Kazemi-Dinan A, Schroeder F, Peters L, Majdi N & W Traunspurger (2014). The effect of trophic state and depth on periphytic nematode communities in lakes. Limnologica 44: 49-57. DOI: http://dx.doi.org/10.1016/j.limno.2013.05.011
The effect of trophic state and depth on periphytic nematode communities in lakes
Ardeshir Kazemi-Dinan, Fabian Schroeder, Lars Peters, Nabil Majdi & Walter Traunspurger
The aim of this study was to investigate whether nematode community patterns are shaped by nutri- ent and light availability. Accordingly, nematode communities inhabiting periphyton were investigated at gradual water depths (50, 150 and 250 cm) in three Swedish lakes showing graded trophic states. It was hypothesized that: (1) nematode density correlates positively with increasing nutrient availability and negatively with increasing depth; (2) increasing nutrient availability favors species and feeding type richness; (3) increasing depth favors deposit-feeders; and (4) differences in the algal composition of the periphyton affect the diet of algal-feeders. Our results showed that the biomass of periphytic algae increased with nutrient availability and decreased with increasing depth. Nematode density also increased with increasing trophic state. Species richness decreased with increasing depth in the investigated oligotrophic lake, while the opposite pattern was determined in the other two lakes. Lake trophic state significantly affected the trophic structure of the nematode community, with more algal-feeders occurring in the eutrophic lake whereas chewers were found only in the meso- and eutrophic lakes. Water depth was also shown to influence nematode feeding type structure, as in all lakes the abundance of deposit-feeders was greater at increasing depth. While diatoms dominated the periphytic algal community at all lakes and depths, analyses of the gut pigment content of nematodes showed that their diet shifted toward green algae in the oligotrophic lake and in shallow zones of the mesotrophic lake.
Limnologica 44: 49-57 (2014)
Schroeder F, Peters L & W Traunspurger (2013). Nematodes in the periphyton of lakes: Variations in diversity, species composition, age structure and sex ratio. International Review of Hydrobiology 98(6): 322–333. DOI: http://dx.doi.org/10.1002/iroh.201301652
Nematodes in the periphyton of lakes: Variations in diversity, species composition, age structure and sex ratio
Fabian Schroeder, Lars Peters & Walter Traunspurger
Temporal fluctuations in the diversity, sex ratio, age, and species composition of free-living nematodes inhabiting the periphyton of stony hard-substrates were determined in three Swedish lakes differing in trophic state. Over a two-year sampling period, different temporal patterns were observed. In the oligotrophic lake, nematode diversity showed moderate fluctuations and peaked in early summer. Diversity in meso- and eutrophic lakes showed the opposite pattern. Species composition changed along seasons, enabling to identify typical early and late season assemblages. This succession was linked to different reproduction periods of dominant species. The age structure and sex ratio of periphytic nematode communities varied both temporally and between lakes according to species traits. As an example, the male/female ratio increased with increasing lake trophic state. This trend reflects the decrease of partenogenetically reproducing species with increasing lake trophic state, and may be further considered as an indicator of lake trophic state.
International Review of Hydrobiology 98(6): 322–333 (2013)
Schroeder F, Kathöfer D, Traunspurger W & L Peters (2013). Grazing impacts on periphytic assemblages in lakes across different depth levels. Freshwater Science 32(4): 1088-1100. DOI: http://dx.doi.org/10.1899/12-214.1
Grazing impacts on periphytic assemblages in lakes across different depth levels
Fabian Schroeder, Dominik Kathöfer, Walter Traunspurger and Lars Peters
The periphyton of stony hard substrates in the littoral zone of lakes is inhabited by an abundant and diverse algae and meiofauna assemblage that is regulated by grazing. The objective of our study was to examine the effect of macroinvertebrate grazers on periphytic algae and meiofaunal organisms at different depths in the littoral zone of Lake Erken (Sweden). To this end, a 2-factorial field experiment was carried out in which macrofaunal access to the periphyton was manipulated at 3 different water depths (30, 70, and 200 cm). Grazing effects on algal biomass varied among depths and were highest in both deeper zones. Compared to algal biomass, the abundance of meiofaunal organisms was less affected by grazing because macrograzers significantly reduced meiofauna only at the 200-cm depth. The organism mainly responsible for the depth-dependent differences in grazer effects was the snail Theodoxus fluviatilis, which dominated macrofaunal assemblage at depths where grazing effects were the strongest (70 and 200 cm). The abundance of T. fluviatilis was positively correlated with the proportions of reduced algal biomass and reduced meiofaunal abundance. Meiofaunal groups and individual nematode species responded differently to grazing, so our results further revealed that grazing macroinvertebrates affected the composition of the meiofaunal assemblage. However, meiofaunal and nematode assemblages differed more across depths than across grazing treatments, suggesting that other depth-related factors (e.g., hydrodynamics or light) also were important for structuring periphytic meiofaunal assemblages.
