Aquatic Invertebrate Community Composition Research Articles

Effects of river regulation on aquatic invertebrate community composition: A comparative analysis in two southern African rivers.

While natural floods play a crucial role in shaping the composition of aquatic communities, the most rivers worldwide are regulated or dammed for anthropogenic purposes, resulting in alterations to the biological and chemical composition of these ecosystems. Studies have demonstrated various negative effects of river regulation on aquatic invertebrate communities globally. However, there is a scarcity of research in Africa, despite its vulnerability to anthropogenic impacts. This study aimed to compare aquatic invertebrate communities in the Phongolo River, an impacted regulated river, and the Usuthu River, a less impacted unregulated river, in South Africa. It further aimed to ascertain whether Lake Nyamithi, a naturally saline lake receiving water from both of the aforementioned systems, exhibited a stronger similarity to one of the two rivers in terms of its aquatic invertebrate composition. Aquatic invertebrate and water samples were collected from 2012 to 2018 over several surveys. The Usuthu River demonstrated a diverse and sensitive aquatic invertebrate community, emphasising its high conservation value. The Phongolo River demonstrated effects of anthropogenic impact, with taxa more resilient to changes in water quality and flow compared to the Usuthu River. Mismanagement and excessive water use may lead to the loss of any remaining sensitive aquatic invertebrate communities in this river. The presence of invasive molluscan in the Phongolo River and Lake Nyamithi also poses a threat to the native aquatic invertebrate communities. These invasive species are currently absent from the Usuthu River although other invasive species, such as the Australian redclaw crayfish, are found in both river systems. Lake Nyamithi displayed a unique aquatic invertebrate community, distinct from both rivers and their floodplains. This study provides important baseline information on the Usuthu River's aquatic invertebrates and emphasises the need to maintain adequate water flow in rivers and floodplains to protect biodiversity and sensitive species.

Assessing the influence of wildfire on leaf decomposition and macroinvertebrate communities in boreal streams using mixed‐species leaf packs

Abstract We investigated how compositional differences in riparian leaf litter derived from burned and undisturbed forests influenced leaf breakdown and macroinvertebrate communities using experimental mixed‐species leaf packs in boreal headwater streams. Leaf pack mixtures simulating leaf litter from dominant riparian woody‐stem species in burned and undisturbed riparian zones were incubated in two references and two fire‐disturbed streams for 5 weeks prior to measuring temperature‐corrected breakdown rates and macroinvertebrate community composition, richness, and functional metrics associated with decomposers such as shredder abundance and % shredders. Leaf litter breakdown rates were higher and had greater variability in streams bordered by reference riparian forests than in streams where riparian forests had been burned during a wildfire. Streams bordered by fire disturbance showed significant effects of litter mixture on decomposition rates, observed as significantly higher decomposition rates of a fire‐simulated leaf mixture compared to all other mixtures. Variation among sites was higher than variation among litter mixtures, especially for macroinvertebrate community composition. In general, fire‐simulated leaf mixtures had greater shredder abundances and proportions, but lower overall macroinvertebrate abundance; however, the shredder abundance trend was not consistent across all leaf mixtures at each stream. These results show that disturbance‐driven riparian forest condition and resulting composition of leaf subsidies to streams can influence aquatic invertebrate community composition and their function as decomposers. Therefore, if one of the primary goals of modern forest management is to emulate natural disturbance patterns, boreal forest managers should adapt silvicultural practices to promote leaf litter input that would arise post‐fire, thereby supporting stream invertebrate communities and their function.

Validating anthropogenic threat maps as a tool for assessing river ecological integrity in Andean-Amazon basins.

Anthropogenic threat maps are commonly used as a surrogate for the ecological integrity of rivers in freshwater conservation, but a clearer understanding of their relationships is required to develop proper management plans at large scales. Here, we developed and validated empirical models that link the ecological integrity of rivers to threat maps in a large, heterogeneous and biodiverse Andean–Amazon watershed. Through fieldwork, we recorded data on aquatic invertebrate community composition, habitat quality, and physical-chemical parameters to calculate the ecological integrity of 140 streams/rivers across the basin. Simultaneously, we generated maps that describe the location, extent, and magnitude of impact of nine anthropogenic threats to freshwater systems in the basin. Through seven-fold cross-validation procedure, we found that regression models based on anthropogenic threats alone have limited power for predicting the ecological integrity of rivers. However, the prediction accuracy improved when environmental predictors (slope and elevation) were included, and more so when the predictions were carried out at a coarser scale, such as microbasins. Moreover, anthropogenic threats that amplify the incidence of other pressures (roads, human settlements and oil activities) are the most relevant predictors of ecological integrity. We concluded that threat maps can offer an overall picture of the ecological integrity pattern of the basin, becoming a useful tool for broad-scale conservation planning for freshwater ecosystems. While it is always advisable to have finer scale in situ measurements of ecological integrity, our study shows that threat maps provide fast and cost-effective results, which so often are needed for pressing management and conservation actions.

