters are well documented (e.g., Kauppila et al. 2016), their effects on the biota of recipient lakes are not. Effective and accurate assessment of lake ecological status require long-term environmental data to define natural or reference conditions. Unfortunately, reliably measured data prior to anthropogenic impacts are rarely available (Smol 1992). Fortunately, in lakes, paleolimnology can be applied cost-effectively to assess, monitor and evaluate ecosystem changes caused by different phenomena such as climate change, sedimentation processes, deforestation, eutrophication, acidification and can include the analyses of changes in particle sizes, stable isotope signatures, minerals, metals, and diatom, invertebrate, plant and testate amoeba communities (e.g., Björck and Wohlfarth 2001, Abbott et al. 2000, Scholz et al. 2001, Meriläinen et al. 2003, Kilhman and Kauppila 2009, Wall et al. 2010, Kauppila et al. 2012). Additionally, to evaluate the transport of particles from peat extraction areas to lake sediments, particle tracking offers a practical solution to assess transport pathways of different sediments and to identify source-sink relations (Black et al. 2007). Testate amoebae (TA) are a polyphyletic group of diverse, morphologically distinctive, ubiquitous protists characterized by outer shells (Tolonen 1986, Warner 1990) that preserve well in lakes sediments and peat deposits (Mitchell et al. 2007) even at low pH values that would affect the preservation of other fossil indicators such as molluscs, chironomids and ostracods (Dallimore et al. 2000, Beyens and Meisterfeld 2001). In addition, TA are highly abundant in wet environments and sensitive to environmental changes, i.e., they bear characteristics of ideal paleo-environmental indicators (Dallimore et al. 2000). TA communities from lentic ecosystems for example, have been used to study environmental changes caused by human activities such as land use changes and eutrophication (e.g., Boudreau et al. 2005, Reinhardt et al. 2005). Further, the material transported from peatlands downstream, typically includes organic particles smaller than 450 μm in size (Marttila and Kløve 2010), comprising the size range of TA and making them a potentially suitable particle tracer. In this study, we evaluate the applicability of TA communities as potential indicators of organic matter leaching from peat extraction areas to lake sediments, and discuss whether there is an overall effect of sediment run-off from peat extraction areas on TA communities from receiving lakes compared with areas under other peatland use. For this, we compared surface lake sediments (current TA communities) with sediments before peat extraction started in Finland from unaffected lakes and lakes affected by peat extraction water discharge. Material and methods Study site and field sampling A total of 36 lakes were selected in central Finland on the basis of possible impact from catchment peatland use: i) lakes with watersheds affected by peat extraction (impact); and ii) lakes with watersheds under different peatland use (control) (Fig. 1). In all catchment areas, other peatland uses such as agriculture and forestry were also prevalent. Lakes were paired (impact vs. control) according to their spatial proximity to the peat extraction sites. The physical, geological, and environmental settings in the catchments were identified, and in some cases, both impact and control lakes partly shared the same catchment while other pairs did not (Table 1). In cases where lake pairs shared the same catchment, the control lake received no influx from peat extraction areas and was situated upstream of the impact lake. From each lake, TA commu- BOREAL