Freshwater Science 32(4): 1088-1100 (2013)
Estifanos TK, Traunspurger W & L Peters (2013). Selective feeding in nematodes: a stable isotope analysis of bacteria and algae as food sources for free-living nematodes. Nematology 15: 1-13. DOI: http://dx.doi.org/10.1163/156854112×639900
Selective feeding in nematodes: a stable isotope analysis of bacteria and algae as food sources for free-living nematodes
Tafesse K Estifanos, Walter Traunspurger & Lars Peters
Laboratory experiments with stable isotopes (C-13 and N-15) were conducted to determine the importance of bacteria and algae as food sources for free-living nematodes. All tested bacterivorous nematodes (Caenorhabditis elegans, Acrobeloides tricornis, Poikilolaimus sp. and Panagrolaimus sp.) were found to be depleted in delta C-13 (on average by -1.71 +/- 0.56 parts per thousand) and enriched in delta N-15 (on average by 3.17 +/- 1.27 parts per thousand) relative to their bacterial diets of Escherichia coil and Matsuebacter sp. The nematode species showed considerable differences in their stable isotope composition with respect to food sources. Moreover, they differed significantly in delta C-13 and delta N-15 values when placed on the same bacterial diet of E. coli, consistent with differences in their trophic shifts. Conversely, no differences in delta C-13 values were observed among nematode species placed on the same Matsuebacter sp. diet. In mixed food sources of E. coli and Matsuebacter sp., E. coli contributed 71% of the carbon to C. elegans and Matsuebacter sp. more than 90% of the carbon to A. tricornis. An enrichment experiment based on C-13-enriched (NaHCO3)-C-13, C-13(6)-glucose and N-15-enriched (NaNO3)-N-15 tracers in a freshwater periphytic community showed the importance of micro-algae and diatoms over heterotrophic bacteria as the main food sources of free-living periphytic nematodes. In this respect, direct grazing may predominate, possibly together with the use of extracellular polymeric substances (EPS) from diatoms. In general, the use of stable isotopes to study nematode feeding ecology can be useful to investigate directly the type of ingested food item(s), different bacteria and algae, and the contribution to nematode diet, in addition to the conventional feeding type scheme.
Nematology 15: 1-13 (2013)
Schroeder F, Traunspurger W, Pettersson K & L Peters (2012). Temporal changes in periphytic meiofauna in lakes of different trophic states. Journal of Limnology 71(1): 216-227. DOI: http://dx.doi.org/10.4081/jlimnol.2012.e23
Temporal changes in periphytic meiofauna in lakes of different trophic states
Fabian Schroeder, Walter Traunspurger, Kurt Pettersson & Lars Peters
Meiofaunal organisms in the periphyton of stony hard-substrates (epilithon) were studied in three Swedish lakes with different trophic states (oligo-, meso- and eutrophic) with respect to seasonal successions in abundance, biomass, and production. Over a period of 2 years, the meiofaunal population of all three lakes fluctuated greatly, with densities varying up to nine-fold within a season. In the oligotrophic lake, a significant decrease in meiofauna in winter was striking, whereas in the other two lakes, richer in nutrients, there was a pronounced peak in early summer Although the lakes, on average, did not differ in epilithic organic and inorganic material, the differences in meiofaunal abundance, biomass, and production were significant. Correlation analysis revealed that altogether the meiofaunal biomass was positively related to the lakes trophic state (total phosphorus), while the meiofaunal abundance and production along the trophic spectrum displayed a humped-shape distribution, with maximum values measured in the mesotrophic Lake Erken (1324 ind cm(-2) and 2249 mu g DW cm(-2) y(-1)). Nematodes were the dominant meiofaunal group in the epilithon of all three lakes, accounting for up to 58% in abundance, 33% in biomass and 55% in production of the whole meiofaunal community. However their relative importance tended to decrease with increasing trophic state. Beside nematodes, rotifers, oligochaetes, copepods and tardigrades were also found in large numbers in the epilithon. Overall, the results demonstrated that, due to their high abundance, biomass, and production, meiofaunal organisms play an important role in epilithic communities.
