Community Composition In Streams Research Articles

Meta-analysis contrasting freshwater biodiversity in forests and oil palm plantations with and without riparian buffers.

The expansion of oil palm plantations has led to land-use change and deforestation in the tropics, which has affected biodiversity. Although the impacts of the crop on terrestrial biodiversity have been extensively reviewed, its effects on freshwater biodiversity remain relatively unexplored. We reviewed the research assessing the impacts of forest-to-oil palm conversion on freshwater biota and the mitigating effect of riparian buffers on these impacts. We searched for studies comparing taxa richness, species abundance, and community composition of macroinvertebrates, amphibians, and fish in streams in forests (primary and disturbed) and oil palm plantations with and without riparian buffers. Then, we conducted a meta-analysis to quantify the overall effect of the land-use change on the 3 taxonomic groups. Twenty-nine studies fulfilled the inclusion criteria. On average, plantations lacking buffers hosted 44% and 19% fewer stream taxa than primary and disturbed forests, respectively. Stream taxa on plantations with buffers were 24% lower than in primary forest and did not differ significantly from disturbed forest. In contrast, stream community composition differed between forests and plantations regardless of the presence of riparian buffers. These differences were attributed to agrochemical use and altered environmental conditions in the plantations, including temperature changes, worsened water conditions, microhabitat loss, and food and shelter depletion. On aggregate, abundance did not differ significantly among land uses because increases in generalist species offset the population decline of vulnerable forest specialists in the plantation. Our results reveal significant impacts of forest-to-oil palm conversion on freshwater biota, particularly taxa richness and composition (but not aggregate abundance). Although preserving riparian buffers in the plantations can mitigate the loss of various aquatic species, it cannot conserve primary forest communities. Therefore, safeguarding primary forests from the oil palm expansion is crucial, and further research is needed to address riparian buffers as a promising mitigation strategy in agricultural areas.

Effect of metal pollution from mining on litter decomposition in streams

Litter decomposition is critical to stream biogeochemical cycles. Metal pollution from past or present mining activities seriously threatens stream ecosystems. However, its effects on litter decomposition in streams remain unclear. A field litterbag experiment was conducted to determine the direct (i.e., via changes in stream water quality: a mine-affected vs. forest stream) and indirect (i.e., via changes in litter traits: polluted vs. non-polluted litter) effects of metal pollution from mining activities on leaf litter decomposition (total vs. microbial-driven) and the associated microbial activity and community composition in streams. Platanus acerifolia leaf litter collected from a polluted and a non-polluted site was enclosed in fine and coarse mesh bags and incubated in a mine-affected stream and a forest stream. The litter from the polluted site had a higher Pb, Zn, Cd, N, soluble sugar concentrations, specific leaf area and pH, and lower leaf toughness and lignin concentration than the litter from the non-polluted site. After incubation in situ, litter mass loss did not significantly differ between streams, but the mine-affected stream had a greater impact on total-driven decomposition rates than microbial-driven decomposition rates. Polluted litter had a significantly higher decomposition rate than non-polluted litter. The decomposition potential of polluted litter produces faster nutrient cycling and supports higher microbial colonization. Litter traits and decomposer community type modulate the influence of metal pollution on litter decomposition. The results suggest that the indirect effects of mining activities on litter decomposition were stronger than the direct effects.

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

Editorial: Green or red: Challenges for fish and freshwater biodiversity conservation related to hydropower

The Effects of Road De-icing Salts on Water Quality and Macroinvertebrates in Australian Alpine Areas.