ENV. RES. Vol. 25 • Use of testaceans to trace matter from peatlands to lakes 21 nities were sampled from both sediments representing current and pre-peat extraction periods. Thus, the data set was divided into four groups: i) TA present day communities from control lakes; ii) TA present day communities from impact lakes; iii) TA communities predating peat extraction from control lakes; and iv) TA communities predating peat extraction from impact lakes. For brevity, groups will be referred to as: i) control surface; ii) impact surface; iii) control bottom; and iv) impact bottom, respectively. Hydrological properties were used to classify the lakes into impact and control lakes (Appendix Table A1). We consider that a lake is possibly affected by peat production (impact) if it is located downstream of peat production areas or is directly receiving waters from the production area. The lake is considered unaffected by peat extraction (control) when there are no upstream peat production areas in the catchment. The average lake area was 94.3 ha for impact (SD = 134.37) and 109.8 ha (SD = 164.1) for control lakes, whereas the average catchment area was 10 826.2 ha (SD = 8996.73) and 13 983.8 ha (SD = 9693.36), respectively. The average peatland area within impact lake Fig. 1. Distribution area of the study sites in central Finland 22 Daza Secco et al. • BOREAL ENV. RES. Vol. 25 Table 1. Sediment depth–age levels, rate of deposition and depth of peak of AD 1986 Chernobyl 137Cs from the sediment cores of the studied lakes. Lake Lake code* Quality of 137Cs Estimated depth Average rate of Estimated # of Estimated decade Maximum 137Cs analysis of AD 1986 deposition between years in the for the sediment concentration Chernobyl 137Cs 1986–2013 (2014) modern sample depth of 15 cm (Bq/kg) peak (cm) (mm/yr) (0–1 cm) Eitikka 1410 good 10 3.3 2 1970 483.69 Iso-Pajunen 1410 — n/d — — 322.70 Peurajärvi 1310 poor 3 1 7 1860 926.88 Halmejärvi 1310 average 7 2.3 4 1950 1287.73 Haukilampi 1307 good 8 2.6 3 1960 7277.04 Hepojärvi 1307 good 3 1 7 1860 3389.62 Hietalampi 1402 good 5 1.7 5 1930 4004.22 Hirvijärvi 1402 poor 15 5 1 1985 1538.62 Ohenjärvi 1309 average 6 2 4 1950 1300.46 Ilkonlampi 1309 average 8 2.6 3 1960 1767.56 Iso Kiuloinen 1303 — n/d — — 147.03 Sarvijärvi 1303 — n/d — — 156.64 Kangaslampi 1401 good 4 1.3 6 1900 35531.21 Iso-Musta 1401 good 3 1 7 1860 8712.19 Kokko-Valkeinen 1304 average 3.5 1.2 6 1880 5921.71 Joutenjärvi 1304 average 4 1.3 6 1900 1478.78 Jyrkkä 1302 average 9 3 2 1970 1069.44 Päsmäri 1302 good 3 1 7 1860 1061.44 Jänkkärä 1311 average 3 1 7 1860 10381.34 Levänen 1311 good 6 2 4 1950 3872.93 Pitkänjärvi 1404 good 4 1.3 6 1900 873.82 Kotjonjärvi 1404 average 4.5 1.5 5 1920 1072.31 Lehmilampi 1305 good 5 1.7 5 1930 5363.70 n/d refers to those lakes where a 137Cs Chernobyl peak could not be identified * refers to the codes given in Fig. 1 BOREAL ENV. RES. Vol. 25 • Use of testaceans to trace matter from peatlands to lakes 23 Table 1. (continued) Lake Lake code* Quality of 137Cs Estimated depth Average rate of Estimated # of Estimated decade Maximum 137Cs analysis of AD 1986 deposition between years in the for the sediment concentration Chernobyl 137Cs 1986–2013 (2014) modern sample depth of 15 cm (Bq/kg) peak (cm) (mm/yr) (0–1 cm) Uitamonjärvi 1305 good 5 1.7 5 1930 3730.08 Marttisenjärvi 1301 average 5 1.7 5 1930 765.01 Salahminjärvi 1301 average 10 3.3 2 1970 489.89 Moskulanlampi 1403 average 11 3.7 2 1975 11086.68 Suojärvi 1403 poor 4 1.3 6 1900 2881.29 Valkeisjärvi 1308 — n/d — — 754.08 Osmanginjärvi 1308 poor 3 1 7 1860 284.29 Vehkaputti 1407 average 5 1.7 5 1930 780.07 Pieni-Musta 1407 poor 5 1.7 5 1930 1895.74 Tiisjärvi 1409 poor 12 4 2 1980 