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Benthic macroinvertebrates play a crucial role in river ecosystems. The cascading dams had altered the characteristics of the river environment, consequently impacting the spatial distribution of these organisms. We compared water physicochemical and benthic macroinvertebrates collected in July 2021 among sites located above and below a series of dams. The impact of high-density cascading dams on benthic macroinvertebrates and physicochemical characteristics were analyzed in the Oujiang River mainstem. Our results revealed a noticeable change in the benthic macroinvertebrates from upstream to downstream in the Oujiang River. Due to the construction of dams, with the increase of water depth, the ecologically sensitive taxa (Ephemeroptera, Plecoptera, Trichoptera) disappeared as we moved from the natural river sections to the upstream sections of the dams. In contrast, Bivalves and Oligochaetes, which are well-suited for still water, exhibited an increasing trend. However, the species number, biomass, and biodiversity index significantly decreased. The downstream sections of dams affected by the discharge of low-temperature water had a relatively low number of Oligochaete species. The CCA analysis revealed that total nitrogen, water depth, and water temperature were the main factors influencing benthic macroinvertebrates in the mainstream of Oujiang River. The contribution rates of these factors were 21.1, 16.4, and 4.5%, respectively. These findings can be valuable for supporting ecological management and biodiversity conservation in mountainous rivers with high-density barrage dams. [ABSTRACT FROM AUTHOR]

Due to intensified human activities like hydropower development, biodiversity in the upper Yellow River faces severe threats. In 2019, we conducted a survey across all reservoirs in the river section from Longyangxia to Liujiaxia in the upper Yellow River, focusing on key aquatic organisms such as benthic macroinvertebrates and fish. The benthic index of biotic integrity (B-IBI) and the fish stocking index (FSI) were used to assess the river's biotic integrity. We collected 54 macroinvertebrate species with an average biomass of 1.28g/m², predominantly featuring species like Gammarus sp. and Palaemon modestus. Additionally, 39 fish species were captured, with Gymnocypris eckloni, Pseudorasbora parva, and Triplophysa pappenheimi being the most common, with an average weight of 43.27 g per individual. The B-IBI scores ranged from 1.06 to 3.04, averaging 78; the number of native fish species varied from 3 to 15 per location, resulting in an FSI score of 69. This indicated that the biotic integrity of the Longyangxia to Liujiaxia section was common yet still significantly impacted by human activities. This study highlights the impacts of human activities on the river's ecosystem and aims to guide ecological protection and restoration efforts in the upper Yellow River. [ABSTRACT FROM AUTHOR]

Understanding the relationship between a dam's size and its ecological effects is important for prioritization of river restoration efforts based on dam removal. Although much is known about the effects of large storage dams, this information may not be applicable to small dams, which represent the vast majority of dams being considered for removal. To better understand how dam effects vary with size, we conducted a multidisciplinary study of the downstream effect of dams on a range of ecological characteristics including geomorphology, water chemistry, periphyton, riparian vegetation, benthic macroinvertebrates, and fish. We related dam size variables to the downstream–upstream fractional difference in measured ecological characteristics for 16 dams in the mid‐Atlantic region ranging from 0.9 to 57 m high, with hydraulic residence times (HRTs) ranging from 30 min to 1.5 years. For a range of physical attributes, larger dams had larger effects. For example, the water surface width below dams was greater below large dams. By contrast, there was no effect of dam size on sediment grain size, though the fraction of fine‐grained bed material was lower below dams independently of dam size. Larger dams tended to reduce water quality more, with decreased downstream dissolved oxygen and increased temperature. Larger dams decreased inorganic nutrients (N, P, Si), but increased particulate nutrients (N, P) in downstream reaches. Aquatic organisms tended to have greater dissimilarity in species composition below larger dams (for fish and periphyton), lower taxonomic diversity (for macroinvertebrates), and greater pollution tolerance (for periphyton and macroinvertebrates). Plants responded differently below large and small dams, with fewer invasive species below large dams, but more below small dams. Overall, these results demonstrate that larger dams have much greater impact on the ecosystem components we measured, and hence their removal has the greatest potential for restoring river ecosystems. [ABSTRACT FROM AUTHOR]

Functional diversity research enhances our understanding of ecosystems and both their functioning and their responses to environmental variations. This study investigated the biological trait responses of benthic invertebrate communities to various environmental conditions in estuarine habitats. We analyzed benthic macroinvertebrate communities in freshwater and estuarine environments to compare their characteristics between estuary sites with and without artificial barriers. Moreover, we combined taxonomic analyses (species richness, abundance, and four community indices) with functional diversity indices and biological trait analyses. The major results are as follows: (i) the most important environmental factors shaping species distribution in estuarine habitats were salinity and electrical conductivity; (ii) comparing functional diversity indices, tidal estuaries revealed that seawater intrusion induced changes in species distribution and the dispersion of benthic macroinvertebrates; (iii) the presence or absence of artificial barriers in estuaries affected biological traits owing to the influence of specific functional strategies of certain species. Consequently, the presence or absence of artificial barriers in estuaries can lead to significant changes in habitat connectivity and functional diversity related to ecosystem functions. These findings indicate that the presence of artificial barriers can significantly influence the ecological dynamics of estuarine ecosystems, thereby affecting species distribution, functional diversity and habitat connectivity. Understanding these effects contributes to a more comprehensive understanding of ecosystem functionings, as it complements existing taxonomic findings and integrates information about the functional aspects of diverse ecosystems. [ABSTRACT FROM AUTHOR]

The biotic community predictive model proposed in the River Invertebrate Prediction And Classification System which compares observed values at test sites with expected values in reference sites is used to perform biological assessments of rivers. In 2021, a Korean River Macroinvertebrate Prediction and Assessment System (KRIMPAS) for river integrity assessment was developed. However, since it was the early stage of development, improvement of the accuracy and precision of assessment was required. Therefore, benthic macroinvertebrates and six environmental variables collected from 357 reference sites between 2010 to 2021 were used to compare the prediction mothods and attempt to optimize the KRIMPAS. Based on the number of taxa (species and family levels) and six biological indices, the existing KRIMPAS method (Original method) was compared with two weighted average methods (W-Avg 1 and 2) according to the probability that a test site was assigned. In terms of statistical significance, observed to expected (O/E) values of the number of taxa, but, there were difference for most of biological indices. When the probability density function based on the log-normal distribution for each derivation method was applied, no difference was observed in the number of taxa; however, there were differences in the mean, median, mode, and variance for each biological index. A fit verification based on the normalized root-mean-square error (NRMSE) for each derivation method was conducted, and the overall fit tended to be higher with the W-Avg 1 and 2 when compared with the Original method. Thus, to correct the current biological assessments of Korean rivers we propose the application of the W-Avg method as this would improve the derivation of the predictive model. [ABSTRACT FROM AUTHOR]

