Benthic Macroinvertebrate Taxa Research Articles

The Determination of Trophic Level of Küçükçekmece Lagoon Lake (İstanbul, Türkiye) by Using Some Environmental Variables with Indicator Benthic Macroinvertebrates Findings

In this study, to determine the trophic level of Küçükçekmece Lagoon Lake, water and sediment samplings were performed at five selected stations seasonally during a year between 2014-2015. The water samples were analyzed to determine some environmental variables (water temperature, pH, conductivity, DO (dissolved oxygen), TDS (total dissolved solids), and salinity. NO3-N, NO2-N, SO4-2, PO4-3, SiO2, chlorophyll-a, TP (total phosphorus), and Secchi disc light permeability) and benthic macroinvertebrates were examined to determine indicator organisms in the sampled sediment material. Bray-Curtis Similarity Index was used to the observed environmental results to determine the similarities of the sampling stations. According to this, station 1 (St. 1) located in the center of the lake, and St. 5 located near the sea were found to be different from other sampling stations while the stations located near the creeks were found to have much more similar to each other. In addition, to determine the trophy level of the lake, Carlson Trophic State Index (CTSI) was used to the obtained some physicochemical results (Secchi disc permeability, total phosphorus, chlorophyll-a) and it was found that the lake showed a eutrophic character during all seasons. According to the result of sediment sampling, an average of 350 individuals per m2 (44.3 % belonging Polychaeta group; 29.5 % belonging Chironomidae group; 19.7 % belonging Oligochaeta group; 6.5 % belonging Bivalvia group) in a total of 6 benthic macroinvertebrate taxa (Bivalvia, Polychaeta, Tubificoides benedii (Oligochaeta), Tubificoides sp. (immature Oligochaeta), Limnodrilus hoffmeisteri (Oligochaeta), and Chironomus salinarius (Chironomidae) were determined. Thus, it is observed that the presence of some indicator species supported eutrophic conditions qualitatively. As a result of this study, it was determined that Küçükçekmece Lagoon lake going on to expose the increasing pollution load.

Elevated levels of per- and polyfluoroalkyl substances (PFAS) in freshwater benthic macroinvertebrates from the Hudson River Watershed

Per- and polyfluoroalkyl substances (PFAS) are contaminants of global concern due to their persistence and associated negative health effects. Considerable attention has been given to monitoring PFAS in the aquatic environment, however, few investigations have done so using freshwater benthic macroinvertebrates (BMIs). As these bottom-dwelling animals are known to bioconcentrate exogenous pollutants to a high degree, studying their PFAS levels may provide a more integrated view of PFAS contamination in the aquatic environment. In this study, BMIs, sediment, and surface water were collected from two streams in the Hudson River Watershed (one historically-impacted by PFAS) and analyzed for 44 PFAS using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Orbitrap high-resolution mass spectrometry (HRMS) was used to confirm the identities of quantitated analytes. Across all matrices, 17 analytes were detected with PFOA dominating in surface water and PFOS in sediment/BMIs. PFOS bioaccumulation factors (BAFs) were approximately one order of magnitude higher than those of PFOA and ranged from 857 to 5151 L kg−1 across different BMI taxa. While PFAS concentrations in surface water and sediment were not excessively high, elevated levels were still measured in most BMI taxa. This observation suggests that the extent of PFAS contamination in a local system may be severely underestimated if only surface water and sediment are used for monitoring. Moreover, these findings have relevance for human exposure assessment considering BMIs are the primary food source of many fish.

Assessing the feasibility and value of employing an ecosystem services approach in chemical environmental risk assessment under the Water Framework Directive