Debris dams as habitat for aquatic invertebrates in forested headwater streams: a large-scale field experiment

To evaluate the effects of debris dams on aquatic invertebrate communities, we sampled benthic invertebrates in debris dams and riffles in three forested headwater streams in New Zealand. As part of a large-scale field experiment, debris dams were subsequently removed from three treatment sections in each of the streams to assess effects on invertebrate communities. Prior to debris dam removal, total invertebrate densities in debris dams were not significantly different from those in riffles. However, densities of Ephemeroptera, Plecoptera and Trichoptera taxa were significantly higher in debris dams than in riffles. Debris dams contained a higher number of less common taxa (defined as <1% of total catch) and significantly higher densities of shredders. Densities for Coleoptera, Diptera and Trichoptera taxa were significantly higher in the autumn than in the spring. Non-metric multidimensional scaling axis scores indicated that both habitat and season had a significant effect on aquatic invertebrate community composition. At the reach scale, the effects of debris dam removal on the aquatic invertebrate communities were not statistically detectable because debris dams comprised only a small proportion of total habitat. However, these data highlight the importance of debris dams in contributing to the diversity of aquatic invertebrates in forested headwater streams.

Snails (Mollusca: Gastropoda) as potential surrogates of overall aquatic invertebrate assemblage in wetlands of Northeastern China

Aquatic invertebrates constitute a large proportion of biological diversity in wetlands and can be useful indicators of wetland environmental conditions; however, their assessment can be time consuming and requires special expertise. So it may be useful to screen for potential surrogates to represent overall aquatic invertebrate assemblages and make bioassessments more feasible. The composition of aquatic invertebrate communities were studied in 15 floodplain wetlands of the Wusuli River and 14 non-floodplain wetlands, all located in Northeastern China’s Sanjiang Plain. Our study showed that aquatic invertebrate assemblages in non-floodplain wetlands differed from floodplain wetlands. Then the potential surrogates were identified for 11 aquatic invertebrate groups across all 29 wetlands. Gastropoda proved to be potential surrogates of overall aquatic invertebrate species density, species richness and community similarity, and could be used to classify floodplain and non-floodplain wetlands. Nine Gastropoda species were indicators for specific wetland types. Using snail assemblages as surrogates for overall aquatic invertebrate communities may make rapid assessments of wetland condition using aquatic invertebrates simple yet effective.

Indication of pesticide effects and recolonization in streams

The agricultural use of pesticides leads to environmentally relevant pesticide concentrations that cause adverse effects on stream ecosystems. These effects on invertebrate community composition can be identified by the bio-indicator SPEARpesticides. However, refuge areas have been found to partly confound the indicator. On the basis of three monitoring campaigns of 41 sites in Central Germany, we identified 11 refuge taxa. The refuge taxa, mainly characterized by dispersal-based resilience, were observed only nearby uncontaminated stream sections and independent of the level of pesticide pressure. Through incorporation of this information into the revised SPEARpesticides indicator, the community structure specifically identified the toxic pressure and no longer depended on the presence of refuge areas. With regard to ecosystem functions, leaf litter degradation was predicted by the revised SPEARpesticides and the median water temperature at a site (R2 = 0.38, P = 0.003). Furthermore, we designed the bio-indicator SPEARrefuge to quantify the magnitude of general recolonization at a given stream site. We conclude that the taxonomic composition of aquatic invertebrate communities enables a specific indication of anthropogenic stressors and resilience of ecosystems.

Influence of land-use on structural and functional macroinvertebrate composition communities associated on detritus in Subtropical Atlantic Forest streams

Abstract Aim Our aim in this study was to evaluate the effects of land use in drainage basins of the streams on the taxonomic and functional composition of aquatic invertebrate communities associated in leaf litter. Methods We evaluated the colonisation of invertebrates in the incubated plant debris in streams with presence and absence of riparian vegetation and different land-uses in the drainage area. We used the litter bags approach. Results The taxonomic and functional composition invertebrate associated with leaf litter ranged between streams. In addition, streams with presence of vegetation showed less variation taxonomic and functional composition communities. Still, the density of shredders invertebrates were lower in streams without vegetation. Conclusions The riparian vegetation is an important environmental factor in the composition of invertebrates. However, the land-use throughout the drainage basin should be considered as relevant factor in structuring aquatic biota.