This research summarizes the data on benthic macroinvertebrates collected in the 15 streams during spring (June) and fall (September–October) of 2022. The objectives of this study were (i) to evaluate the quality of surface waters, sediments, and benthic macroinvertebrates; and (ii) to compare the relationship with the environmental variables in water, sediments and benthic macroinvertebrates that inhabit 15 streams. A total of 114 taxa were collected. The assemblages from the 15 sites were dominated by Chironomidae and Tubificidae, especially Chironomidae constituted 45.0% density occurrence. The low grades of Benthic Macroinvertebrate Index (BMI) were calculated in 10 sites with disturbed ("poor" or "very poor"). Low BMI sites mostly showed Tubificidae or Chironomidae dominant characteristics. The biological indices, BMI, % Tubificidae, and % Chironomidae, were significantly correlated with DO and conductivity. DO was also significantly correlated with all the benthic macroinvertebrate factors and diversity except percent Tubificidae. The heavy metal parameters were correlated mostly with species number, BMI, and diversity index. The objectives of this study examine the diversity of benthic macroinvertebrate in the 15 streams and investigate the relative importance of environmental quality for benthic macroinvertebrate distribution. [ABSTRACT FROM AUTHOR]

Benthic macroinvertebrate taxa vary in their sensitivities to water quality and habitat conditions, contributing to their extensive use as ecological indicators. As climate change and landscape alteration increasingly impact stream temperatures, interest is growing in expanding our knowledge of how macroinvertebrates are affected by current and future thermal conditions. Using samples from 3501 sites, we evaluated relationships between macroinvertebrate taxa and modeled stream temperatures across Oregon and Washington, in the U.S. Pacific Northwest. We used Maximum Weekly Maximum Temperature (MWMT) values from the NorWeST temperature dataset, which is the same metric used for numeric water temperature standards in Oregon and Washington. MWMT captures peak thermal stress, when cold-water adapted aquatic biota are closest to their upper physiological limits. For each macroinvertebrate taxon, we characterized relationships between MWMT and their distributions with three measures: 1) central thermal tendency, based on weighted average (WA) optima calculations and relative abundance data; 2) lower and upper thermal limits, based on the 10th and 90th percentiles of taxon occurrence, using presence data; and 3) thermal sensitivity curve shape, based on Generalized Additive Model (GAM) plots. We assigned 521 taxa, from species to phyla, to seven thermal preference categories, ranging from cold and warm stenotherms (narrow range) to eurythermal (wide range). Thermal sensitivity and variability within each taxonomic group were identified for establishing taxonomic targets for regional monitoring programs. We also developed the Macroinvertebrate Thermal Tolerance Index (MTTI) to represent the assemblage-level response to available thermal habitats, using WA optima and relative abundances for 324 taxa. The MTTI model had a strong relationship with modeled temperatures (R2 = 0.68) and a root-mean-square-error of 2.5 °C. Our work builds on previous regional and national efforts to identify thermal indicator taxa by using modeled stream network temperatures and a thermal metric that corresponds directly to regional water temperature standards. Both the taxa thermal preferences and the MTTI can be used to help identify causes of biological impairment, prioritize restoration and protection actions, and monitor assemblage-wide changes in thermal tolerance over time.

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Turkey has many ecological characteristics due to its geographical location, allowing it to have a rich biodiversity in freshwater ecosystems. This study was carried out on the Kızılırmak river, the longest river (1.355 km) in the country; it originates and empties into the sea within its borders. The Kızılırmak river serves various agricultural, industrial, drinking water-related, and recreational purposes and greatly contributes to the region's economy. This study aimed to determine the distribution of the river's macroinvertebrate fauna and evaluate the impact of environmental variables on species distribution. In addition, using species-based biodiversity indices such as the Biological Monitoring Working Party (BMWP), Average Score per Taxon (ASPT), the Shannon–Wiener index, and evenness analysis, spatial and temporal similarities and differences were determined. According to the results, the ten taxonomic groups in the Kızılırmak river belong to the following categories: Gastropoda (81.5%), Gammaridae (9.8%), Oligochaeta (6.2%) Chironomidae (2.1%), Hirudinea (0.3%), and various others (0.1%). The Shannon–Wiener and evenness indexes were 0.29–1.9 and 0.46–0.14, respectively. TR-BMWP scores are in the poor to very poor water quality classes, and the ASPT ranges from moderate to poor water quality. Correlation analysis between species and physicochemical parameters indicated that the benthic macroinvertebrate fauna diversity of the river is affected by natural and anthropogenic factors. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of anthropogenic stressors (landfilling, navigation for transport of goods, cooling in fossil fuel, urbanization, industrial expansion, agriculture activities, and recreational activities) on environmental variables, microbiological quality, and sediment properties using benthic macroinvertebrates as a bioindicator within Lagos Lagoon, Nigeria. Four (4) sampling stations were established with respect to their importance/anthropogenic activities within the Lagos Lagoon. Surface water, bottom substrates, and benthic macroinvertebrate fauna samples were collected bimonthly from each sampling station for a year and analyzed using appropriate standard methods and procedures. The highest pH range of 7.96–8.01 (7.98 ± 2.35) was recorded at Site IV, while the lowest range of 6.41–7.01 (6.15 ± 1.14) was observed at Site II, and there was a significant difference (p

IntroductionArctic freshwater ecosystems are undergoing rapid environmental transformation because of climate change, which is predicted to produce fundamental alterations in river community structure and function.MethodsWe explored how climate change affects benthic invertebrate communities of Arctic streams by examining patterns of their biological traits along latitudinal and climatic gradients in eastern North America (Canada) and northwestern Europe (Sweden, Norway).ResultsDespite differences in taxonomic composition between continents, we identified similarities in the functional trait niche (FTN) of predominant macroinvertebrate taxonomic groups. Trait composition differed by latitude in eastern Canada, with a predominance of cold-tolerant taxa, tubular body shape, and cased and attached habits at the highest latitudes. Differences in trait composition were evident among ecoregions in Europe, with trait dominance at the highest latitudes that was comparable to North America. There was a similar increase in the relative abundance of cold tolerance and tubular body shape and a decrease in obligate shredders and trait richness with decreasing temperatures across both continents.DiscussionThese patterns are indicative of FTNs that include physiological traits and habits that are advantageous for the low temperatures, short ice-free period, and low riparian vegetation cover at the highest latitudes. We predict that climate change will lead to an increase in functional diversity at high latitudes, as organisms with trait modalities that are currently only found at lower latitudes move northward. However, this change in trait composition will be mediated by the effect of spatial connectivity on dispersal ability, with slower change occurring on Arctic islands. These findings can support modelling of future change in Arctic freshwater assemblages in response to ongoing climate change.