The feasibility and added value of an ecosystem services approach in retrospective environmental risk assessment were evaluated using a site-specific case study in a lowland UK river. The studied water body failed to achieve good ecological status temporarily in 2018, due in part to the exceedance of the environmental quality standard (annual average EQS) for zinc. Potential ecosystem service delivery was quantified for locally prioritised ecosystem services: regulation of chemical condition; maintaining nursery populations and habitats; recreational fishing; nature watching. Quantification was based on observed and expected taxa or functional groups within WFD biological quality elements, including macrophytes, benthic macroinvertebrates and fish, and on published functional trait data for constituent taxa. Benthic macroinvertebrate taxa were identified and enumerated before, during and after zinc EQS exceedance, enabling a generic retrospective risk assessment for this biological quality element, which was found to have good ecosystem service potential. An additional targeted risk assessment for zinc was based on laboratory-based species sensitivity distributions normalised using biotic-ligand modelling to account for site-specific, bioavailability-corrected zinc exposure. Risk to ecosystem services for diatoms (microalgae) was found to be high, while risks for benthic macroinvertebrates and fish were found to be low. The status of potential ecosystem service delivery (ESD) by fish was equivalent to high ecological status defined under the WFD, while ESD was higher for benthic macroinvertebrates than defined by WFD methods. The illustrated ecosystem services approach uses readily available data and adds significantly to the taxonomic approach currently used under the WFD by using functional traits to evaluate services that are prioritised as being important in water bodies. The main shortcomings of the illustrated approach were lack of: representation of bacteria and fungi; WFD predicted species lists for diatoms and macrophytes; site-specific functional trait data required for defining actual (rather than potential) ecosystem service delivery.

Biomass, Productivity, and Biomass Turnover (P/B) Ratios of Benthic Macroinvertebrates in High Elevation Ponds in St. Ann, Jamaica (West Indies)

From January 2014 to April, 2015, eight high elevation ponds were sampled in St. Ann Parish, Jamaica. These ponds were classified as small, mixed, or large based on cluster analysis, which created these groups based on size and physicochemical parameters. Regression of mass on length was completed for most benthic macroinvertebrate taxa, and consequently 170 length-mass equations were developed for use in mass determination locally and regionally. The sample area was taxonomically rich, consisting of 78 species, 43 families, and 14 orders, with class Insecta having the largest number of taxa. Biomass was constant over time, which implied that food availability was not limited for invertebrates in the sample area. The results indicated that biomass in the sample area was dominated by Aeshnidae and Belostomatidae, which had significantly higher values than most other taxa. Culicidae, and the families of Diptera in general, were not well represented in the biomass within the sample area. Total production for the sample area was estimated to be 398.87 g m-2yr-1, with the highest values for production being obtained for Anisoptera, Podocopoida, and Ephemeroptera; while the P/B ratio of Podocopoida was significantly higher than most taxa. When the results were assessed based on pond groups, families of the class Insecta, particularly Aeshnidae and Belostomatidae, had significantly high biomass in large and mixed ponds, while Physidae dominated the biomass of small ponds. The productivity results almost mirrored what was observed for biomass; however, Cypridoidea (ostracods) showed high productivity in the mixed group although its biomass contribution was <3%. These findings are the first to examine biomass, production and P/B ratios in a lentic habitat in Jamaica, compute length-mass equations, and form an important record against which other studies within the island and throughout the Caribbean can be compared to.

Taxonomic Diversity and Structure of Benthic Macroinvertebrates of Taabo Lake (Basin of Bandama; Ivory Coast)

The taxonomic diversity and structure of benthic macroinvertebrates of Taabo Lake (Ivory Coast), from November 2017 to October 2018 were evaluated. Water quality parameters, such as temperature (T °C), water transparency (cm), dissolved oxygen (mg.L-1), pH, turbidity (NTU), electrical conductivity (EC, µS.cm-1) were measured in situ using a multi-parameter probe HANNA, from four sampling points (littoral and sub-littoral zones) in Taabo Lake. Benthic macroinvertebrates sampling were collected by using Van veen in stainless steel. A total of 63 benthic macroinvertebrates taxa belonging to 23 Families, 8 Orders, 2 Classes and 2 Phylums (Molluscs and Arthropods) were identified. The most abundant of benthic macroinvertebrates were Mesogastropoda (66%) represented in all sampling points. They were followed by Diptera (25%), Odonata (3%), Ephemeroptera (3%), Basommatophora (2%), Heteroptera (1%), Lepidoptera and Coleoptera (less than 1%). The values of diversity indices of benthic macroinvertebrates collected in Taabo Lake showed no significant variations between sampling points.