Temporary co-existence of aquatic and terrestrial invertebrates in shallow periodically flooded and frozen cave

Abstract The effect of specific microclimatic conditions and temporary flooding on terrestrial and aquatic invertebrate community composition as well as on parietal fauna was investigated in a cave located on the Krakow-Wieluń Upland. Studies of the fauna started after partial water retreat from the cave. Microclimate conditions and water chemistry parameters were also investigated. Due to the cave geometry and its size, temperatures recorded during summer were relatively high, whereas almost all its parts were frozen in winter. Temporary cave flooding promoted reproducing populations of Asellus aquaticus, Pseudocandona sarsi and copepods (Diacyclops bicuspidatus, Megacyclops viridis). Completely depigmented (including eyes), slightly, as well as fully pigmented individuals of A. aquaticus were found. Some dipterans started to reproduce in the flooded cave but drying stopped their development. Some taxa typical for terrestrial habitats (Collembola and Acari) and for parietal fauna (spider Meta menardi, moth Triphosa dubitata, dipterans from families Helomyzidae and Mycethophilidae) were not observed. Moreover, cave freezing significantly diminished the number of Culicidae, Oniscus sp., gastropods and Nesticus cellulanus wintering in the cave. The recolonization process was possible due to the cave location at the shallow subsurface and multiple entrances. The diversity of terrestrial invertebrates in the cave is very low as the effect of periodical flooding and freezing.

Aquatic communities in arid landscapes: local conditions, dispersal traits and landscape configuration determine local biodiversity

Aim To understand how environmental conditions and landscape structure interact at different spatial scales to shape the community composition of arid zone aquatic invertebrates with different dispersal abilities. Location Australia. Methods For each of five drainage basins and for their encompassing region (Pilbara), we built matrices of dissimilarities in presence–absence patterns of aquatic invertebrate community composition. This was carried out for all taxa collectively and separately for five dispersal trait groups: obligate aquatics, passive aerial dispersers, animals moving by aerial phoresy, weak and strong fliers. We analysed correlations between community dissimilarities and (1) dissimilarities in local environmental conditions, (2) geographic distances and (3) landscape resistance distances among the sites from which invertebrates were sampled. Calculation of landscape resistances accounted for longitudinal connectivity along the river channels (least-cost-path), lateral connectivity between streams and the potential effects of rugged topography on invertebrate dispersal. Results Local environmental factors and landscape resistances explained differences in community composition at the regional scale. In basins with complex topography, local environmental conditions were the main factor explaining community dissimilarities in most dispersal groups. Conversely, in basins where flatter topography meant that moderate to high lateral connectivity between streams is possible, the spatial configuration of the dendritic network determined the community composition of most dispersal trait groups. Geographic and least-cost-path distances were poor predictors of community composition. None of the groups showed a consistent correlation with environmental factors alone, or just landscape resistances, across all basins. Main conclusions Local environmental conditions, hydrological connectivity and landscape resistance to dispersal are all important influences on community composition of arid zone aquatic invertebrates. The impact of each of these factors varies with dispersal trait group and spatial configuration of basins: the importance of lateral connectivity for explaining a substantial proportion of community composition points to a major role of flooding regimes in maintaining biological communities.

Links between two interacting factors, novel habitats and non-native predators, and aquatic invertebrate communities in a dryland environment

In dryland regions, increased demand for water has led to the reduction of natural aquatic habitats and threatens persisting aquatic habitats. In the Madrean Sky Islands (MSI), water demands have also resulted in the creation of novel aquatic habitats, including stock ponds. Stock ponds are important surrogate habitat for native species, yet little is known about the aquatic invertebrates utilizing these habitats. Additionally, stock ponds support non-native vertebrate predators including American bullfrogs (Lithobates catesbeiana) and Western mosquitofish (Gambusia affinis), and the effects of these predators on invertebrate communities in stock ponds are unknown. We explored similarities in invertebrate communities in stream pools and stock ponds and compared aquatic invertebrate community composition, abundance, and richness in stock ponds with and without non-native predators. We found that despite considerable functional (trait-based) overlap in aquatic invertebrate communities, a large majority (81%) of taxa were exclusive to either stock ponds or stream pools. Additionally, we observed few differences in aquatic invertebrate community composition, abundance, and richness in stock ponds with and without non-native predators. We discuss ecological implications of our observations, limitations of our approach, and the importance of future work in determining the role of stock ponds in conservation of the region’s aquatic invertebrates.