Aquatic macroinvertebrates are an important component of biodiversity in stream Ecosystems. Conserving and enhancing freshwater biodiversity is important for maintaining ecosystem integrity and sustainability. This requires understanding how the composition of biological communities is influenced by environmental factors at different scales. Factors such as water chemistry, temperature, flow, and land use can all affect the distribution and abundance of different species in freshwater ecosystems. The North of Algeria has a complex hydrographic network, but the inventory of aquatic macroinvertebrates community remains incomplete. This study aimed at compiling an inventory of the macroinvertebrate inhabiting the aquatic ecosystems of each stations in Chréa National Park (province of Blida, Algeria). The results were used to answer two questions: (i) macroinvertebrate composition and richness in these protected ecosystems? (ii) Which taxon or group of taxa is the most dominant?. Different sampling methods (Surber, kick samplers and artificial substrate) were used depending on the characteristics of the sites chosen. The sampling was carried out during three months (February to April, 2021). It was analyzed and identified 1345 organisms belonging to 41 macroinvertebrate families. The system showed high richness and diversity of organisms in response to water quality. The presence of Leptophlebiidae, Baetidae, Heptageniidae and Chironomidae with high abundance of the families showed the potential as biological indicators of a clean ecosystem. To collect the samples, It was used a surber sampler 1 mm mesh every week, with six repetitions in each station, from February to April, 2021. After cleaning and removal of debris. we proceeded by a pre-sorting in morpho-species, then a sorting of the different taxa was carried out in the laboratory. the organisms were identified using a stereoscopic microscope and identification keys. The community structure including abundance, richness and composition was statistical different between stations. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the diversity of benthic macroinvertebrates and the quality of rivers in the North East of Idjwi Island, Democratic Republic of the Congo. Macroinvertebrates were collected from June to September 2017 in 4 rivers: Nyamisheke, Tama, Miriri and Nyahonga. Eight sampling trips were conducted and 32 samples taken in 20 sites (5 sites per river) using a dip net. The results obtained revealed 5531 specimens captured in total. These macroinvertebrates are distributed in 3 phyla (arthropods, mollusks and annelids), 5 classes (insects, crustacea, gastropods, oligochaetes and achaetes), 11 orders and 43 families. Their relative abundance varies according to the rivers: Nyamisheke (31%), Tama (28%), Miriri (25%) and Nyahonga (16%). The Shannon index calculated variates between 1.4 and 2.6 and reflects a disproportionate diversity across sites. Overall, the stations located upstream are more diverse than those located downstream. However, the Global Normalized Biological Index (GNBI) values indicate significant pollution in the four rivers, which is a consequence of the multiple anthropogenic activities (overexploitation of sand, fishing, washing up, bathing and presence of agricultural organic waste) in and around these rivers. This excessive pollution negatively impacts the diversity and abundance of macroinvertebrates in these sites. Therefore, measures should be taken by the competent structures to discourage these anthropic activities in order to preserve the health of these river ecosystems and of human populations.

AbstractThe biotic community predictive model proposed in the River Invertebrate Prediction And Classification System which compares observed values at test sites with expected values in reference sites is used to perform biological assessments of rivers. In 2021, a Korean River Macroinvertebrate Prediction and Assessment System (KRIMPAS) for river integrity assessment was developed. However, since it was the early stage of development, improvement of the accuracy and precision of assessment was required. Therefore, benthic macroinvertebrates and six environmental variables collected from 357 reference sites between 2010 to 2021 were used to compare the prediction mothods and attempt to optimize the KRIMPAS. Based on the number of taxa (species and family levels) and six biological indices, the existing KRIMPAS method (Original method) was compared with two weighted average methods (W-Avg 1 and 2) according to the probability that a test site was assigned. In terms of statistical significance, observed to expected (O/E) values of the number of taxa, but, there were difference for most of biological indices. When the probability density function based on the log-normal distribution for each derivation method was applied, no difference was observed in the number of taxa; however, there were differences in the mean, median, mode, and variance for each biological index. A fit verification based on the normalized root-mean-square error (NRMSE) for each derivation method was conducted, and the overall fit tended to be higher with the W-Avg 1 and 2 when compared with the Original method. Thus, to correct the current biological assessments of Korean rivers we propose the application of the W-Avg method as this would improve the derivation of the predictive model.

Predictive models for the benthic macroinvertebrate community based on environmental variables facilitate the identification of the organisms expected to inhabit an area according to the target environmental conditions when restoring rivers. In this investigation, a biotic community predictive model was developed using benthic macroinvertebrate and environmental variable data collected from 1,210 sites in the Republic of Korea from 2010 to 2020. The sites were classified into six groups according to Two Way Indicator Species Analysis (TWINSPAN) and based on their individual abundance/m2 of benthic macroinvertebrates. The TWINSPAN groups were related to 14 variables by stepwise multi-discriminant analysis. The relative importance of the environmental variables that classified each TWINSPAN group was in the order of mean diameter of particle size, catchment area, altitude, velocity, total phosphorus, latitude, pH, longitude, conductivity, water depth, suspended solids, biochemical oxygen demand, stream order, and total nitrogen. Discriminant functions 1–4 showed statistically significant and a predictive model was developed using functions 1 and 2 based on Wilks’ lambda values. The fit of the derived model was confirmed using Sørensen similarity (number of taxa) and Bray–Curtis dissimilarity (individual abundance/m2) analyses between the predicted organisms and those observed at the sites. The distributions of similarity and dissimilarity that were confirmed by stream type ranged from 0.60 to 0.72 and 0.46–0.56, respectively, based on the mean. Based on the predicted and observed values, the ratio of shredders and scrapers to collectors showed similar results overall for each stream type. The predictive model derived using nationally managed available data is expected to be applicable to stream and river restorations in the future, as it provides a statistical assessment of the biotic communities that are expected to inhabit a given environment.

This study was carried out in July and August 2019 as a preliminary study to determine the benthic macroinvertebrate fauna of Karagöl, Çömçe and Yıldız Lakes, which are high-altitude lakes in the Aladağlar mountains. As a result of the examination of the collected macrobenthic fauna, seven speciesbelongingtothreefamiliesfromthreeorders(Diptera,ColeopteraandTrichoptera)inKaragöl Lake, four species belonging to three families from two orders (Diptera, Haplotaxida) in Çömçe Lake, and five species belonging to three families from three orders (Diptera, Trichoptera, Haplotaxida)inYıldızLakeweredetermined.Thetaxadetectedisanewrecordforthestudiedlakes. Shannon-Weaver diversity (H) and Shannon-Evenness density (EH) indices were applied in ordertodeterminethespeciesrichnessofthelakesandthedensityrelationshipsamongthespecies, respectively. Accordingly, the highest diversity was observed in Çömçe Lake with a value of 1.18, followed by Karagöl Lake, and Yıldız Lake with values of 0.87 and 0.83, respectively. While the most balanced distribution was observed in Çömçe Lake with a value of 0.81, this was followed by Yıldız Lake and Karagöl Lake, with values of 0.46 and 0.34, respectively. In order to determine the similaritiesbetweenthestationsaccordingtothedistributionofthedetectedtaxa,atwo-wayclusteringanalysisbasedontheBray-Curtissimilarityindexwasapplied.Accordingly,whilethehighestsimilaritywascalculatedbetweenKaragölLakeandYıldızLake,itwasdeterminedthatthere was no similarity between Yıldız Lake and Çömçe Lake.