Assessing the ecological status of fluvial ecosystems employing a macroinvertebrate multi-taxon and multi-biomarker approach

Biomarkers are recognised sensitive early-warning tools of biological effects in aquatic organisms. In this scope, the main aim of this study was to investigate the potential usefulness of a battery of biomarkers, evaluated in different benthic macroinvertebrate taxa, to discriminate aquatic ecosystems with different levels of ecological status and to provide further clues supporting environmental management. The study took place during the autumn of 2013 and the spring and summer of 2014, and the study cases were two Mediterranean rivers (Âncora and Ferreira rivers), differing in their ecological status. The biomarkers determined are widely employed and comprise a large set of biochemical responses: the activity of enzymes (cholinesterases, glutathione S-transferases, catalase and lactate dehydrogenase) and the levels of lipid peroxidation. They were assessed seasonally and in different macroinvertebrate taxa. Thirteen water physico-chemical parameters were also seasonally determined, and the concentration of seven organophosphorus pesticides and the percentage of 32 trace metals in sediments were determined in the spring. This is particularly useful for water management. Based on this, authorities can take actions to prevent further damage in the ecological status. Multivariate analyses showed distinct patterns of biological response for the Calopteryx spp., Chironomidae and Baetis spp. taxa. Calopteryx spp. and Chironomidae, in particular, showed distinct response patterns for the two rivers, which were fairly stable across seasons. This study sets the foundations for future cost-effective biomonitoring campaigns in Mediterranean rivers, allowing to establish historical data important to understand ecosystem evolution, as well as baseline levels of diagnostic biomarkers in informative macroinvertebrate taxa.

Dam Removal Effects on Benthic Macroinvertebrate Dynamics: A New England Stream Case Study (Connecticut, USA)

Dam removal is an increasingly common stream restoration tool. Yet, removing dams from small streams also represents a major disturbance to rivers that can have varied impacts on environmental conditions and aquatic biota. We examined the effects of dam removal on the structure, function, and composition of benthic macroinvertebrate (BMI) communities in a temperate New England stream. We examined the effects of dam removal over the dam removal time-series using linear mixed effects models, autoregressive models, non-metric multidimensional scaling, and indicator and similarity analyses. The results indicated that the dam removal stimulated major shifts in BMI community structure and composition above and below the dam, and that the BMI communities are becoming more similar over time. The mixed model analysis revealed that BMI functional groups and diversity were significantly influenced by sample site and several BMI groups also experienced significant interactions between site and dam stage (P &lt; 0.05), while the multivariate analyses revealed that community structure continues to differ among sites, even three years after dam removal. Our findings indicate that stream restoration through dam removal can have site-specific influences on BMI communities, that interactions among BMI taxa are important determinants of the post-dam removal community, and that the post-dam-removal BMI community continues to be in a state of reorganization.

Small Parks as Local Social–Ecological Systems Contributing to Conservation of Small Isolated and Ephemeral Wetlands

Publicly owned lands designated as parks can be important tools for biodiversity conservation. In the U.S., state parks are afforded direct protection from localized development pressures, which may help to protect small, ecologically significant ecosystems such as isolated and ephemeral wetlands and headwater streams. We used the South Carolina State Park system as a case study to examine the structural and functional differences between small wetlands located inside vs. outside of parks in the Piedmont and Blue Ridge ecoregions in order to evaluate the efficacy of a small-scale conservation framework for protecting small, under-protected freshwater ecosystems. We evaluated data relating to water quality, wetland structure, and biodiversity parameters collected between January 2010 and June 2011. Our results indicated marked differences between park and non-park wetlands, with park wetlands having shallower depths, higher abundances of sensitive benthic macroinvertebrate taxa, and lower average tolerance values consistent with more sensitive macroinvertebrate species and higher water quality. These findings demonstrate that state parks can serve to protect freshwater ecosystems and biodiversity. State parks, thus, represent a preexisting network of protected areas to aid in the protection of localized habitats, such as small isolated and ephemeral wetlands, that may not otherwise receive the conservation protection warranted by their ecological function.