Spatial and temporal organization of macroinvertebrate assemblages in a lowland floodplain ecosystem

An important goal in ecology is to understand controls on community structure in spatially and temporally heterogeneous landscapes, a challenge for which riverine floodplains provide ideal laboratories. We evaluated how spatial position, local habitat features, and seasonal flooding interact to shape aquatic invertebrate community composition in an unregulated riverine floodplain in western Alabama (USA). We quantified sediment invertebrate assemblages and habitat variables at 23 sites over a 15-month period. Dissolved oxygen (DO) varied seasonally and among habitats, with sites less connected to the river channel experiencing frequent hypoxia ( 14 °C during spring and summer as sites became isolated. Overall, local habitat conditions were more important in explaining patterns in assemblage structure than was spatial position in the floodplain (e.g., distance to the main river channel). DO was an important predictor of taxonomic richness among sites, which was highest where hydrologic connections to the main river channel were strongest. Compositional heterogeneity across the floodplain was lowest immediately following inundation and increased as individual sites became hydrologically isolated. Our results illustrate how geomorphic structure and seasonal flooding interact to shape floodplain aquatic assemblages. The flood pulse of lowland rivers influences biodiversity through effects of connectivity on hydrologic flushing in different floodplain habitats, which may prevent the development of harsh environmental conditions that exclude certain taxa. Such interactions highlight the ongoing consequences of river regulation for taxonomically diverse floodplain ecosystems.

EFFECTS OF GEOMORPHIC PROCESS DOMAINS ON RIVER ECOSYSTEMS: A COMPARISON OF FLOODPLAIN AND CONFINED VALLEY SEGMENTS

ABSTRACTThe geomorphic template of streams and rivers exerts strong controls on the structure and function of aquatic ecosystems. However, relationships between stream geomorphology and ecosystem structure and function are not always clear and have not been investigated equally across spatial scales. In montane regions, rivers often alternate between canyon‐confined segments and unconfined floodplain segments. Yet, few studies have evaluated how this pattern influences aquatic ecosystems. Here, we compared five confined river segments to five paired floodplain segments in terms of allochthonous inputs, aquatic primary producer and invertebrate production, stream retentive capacity, and aquatic invertebrate community composition. We found that floodplains had a higher (up to 4×) retentive capacity, a greater richness (58%) of aquatic invertebrates, and a distinctly different invertebrate community, relative to confined segments. Contrary to our expectations, allochthonous inputs were approximately 2× greater for confined segments, and aquatic primary and invertebrate production exhibited no consistent differences between segment types. However, results did indicate that floodplains had greater overall community respiration than confined segments. Together, these findings suggest that floodplain and confined segments do indeed differ in terms of aquatic ecosystem structure and function but not entirely as expected. Confined segments had greater allochthonous inputs but a lower capacity to retain those inputs, whereas floodplains had a high capacity to retain transported organic matter and also a more diverse community of invertebrates and higher overall community respiration to ‘digest’ retained organic matter. If these findings are generalizable, then they would indicate that confined segments are sources for organic matter within river networks, whereas floodplains act as filters, removing and processing organic matter transported from upstream confined segments. Copyright © 2013 John Wiley & Sons, Ltd.

Effects of nutrient additions and macrophyte composition on invertebrate community assembly and diversity in experimental ponds

Macrophytes and nutrient loading are two factors that can strongly determine the diversity and composition of aquatic invertebrate communities. Both factors may also interact, because macrophyte species may be differentially affected by nutrients. Macrophyte community characteristics, such as species composition, morphotype and biomass have the potential to mediate the response of invertebrate communities to nutrient loading. In 36 newly constructed experimental ponds, we orthogonally combined three macrophyte community types ( Chara-, Potamogeton- and Elodea-dominated) with two levels of nutrient additions (no addition and an addition of 0.5 mg P and 3 mg N/L per week) and studied community assembly in three functional groups of invertebrates (epiphytic macroinvertebrates, littoral and pelagic crustacean zooplankton). Macrophyte biomass was negatively affected by nutrient addition. General linear models indicated negative responses of species richness in the zooplankton functional groups to nutrient addition and phytoplankton chlorophyll-a, but demonstrated no effects of macrophyte community type. Conversely, macroinvertebrate taxon richness differed among macrophyte community types but showed no response to nutrient enrichment. Macrophyte biomass correlated positively with the richness of littoral zooplankton and macroinvertebrates and was a better predictor of these diversity variables than macrophyte community type. Overall, our results indicate that lake management practices that aim at obtaining a nutrient poor and macrophyte dominated clear water state contribute also to the maintenance of aquatic invertebrate diversity.