Predictive models for the benthic macroinvertebrate community based on environmental variables facilitate the identification of the organisms expected to inhabit an area according to the target environmental conditions when restoring rivers. In this investigation, a biotic community predictive model was developed using benthic macroinvertebrate and environmental variable data collected from 1,210 sites in the Republic of Korea from 2010 to 2020. The sites were classified into six groups according to Two Way Indicator Species Analysis (TWINSPAN) and based on their individual abundance/m2 of benthic macroinvertebrates. The TWINSPAN groups were related to 14 variables by stepwise multi-discriminant analysis. The relative importance of the environmental variables that classified each TWINSPAN group was in the order of mean diameter of particle size, catchment area, altitude, velocity, total phosphorus, latitude, pH, longitude, conductivity, water depth, suspended solids, biochemical oxygen demand, stream order, and total nitrogen. Discriminant functions 1–4 showed statistically significant and a predictive model was developed using functions 1 and 2 based on Wilks' lambda values. The fit of the derived model was confirmed using Sørensen similarity (number of taxa) and Bray–Curtis dissimilarity (individual abundance/m2) analyses between the predicted organisms and those observed at the sites. The distributions of similarity and dissimilarity that were confirmed by stream type ranged from 0.60 to 0.72 and 0.46–0.56, respectively, based on the mean. Based on the predicted and observed values, the ratio of shredders and scrapers to collectors showed similar results overall for each stream type. The predictive model derived using nationally managed available data is expected to be applicable to stream and river restorations in the future, as it provides a statistical assessment of the biotic communities that are expected to inhabit a given environment. A biotic community predictive model is presented. The model was developed using benthic macroinvertebrate and environmental variable data collected from 1,210 sites across the Republic of Korea from 2010 to 2020. The purpose of the model is to identify communities that should be present in river environments after restoration under modified environmental conditions. The model can function on a larger scale to address the increasing need for river restoration from a broader perspective. Model usage will provide successful and sustainable results and meet the needs of policy makers to restore riverine environments. [ABSTRACT FROM AUTHOR]

This study was carried out in July and August 2019 as a preliminary study to determine the benthic macroinvertebrate fauna of Karagöl, Çömçe and Yıldız Lakes, which are high-altitude lakes in the Aladağlar mountains. As a result of the examination of the collected macrobenthic fauna, seven species belonging to three families from three orders (Diptera, Coleoptera and Trichoptera) in Karagöl Lake, four species belonging to three families from two orders (Diptera, Haplotaxida) in Çömçe Lake, and five species belonging to three families from three orders (Diptera, Trichoptera, Haplotaxida) in Yıldız Lake were determined. The taxa detected is a new record for the studied lakes. Shannon-Weaver diversity (H) and Shannon-Evenness density (EH) indices were applied in order to determine the species richness of the lakes and the density relationships among the species, respectively. Accordingly, the highest diversity was observed in Çömçe Lake with a value of 1.18, followed by Karagöl Lake, and Yıldız Lake with values of 0.87 and 0.83, respectively. While the most balanced distribution was observed in Çömçe Lake with a value of 0.81, this was followed by Yıldız Lake and Karagöl Lake, with values of 0.46 and 0.34, respectively. In order to determine the similarities between the stations according to the distribution of the detected taxa, a two-way clustering analysis based on the Bray-Curtis similarity index was applied. Accordingly, while the highest similarity was calculated between Karagöl Lake and Yıldız Lake, it was determined that there was no similarity between Yıldız Lake and Çömçe Lake. [ABSTRACT FROM AUTHOR]

Flooding is an important process in natural fluvial floodplains. How the flood shapes aquatic community diversity in highland floodplains is still poorly understood. The aim of this study was to unravel the multi-faceted responses of benthic macroinvertebrate diversity to flooding and habitat environments in the Baihe River Basin from a taxonomic, phylogenetic, and functional perspective. We examined the alpha and beta diversity patterns of benthic macroinvertebrate communities in the mainstream, tributaries, and oxbow lakes during the normal water and flood periods. The results showed that the traditional alpha taxonomic diversity (TD) varied across habitats, despite minor changes after flood pulse. Alpha phylogenetic diversity (PD) decreased and alpha functional diversity (FD) markedly increased after flooding, with functional traits transiting toward risk avoidance. While all the three facets of beta diversity significantly responded to habitat differences, beta TD and PD shifted in response to flooding. Species turnover prominently increased in beta TD and PD after flood pulse, which contrasted with a weaker response of this process in FD. The explanatory power of significant environmental factors on both alpha and beta diversity was reduced by flooding. Compared with traditional TD, cooperating multi-faceted diversity could better depict the responses of benthic macroinvertebrate communities to flooding. The assessment and conservation of aquatic biodiversity in highland floodplains should take into account the three facets of alpha and beta diversity. • The benthic responded significantly to flood pulse in a highland floodplain. • TD varied across habitats, whereas PD and FD changed after flooding. • βsor and βsim respectively characterize habitat differences and flooding. • Functional traits shift to risk avoidance abilities after flooding. • Flooding weakens environmental effects on macroinvertebrate diversity. [ABSTRACT FROM AUTHOR]

Lotic freshwater macroinvertebrate species distribution models (SDMs) have been shown to improve when hydrological variables are included. However, most studies to date only include data describing climate or stream flow-related surrogates. We assessed the relative influence of climatic and hydrological predictor variables on the modelled distribution of macroinvertebrates, expecting model performance to improve when hydrological variables are included. We calibrated five SDMs using combinations of bioclimatic (bC), hydrological (H) and hydroclimatic (hC) predictor datasets and compared model performance as well as variance partition of all combinations. We investigated the difference in trait composition of communities that responded better to either bC or H configurations. The dataset bC had the most influence in terms of proportional variance, however model performance was increased with the addition of hC or H. Trait composition demonstrated distinct patterns between associated model configurations, where species that prefer intermediate to slow-flowing current conditions in regions further downstream performed better with bC–H. Including hydrological variables in SDMs contributes to improved performance, it is however, species-specific and future studies would benefit from hydrology-related variables to link environmental conditions and diverse communities. Consequently, SDMs that include climatic and hydrological variables could more accurately guide sustainable river ecosystem management. [ABSTRACT FROM AUTHOR]

Selenium (Se) is a contaminant of concern in Canada mainly due to its teratogenic effects on fish and birds. However, few studies have assessed the effects of Se on invertebrates in a field setting. The objective of this experiment was to assess potential community‐level impacts of Se additions on zooplankton and benthic macroinvertebrates in a boreal lake ecosystem. From June to August 2018, Se (as selenite) was added to six limnocorrals in Lake 239 at the International Institute for Sustainable Development–Experimental Lakes Area, Northwestern Ontario, Canada, to achieve mean measured aqueous concentrations of 0.4, 0.8, 1.6, 3.4, 5.6 and 7.9 µg Se/L, with three untreated limnocorrals serving as controls (background Se = 0.08–0.09 µg/L). Periphyton, phytoplankton, and invertebrates (zooplankton and benthos) were monitored for 63 days. Zooplankton community composition shifted as a function of Se exposure, with Cladocera biomass and density decreasing with increasing Se concentrations. Similarly, cumulative abundance and biomass of Heptageniidae decreased with increasing Se treatment throughout the experimental period. The present study demonstrated that Se can have impacts on aquatic invertebrates at environmentally relevant exposure levels, and that future ecological risk assessments should consider the impacts of Se on both vertebrates and invertebrates. Environ Toxicol Chem 2022;41:95–107. © 2021 SETAC [ABSTRACT FROM AUTHOR]