Evaluation of Plecoptera (Insecta) community composition using multivariate technics in a biodiversity hotspot

Eastern Black Sea Region of Turkey is a sub-ecoregion of the Caucasus Ecoregion, and its Plecoptera fauna is similar to fauna of Caucasus with unique endemic species of the region. The Caucasus Ecoregion is one of the “WWF Global 200 Ecoregions,” and it is also included in the list of top 25 hotspots in the World. Running water ecosystems of Eastern Black Sea sub-ecoregion are the most sensitive to land use change and global climate change. High-altitude aquatic ecosystems are more strongly threatened by global climate change in the region. Plecoptera constitute the most important part of the biodiversity of running waters in the region. Among the benthic macroinvertebrate taxa, Plecoptera is the best indicator of ecological conditions of running waters. The influence of environmental variables on the distribution of twenty Plecoptera species in running water ecosystems (headwaters, crenon, epirhithron, metarhithron) was assessed using canonical correspondence analysis. Sampling was carried out in 2009 and 2011. Eleven end groups were generated from the TWINSPAN analysis. Isoperla rhododendri, Isoperla grammatica, Protonemura bifida, Protonemura eumontana and Perla caucasica were closely related to pH, dissolved oxygen and riparian vegetation. Brachyptera transcaucasica transcaucasica, Nemoura martynovia, Nemoura taurica and Protonemura eumontana were related to Mg and Cu. The results show that the Plecoptera assemblage composition was affected by DO, pH, EC, temperature, nitrite, Ca, Mg, Fe, Cu, Zn, Al, riparian vegetation, altitude and stream width.

Habitat suitability curves for benthic macroinvertebrates from a small New Zealand river

We developed habitat suitability curves (HSC) using generalised additive models (GAMs) for nine benthic macroinvertebrate taxa from a small New Zealand river for hydraulic-habitat modelling assessments of instream flow requirements. We included interaction terms between the primary variables (water depth, velocity, substrate) when significant, to address a longstanding criticism of univariate HSC. To date, only large-river univariate HSC have been available and these have been used in hydraulic-habitat applications on small rivers, despite doubt over the transferability of HSC between rivers of different size and type. We tested the outcome on the predicted abundance–flow relationship of applying the small-river habitat suitability GAMs versus large-river GAMs for two taxa on the same small river. We found the effects of flow allocation were overestimated by the large-river GAMs relative to the small-river GAMs. Further research to develop general HSC for categories of river size and type is needed to better inform hydraulic-habitat modelling applications.

Relationship of bifenthrin sediment concentrations to grain size and total organic carbon in California waterbodies: implications for ecological risk.

A summary analysis of data sets from six California waterbodies was conducted to determine the relationship of bifenthrin sediment concentrations to: % sand/gravel; % silt; % clay; % silt/clay and % total organic carbon (TOC). The relationship of TOC to % sand/gravel, % silt, % clay, and % silt/clay was also analyzed. Statistically significant and meaningful direct relationships were reported between bifenthrin and % TOC, % silt, % clay and % silt/clay while a significant and meaningful inverse relationship was reported between bifenthrin and % sand/gravel. A significant and meaningful inverse relationship was reported between % TOC and % sand/gravel, while a significant and meaningful direct relationship was reported between % TOC and % silt, % clay and % silt/clay. Significant bifenthrin sediment concentrations would not be expected in non-depositional (sand/gravel) areas which have been reported to be dominant in various streams in California's Central Valley and are also the preferred habitat for many benthic macroinvertebrate taxa.

Drought effects on the colonization of benthic macroinvertebrate communities in the early successional phases in experimental mesocosm wetlands

We investigated the drought effects on the colonization rate and pattern of benthic macroinvertebrate communities in newly created mesocosm wetlands in the central Korean Peninsula, from June 2011 to June 2013. The comparison was made between the initial colonization after mesocosm construction (pre-drought) and the recolonization after a drought event (post-drought) with a drought period of 50 days between them. In addition, we categorized communities according to their biological traits in relation to drought. Our results showed that aquatic vegetation abundance and covering degree were higher in post-drought than in pre-drought, thereby influencing rapid colonization. Drought-resistant benthic macroinvertebrates colonized rapidly in post-drought; consequently, the colonization speed was 2.5-fold higher in post-drought than in pre-drought. We classified the benthic macroinvertebrate taxa into three groups: (1) a resistant group which generally emerged after the initial colonization period (e.g., Mollusca, Turbellaria, and Oligochaeta); (2) a sensitive group with diverse life history strategies and biological traits such as active migration or population decline after drought disturbance (e.g., Diptera: Chironominae, Odonata: Orthetrum, Coleoptera: Agabus and Rhantus); and (3) a seasonal group, which emerged only during certain periods and were not markedly influenced by drought (e.g., Ephemeroptera: Cloeon, Diptera: Culicidae, Odonata: Zygoptera and Pantala). Our findings elucidated the effects of drought on benthic macroinvertebrate communities in wetlands by using a mesocosm experiment.