The application of road de-icing salts has the potential to salinize fresh waters and degrade habitat for aquatic organisms. In the Australian Alps, the ecological effects of even small salinity increases from de-icing may be different than in North America and Europe because of (1) differences in the evolutionary history, and (2) areas with de-icing in Australia are not located in urbanized landscapes where de-icing has been largely studied elsewhere. In this study, we tried to determine the salinity increases attributable to de-icing in Australia and the effects of this increase in salinity to stream macroinvertebrates. We observed increased salt concentrations (as measured by continuous measurements of electrical conductivity (EC) and periodic measurements of chloride concentrations) in streams near two Australian ski resorts, during the snow seasons (June to September) of 2016 to 2018. The maximum EC observed in streams in salted sites near Perisher, New South Wales, was 390 µS cm-1 compared with a maximum of 26.5 µS cm-1 at unsalted sites. Lower EC values (i.e., maximum 61.1 µS cm-1) and short durations of salinity increases in streams near Falls Creek, Victoria, were not expected to cause an adverse biological response. Salt storage in the landscape was evident at salted sites near Perisher where EC was above background levels during periods of the year when no salt was applied to roads. Stream macroinvertebrate community composition differed at sites receiving run-off from road salting activities near Perisher. Abundances of Oligochaeta (worms) (up to 11-fold), Dugesiidae (flat worms) (up to fourfold), and Aphroteniinae (chironomids) (up to 14-fold) increased, whereas Leptophlebiidae (mayflies) decreased by up to 100% compared with non-salted sites. The taxa that were less abundant where de-icing salts were present tended to be the same taxa that toxicity testing revealed to be relatively salt sensitive species. This study demonstrates a causal link between de-icing salts, elevated stream salinity, and altered macroinvertebrate community composition in streams that received run-off from road de-icing activity in the Australian Alps.

DNA metabarcoding of stream invertebrates reveals spatio-temporal variation but consistent status class assessments in a natural and urban river

Abstract DNA metabarcoding of macroinvertebrates is increasingly used for aquatic bioassessment and -monitoring. A major strength of metabarcoding is the high taxonomic resolution provided while the inability to deliver reliable abundance data is regarded a main drawback. Data on the potential of metabarcoding to disentangle site-specific and seasonal variation with presence/absence data have been poorly explored. In addition, the robustness of ecological status assessments compliant with the European Water Framework Directive (Directive 2000/60/EG) have only been compared in few studies, none of which adressed changes across seasons. Therefore, we here investigated seasonal as well as site-specific effects on macroinvertebrate communities at six river sites in a near-natural (Sieg) and urban (Emscher) German river through metabarcoding. Furthermore, we evaluated the usability of the method for ecological status assessments. Our data showed distinct seasonal effects on OTU composition at the near-natural river Sieg. However, ecological status assessment was constant through seasons and comparable to assessments based on available morphological identification. In contrast to the river Sieg, we found strong site and stressor-specific impacts in the heterogeneous urban river Emscher. Here, ecological status assessment varied between sampling sites ranging from good to bad status but was largely consistent between seasons. Our study demonstrates the ability of presence/absence metabarcoding data to reliably assess invertebrate community composition in streams and infer environmental (natural or anthropogenic) impacts. Together with the technical robustness, our study encourages the wider adoption of the technique in stream bioassessment and -monitoring.

Effects of urban wastewater on hyporheic habitat and invertebrates in Mediterranean streams

Wastewater discharges into fluvial ecosystems represent a significant and continuous source of fine particles and nutrients that can severely modify stream community composition and functionality. Depending on both wastewater and stream features (e.g., nutrient removal treatments and stream dilution capacity), the ecological effects can be more or less severe. To determine how hyporheic habitat and hyporheos are affected, we analysed eight Mediterranean streams both upstream and downstream of a wastewater effluent. The results demonstrated that environmental factors associated with clogging, such as the quantity of fine particulate and organic matter in sediment, were magnified downstream of the wastewater inputs. Likewise, dissolved nutrients also increased but depended to a greater extent on the presence of a wastewater treatment plant and on the nitrogen and phosphorus removal treatments. The hyporheic invertebrates were more affected by clogging than by eutrophication. Both richness and diversity parameters were negatively correlated with clogging features but were not correlated with eutrophication. The most affected taxa were Macrocrustaceans, Hydrachnidia and several insect species, which decreased or were not detected downstream of the effluents. On the contrary, other taxa such as Naididae (Oligochaeta), Orthocladiinae (Chironomidae) and Potamopyrgus antipodarum (Gastropoda) benefited from the wastewater inputs.

Utilizing Environmental DNA to Assess Fish Community Composition of the West Run Watershed, Monongalia County, WV

Identification of species composition is one of initial steps to undertaking the assessment of overall ecosystem biodiversity and health. An accurate and efficient evaluation method for obtaining the means for identification can be difficult to pinpoint, and traditional invasive methods (i.e., electroshocking, nets or traps), can potentially inflict injury, and can have low detection rates. Through the collection of environmental DNA (eDNA), a variety of organisms can be detected noninvasively. For the present study we analyzed community composition of freshwater streams from the West Run Watershed (Monongalia County, WV). We employed, eDNA filtration capturing methods in the field with chloroform-isomyl alcohol extractions in the laboratory. Small fragments 12s and 16s mitochondrial RNA regions were amplified and sequenced using conventional PCR (cPCR) methods in conjunction with next generation sequencing (NGS) technologies in order to assess headwater stream community composition.