Shale-gas production could impact freshwater quality through contamination of the physical and chemical habitat (e.g., fracturing fluids, untreated or treated effluent) or development-related impacts. Despite environmental concerns, information is lacking to support biomonitoring as a diagnostic tool to assess impacts of shale-gas production. We characterized water quality and biota in areas of high shale gas potential (Early Carboniferous bedrock in New Brunswick, Canada) and surrounding geologic areas, and we assessed patterns in benthic macroinvertebrate (BMI) and fish assemblages. Early Carboniferous stations differed primarily based on water chemistry, and BMI were associated with a gradient in conductivity and temperature across geologic classes. Concordance analysis indicated similar classification of stations by both organism groups, though fish were more related to turbidity and nutrients. Concordance among fish and BMI was strongest at high conductivity, Early Carboniferous stations. These results suggest that geology plays a strong role in driving abiotic habitats and biotic communities of streams, even at small spatial scales. Furthermore, they suggest BMI and fish can provide complementary information for biomonitoring in shale-gas development areas, with BMI responding to increased ion concentrations from surface water contamination, and fish responding to changes in nutrients and turbidity resulting from development.

The aim of this study conducted to collect and produce survey data on the distribution status of benthic macroinvertebrates in the Wangpi-cheon Basin (2017), which has been designated and managed as an Ecological Landscape Conservation Area (2005). A total 153 species of benthic macroinvertebrates in 74 families, 18 orders, 8 classes and 5 phyla were collected including 8 Endemic Species of Korea and 16 Out-of-the-country Transportation Permit Required Species. The dominant species was Simulium sp. (16.1 %), and the subdominant species was Chironomus sp. (7.4 %).

Vehicle wash wastewater (VWW) contains a wide range of contaminants and discharge of such contaminated wastewater into the surface water bodies degrade water quality and affect aquatic ecosystems. This study, presents an impacts of discharging VWW into the stream Olarong Chhu in Thimphu and river Paa Chhu in Paro using water chemistry and benthic macroinvertebrates data sets obtained over a period of 6 months. Water samples and benthic macroinvertebrates were sampled once in a month from upstream, impact, and downstream sites in premonsoon (March to May) and post-monsoon (September to November) seasons in 2016. Significant levels of contaminants associated with vehicle washing were detected in water samples of impact sites whose cumulative effects on benthic macroinvertebrate assemblages were supported by HKHbios index, biological indices, and statistical analyzes. Canonical correspondence analysis indicated that T, dissolved oxygen, pH, biological oxygen demand, chemical oxygen demand, total suspended solids, turbidity, oil and grease, and sulfate significantly alter water quality and affect benthic macroinvertebrate assemblages. With the increasing number of vehicles, management of VWW is becoming a serious issue in Bhutan. Hence, there should be proper enforcement of water and environmental legislations and effective measures like constructions of wastewater treatment facilities should be considered for protecting Bhutan’s surface water resources and aquatic ecosystems.

Modified composite biochar offers a cost-effective solution for the remediation of contaminated sediments; however, few studies have evaluated the effects of modified composite biochar amendment on the ecotoxicity of contaminated sediment based on benthic macroinvertebrates. A 21-day sediment toxicity test was conducted using the freshwater snail Bellamya aeruginosa to examine the intrinsic ecotoxicity of a novel KOH-modified composite biochar (KOH-CBC) and its efficacy for reducing the bioavailability, uptake, and ecotoxicity of perfluorooctanoic acid (PFOA). It was found that KOH-CBC is toxic to B. aeruginosa, which may be attributed to its high polycyclic aromatic hydrocarbons (PAHs) content and alkalinity. The addition of KOH-CBC to PFOA-contaminated sediments can markedly reduce the bioavailability and uptake of PFOA by more than 90% and 50%, respectively, and subsequently alleviate the toxicity of PFOA to B. aeruginosa by at least 30%. Increasing the KOH-CBC dosage is not beneficial for further mitigating the toxicity of PFOA-contaminated sediments. Our findings imply that KOH-CBC is a promising sorbent for the in-situ remediation of PFOA-contaminated sediments. Application of acidified KOH-CBC at a dosage of approximately 1–3% will be sufficient to control the ecotoxicity of PFOA; however, its long-term environmental effects should be further validated.

• We assigned 521 macroinvertebrate taxa to seven thermal preference categories. • Weighted averaging was used to develop an assemblage-level thermal tolerance index. • Thermal preference metrics can identify streams suitable for endangered fish. • Modeled stressor gradients can provide equivalent results to field measurements. • Adhering to regional taxonomic standards improved thermal sensitivity. Benthic macroinvertebrate taxa vary in their sensitivities to water quality and habitat conditions, contributing to their extensive use as ecological indicators. As climate change and landscape alteration increasingly impact stream temperatures, interest is growing in expanding our knowledge of how macroinvertebrates are affected by current and future thermal conditions. Using samples from 3501 sites, we evaluated relationships between macroinvertebrate taxa and modeled stream temperatures across Oregon and Washington, in the U.S. Pacific Northwest. We used Maximum Weekly Maximum Temperature (MWMT) values from the NorWeST temperature dataset, which is the same metric used for numeric water temperature standards in Oregon and Washington. MWMT captures peak thermal stress, when cold-water adapted aquatic biota are closest to their upper physiological limits. For each macroinvertebrate taxon, we characterized relationships between MWMT and their distributions with three measures: 1) central thermal tendency, based on weighted average (WA) optima calculations and relative abundance data; 2) lower and upper thermal limits, based on the 10th and 90th percentiles of taxon occurrence, using presence data; and 3) thermal sensitivity curve shape, based on Generalized Additive Model (GAM) plots. We assigned 521 taxa, from species to phyla, to seven thermal preference categories, ranging from cold and warm stenotherms (narrow range) to eurythermal (wide range). Thermal sensitivity and variability within each taxonomic group were identified for establishing taxonomic targets for regional monitoring programs. We also developed the Macroinvertebrate Thermal Tolerance Index (MTTI) to represent the assemblage-level response to available thermal habitats, using WA optima and relative abundances for 324 taxa. The MTTI model had a strong relationship with modeled temperatures (R2 = 0.68) and a root-mean-square-error of 2.5 °C. Our work builds on previous regional and national efforts to identify thermal indicator taxa by using modeled stream network temperatures and a thermal metric that corresponds directly to regional water temperature standards. Both the taxa thermal preferences and the MTTI can be used to help identify causes of biological impairment, prioritize restoration and protection actions, and monitor assemblage-wide changes in thermal tolerance over time. [ABSTRACT FROM AUTHOR]