2239.18 Saukkojärvi 1409 poor 5 1.7 5 1930 1427.64 Valkeislampi 1405 average 6 2 4 1950 9540.67 Ylemmäinen 1405 — n/d — — 1002.03 n/d refers to those lakes where a 137Cs Chernobyl peak could not be identified * refers to the codes given in Fig. 1 24 Daza Secco et al. • BOREAL ENV. RES. Vol. 25 catchments was 2492.6 ha (SD = 2606.98), and 3619 ha (SD = 3249.03) within the control lake catchments (Appendix Table A1). Only three catchments have a percentage of ditched area below 80%, and hence, none of the catchments can be considered to be near-pristine. However, in terms of catchment properties, all lakes represent typical lakes from peatland-dominated areas that have been affected by different anthropogenic land uses. The percentage of ditched area was higher for the impact sites (Paired t-test, t = 2.27, p = 0.03), while no differences were found between impact and control lakes for peatland percentage and percentage of production area (t = 0.77, p = 0.44 and t = 0.76, p = 0.45, respectively). Lake echo-sounding studies were conducted during the springs and summers of 2013 and 2014 and the sediment sampling points were selected from the optimal sedimentation areas based on the echo-sounding study. Sediment samples were taken using a limnos sediment corer (for details see Kansanen et al. 1991). The first layer (current TA communities) and 15 cm depth samples (pre-peat extraction TA communities) of sediment were saved in plastic bags for TA extraction. The 15 cm depth sample was selected as the pre-peat extraction sample taking into account the annual sedimentation rate for a typical lake located in a peatland catchment. Thus, the 15 cm depth sample was expected to represent the sediments before the mid-1970s where industrial peat extraction began in Finland. Sediment core dating Caesium-137 is a radioactive isotope produced as a result of nuclear weapon testing and nuclear power plant accidents after the Second World War. Having no natural sources, 137Cs contamination in environment stems from anthropogenic sources alone. The vertical distribution of caesium (137Cs) provides an important dating method in establishing age−depth models of near-surface sediments (Appleby 2000). Based on annually laminated sediments (Ojala et al. 2012, Zolitschka et al. 2015), the 1986 peak from the Chernobyl accident is the dominant feature in sediments in southern and central Finland and central Sweden, completely masking the preceding features of the 137Cs curve formed during the atmospheric nuclear weapons testing of the 50s and 60s (Klaminder et al. 2012, Ojala et al. 2016). Consequently, as our study area is mainly located within the Chernobyl fallout area, we interpreted observed peaks in 137Cs in the recent sediments to be indicative of the year AD 1986. All Caesium-137 analyses were performed using two different gamma spectrometers, an older EGandG Ortec ACE™-2K equipped with a four-inch NaI/TI detector and a new fully digital BrightSpec bMCA-USB pulse height analyser coupled to a well-type NaI(Tl) detector. Ojala et al. (2016) showed that despite detector-specific differences, both instruments provide similar results for the Chernobyl-age sediments, regardless of the sample pre-treatment or normalizing procedure. Here, 137Cs concentrations of 36 study lakes were measured with a 1 cm resolution. The length of the sediment sections measured from each lake varied between 10 cm and 20 cm, and some of the measurements were repeated using parallel sediment sequences to assure the quality of caesium-137 determinations and sediment subsampling. Testate amoebae sample processing Sediments were preserved in plastic bags at 4°C and analysed during the following weeks after