Journal of Limnology 71(1): 216-227 (2012)
Schroeder F, Peters L & W Traunspurger (2012). Temporal variations in epilithic nematode assemblages in lakes of different productivities. Fundamental and Applied Limnology 181(2): 143-157. DOI: http://dx.doi.org/10.1127/1863-9135/2012/0332
Temporal variations in epilithic nematode assemblages in lakes of different productivities
Fabian Schroeder, Lars Peters & Walter Traunspurger
The aim of the present study was to examine: (1) the response of nematodes to temporal changes in the periphyton of stony hard-substrates (epilithon) and (2) the distribution of the nematode species among lakes of different productivities. Accordingly, epilithic nematode assemblages of three Swedish lakes with different trophic states were analyzed over a 2-year period. Depending on habitat size and food availability measured as organic material, algal biomass and inorganic material, nematode populations showed distinct temporal patterns, reaching maximum densities up to 1014 ind. cm(-2) in spring and lowest densities in winter (minimum abundance 27 ind. cm(-2)). A comparison of the analyzed lakes revealed clear differences in nematode species composition. A multivariate statistical analysis showed that the distribution of nematode species along the lakes was significantly linked to the nutrient conditions of the lakes and to the algal biomass in the epilithon. Accordingly, several nematode species could be classified as bioindicators of lake trophic state. Whereas, for example, the two dominant algal-feeding species, Punctodora ratzeburgensis and Chromadorina viridis, were dependent on high nutrient levels, the abundance of species belonging to the genera Rhabdolaimus (R. aquaticus, R. terrestris) and Eumonhystera (E. vulgaris, E. simplex, E. pseudobulbosa) correlated negatively with trophic state. Also linked to increasing nutrient conditions was the change in the composition of the nematode feeding types among the lakes, from one dominated by bacterial feeders to one in which algal feeders predominated. The trophic structure of the assemblage changed in parallel, with a larger proportion of predatory species (chewers) in the eutrophic lake than in the two lakes which were more nutrient poor. For suction feeders, the inverse pattern was observed. Our results underline the importance of the epilithon as the habitat of a highly abundant and diverse nematode fauna that is strongly influenced by the trophic state of its resident lake.
Fundamental and Applied Limnology 181(2): 143-157 (2012)
Peters L, Faust C & W Traunspurger (2012). Changes in community composition, carbon and nitrogen stable isotope signatures and feeding strategy in epilithic aquatic nematodes along a depth gradient. Aquatic Ecology 46(3): 371-384. DOI: http://dx.doi.org/10.1007/s10452-012-9408-x
Lars Peters, Carsten Faust & Walter Traunspurger
Periphyton is an important component within the littoral zones of lakes, but it is known to vary dramatically on small (cm-m) and large (km) spatial scales, showing differences in composition and abundance. Until relatively recently, changes in periphyton composition along depth gradients have not been studied sufficiently and the response of small meiobenthic invertebrates inhabiting the periphyton to vertically changing environmental conditions such as light are poorly understood. To investigate the changing community composition of epilithic (on stones) nematodes along a depth gradient, we conducted a field study at Lake Erken, Sweden, with the specific objective to investigate whether changes in periphyton composition (algae, bacteria) are reflected in changing nematode feeding types and what the consequences are for nematodes and their resource consumption. We analysed the abundance, species composition and feeding type distribution of epilithic nematodes along 11 depth levels, from 5 to 300 cm water depth. Our study resulted in the first measurements of carbon (C-13) and nitrogen (N-15) stable isotopes in free living nematodes in lakes. Nematode community composition and feeding type distribution exhibited dramatic changes along the depth gradient. Nematode feeding types changed from a dominance of algae-feeding species in the shallow littoral zone to one of bacteria-feeding species in the deep littoral zone. The C-13 stable isotope signatures of nematodes and the small (< 20 µm) periphyton fraction changed with increasing depth, with nematodes shown to feed on this small periphytic component. Nematodes were identified as primary consumers by means of trophic level calculations based on N-15 stable isotopes.