Nestedness patterns and dispersal dynamics in tropical central Indian stream fish metacommunities

Dispersal processes, such as immigration and extinction rates, and habitat properties play a crucial role in determining species composition and nestedness patterns within communities. In the current global scenario of changing environmental conditions and habitat fragmentation, information on the role of natural dispersal mechanisms and disturbance factors are especially important for understanding dynamics of species composition changes in stream ecosystems. We investigated spatial and temporal patterns of nestedness of fish communities in tropical stream systems of central India and the relationship of various dispersal factors (immigration–extinction rates and their variability) with habitat properties (habitat size and heterogeneity) and anthropogenic disturbances. We tested predictions of the classical model by Schlosser on immigration–extinction dynamics along longitudinal gradients in stream community composition for these streams. The results revealed significant patterns of nestedness for all study sites. Sites exposed to varying degrees of disturbance (induced by human activities) showed lower nestedness than undisturbed ones. Immigration rates did not show strong relations with nestedness but extinction rates were significantly related (negatively) to nestedness. In addition, disturbance played an important role in determining immigration rates and variability in immigration rates. Stream characteristics, such as habitat-size and habitat-variability gradients, were not statistically significant predictors of immigration and extinction rates. Our results demonstrate the influence of local anthropogenic disturbances on dispersal dynamics of species. A reduction in availability of suitable habitats could lower immigrations.

Co‐varying impacts of land use and non‐native brown trout on fish communities in small streams

Summary Evaluating the biological integrity of stream ecosystems requires a clear understanding of biological responses to anthropogenic stressors. Co‐variation of stressors with natural landscape gradients has been shown to complicate the ability of biological assessments to detect community‐level responses to anthropogenic stressors. Similarly, the co‐varying occurrence of non‐native species would also likely confound the ability of biological assessments to accurately determine biological integrity, although these relationships have been less studied. We compared fish communities in 99 wadeable tributaries (with catchments of 10–35 km2) of the upper Allegheny River watershed, Pennsylvania, U.S.A., to disentangle the effects of human‐induced stressors associated with agricultural development, the presence of non‐native brown trout (Salmo trutta) and background variation in community composition associated with natural landscape features. Multivariate analyses using both taxonomic and trait‐based data revealed that environmental gradients sorted fish species into different thermal communities (coolwater versus warmwater). Layered over the shift in thermal communities was the presence of large‐bodied (piscivorous) brown trout, which along with agricultural land use, was a consistent determinant of community diversity and presence–absence of nine common native species. Small‐bodied taxa (minnows, darters) were the most responsive to the presence of these large non‐native predators. Our results highlight how the presence of a non‐native species can modify the interactions between natural and anthropogenic stressor gradients and therefore confound the ability to detect signals between land use stressors and local stream community composition. The complicated interaction between brown trout and other anthropogenic stressors documented herein is likely to be a widespread phenomenon given the global introductions of many salmonid species into systems with varying anthropogenic stressor gradients. Overall, understanding how non‐native species influence stream community composition should lead to biological assessments with greater capabilities for detecting non‐native effects on biological integrity relative to the more frequently evaluated land use stressors.

Vulnerability of stream community composition and function to projected thermal warming and hydrologic change across ecoregions in the western United States.

Shifts in biodiversity and ecological processes in stream ecosystems in response to rapid climate change will depend on how numerically and functionally dominant aquatic insect species respond to changes in stream temperature and hydrology. Across 253 minimally perturbed streams in eight ecoregions in the western USA, we modeled the distribution of 88 individual insect taxa in relation to existing combinations of maximum summer temperature, mean annual streamflow, and their interaction. We used a heat map approach along with downscaled general circulation model (GCM) projections of warming and streamflow change to estimate site-specific extirpation likelihood for each taxon, allowing estimation of whole-community change in streams across these ecoregions. Conservative climate change projections indicate a 30-40% loss of taxa in warmer, drier ecoregions and 10-20% loss in cooler, wetter ecoregions where taxa are relatively buffered from projected warming and hydrologic change. Differential vulnerability of taxa with key functional foraging roles in processing basal resources suggests that climate change has the potential to modify stream trophic structure and function (e.g., alter rates of detrital decomposition and algal consumption), particularly in warmer and drier ecoregions. We show that streamflow change is equally as important as warming in projected risk to stream community composition and that the relative threat posed by these two fundamental drivers varies across ecoregions according to projected gradients of temperature and hydrologic change. Results also suggest that direct human modification of streams through actions such as water abstraction is likely to further exacerbate loss of taxa and ecosystem alteration, especially in drying climates. Management actions to mitigate climate change impacts on stream ecosystems or to proactively adapt to them will require regional calibration, due to geographic variation in insect sensitivity and in exposure to projected thermal warming and hydrologic change.