Benthic macroinvertebrate communities in five rivers of the Coastal Hudson Bay Lowland

As a precursor to developing a biomonitoring program for rivers of the Coastal Hudson Bay Lowland, this study characterized and compared the benthic macroinvertebrate communities and water chemistry in 5 remote, previously undescribed, rivers near Fort Severn, Ontario, Canada. The pH of river water ranged from 8.1 to 8.7, total phosphorus from 11 to 26 μg L−1, dissolved organic carbon from 8 to 12 mg L−1, and chloride from 56 to 153 mg L−1. A total of 57 benthic macroinvertebrate taxa were represented, and the 10 most numerically dominant were the Chironominae (26 % of collected individuals), Orthocladiinae (16 %), oligochaetous clitellata (9 %), Hyalellidae (7 %), Hydropsychidae (6 %), Gammaridae (5 %), Elmidae (5 %), Sphaeriidae/Pisidiidae (4 %), Nemata (3 %), and Tanypodinae (3 %). Rivers’ positions in ordinations of chemical and biological datasets were similar, suggesting that water chemistry has a role in structuring riverine benthic communities in the study region. Correlations between water-chemistry or habitat predictors and site-scores in the ordination of benthic macroinvertebrate taxa counts suggested that biological community structure was most associated with river-water pH, nutrient concentrations (e.g., total phosphorus, nitrogenous compounds, dissolved organic carbon, calcium, and silicate), the relative abundance of submerged macrophytes, conductivity (i.e., the concentrations of chloride and various other dissolved ions), and several geomorphological variables (e.g., bank-full river width, current speed, and the size of the dominant inorganic particles in the pavement layer of the streambed). Interest in mineral extraction and other resource-based exploration in Ontario’s Far North is increasing. This study represents a start on baseline characterization for ecological monitoring and cumulative effects assessment that should proceed along with northern development.

Riffle Beetle Communities of Perennial and Intermittent Streams in Northern Nevada, USA, with a New State Record forOptioservus castaneipennis(Fall) (Coleoptera: Elmidae)

Long-lived, benthic macroinvertebrate taxa are often poorly represented in intermittent streams because the periodic lack of water eliminates colonization habitat for those invertebrates, especially among those for which burrowing is not part of their life history. In the western United States, elmid beetles, which do not burrow, have a multiple-year life cycle, and multiple species are often found coexisting, even in intermittent streams. The elmid beetle communities of 21 sites on eight streams in northern Nevada were examined to determine patterns of occurrence and their relation to water permanence in those streams. Samples were collected in June 2006, May 2007, September 2010, and July 2011. In two streams, no elmid beetles were collected, probably due to the habitat not being conducive to elmid beetle presence (mucky substrate). Among the perennial stream sites, one or two species were consistently dominant, and the relative abundances of species were similar throughout all years. In contrast, elmid beetles were often, but not always, absent from intermittent streams even when water was present, and species dominance was usually different among the years when elmid beetles were present in those streams. These data suggest a strong role of opportunistic colonization in intermittent headwater streams, with more stable communities fostered by perennial streams. Collection records are presented for Optioservus castaneipennis (Fall), new state record, which heretofore had not been reported from Nevada.