Aquatic Ecology 46(3): 371-384 (2012)
Peters L & W Traunspurger (2012). Temporal patterns in macrograzer effects on epilithic algae and meiofauna: a comparative approach to test for single species and whole grazer community effects. Aquatic Sciences 74(2): 229-240. DOI: http://dx.doi.org/10.1007/s00027-011-0214-7
Temporal patterns in macrograzer effects on epilithic algae and meiofauna: a comparative approach to test for single species and whole grazer community effects
Lars Peters & Walter Traunspurger
Within the shallow littoral zones of lakes, periphyton is an essential component, representing an important source of primary production and a food resource for herbivores. Periphytic communities are abundantly inhabited by meiofaunal organisms, which are mostly dominated by nematodes. During the last 3 decades, consumer resource interactions between herbivore consumers and periphytic components (mainly algae) have been intensively studied. Although whole grazer community and single species effects on periphyton are known from field and laboratory experiments, the importance of single, dominant grazer taxa in direct comparison to whole community impacts is unknown. To investigate the continuity of grazing effects of a single, dominant macro grazer (Theodoxus fluviatilis, Gastropoda, Prosobranchia) on epilithic meiofauna and algae with respect to the whole grazer community, a temporally structured field experiment was carried out in Lake Erken (Sweden). Grazer impacts on periphytic algae and meiofauna were tested by controlling macrograzer access to littoral periphyton communities for 8 weeks in an exclosure/enclosure experimental design. Overall, the results showed macrograzer presence to have temporally constant, strongly negative effects on algal biomass as well as meiofaunal abundance and community composition. Moreover, T. fluviatilis alone accounted for up to 80% of the grazing effects, indicative of their ability to regulate periphytic communities in lakes. The present study yields new insights into the effects of a single grazer species and stressed temporal patterns of consumer resource interactions in freshwater lakes.
Aquatic Sciences 74(2): 229-240 (2012)
Probst WN, Stoll S, Peters L, Fischer P & R Eckmann (2009). Lake water level increase during spring affects the breeding success of bream Abramis brama (L.). Hydrobiologia 632(1): 211-224. DOI: http://dx.doi.org/10.1007/s10750-009-9842-5
Lake water level increase during spring affects the breeding success of bream Abramis brama (L.)
Wolfgang N Probst, Stefan Stoll, Lars Peters, Philipp Fischer P & Reiner Eckmann
In Lake Constance, Eurasian bream Abramis brama (L.) spawn in very shallow littoral areas by the beginning of May. They attach their adhesive eggs to pebble and cobble substratum at
Hydrobiologia 632(1): 211-224 (2009)
Hodda M, Peters L, & W Traunspurger (2009). Nematode Diversity in Terrestrial, Freshwater Aquatic and Marine Systems in M. Wilson, & T. Kakouli-Duarte (Eds.): Nematodes as Environmental Indicators, pp. 45–93, CABI Publishing, Oxfordshire, UK. ISBN 1845933850
Peters L, Wetzel MA, Traunspurger W & KO Rothhaupt (2007). Epilithic communities in a lake littoral zone: the role of water-column transport and habitat development for dispersal and colonization of meiofauna. Journal of the North American Benthological Society 26(2): 232-243. DOI: http://dx.doi.org/10.1899/0887-3593(2007)26[232:eciall]2.0.co;2
Epilithic communities in a lake littoral zone: the role of water-column transport and habitat development for dispersal and colonization of meiofauna
Lars Peters, Markus A Wetzel, Walter Traunspurger & Karl-Otto Rothhaupt
During the past 30 y, periphyton has been recognized as a key component in the benthos of lake littoral zones. However, the role of meiofauna-sized organisms living in the periphyton and mechanisms regulating and influencing those communities largely have been neglected, and the process of community development and colonization pathways of periphytic meiofauna are unknown in lakes. We studied these processes on littoral hard substrates in an oligotrophic lake. We manipulated the access of meiofauna to artificial hard substrates for a period of 57 d in a field experiment. In one treatment, the direct colonization pathway via active crawling was prohibited by elevating substrates into the water column. Development of the meiofaunal community was compared between elevated and nonelevated (control) treatments. In addition, relationships among the meiofaunal communities on the substrates in the field experiment and those in sediment traps and on natural hard substrates were examined. Periphyton biomass (chlorophyll a, total organic matter) and inorganic matter increased significantly in both experimental treatments throughout the experiment. Meiofauna colonized the substrates quickly and reached maximum densities of 107 ind./cm(2). The initial colonization phase (2-8 d) was characterized by a great variation in meiofaunal community structure; rotifers and crustaceans were the most abundant groups. Communities became less variable during the experiment and resembled natural communities on hard substrates at the end of the experiment. In general, development of meiofaunal abundance and periphyton biomass was rapid and proceeded similarly in both treatments. Our results show that colonization of littoral hard substrates can be driven by water-column transport of meiofauna and point to the importance of this pathway for dispersal and colonization of hard substrates by meiofauna.