Indices of biotic integrity (IBIs) are widely used to assess aquatic ecosystem health. However, there are few studies on their relationships. Based on fish, macroinvertebrate and plankton survey data collected in the Ganjiang River system from 2016 to 2017, redundancy analysis (RDA) and canonical correspondence analysis (CCA) were used to analyze how the community structures of these organisms respond to environmental variables. The fish IBI (F-IBI), benthic macroinvertebrate IBI (B-IBI), and phytoplankton IBI (P-IBI) were applied to evaluate the health status of the aquatic ecosystem. A Kruskal–Wallis test (p < 0.05) and Spearman’s correlation coefficient analysis were performed to evaluate the spatiotemporal heterogeneity of the results. Our results suggested that the F-IBI-, B-IBI-, and P-IBI-based assessments indicated good, fair, and healthy Ganjiang River system ecosystem health statuses, respectively, and significant differences existed among these indices (p < 0.05). The main environmental factors affecting F-IBI, B-IBI, and P-IBI were different. At the temporal scale, the F-IBI and B-IBI were stable, while the P-IBI fluctuated obviously. The consistency between the F-IBI and B-IBI results was better than that between each of these indices and the P-IBI results, and the consistency was better on a larger scale. These research results show that comprehensive assessments based on multiple groups rather than a single group can better characterize the impacts of environmental pressures on water ecosystems.

Benthic macroinvertebrates and microorganisms in six habitats in the Yellow River Delta wetlands, including the intertidal zone, Suaeda salsa area, Phragmites australis shoal, P. australis deep beach, Tamarix chinensis area, and inland river beach, were sampled and analyzed in summer and autumn. The results showed that the richness and diversity indices of benthic macroinvertebrates and microorganisms were higher in autumn than in summer. Differences in the vegetation coverage of different habitats were the main factors affecting the community structures of benthic macroinvertebrates and microorganisms. In addition, the study provided a new respect of the interaction between benthic macroinvertebrates and microorganisms based the life styles of benthic macroinvertebrates, and found that the life styles of benthic macroinvertebrates had varied effects on the distribution of microorganisms. The study suggested that the interactions of organisms were important factors affecting and regulating the ecosystem functions of wetlands. [ABSTRACT FROM AUTHOR]

December 2017 and September 2018 by selecting five stations from Goksu Stream. In order to determine the water quality of the Goksu Stream, benthic macroinvertebrate fauna, some physicochemical parameters and biotic indices were used. pH, water temperature (C), DO (dissolved oxygen mg/L), EC (electrical conductivity uS/cm), salinity (%), depth (cm), flow rate (m/s), NH4-N (ammonium nitrogen mg/L), N02-N (nitrite nitrogen mg/L), N03-N (nitrate nitrogen mg/L, P03-P (phosphate mg/L), TP (total phosphorus mg/L), BOD (biochemical oxygen demand mg/L), TSS (total suspended solid mg/L) physicochemical parameters were measured. A number of biotic indices (Biological Monitoring Working Party-BMWP, Average Score Per Taxa-ASPT. Belgian Biotic Index-BBI) and diversity indices (Margalef, Simpson, Shannon Weaver, Simpson Evenness, Shannon Evenness). As a result of this study, a total of 35 taxa were detected. 10 taxa belong to Oligochaeta, 3 taxa belong to Gastropoda, 17 taxa belong to Insecta, 3 taxa belong to Malacos-traca, 1 taxa belong to Polychaeta and 1 taxa belong to Bivalvia. Oligochaeta (61.28 %) was determined to be the most dominant group among benthic ma-croinvertebrates. As a result of the physicochemical variables, macrozoobenthic organisms composition and applied biotic indeces, Goksu Stream has a low quality or high contaminated water quality. [ABSTRACT FROM AUTHOR]

• Ecological quality of Malaysian streams can be assessed using a multimetric index. • Six core metrics were identified to develop a MIBI. • MIBI discriminates the reference and test sites very well. • MIBI's efficiency has been tested in various stream to verify its reliability. Economic and industrial growth in Malaysia has led to various environmental problems, which in turn affected the quality of human life and nature. At present, the management plans, particularly for river rehabilitation, are less effective in addressing issues related to Malaysian rivers. To date, most of the efforts undertaken have focused on evaluating the physicochemical properties of water, whereas biological evaluation determining the health of a river ecosystem is less attended to. Therefore, this study has aimed to develop a multimetric index and biocriteria applicable to the biological assessment of Malaysian streams. Four rivers in the state of Johor have been selected as the sources, each representing different gradients of land use. The reference and impaired sites both have been determined based on various physicochemical, instream features and riparian habitat quality criteria. The resulting candidate metrics have then been evaluated in terms of redundancy, sensitivity and responsiveness to environmental changes, using the stepwise procedures. Integration of six potential metrics across three categories (i.e. taxonomic richness, taxonomic composition, and tolerance and intolerance index) has consequently produced a four-level discriminatory biocriteria for river health assessment: <20% (severely impaired); 20%−55% (moderately impaired); 56%−92% (slightly impaired); and >93% (non-impaired). The re-scored result has revealed that the water quality of Sg Ayer Hitam Besar to be non-impaired, with excellent water quality. Meanwhile, Sg Berasau and Sg Mengkibol have slightly impaired water quality, whereas Sg Melana is moderately impaired with fair to poor water quality. Thus, this multimetric index has strongly differentiated the reference and impaired conditions accordingly, which substantiated the suitability of the discriminatory criteria for Johor stream assessment. Hence, the establishment of macroinvertebrate-based index of biotic integrity (MIBI) and biological criteria may provide indispensable information in managing river ecosystem more effectively. [ABSTRACT FROM AUTHOR]

Copyright of Knowledge & Management of Aquatic Ecosystems is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reduced impact logging has emerged as one alternative to reduce the effects of timber harvesting. However, the effects of this method on aquatic ecosystems still need to be tested. We studied the effects of logging (reduced-impact logging—RIL and conventional logging methods—CL) on the chemical water quality and physical habitat conditions of streams in eastern Amazonia, as well as on Ephemeroptera diversity. Were analyzed control streams (without logging—CONTROL), streams with RIL and streams with CL, located in the Capim River Basin. Specimens were collected using a dipnet, following a standard protocol and abiotic data were measured with a multiparameter probe. Conventional logging in proximity to streams increased the conductivity and pH of the water, reduced dissolved oxygen and canopy cover of the stream’s channel, altering the composition of Ephemeroptera when compared with CONTROL and RIL areas. We verified that specialist Ephemeroptera species within control environments were replaced by species more tolerant to changes in the natural habitat conditions. In contrast, there was species similarity between RIL and CONTROL streams. [ABSTRACT FROM AUTHOR]