Land use impacts on stream community composition and concordance along a natural stress gradient

Most ecosystems are subjected to multiple stressors derived from natural and anthropogenic sources and community responses to human disturbance in naturally stressful habitats may differ from those in more benign habitats. We examined the influence of a natural (geology-driven acidity) vs. human-induced stress (land drainage) and their interaction on the composition and concordance of stream diatom, bryophyte and invertebrate communities. To account for differing drainage impacts in circumneutral (sedimentation) and naturally acid (reduced pH and increased metal concentrations) streams we investigated concordance in three groups of streams: reference (circumneutral and naturally acidic reference), circumneutral (reference and drained) and naturally acidic (reference and drained) streams. We expected diatoms to respond more strongly to anthropogenic acidification and more weakly to sedimentation compared to bryophytes and invertebrates. We expected overall strong concordance among the three taxonomic groups, but especially so in reference streams. All three organism groups had distinct species composition in naturally acidic vs. circumneutral streams. Concordance between communities was overall strong, especially so in the reference streams. All groups responded to drainage disturbance in both types of streams. Invertebrates were slightly less responsive to increased acidification in the naturally acidic streams but were more affected by sedimentation in the circumneutral streams than were the other two groups. The natural stressor affected communities more than the anthropogenic stressors. Naturally stressed communities were affected by an anthropogenic stressor as much as those in more benign habitats, although the additional stressor was similar to the initial stress (further reduction of stream pH). Naturally acid streams may need special concern in bioassessment because models based on circumneutral reference sites will likely produce biased predictions for these streams.

Shading effects on community composition and food web structure of a deforested pasture stream: Evidences from a field experiment in Brazil

Experimental manipulations in the field can evidence cause–effect relations from the manipulated variables. In this context, the aim of the present study was to investigate the effects of shading on stream community composition and food web structure. The experiment was conducted in two reaches of a pasture stream: one that remained open (control) and another that was covered with 75% factor shading cloth (treatment), sampled before and after 21 months. At each sampling, algae, macrophytes, plankton, meiofauna, macroinvertebrates, and fish were collected. All heterotrophic organisms were submitted to diet analysis and dietary data was used to calculate food web parameters. Community composition was evaluated through cluster analysis. A total of 7556 individuals of 148 taxa were identified. The control reach presented lower richness, abundance, and food web parameter values than the treated reach before shading cloth installation, whereas after the experiment the opposite was observed. Despite these differences, both reaches had changed over the experimental period for being under increased siltation as a result of long term land use effects, which resulted in higher similarity of community composition between periods than between treatments. This observation was corroborated by higher food web complexity before the experiment, with decreases in all food web parameters (except connectance) after 21 months, especially in the treated reach. Hence, decreases in community attributes and food web parameters after the experiment evidenced the effects of siltation, while the strongest decreases observed at the treated reach evidenced the effects of shading. Finally, we stress that the artificial shading itself does not promote allochthonous materials inputs (which add up to food web basis and promote habitat heterogeneity), so full-canopy riparian forest restoration is of fundamental importance for low-order streams.