Journal of the North American Benthological Society 26(2): 232-243 (2007)
Peters L, Hillebrand H & W Traunspurger (2007). Spatial variation of grazer effects on epilithic meiofauna and algae. Journal of the North American Benthological Society 26(1): 78-91. DOI: http://dx.doi.org/10.1899/0887-3593(2007)26[78:svogeo]2.0.co;2
Spatial variation of grazer effects on epilithic meiofauna and algae
Lars Peters, Helmut Hillebrand & Walter Traunspurger
Periphyton is a key component of shallow littoral zones of lakes and streams because it is an important source of primary production and a food resource for herbivores. Meiofauna are abundant in periphyton, but macroinvertebrate grazer (macrograzers) effects on periphytic meiofauna have not been studied so far. We used a spatially structured field experiment (hierarchical nested design consisting of 3 subsites at each of 3 sites) in Lake Erken (Sweden) to investigate the effect of macrograzers on epilithic meiofauna and algae in periphyton by controlling macrograzer access to littoral periphyton communities. Overall, we found a strong negative effect of macrograzer presence on algal biomass and some evidence for negative macrograzer effects on meiofaunal abundance and community composition. The impact of macrograzers on both algae and meiofauna were highly variable between sites and subsites. The largest spatial differences were for macrograzer effects on meiofaunal abundance and composition. We also investigated the ability of macrograzers to reduce spatial heterogeneity of periphyton biomass, but the presence of macrograzers did not alter the variation in algal biomass and associated meiofauna among replicates. We conclude that strong local variability in algal biomass and meiofauna abundance exists between neighboring sites even in the presence of strong overall macrograzer effects. This local variability could be based on factors known to cause spatial heterogeneity, such as hydrodynamics, nutrients, substrate characteristics (size, texture, exposure), or biotic interactions.
Journal of the North American Benthological Society 26(1): 78-91 (2007)
Fink P, Peters L & E Von Elert (2006). Stoichiometric mismatch between littoral invertebrates and their periphyton food. Archiv für Hydrobiologie 165(2): 145-165. DOI: http://dx.doi.org/10.1127/0003-9136/2006/0165-0145
Stoichiometric mismatch between littoral invertebrates and their periphyton food
Patrick Fink, Lars Peters & Eric von Elert
Ecological stoichiometry is considered a key concept in understanding constraints in energy transfer at the plant-herbivore interface. However, whether this concept is relevant for benthic freshwater ecosystems is not fully known. Therefore, a field survey was conducted in 2003 during the growing season in the littoral zone of Lake Constance, a large pre-alpine lake in central Europe. The aim was to assess temporal variation in the elemental stoichiometric composition in both herbivorous macro-invertebrates and their food resource, the periphyton in two different lakes. The periphyton showed large temporal and spatial variation in carbon, nitrogen, and phosphorus content, with particularly high molar C:P ratios of up to 1225:1. Periphyton C:P and C:N ratios were often high and constantly above the Redfield ratio that is considered optimal for autotrophic growth. In contrast to the pronounced fluctuations in the nutrient ratios of their food resource, the herbivorous macroinvertebrates showed only very little variation in their nutrient ratios, which indicated that they are homeostatic, i.e., physiologically restricted to a comparatively narrow range of C:P and C:N ratios. Distinct species-specific C:P and C:N ratios were found for different taxonomic groups of macroinvertebrates, which indicated different requirements of optimal dietary C: P and C: N ratios and which might influence the ability of the taxa to compete for limiting elemental nutrients. Considering the temporally very high C: P and C: N ratios of the periphytic resource and the very low ratios of the consumer body tissue, this stoichiometric mismatch is likely to constrain growth and reproduction of these littoral invertebrates. Therefore, the concept of stoichiometric food quality limitation might also be applicable to the littoral food web in lakes.