sampling. Sediments were gently mixed inside the bags to homogenize the sample. To obtain TA, 2 g of sediment were used. The subsamples were transferred to 250 ml flasks with 100 ml of distilled water and one tablet of Lycopodium clavatum (Batch 1031) standard preparation from Lund University (Sweden). After boiling, samples were gently sieved through a 300 μm mesh to remove coarse material (protocol slightly modified from Booth 2010). To retain TA, the mesh size commonly used in these types of studies ranges between 30 μm and 60 μm. However, in this study a 21 μm mesh was purposefully used to also include small TA. Retained material was centrifuged for 5 min at 3000 rpm. The supernatant was removed and BOREAL ENV. RES. Vol. 25 • Use of testaceans to trace matter from peatlands to lakes 25 samples were stored in Eppendorf tubes for further analysis. Since TA concentrations were typically very low in this study, samples with more than 30 TA were included in analyses. All TA were identified using 400× magnification (Olympus BX41 microscope) and was estimated using the Lycopodium counts as an external marker (see Stockmarr 1971 for details). TA identification was based on test characteristics following several taxonomic keys (Kumar and Dalby 1998, Charman et al. 2000, Meisterfeld 2002, Mitchell 2002, Clarke 2003, Mitchell 2003). Data analysis Lake pairs with a total TA count lower than 30 in either lake, were removed from the analysis. Paired t-tests were used to check for differences in catchment and lake properties between lake groups (control and impact). To keep a balanced design, both sediment layers from the lake and its pair, were removed, leaving a total of 28 lakes (14 control lakes and 14 impact lakes). TA concentration, taxa richness, and Shannon’s diversity index (Morris et al. 2014) were calculated for each sediment layer and averaged by group and tested using paired t-tests. To identify differences in the community structures, a NonMetric Multidimensional Scaling (NMDS) based on Sørensen’s (Bray-Curtis) distance was performed on TA communities. To determine if lake or catchment properties explained the current community structure and composition of control and impact lakes, environmental variables were fitted into an NMDS ordination in a constrained analysis. All calculations were done using R (ver. 3.0.2) and the vegan package for NMDS analysis (Oksanen et al. 2015). Results Sediment cores The quality of the 137Cs dating profiles varied between the sites with regards to the shape of the curve as well as the dating potential (Fig. 2). For that reason, sediment sequences were classified according to the quality of 137Cs dating based on the appearance and distinctiveness of the Chernobyl-derived AD 1986 peak. They were classified as: (i) good; (ii) moderate; (iii) poor; and (iv) undatable. Below, we will describe the quality of each record and provide the dating basis for estimates of different sediment depth–age levels and the rate of deposition (Table 1). Many lakes showed a distinct AD 1986 137Cs peak at the depth between 3 cm and 10 cm (Fig. 2) and were rated as “good”, and i.e., they could be successfully dated with the profiles of the uppermost sediment sections. In some lakes however, the shape of the 137Cs curve with a wide maximum peak of concentration spanning between ca. 4–12 cm being different compared to any of the other analysed lakes. We interpret that the lower section (9 cm) of these peaks represents AD 1986, because at this sediment depth, the 137Cs concentration clearly rises above the background level. However, in these cases the shape of the curve is less clear due to a lower number of actual data points below the peak and thus the