Effect of Native Vegetation Loss on Stream Ecosystem Processes: Dissolved Organic Matter Composition and Export in Agricultural Landscapes

Stream and river ecosystems are dependent on energetic inputs from their watersheds and thus shifts in land use from forest cover to agriculture will affect stream community composition and function. The disruption of forest-aquatic linkages alters the organic matter resources in agricultural streams. Dissolved organic matter (DOM) is the dominant form of organic matter in aquatic ecosystems, and a microbial energy source that is important for stream respiration. The concentrations and characteristics of DOM are regulated by both terrestrial (for example, terrestrial organic matter supply) and in-stream processes (for example, microbial respiration and periphyton production) that are influenced by land management. The effects of watershed land use and topographic, soil and climatic variables on DOM quantity (dissolved organic carbon concentration and load), source (terrestrial or in-stream) and quality (composition and lability) were measured in 14 streams across an agricultural land-use gradient. DOC concentration was positively correlated with watershed pasture cover and negatively correlated with watershed relief. No watershed variables were important correlates of DOC load. Stream DOM was primarily of terrestrial origin, but DOM in agricultural streams had a greater proportion of sources from in-stream sources. This may be due to reduced connection with riparian vegetation and increased in-stream primary production. We suggest that maintaining watershed tree cover greater than 52% and ensuring less than 10% of the length of riparian corridor is cleared for pasture could minimize changes to DOM composition. This is important to avoid flow-on effects for stream ecosystem processes that are mediated by DOM. Long-term DOM monitoring will be valuable for assessing the functional impacts of land-use change.

Regional-scale patterns in community concordance: testing the roles of historical biogeography versus contemporary abiotic controls in determining stream community composition

The determinants of a local-scale biological community can include both abiotic and biotic factors acting at a variety of spatial and temporal scales. Previous studies have shown that the Precambrian Shield, a broad-scale geological feature, has distinct abiotic conditions and aquatic communities in lotic systems as compared with systems off-Shield. The relative importance of historical biogeography and postglacial colonization in Ontario versus the role of contemporary abiotic conditions has been debated in determining fish community composition. In this study, we sampled fish and macroinvertebrate community data from south-central Ontario streams to examine the degree of community concordance between fishes and macroinvertebrates and to determine the main abiotic drivers for this biological distinction between Shield and off-Shield areas. This study shows that low-order lotic systems on the Shield differ both abiotically and biotically from adjacent off-Shield systems and that similar abiotic drivers are responsible for structuring both groups of taxa. However, water chemistry and land-use variables are the most important in structuring macroinvertebrate communities, whereas physical habitat plays a larger role for fish communities.

Bridging the gap between theoretical ecology and real ecosystems: modeling invertebrate community composition in streams

For the first time, we combine concepts of theoretical food web modeling, the metabolic theory of ecology, and ecological stoichiometry with the use of functional trait databases to predict the coexistence of invertebrate taxa in streams. We developed a mechanistic model that describes growth, death, and respiration of different taxa dependent on various environmental influence factors to estimate survival or extinction. Parameter and input uncertainty is propagated to model results. Such a model is needed to test our current quantitative understanding of ecosystem structure and function and to predict effects of anthropogenic impacts and restoration efforts. The model was tested using macroinvertebrate monitoring data from a catchment of the Swiss Plateau. Even without fitting model parameters, the model is able to represent key patterns of the coexistence structure of invertebrates at sites varying in external conditions (litter input, shading, water quality). This confirms the suitability of the model concept. More comprehensive testing and resulting model adaptations will further increase the predictive accuracy of the model.

Ecology of freshwaters: a view for the twenty-first century

Ecology of freshwaters: a view for the twenty-first century

The hyporheic assemblage of a recently formed stream following deglaciation in Glacier Bay, Alaska, USA

Many studies focus on the recovery of stream communities following disturbances such as high flows (secondary succession); relatively few examine community composition in streams undergoing primary succession and even fewer detail the hyporheic community in such streams. We examined the composition and temporal distribution of invertebrates in the shallow hyporheic sediments of Stonefly Creek, a recently deglaciated stream in Glacier Bay, Alaska, USA, whose lower reaches became ice free in the late 1970s. We used modified polyvinyl chloride wells at four contrasting sites over two years in this stream and collected data on stream temperature, discharge, and suspended solids. A diverse assemblage of 19 taxa was found, including cyclopoid and harpacticoid Copepoda, Ostracoda, Cladocera, tardigrades, and macroinvertebrates, but the nature and extent of the goods and services provided by the hyporheos of this young stream to the whole river ecosystem are unclear. The hyporheic assemblage differed strongly between sites and years and was significantly more abundant and diverse where there was minimal disturbance by redd-digging salmon. This study gives an insight into the development of the hyporheos in a primary successional context and our findings are also relevant to new streams created during river engineering.