Multi-biochemical responses of benthic macroinvertebrate species as a complementary tool to diagnose the cause of community impairment in polluted rivers

Biological indexes, based on benthic macroinvertebrate taxa, are currently used worldwide to measure river ecological quality. These indexes assign a global ecological status of the biotic community, but not necessarily may detect specific effects of water pollutants. Conversely a large set of biochemical markers measured in macroinvertebrate benthic species can detect sublethal effects and inform us about additional environmental factors that are impairing benthic communities. This is especially interesting in moderately polluted sites, where other stressors are already affecting communities but not too strongly to be detected by biotic indexes. Up to ten different markers belonging to distinct metabolic paths and 42 contaminants measured in sample collections of the caddis fly Hydropsyche exocellata were assessed across a polluted gradient in the industrialized Mediterranean River basins of Besós and Llobregat (NE, Spain). Twenty four sample collections were selected to include macroinvertebrate communities representing the five impairment degrees defined by the Spanish Environmental authorities using the biotic metrics. Results evidenced a clear deterioration of the ecological water quality parameters and benthic communities towards downstream reaches. Biochemical responses varied significantly across the studied samples and were able to differentiate samples within communities having a good and deteriorated ecological stage. Principal Component Analyses indicated that salinity was one of the major stresses affecting macroinvertebrate assemblages, whereas antioxidant and metabolizing enzymes responded differently and were closely related to high and presumably toxic levels of accumulated organic pollutants. Therefore these results indicate that the use of multiple -markers sensitive to water pollution may provide complementary information to diagnose environmental factors that are impairing macroinvertebrate communities.

Biodiversity of Koshi Tappu Wildlife Reserve: a post flood assessment

Koshi Tappu Wildlife Reserve and its associated wetlands including Saptakoshi River are important wetland habitats for the critically endangered Wild Water Buffalos (Bubalus bubalis arnee), Migratory Birds and River Dolphins (Platanista gangetica). Rapid and complete inundation of the Reserve during monsoon and frequent changes in river courses almost every year has been the biggest threat to the existence of wild buffalo (locally known as 'Arna') and other wildlife. The breach of eastern embankment of the Koshi barrage at Kusaha of Sunsari district on 18th August 2008, created havoc for wildlife and their habitats, people’s livelihood and welfare. A study was therefore conducted to ascertain the status of biodiversity within Koshi Tappu Wildlife Reserve and its Buffer Zone from March to November 2009 to come up with the status of Arna, dolphins, marsh mugger crocodile, Swamp francolin (Simtitra), and vulture population and assess the ecological status of wetlands. Direct count method, transect method, point counts, qualitative samplings, field observation and social survey were carried out to study the biodiversity status. A total of 219 wild water buffalo, 11 dolphins, 5 marsh mugger crocodiles, 52 to 74 Swamp francolin and 517 vultures. The studied wetlands were moderately polluted. Altogether 42 taxa of benthic macro invertebrates were recorded. The results were further compared with a few years of data before the flood occurrence. The current result showed an encouraging population of key species at the Reserve but the threats for conservation still remain challenging. Key words: biodiversity; critically endangered; human pressure; Koshi breach; stewardship; wetlands DOI: 10.3126/jowe.v4i0.3734Journal of Wetlands Ecology, (2010) Vol. 4, pp 69-82

Composition and structure of benthic macroinvertebrate community in two reservoirs in Hubei province, China: Response to eutrophication

Water quality and benthic macroinvertebrate samples were collected from two reservoirs in central China from November 2006 to August 2007. Twenty-nine benthic macroinvertebrate taxa were identified, including 10 oligochaetes, 15 aquatic insects and four molluscs. Some of the most common taxa were Aulodrilus pluriseta, Limnodrilus hoffmeisteri, Cryptochironomus sp., Polypedilum sp. and Tokunagayusurika akamusi. Average densities of the macroinvertebrates were similar in both reservoirs (about 300 ind.m−2), whereas there was a large difference in biomass with 430.7 mg.m−2 in Daoguanhe reservoir and 1294.3 mg.m−2 in Jinshahe. Density and biomass of the benthic macroinvertebrates varied over time in both reservoirs with the highest values in November of 2006. Density and biomass also varied spatially. Water temperature, depth, sediment composition and nutrients were correlated with the density of benthic organisms. The biological quality of reservoirs was evaluated with the Shannon diversity, Margalef richnes...

Benthic macroinvertebrate communities in agriculturally impaired streams.