quality of dating was considered to only be of “moderate” accuracy. Some 137Cs profiles were categorized to represent “poor” quality of dating because they were missing a clear peak values but show some indications of elevated concentration that were interpreted to represent AD 1986. There were also lakes that we considered entirely unsuitable for dating. Many of the unsuitable lakes had low concentration of caesium in the sediment, and were located in areas that are known to have received much less fallout from the Chernobyl accident than the other studied lakes. Finally, in general, the estimated age of the sediment at 15 cm depth followed our expectations and predated the industrial extraction of peat for all but one impact lake i.e., Hirvijärvi. We therefore ran the analysis both including the lake pair 1402 and excluding it to assess its impact on the overall results. As the results did not change significantly, we present the results including the lake pair: Hirvijärvi-Hietalampi. TA communities A total of 54 TA taxa were identified in all the samples analysed. Overall, TA concentration was 26 Daza Secco et al. • BOREAL ENV. RES. Vol. 25 slightly higher in the impact surface sediments, the highest taxa richness was found in the control bottom sediments and the highest diversity in the control surface sediments (Fig. 3). However, no significant differences were found when comparing concentration, richness and diversity between sample pairs: current communities from control lakes vs. impact lakes, current communities vs. pre-peat extraction in both control and impact lakes (paired t-test, p > 0.1). On average, Trinema lineare was the most abundant taxa in all the sediment samples except for the impact bottom sediments where Difflugia oblonga “glans” showed the highest numbers, representing 11.8% of the community in that sample (Appendix Table A2). In general, TA from the genus Difflugia were abundantly found in all samples; the most common taxa being Difflugia pulex, D. oblonga “oblonga”, D. oblonga “glans”, D. oblonga “bryophyla”, D. urceolata “urceolata”, D. urceolata “elongata” and D. protaeiformis “acuminata”. Euglypha rotunda and Trinema-Corythion were also two abundant groups among all samples. The different forms of the taxa listed in this study (Appendix Table A2), correspond to morphological varieties that have been separated into sub-groups by the taxonomic key for lake sediment TA designed by Kumar and Dalby (1998). However, despite the observed patterns, no association between specific taxa and sediment layers or catchment land use were identified. NMDS ordinations repeated patterns observed for community indices (diversity and Fig. 2. Vertical distributions of caesium (137Cs) in sediment cores of studied lakes. BOREAL ENV. RES. Vol. 25 • Use of testaceans to trace matter from peatlands to lakes 33 Table A1. Geographic location (EUREF_FIN_TM35FIN WKID: 3067 Authority: EPSG), classification (Impact and Control paired according to their physical similarities and proximity) and summary of lake and catchment properties. Lake Status Lake Sampling Coordinates Lake area Mean Catchment Peatland Ditched Peatland Peat code (+) year X Y (ha) depth (m) area (ha) area (ha) area (%) (%) Prod. (%) Eitikka Control 1410 2014 546619.3564 7013137.174 97 2.1 8373 871 89.2 10.4 0.0 Iso-Pajunen Impact 1410 2014 545089.8543 7012346.794 58 0.9 9144 1769 90.5 19.3 0.4 Peurajärvi Control 1310 2013 590739.9878 7071338.286 19 6.2 26191 3678 86.6 14.0 0.0 Halmejärvi Impact 1310 2013 588743.6577 7071904.004 24 5.0 13153 2739 92.2 20.8 1.2 Haukilampi Control 1307 2013 514085.5042 6875321.243 16 * 37161 9904 90.2 26.7 4.6 Hepojärvi Impact 1307 2013 513816.6089 6878865.772 