The study on the structure of benthic macroinvertebrate communities took place in the Lower Mure defile (May 2011, 18 sampling points). Following the processing of benthos samples, 20485 individuals were identified, belonging to 14 groups of benthic macroinvertebrates.In all sampling points the clean water indicator groups (Amphipoda, Efemeroptera, Plecoptera, Trichoptera) registered a high abundance. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the impact of anthropogenic stressors (landfilling, navigation for transport of goods, cooling in fossil fuel, urbanization, industrial expansion, agriculture activities, and recreational activities) on environmental variables, microbiological quality, and sediment properties using benthic macroinvertebrates as a bioindicator within Lagos Lagoon, Nigeria. Four (4) sampling stations were established with respect to their importance/anthropogenic activities within the Lagos Lagoon. Surface water, bottom substrates, and benthic macroinvertebrate fauna samples were collected bimonthly from each sampling station for a year and analyzed using appropriate standard methods and procedures. The highest pH range of 7.96-8.01 (7.98 ± 2.35) was recorded at Site IV, while the lowest range of 6.41-7.01 (6.15 ± 1.14) was observed at Site II, and there was a significant difference (p < 0.05) among the pH mean values across the sites. High values of salinity, chloride, sodium, COD, BOD, manganese, nickel, cadmium, and nitrate were recorded among the surface water physicochemical parameters, which were above WHO (2011) permissible limits, while the high concentrations of toxic metals (Pb, Cr, Zn, and Cd) was recorded in sediment. A total of 26 species of benthic macroinvertebrates were recorded during this study, which belongs to eight (8) classes. Gastropoda recorded the highest percentage contribution of 39.12%, followed by polychaeta accounting for 30.34%, while malacostraca contributed 2.63%. The highest abundance of macroinvertebrates was recorded at Site I (256 Indiv/m 2 ), followed by Site IV (252 Indiv/m 2 ), and the least was observed at Site II (195 Indiv/m 2 ). Based on the results of the physico-chemical, heavy metals, microbial quality, and macroinvertebrates assemblage obtained from this study revealed the adverse effect of anthropogenic activities on water quality degradation. It plays a significant role in the distribution and diversity of benthic macroinvertebrates in an aquatic environment., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Published by Elsevier Ltd.)

Rapid agricultural development has induced severe environmental problems to freshwater ecosystems. In this study, we aimed to examine the structure and environmental determinants of macroinvertebrate assemblages in an agriculture dominated Lake Chaohu Basin, China. A cluster analysis of the macroinvertebrate communities identified four groups of sites that were characterized by significantly different macroinvertebrate species. These four groups of sites had concentric spatial distribution patterns that followed the variation in the environmental conditions from the less anthropogenically disturbed headwaters towards the more anthropogenically disturbed lower reaches of the rivers and the Lake Chaohu. Moreover, taxa richness decreased from the headwaters towards the Lake Chaohu. The increasing practice of agriculture has reduced the abundances and richness of pollution sensitive species while opposite effects on pollution tolerant species. The study identified substrate heterogeneity and nutrient concentrations as the key environmental factors regulating the changes in the macroinvertebrate communities. We propose that particular attentions should be paid to reduce the nutrient enrichment and habitat degradation in the Lake Chaohu Basin and similar agriculture dominated basins. [ABSTRACT FROM AUTHOR]

Abstract: Assessment of uranium (U)‐contaminated sediment is often hindered by the inability to accurately account for the physicochemical properties of sediment that modify U bioavailability. The present goal was to determine whether sediment‐associated U bioavailability could be predicted over a wide range of conditions and sediment properties using simple regressions and a geochemical speciation model, the Windermere Humic Aqueous Model (WHAM7). Data from a U‐contaminated field sediment bioaccumulation test, along with previously published bioaccumulation studies with U‐spiked field and formulated sediments, were used to examine the models. Observed U concentrations in Chironomus dilutus larvae exposed to U‐spiked and U‐contaminated sediments correlated well (r2 > 0.74, p < 0.001) with the WHAM‐calculated concentration of U bound to humic acid, indicating that humic acid may be a suitable surrogate for U binding sites (biotic ligands) in C. dilutus larvae. Subsequently, the concentration of U in C. dilutus was predicted with WHAM7 by numerically optimizing the equivalent mass of humic acid per gram of organism. The predicted concentrations of U in C. dilutus larvae exposed to U‐spiked and U‐contaminated field sediment compared well with the observed values, where one of the regression models provided a slightly better fit (mean absolute error = 18.1 mg U/kg dry wt) than WHAM7 (mean absolute error = 34.2 mg U/kg dry wt). The regression model provides a predictive capacity with a minimal number of variables, whereas WHAM7 provides additional complementary insight into the chemical variables influencing the speciation, sorption, and bioavailability of U in sediment. The present results indicate that physicochemical properties of sediment can be used to account for variability in U bioavailability as measured through bioaccumulation in chironomids exposed to U‐contaminated sediments. Environ Toxicol Chem 2018;37:1146–1157. © 2017 SETAC [ABSTRACT FROM AUTHOR]

Terrestrial allochthonous organic matter represents a structuring element and an important source of energy and carbon to fauna in small forested streams. However, the role of this matter as a food resource for benthic macroinvertebrates, and consequently, for shredders and their performance in riverine processes, is not clear in low-order tropical streams. Aiming to investigate the relationship between shredders and leaves, we analyzed along a gradient of 8-93% canopy cover biomass and abundance of shredders, accumulated leaves and breakdown rates of local leaves to verify if these parameters were related to shade conditions and to each other. Three hypotheses were tested: i) shredder biomass, accumulated leaves and breakdown rates are related to canopy cover and exhibit higher values in shaded sites; ii) shredder biomass is positively related to accumulated leaves and breakdown rates; and iii) due to the relatively large body size of the important shredders, the association of shredders with leaves and importance to leaf processing should be better expressed in terms of guild biomass than abundance. Shredder biomass varied between 846 and 1506 mg dry mass (DM) m-2 and accumulated leaves varied between 479 and 1120 g ash free dry mass (AFDM) m-2 across sites. Leaf breakdown rate (k), the only measured variable that varied significantly among sites, varied between -0.0015 and -0.0238 day-1. Neither shredder biomass nor leaf biomass were associated with the shading gradient. On the other hand, shredder abundance and biomass, mainly represented by Triplectides (Trichoptera, Leptoceridae), was positively related to accumulated leaves within sites and to breakdown rates assessed by leaf packs. Leaf breakdown, as assessed by the experimental leaf packs, was associated with shredder biomass, but not with shredder abundance. This result suggests that macroinvertebrates are important for leaf detritus processing and that their biomass reflects their activity, presumably because it is related to their secondary production and perhaps non-consumptive action. Their activity was observed at the scale of leaf packs and not at the scale of variation in canopy cover because apparently canopy did not modulate availability of leaves, which were apparently not limiting to the shredders. [ABSTRACT FROM AUTHOR]