Composition of aquatic invertebrates associated with macrophytes in Lake Tonle Sap, Cambodia

Faunal composition of aquatic invertebrate communities associated with submerged parts of several species of macrophytes were studied in different areas in littoral Lake Tonle Sap in Cambodia, with special reference to those in root systems (interrhizon) of a free-floating water hyacinth (Eichhornia crassipes). Nine phyla of invertebrates were collected, of which oligochaetes, shrimps and Limnoperna mussels were abundant along with meiobenthic crustaceans. The macrophyte-associated invertebrates in Lake Tonle Sap might be unique in having abundant sessile animals, such as sponges, bryozoans and Limnoperna mussels. The Limnoperna mussels attached to macrophytes were more abundant in offshore and inundated forest than in secluded vegetational stands toward the shoreline. It suggests that water movement can be an important factor determining the distribution and abundance of the sessile animals by controlling larval dispersions and might be associated with the hydrological characteristic of the lake, i.e., the lake opens to the large Mekong River with drastic seasonal changes in water level.

Analyzing effects of pesticides on invertebrate communities in streams

The aim of this investigation was to find patterns in aquatic invertebrate community composition that are related to the effects of pesticides. Investigations were carried out in 20 central European streams. To reduce the site-specific variation of community descriptors due to environmental factors other than pesticides, species were classified and grouped according to their vulnerability to pesticides. They were classified as species at risk (SPEAR) and species not at risk (SPEnotAR). Ecological traits used to define these groups were sensitivity to toxicants, generation time, migration ability, and presence of aquatic stages during time of maximum pesticide application. Results showed that measured pesticide concentrations of 1:10 of the acute 48-h median lethal concentration (LC50) of Daphnia magna led to a short- and long-term reduction of abundance and number of SPEAR and a corresponding increase in SPEnotAR. Concentrations of 1:100 of the acute 48-h LC50 of D. magna correlated with a long-term change of community composition. However, number and abundance of SPEAR in disturbed stream sections are increased greatly when undisturbed stream sections are present in upstream reaches. This positive influence compensated for the negative effect of high concentrations of pesticides through recolonization. The results emphasize the importance of considering ecological traits and recolonization processes on the landscape level for ecotoxicological risk assessment.

Effects of forest harvesting and woody debris removal on two Northland streams, New Zealand

The short‐term effects of Pinus radiata forest harvesting to the stream edge followed by stream‐cleaning (removal of woody debris from the stream channel), on instream light levels, stream temperature, dissolved oxygen concentrations, and aquatic invertebrates were assessed in streams draining partly (25% clear‐cut) and totally (100% clear‐cut) harvested catchments, compared with nearby indigenous forest and mature pine plantation reference sites. There were marked increases in in‐stream light levels and water temperatures following forest harvest and stream‐cleaning at both sites. In‐stream light levels increased from 8–13% to 60–90% and maximum monthly water temperatures increased on average by 5.6°C in the partly harvested and 3.6°C in the fully harvested catchment. Dissolved oxygen levels decreased at both sites shortly after harvest (94%‐71% saturation in the partly harvested catchment; 72%‐37% saturation in the totally harvested catchment), increasing to 75% and 81%, respectively, 1 year later. Although aquatic invertebrate mean density and taxa richness increased at both sites following harvest, the relative abundance of sensitive mayfly, caddisfly, and stonefly species decreased and community composition changed to one dominated by Chironomidae (midges) or Mollusca. Impacts relative to pre‐harvest conditions were not as marked in the totally harvested catchment, possibly because of pre‐existing elevated stream temperatures and high levels of sand and silt. Any downstream protection provided by the forested headwaters of the partly harvested catchment was soon lost after the stream entered the clear‐cut area, although these forested headwaters may provide a potential source of aquatic invertebrates for re‐colonisation in the future as water quality and habitat recover. Our results suggest that: (1) pre‐existing constraints on habitat quality can influence the magnitude of harvesting impacts; and (2) length of stream edge harvested may be a better indicator of impact on some aspects of stream ecology, such as lighting, stream temperature, dissolved oxygen, and aquatic invertebrate community composition, than percentage of catchment harvested. This study also highlights the importance of considering the hydro‐logical and landscape context for mitigating harvesting and wood management impacts on stream ecosystems.