77 * 37161 9904 90.2 26.7 4.6 Hietalampi Control 1402 2014 371231.4997 6929710.647 18 * 9486 2227 95.3 23.5 6.6 Hirvijärvi Impact 1402 2014 371888.3254 6932875.181 92 1.0 9486 2227 95.3 23.5 6.6 Ohenjärvi Control 1309 2013 488721.9734 6999088.983 28 * 12014 2692 96.3 22.4 1.3 Ilkonlampi Impact 1309 2013 487280.5553 7001033.587 17 * 2231 336 98.0 15.1 3.7 Iso Kiukoinen Control 1303 2013 488888.5289 7014326.075 14 * 13417 2888 93.4 21.5 1.4 Sarvijärvi Impact 1303 2013 491305.384 7016530.764 8 * 13417 2888 93.4 21.5 1.4 Kangaslampi Control 1401 2014 396296.9946 6939831.421 10 5.2 7108 1598 92.5 22.5 2.0 Iso-Musta Impact 1401 2014 395246.7104 6939722.847 22 3.5 7108 1598 92.5 22.5 2.0 Kokko -Valkeinen Control 1304 2013 368752.985 6973747.704 26 * 17173 7335 76.4 42.7 5.2 Joutenjärvi Impact 1304 2013 371199.642 6971581.118 42 0.9 15083 4985 76.6 33.0 6.2 Jyrkkä Control 1302 2013 538481.0418 7071670.186 529 2.8 28103 6938 93.3 24.7 0.0 Päsmäri Impact 1302 2013 537517.0826 7069640.798 283 1.9 28103 6938 93.3 24.7 0.0 Jänkkärä Control 1311 2013 483264.5481 6917034.226 167 4.2 4314 748 94.9 17.3 2.9 Levänen Impact 1311 2013 482174.5023 6915527.398 31 1.1 4314 748 94.9 17.3 2.9 Pitkänjärvi Control 1404 2014 552439.3586 7070013.339 155 3.4 20226 6991 92.6 34.6 0.6 Kotjonjärvi Impact 1404 2014 556836.7424 7063456.951 79 2.2 4252 1609 87.4 37.8 4.9 Lehmilampi Control 1305 2013 386479.1559 6923821.825 18 2.9 3483 110 100.0 3.1 0.0 Uitamonjärvi Impact 1305 2013 388093.4919 6924280.878 51 4.9 2213 327 100.0 14.8 0.0 + refers to the codes given in Fig. 1 * refers to missing average depths Appendix 34 Daza Secco et al. • BOREAL ENV. RES. Vol. 25 Table A1. (continued) Lake Status Lake Sampling Coordinates Lake area Mean Catchment Peatland Ditched Peatland Peat code (+) year X Y (ha) depth (m) area (ha) area (ha) area (%) (%) Prod. (%) Uitamonjärvi Impact 1305 2013 388093.4919 6924280.878 51 4.9 2213 327 100.0 14.8 0.0 Marttisenjärvi Control 1301 2013 498022.5109 7087093.65 526 3.0 6513 1503 91.9 23.1 0.1 Salahminjärvi Impact 1301 2013 494858.5307 7081086.513 520 7.3 5375 890 91.6 16.6 3.2 Moskulanlampi Control 1403 2014 506221.3537 6955295.856 9 * 12621 1545 99.3 12.2 1.0 Suojärvi Impact 1403 2014 510546.0734 6955459.298 26 * 12621 1545 99.3 12.2 1.0 Valkeisjärvi Control 1308 2013 479522.2424 7067206.565 159 1.1 15672 7258 95.1 46.3 4.5 Osmanginjärvi Impact 1308 2013 472329.621 7066898.153 286 1.2 7439 1105 97.0 14.9 0.8 Vuorilampi Control 1407 2014 3419342.339 6916621.236 8 * 4437 284 97.4 6.4 1.0 Pieni-Musta Impact 1407 2014 421668.7425 6913433.265 8 2.0 5510 290 92.7 5.3 1.0 Tiisjärvi Control 1409 2014 306588.9376 6973309.942 170 * 22727 8422 85.6 37.1 2.1 Saukkojärvi Impact 1409 2014 310302.0836 6952549.14 60 0.6 12532 4678 73.9 37.3 0.2 Valkeislampi Control 1405 2014 467172.0509 6898602.014 8 * 2690 152 94.3 5.6 0.0 Ylemmäinen Impact 1405 2014 470895.6845 6902925.298 14 * 5729 293 99.1 5.1 0.4 + refers to the codes given in Fig. 1 * refers to missing average depths BOREAL ENV. RES. Vol. 25 • Use of testaceans to trace matter from peatlands to lakes 35 Table A2. Mean abundance (%) of testate amoebae taxa in surface and bottom sediment layers of control and impact lakes. Standard deviations are given in parenthesis. Taxa Control Impacted (abundance %) (abundance %) Surface Bottom Surface Bottom Archerella flavum 0.00 0.30 0.00 0.89 (0.00) (0.78) (0.00) (1.80) Assulina muscorum 0.00 0.00 0.00 0.37 (0.00) (0.00) (0.00) (0.91) Arcella vulgaris 1.87 1.12 1.69 0.76 (2.41) (1.54) (2.27) (1.61) Arcella catinus 0.46 0.57 0.00 0.05 (1.72) (1.71) (0.00) (0.19) Centropyxis aculeata "aculeata" 1.29 1.08 0.08 0.60 (2.88) (2.25) (0.30) (1.21) C. aculeata "discoides" 0.57 2.40 0.69 