Understanding the drivers of community structure is fundamental for adequately managing ecosystems under global change. Here we used a large dataset of eighty-four headwater stream sites in three catchments in the Eastern Highlands of Zimbabwe, which represent a variety of abiotic conditions and levels of impairment, to examine the drivers of benthic macroinvertebrate community structure. We focused our assessment on macroinvertebrate family level community composition and functional feeding group classifications. Taxonomic richness was weakly positively correlated with ammonium, phosphates and pH, and weakly negatively correlated with detrital cover and dissolved oxygen. Measured abiotic variables, however, had limited influence on both macroinvertebrate diversity and functional feeding group structure, with the exception of ammonium, channel width and phosphates. This reflected the fact that many macroinvertebrate families and functional feeding guilds were well represented across a broad range of habitats. Predatory macroinvertebrates were relatively abundant, with collector-filterers having the lowest relative abundances. The findings of the study suggest that for certain ecological questions, a more detailed taxonomic resolution may be required to adequately understand the ecology of aquatic macroinvertebrates within river systems. We further recommend management and conservation initiatives on the Save River system, which showed significant impact from catchment developmental pressures, such as urbanisation, agriculture and illegal mining. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Terrestrial allochthonous organic matter represents a structuring element and an important source of energy and carbon to fauna in small forested streams. However, the role of this matter as a food resource for benthic macroinvertebrates, and consequently, for shredders and their performance in riverine processes, is not clear in low-order tropical streams. Aiming to investigate the relationship between shredders and leaves, we analyzed along a gradient of 8-93% canopy cover biomass and abundance of shredders, accumulated leaves and breakdown rates of local leaves to verify if these parameters were related to shade conditions and to each other. Three hypotheses were tested: i) shredder biomass, accumulated leaves and breakdown rates are related to canopy cover and exhibit higher values in shaded sites; ii) shredder biomass is positively related to accumulated leaves and breakdown rates; and iii) due to the relatively large body size of the important shredders, the association of shredders with leaves and importance to leaf processing should be better expressed in terms of guild biomass than abundance. Shredder biomass varied between 846 and 1506 mg DM m‑2 and accumulated leaves varied between 479 and 1120 g AFDM m-2 across sites. Leaf breakdown rate (k), the only measured variable that varied significantly among sites, varied between -0.0015 and -0.0238 day-1. Neither shredder biomass nor leaf biomass were associated with the shading gradient. On the other hand, shredder abundance and biomass, mainly represented by Triplectides (Trichoptera, Leptoceridae), was positively related to accumulated leaves within sites and to breakdown rates assessed by leaf packs. Leaf breakdown, as assessed by the experimental leaf packs, was associated with shredder biomass, but not with shredder abundance. This result suggests that macroinvertebrates are important for leaf detritus processing and that their biomass reflects their activity, presumably because it is related to their secondary production and perhaps non-consumptive action. Their activity was observed at the scale of leaf packs and not at the scale of variation in canopy cover because apparently canopy did not modulate availability of leaves, which were apparently not limiting to the shredders.

This paper reports the benthic macroinvertebrate community and chlorophyll a (chl-a) concentration in sediment of three polluted sites in the Lagos Lagoon, Nigeria. Values observed for DO ranged between 3.0 and 4.5 mg/L, while transparency varied from 3 cm to 32 cm. Turbidity ranged between 28 and 80 NTU and depth of the study stations fluctuated between 196.16 and 317.5 cm. Two major macroinvertebrate groups (Annelida and Mollusca) made up of eight species were identified from a total density of 7820 ind/m2. Mollusca were the most abundant group with a density of 7800 ind/m2 and accounted for 99.7 % of the total macroinvertebrate density. Density of benthic macroinvertebrate varied among the study stations, while the variations observed in the values ofchl-a in sediment were mainly in relation to sampling periods. Transparency of water correlated positively and significantly with chl-a in sediment (rs= 1; p< 0.01) while turbidity and depth of water related negatively and significantly with chl-a in sediment. Results obtained in this study suggest that pollution in the three study sites impacted negatively on the benthic community. Key Words: Chl-a, benthic macroinvertebrate, pollution, estuarine ecosystem

This research aims to determine the water quality of tertiary irrigation in several subdistricts in Malang, namely Kepanjen, Karangploso, and Tumpang. The water quality depends on the water quality indices (National Sanitation Foundation’s-NSF Indices and O’Connor’s Indices based on variables TSS, TDS, pH, DO, and Nitrate concentrate) and ecological indices of benthic macroinvertebrate (Diversity Indices Shannon-Wiener, Hilsenhof Biotic Indices-HBI, Average Score per Taxon-ASPT which is calculated by Biological Monitoring Working Party-BMWP, Ephemeroptera Indices, Plecoptera, Trichoptera-EPT). Observation of the physico-chemical water quality and benthic macroinvertebrate on May 2012 to April 2013. The sampling in each subdistrict was done at two selected stations in tertiary irrigation channel with three plot at each station. The data of physico-chemical quality of water were used to calculate the water quality indices, while the benthic macroinvertebrate data were used to calculate the ecological indices. The research findings showed that 27 taxa of benthic macroinvertebrates belong 10 classes were found in the three subdistrict. The pH, DO, Nitrate, TSS and TDS in six tertiary irrigation channels in Malang still met the water quality standards based on Government Regulation No. 82 of 2001 on Management of Water Quality and Water Pollution Control Class III. Based on NSF-WQI indices and O'Connor's Indices, water qualities in these irrigation channels were categorized into medium or moderate (yellow) to good (green) category. However, based on benthic macroinvertebrate communities which was used to determine the HBI, the water quality in the irrigation channels were categorized into the fair category (fairly significant organic pollution) to fairly poor (significant organic pollution), while based on the value of ASPT, the water were categorized into probable moderate pollution to probable severe pollution. The irrigation water which was categorized into good by WQI was consistently included into fair based on HBI and probable moderate pollution based on ASPT.

Including or excluding rare taxa in bioassessment is a controversial topic, which essentially affects the reliability and accuracy of the result. In the present paper, we hypothesize that biological indices such as Shannon-Wiener index, Simpson's index, Margalef index, evenness, BMWP (biological monitoring working party), and ASPT (Average Score Per Taxon) respond differently to rare taxa exclusion. To test this hypothesis, a benthic macroinvertebrate data set based on recent fifteen-year studies in China was built for suppositional plot analyses. A field research was conducted in the Nansi Lake to perform related analyses. The results of suppositional plot simulations showed that Simpson's index placed more weight on common taxa than any other studied indices, followed by Shannon-Wiener index which remained a high value with the exclusion of rare taxa. The results indicated that there was not much of effect on Simpson's index and Shannon-Wiener index when rare taxa were excluded. Rare taxa played an important role in Margalef index and BMWP than in other indices. Evenness showed an increase trend, while ASPT varied inconsistently with the exclusion of rare taxa. Results of the field study also indicated that rare taxa had few impacts on the Shannon-Wiener index. By examining the relationships between the rare taxa and biological indices in our study, it is suggested that including the rare taxa when using BMWP and excluding them in the proposed way (e.g., fixed-count subsampling) to calculate Shannon-Wiener index and Simpson's index could raise the efficiency and reduce the biases in the bioassessment of freshwater ecosystems. [ABSTRACT FROM AUTHOR]