Normal 0 false false false EN-US X-NONE X-NONE This work presents research into the taxonomic composition of macroinvertebrate communities in streams that are under the influence of agricultural pollution A total of 67 macroinvertebrate taxa (including 61 identified species) belonging to 40 families have been identified in the explored streams. The greatest species richness is recorded for the Trichoptera (18 species/1 taxa) and Mollusca (12 species). The molluscs Gyraulus albus, amphipods Gammarus pulex, caddisflies Hydropsyche pellucidula and oligochaetes are detected in all examined streams. There, the number of total benthic macroinvertebrate taxa is highly variable, ranging from 16 to 40. Results show that the examined streams depending on the benthic macroinvertebrate taxonomic composition and predominance of seperate macroinvertebrate groups undergo different pollution. Intolerant to pollution taxa such as Plecoptera, which are the most sensitive to pollution insects, have been found only in 5 of 12 examined streams and in low abundances. The richness and diversity of macrozoobenthos in some streams appear to respond to the water quality deterioration. The present study has found out that in the stream where the total macroinvertebrate taxa, EPT taxa richness are the lowest and a relative abundance of gatherers is the highest, the values of NH 4 -N, NO 3 -N, total N, PO 4 -P and total P in the stream water are the highest, too.

Effects of the invasive Asian clam Corbicula fluminea on benthic macroinvertebrate taxa in laboratory experiments

: The invasive burrowing bivalve Corbicula fluminea has an impact on ecosystem processes and on ortter dynamics in sediments. However, little is known about its effect on benthic communities especially ganic matter dynamics in sediments. However, little is known about its effect on benthic communities, especially on macroinvertebrates. In laboratory experiments, we determined the effect of naturally occurring densities of C. fluminea (1012 ind. m -2 ) on ten macroinvertebrate taxa typical for the littoral zone of Lake Constance: two species of leeches, three species of gastropods, two amphipod species, one isopod, and two taxa of insect larvae (a stonefly and chironomids). We hypothesized that these benthic organisms might prefer C. fluminea over sand in pairwise habitat-choice experiments because of structural and biotic effects of the bivalves. We distinguished between biotic effects of living infaunal C. fluminea that were either starved (only bioturbation) or fed with algae (biodeposition, bioturbation and nutrient reallocation), and we tested the importance of their structural role using C. fluminea valves lying on sand. No benthic taxa avoided areas with live C. fluminea or their valves. The detritivorous gastropod Lymnaea stagnalis and the amphipod Gammarus roeselii were found in higher numbers in areas with fed C. fluminea than in areas with sand. Starved clams were only preferred over sand by the amphipod Dikerogammarus villosus. The epifaunal taxa Erpobdella octoculata, Glossiphonia complanata (Hirudinea), D. villosus, G. roeselii (Amphipoda), Asellus aquaticus (Isopoda), and Centroptilum luteolum (Ephemeroptera) preferred areas with C. fluminea valves to areas with sand. The crustacean species and the leeches preferred valves over sand more than they preferred fed or starved living clams over sand. C. luteolum was the only taxon that responded differently to C. fluminea in the three experiments, whereas gastropods and chironomids did not show differences. We conclude that on poorly structured sediments, valves of C. fluminea, which increase the surface area and substrate diversity, could lead to an increase of most epifaunal benthic invertebrates.

Effects of Cassava effluent on Benthic Macroinvertebrate Assemblages in a Tropical Stream in Southern Nigeria

The study of the effect of cassava effluents on macroinvertebrates along downstream reaches of the Orogodo River, the Niger Delta was carried out monthly from January to June 2006. Three study stations were selected along the river course (upstream of the cassava impacted site, the cassava-impacted site, and downstream of the cassava impacted site). The study showed that cassava effluents caused a decrease in dissolved oxygen and pH and an increase in biochemical demand (BOD) and nitrates. Significant differences in these parameters were established among the stations sampled. A post hoc test indicated that station II (the cassava impacted site) was the cause of the observed differences. A total of 55 benthic macroinvertebrate taxa with a mean of 6,116 individuals were collected from the three stations along the river. The analysis showed that the overall density of fauna differed significantly among the stations. Cassava effluents permitted the dominance of oligochaetes and dipterans at station II and th...