0.51 (1.47) (4.38) (2.45) (1.02) Centropyxis constricta "constricta" 0.74 1.48 1.06 1.52 (1.78) (3.51) (1.77) (2.36) C. constricta "spinosa" 0.06 0.99 0.72 1.36 (0.22) (2.26) (1.22) (4.42) C. constricta "aerophila" 0.14 0.91 0.48 0.38 (0.54) (2.25) (0.84) (0.97) Cryptodifflugia sp. 0.58 0.00 0.07 0.27 (1.79) (0.00) (0.27) (0.89) Cucurbitella tricuspis 1.65 0.75 3.83 1.50 (3.76) (1.26) (9.51) (3.66) Cyphoderia ampulla 1.07 1.37 2.33 0.59 (1.24) (2.66) (3.07) (1.40) Cyclopyxis arcelloides 3.17 2.34 2.06 2.46 (3.19) (2.62) (3.69) (4.55) Difflugia pulex 4.81 10.16 2.24 6.09 (4.41) (7.68) (3.41) (7.64) Difflugia lucida 3.27 3.81 1.13 1.71 (4.52) (4.32) (2.92) (2.98) Difflugia globulosa 2.78 1.36 2.65 3.43 (3.60) (2.26) (3.01) (4.51) Difflugia corona 0.67 0.10 0.51 0.40 (1.32) (0.26) (1.19) (1.36) Difflugia bacillariarum 0.73 0.40 0.96 0.54 (1.82) (0.79) (3.09) (1.82) Difflugia tuberculata 0.04 0.05 0.25 0.00 (0.18) (0.20) (0.94) (0.00) Difflugia pyriformis 0.22 0.18 0.49 0.28 (0.83) (0.69) (1.84) (1.06) Difflugia oblonga "oblonga" 3.67 4.85 3.74 7.94 (3.04) (3.12) (3.61) (5.38) D. oblonga "glans" 5.96 4.90 7.17 11.83 (4.13) (3.93) (4.10) (13.70) D. oblonga "lanceolata" 1.74 0.99 2.87 1.79 (3.93) (1.52) (3.16) (2.64) D. oblonga "bryophila" 3.79 3.25 2.54 5.71 (5.23) (5.22) (3.36) (8.02) D. oblonga "tenuis" 0.75 1.35 1.60 2.57 (1.13) (2.14) (2.87) (3.18) D. oblonga "spinosa" 0.66 1.53 2.80 2.91 (1.54) (5.12) (7.20) (9.90) 36 Daza Secco et al. • BOREAL ENV. RES. Vol. 25 Table A2. (continued) Taxa Control Impacted (abundance %) (abundance %) Surface Bottom Surface Bottom D. oblonga "linearis" 0.33 0.45 0.21 0.25 (0.67) (1.13) (0.50) (0.64) D. urceolata "urceolata" 6.07 3.23 7.85 4.38 (7.12) (4.56) (11.53) (4.26) D. urceolata "elongata" 5.45 3.94 6.37 6.92 (3.82) (4.33) (4.87) (6.88) D. protaeiformis "amphoralis" 1.32 0.46 0.60 0.65 (1.94) (0.52) (1.36) (1.12) D. protaeiformis "acuminata" 6.72 2.07 2.89 4.01 (0.71) (2.71) (3.21) (5.44) D. protaeiformis "claviformis" 1.44 1.75 2.96 3.25 (1.97) (1.98) (2.97) (4.78) Euglypha tuberculata 2.10 1.48 1.04 1.79 (3.36) (1.79) (2.00) (2.89) Euglypha rotunda 3.43 4.51 2.92 2.42 (5.13) (6.86) (5.23) (3.71) Euglypha compressa 1.22 2.28 0.88 0.91 (1.91) (4.35) (1.81) (2.57) Euglypha cristata 0.54 0.00 0.04 0.05 (1.72) (0.00) (0.18) (0.19) Euglypha acanthophora 1.71 1.37 1.08 0.56 (2.53) (2.13) (1.53) (1.10) Hyalosphenia papilio 0.00 0.23 0.11 0.29 (0.00) (0.48) (0.42) (0.77) Heleopera sphagni 0.88 2.71 1.28 2.74 (2.78) (3.13) (2.11) (3.92) Lagenodifflugia vas 1.09 1.20 0.38 0.43 (1.47) (2.85) (1.13) (0.86) Lesquereusia spiralis 1.73 0.62 0.76 1.06 (2.86) (1.17) (1.39) (2.00) Nebela bohemica 0.13 0.38 0.31 0.50 (0.49) (0.95) (1.18) (1.22) Nebela parvula 0.00 0.00 0.04 0.09 (0.00) (0.00) (0.17) (0.25) Nebela marginata 0.04 0.04 0.03 0.28 (0.18) (0.18) (0.13) (0.63) Nebela sp. 0.14 0.18 0.20 0.20 (0.39) (0.40) (0.55) (0.56) Pseudodifflugia fascicularis 1.45 0.78 0.39 0.36 (3.02) (1.64) (1.33) (1.37) Paulinella chromatophora 2.89 0.81 1.47 0.58 (6.12) (1.93) (2.21) (1.41) Pontigulasia compressa 0.24 2.21 1.67 1.02 (0.91) (7.48) (4.63) (2.44) Quadrulela symmetrica 0.65 1.48 0.35 0.40 (1.76) (2.48) (0.68) (0.77) Sphenoderia lenta 1.24 1.17 2.08 0.30 (1.53) (1.61) (2.72) (0.78) Trigonopyxis arcula 0.11 0.00 0.03 0.06 (0.30) (0.00) (0.14) (0.23) Tracheleuglypha dentata 1.91 3.46 3.46 3.91 (2.03) (3.66) (3.61) (3.86) BOREAL ENV. RES. Vol. 25 • Use of testaceans to trace matter from peatlands to lakes 37 Table A2. (continued) Taxa Control Impacted (abundance %) (abundance %) Surface Bottom Surface Bottom Trinema lineare 10.00 10.97 13.66 3.39 (10.92) (12.83) (15.82) (5.98) Trinema-Corythion 6.26 5.76 4.72 2.47 (5.33) (6.29) (7.17) (4.17)