Hyporheic invertebrate community composition in streams of varying salinity in south‐western Australia: diversity peaks at intermediate thresholds

AbstractMany streams of southwestern Australia have become secondarily saline through land clearance and other human activities in their catchments. Elevated salinities impact on aquatic biota and ecological processes of surface streams but little is known of the effects on the diversity and community composition of hyporheic (subsurface) invertebrates occupying the saturated sediments where surface and groundwaters exchange. We hypothesized that biodiversity of hyporheic invertebrates would decline with increasing salinity, especially where saline groundwater upwelled into the surface stream. We also predicted changes in community composition associated with salinity and direction of vertical hydrological exchange. Water and hyporheic invertebrates were sampled from downwelling and upwelling zones of 13 streams in southwestern Australia ranging in median surface water salinity from 0.27 to 17.86 g L−1. Overall, taxa richness of hyporheic invertebrates was uncorrelated with salinity but, surprisingly, correlated positively with the salinity of upwelling water. However, when the sites were divided into ‘fresh’ (<3 g L−1) and ‘mesosaline’ (>3 g L−1) groups, this relationship became non‐significant. Instead, taxa richness and total abundance were correlated positively with salinity of downwelling water in fresh sites and negatively in mesosaline sites, resulting in a peak in richness at intermediate salinities. Community composition was unrelated to direction of hydrological exchange but was strongly associated with hyporheic salinity. Hyporheic assemblages of ‘fresh’ rivers were typified by harpacticoid copepods and candoniid ostracods, whereas the amphipod Austrochiltonia and several dipteran groups were more common below ‘mesosaline’ rivers. Although many hyporheic taxa collected in this study apparently have broad tolerances to salinity, secondary salinization due to human activities potentially changed community composition, possibly altering rates of ecological processes such as organic matter breakdown occurring within the sediments of streams undergoing salinization. Copyright © 2007 John Wiley & Sons, Ltd.

EFFECTS OF ADJACENT AGRICULTURAL ACTIVITIES AND WATERSHED CHARACTERISTICS ON STREAM MACROINVERTEBRATE COMMUNITIES

: Benthic macroinvertebrate communities in streams adjacent to cornfields, streams where cows had unrestricted access, and reference locations without agriculture were compared to examine the effects of local land use and land use/land cover in the watershed. At each local site, macroinvertebrates and a variety of habitat parameters were measured upstream, adjacent, downstream, and farther downstream of the local land use. A geographic information system (GIS) was used to calculate drainage basin area, land use/land cover percentages in each basin, and the distance from sample sites to the stream source. Three-way analysis of covariance (ANCOVA) tests with date, site type, and sampling location as main effects were used to explore differences in macroinvertebrate metrics using median substrate size, percent hay/pasture area, and stream depth as covariates. The covariates significantly improved model fit and showed that multiple contributing factors influence community composition. Local impacts were greatest at sites where cows had access, probably because of sedimentation and embeddedness in the substrate. Differences between the upstream and the adjacent and downstream locations were not as great as expected, perhaps because upstream recolonization was reduced by agricultural impacts or because of differences in the intensity or proximity of agriculture to riparian areas in the watershed. The results underscore the importance of both local and watershed factors in controlling stream community composition.

Taxon-specific fungal primers reveal unexpectedly high diversity during leaf decomposition in a stream

Traditional techniques for studying the fungal community composition in streams favour the detection and identification of aquatic hyphomycetes. Our objective was to use molecular techniques to determine the presence and contributions of other fungal groups. We designed primers specific for the ITS regions in Ascomycota, Basidiomycota, Chytridiomycota, Zygomycota and Oomycota. The primers were used to amplify DNA from linden, maple, and beech leaves, and birch wood submerged in a stream for 4 weeks in summer, autumn, winter and spring. The amplification products were separated by denaturing gradient gel electrophoresis. Ascomycota were present in large phylotype numbers (up to 21) on all substrates and all dates and represented ≥ 75 % of the fungal biomass. Basidiomycota were the second most abundant group in summer and autumn (up to 13 % on wood) and were absent only on linden and maple in spring. There were consistently large numbers of phylotypes from Chytridiomycota and their relative contribution to the microbial community peaked in winter on all substrates. Oomycota were present in summer and abundant only on wood. Zygomycota were present in low numbers and their estimated contribution to fungal biomass was ≤ 1%. Using primers to target individual groups facilitates a more balanced approach to studying fungal diversity in freshwater ecosystems.