Archiv für Hydrobiologie 165(2): 145-165 (2006)
Peters L, Traunspurger W, Wetzel MA & KO Rothhaupt (2005). Community development of free-living aquatic nematodes in littoral periphyton communities. Nematology 7:901-916. DOI: http://dx.doi.org/10.1163/156854105776186352
Community development of free-living aquatic nematodes in littoral periphyton communities
Lars Peters, Walter Traunspurger, Markus Wetzel & Karl-Otto Rothhaupt
The development of an epilithic nematode Community and the mode of colonisation was monitored over a 57-day period during spring in a field experiment in the littoral zone of a large oligotrophic lake. Two types of experimental units were used: one type prohibited direct colonisation via active crawling by elevating substrates into the water column and the second type had substrates placed on the lake bottom. Data from the two types of units and from nearby natural hard substrates were compared. The nematodes quickly colonised on the introduced substrates and reached maximum densities of 123 individuals per 10 cm(2) after 57 days. Nematode densities on elevated and non-elevated substrates did not differ significantly. The nematode abundance and community Structure showed a large initial variation, but became more stable over time and resembled the natural community structure at the end of the experiment. The maximum number of nematode species was reached after 2 weeks of colonisation, with a maximum species number on days 12 and 14 in the experimental units and on day 19 on the surrounding natural hard substrates. The five numerically dominant species, Eumonhystera vulgaris, Chromadorina bioculata, Eumonhystera filiformis, Chromadorina viridis and Daptonema dubium, accounted for most of the variation between the different communities. The results indicate that water-column transport was the main colonisation pathway of epilithic nematodes. The distribution of nematode species points to potential morphological adaptations of some species for persistence on hard substrates.
Nematology 7:901-916 (2005)
Peters L & W Traunspurger (2005). Species distribution of free-living nematodes and other meiofauna in littoral periphyton communities of lakes. Nematology 7: 267-280. DOI: http://dx.doi.org/10.1163/1568541054879520
Species distribution of free-living nematodes and other meiofauna in littoral periphyton communities of lakes
Lars Peters & Walter Traunspurger
Recent studies on meiofaunal and nematode communities have focused on soft sediments in streams, lakes and marine environments. Despite a large number of studies dealing with periphyton, meiofaunal and nematode communities, on littoral hard substrates in lakes have not yet been investigated in detail. Therefore, epilithic communities with particular emphasis on nematode species composition, were analysed in 17 Swedish lakes differing greatly in size, depth, trophic status and epilithic biomass. Nematode abundance ranged from 2.3 to 161.5 cm-2, and the abundance of nematodes relative to total meiofauna ranged from 20 to 77% (mean 53%). Fifty-eight nematode species were identified; species numbers varied from eight to 34 species per lake. The dominant species were Rhabdolaimus aquaticus, Punctodora ratzeburgensis, Eumonhystera dispar and Crocodorylaimus flavomaculatus. Deposit feeders dominated (71% of total fauna), followed by suction feeders (14%), epistrate feeders (12%) and chewers (3%). Of 3624 nematodes examined, 54% were juveniles, 35% females, 6% males and 5% gravid females. Multivariate analysis of the nematode species composition revealed significant differences in the community structures among lakes. This is the first study to show that meiofauna is a numerically abundant group within littoral periphyton communities in lakes, with nematodes representing the dominant group.
Nematology 7: 267-280 (2005)
Peters L, Scheifhacken N, Kahlert M & KO Rothhaupt (2005). An efficient in situ method for sampling periphyton in lakes and streams. Archiv für Hydrobiologie 163(1): 133-141. DOI: http://dx.doi.org/10.1127/0003-9136/2005/0163-0133
An efficient in situ method for sampling periphyton in lakes and streams
Lars Peters, Nicole Scheifhacken, Maria Kahlert & Karl-Otto Rothhaupt
We present an efficient in situ sampling device that allows a simple and quantitative sampling of natural periphyton communities. The Brush Sampler is based on a previously developed sampler, which was improved by the addition of an external water supply, ball valve closing mechanism, and special exchangeable stiff brushes to solve previously reported problems of biomass overestimation and underestimation. The Brush Sampler was tested under ambient conditions in the field at four different sampling sites in a lentic and a lotic system and compared to the old sampler and control samples. The tests revealed a high inaccuracy of the old sampler and showed that biomass estimates (ash-free dry mass and chlorophyll-a content) obtained with the improved Brush Sampler did not significantly differ from biomass values determined from scrapings of control samples collected at the same sites. Therefore, our modified sampling device can be used as a tool for quantitative and qualitative epilithon community analyses.
Archiv für Hydrobiologie 163(1): 133-141. (2005)
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