Occurrence,abundance and distribution of benthic macroinvertebrates in the Nyando River catchment,Kenya

A baseline study was conducted of the occurrence of macroinvertebrates at 26 sites in the Nyando River catchment in 2005–2006. A total of 13 orders and 16 families of Arthropoda, Mollusca, Platyhelminthes and Annelida were collected, with the order Ephemeroptera being most abundant in the up- and mid-stream reaches, followed by Hemiptera and Plecoptera respectively. The downstream sections of the river were dominated by Hirudinea and tubificids, as the water quality deteriorated mainly due to local land use, raw sewage effluent discharge and annual floods. Insects and annelids were the main invertebrates found and the extent of pollution increased from mid-section (Site 15) downwards as the river flowed into the Winam Gulf. Stringent management measures are required to safeguard the environment and ecosystems of Lake Victoria.     

The fauna of the exposed zone of Øvre Heimdalsvatn: Methods, sampling stations and general results

Twenty stations were sampled monthly during the Ice free period (June-September) in 1972. Emergence traps, emptied daily, were also employed. The major macroinvertebrates in the exposed zone were Ephemeroptera, Gammarus lacustris , Trichoptera, Chironomidae, Plecoptera and Coleoptera, and these constituted over 90% of total numbers. Densities of G. lacustris , Ephemeroptera, Tipulidae and Plecoptera showed a positive correlation with detritus. No significant relationship was found for the other taxa. Nearly 70% of the fauna emerged, and did so during the period from June to September. Chironomidae, Ephemeroptera, Plecoptera, Trichoptera and Tipulidae accounted for nearly all emergence and their total average annual emergence was 372 cal m⁻². Of this total, Chironomidae constituted 28%, Ephemeroptera 28%, Plecoptera and Trichoptera 15% each and Tipulidae 4%.     

Estimates of resource transfer via winged adult insects from the hyporheic zone in a gravel‐bed river

Hyporheic zone (HZ) locates below the riverbed providing habitat for macroinvertebrates from where the winged adult insects (i.e., hyporheic insects, HIs) emerge and bring out aquatic resources to the riparian zone. This study estimated mean daily flux as dry biomass (BM), carbon (C), and nitrogen (N) deriving from the dominant HI species Alloperla ishikariana (Plecoptera, Chloroperlidae) for a 4th‐order gravel‐bed river during the early‐summer to summer periods. We hypothesized that HIs were an important contributor in total aquatic resources to the riparian zone. In 2017 and 2018, we set parallelly (May to August) and perpendicularly (June to October) oriented Malaise traps to catch the lateral and longitudinal directional dispersing winged adults of A. ishikariana, and other Ephemeroptera, Plecoptera, Trichoptera, and Diptera from the river and estimated the directional fluxes of them. We further split the directional fluxes as moving away or back to the channel (for lateral) and from down‐ to upstream or up‐ to downstream (for longitudinal). Alloperla ishikariana was similar to other Plecoptera species and differed clearly from Ephemeroptera and Trichoptera in directional characteristics of resources flux, suggesting that the extent and directions of HZ‐derived resource transfer depend on taxon‐specific flight behaviors of HIs. Contributions of A. ishikariana to the riparian zone in total aquatic C and N transfer seasonally varied and were lower in May (5%–6%) and August (2%–4%) and the highest in July (52%–70%). These conservative estimates largely increased (9% in May) after the supplementary inclusion of Diptera (Chironomidae and Tipulidae), part of which were considered HIs. We demonstrated that HZ could seasonally contribute a significant portion of aquatic resources to the riparian zone and highlighted the potential importance of HZ in nutrient balance in the river‐riparian ecosystem.     

A DNA barcode library for Germany′s mayflies,stoneflies and caddisflies (Ephemeroptera,Plecoptera and Trichoptera)

Mayflies, stoneflies and caddisflies (Ephemeroptera, Plecoptera and Trichoptera) are prominent representatives of aquatic macroinvertebrates, commonly used as indicator organisms for water quality and ecosystem assessments. However, unambiguous morphological identification of EPT species, especially their immature life stages, is a challenging, yet fundamental task. A comprehensive DNA barcode library based upon taxonomically well‐curated specimens is needed to overcome the problematic identification. Once available, this library will support the implementation of fast, cost‐efficient and reliable DNA‐based identifications and assessments of ecological status. This study represents a major step towards a DNA barcode reference library as it covers for two‐thirds of Germany's EPT species including 2,613 individuals belonging to 363 identified species. As such, it provides coverage for 38 of 44 families (86%) and practically all major bioindicator species. DNA barcode compliant sequences (≥500 bp) were recovered from 98.74% of the analysed specimens. Whereas most species (325, i.e., 89.53%) were unambiguously assigned to a single Barcode Index Number (BIN) by its COI sequence, 38 species (18 Ephemeroptera, nine Plecoptera and 11 Trichoptera) were assigned to a total of 89 BINs. Most of these additional BINs formed nearest neighbour clusters, reflecting the discrimination of geographical subclades of a currently recognized species. BIN sharing was uncommon, involving only two species pairs of Ephemeroptera. Interestingly, both maximum pairwise and nearest neighbour distances were substantially higher for Ephemeroptera compared to Plecoptera and Trichoptera, possibly indicating older speciation events, stronger positive selection or faster rate of molecular evolution.     

The role of macroinvertebrates for conservation of freshwater systems

Freshwater ecosystems are the most threatened ecosystems worldwide. Argentinian‐protected areas have been established mainly to protect vertebrates and plants in terrestrial ecosystems. In order to create a comprehensive biodiverse conservation plan, it is crucial to integrate both aquatic and terrestrial systems and to include macroinvertebrates. Here, we address this topic by proposing priority areas of conservation including invertebrates, aquatic ecosystems, and their connectivity and land uses. Location: Northwest of Argentina. We modeled the ecological niches of different taxa of macroinvertebrates such as Coleoptera, Ephemeroptera, Hemiptera, Megaloptera, Lepidoptera, Odonata, Plecoptera, Trichoptera, Acari, and Mollusca. Based on these models, we analyzed the contribution of currently established protected areas in the conservation of the aquatic biodiversity and we propose a spatial prioritization taking into account possible conflict regarding different land uses. Our analysis units were the real watersheds, to which were added longitudinal connectivity up and down the rivers. A total of 132 species were modeled in the priority area analyses. The analysis 1 showed that only an insignificant percentage of the macroinvertebrates distribution is within the protected areas in the North West of Argentina. The analyses 2 and 3 recovered similar values of protection for the macroinvertebrate species. The upper part of Bermejo, Salí‐Dulce, San Francisco, and the Upper part of Juramento basins were identified as priority areas of conservation. The aquatic ecosystems need special protection and 10% or even as much as 17% of land conservation is insufficient for species of macroinvertebrates. In turn the protected areas need to combine the aquatic and terrestrial systems and need to include macroinvertebrates as a key group to sustain the biodiversity. In many cases, the land uses are in conflict with the conservation of biodiversity; however, it is possible to apply the connectivity of the watersheds and create multiple‐use modules.     

Aquatic insects (Insecta: Plecoptera, Ephemeroptera, Odonata, and Trichoptera) of the rivers in the Berezinskii Biosphere Reserve

The fauna of aquatic insects was studied in the rivers of the Berezinskii Biosphere Reserve. A total of 108 species of 4 orders were found: Plecoptera (10 species), Ephemeroptera (24), Odonata (25), and Trichoptera (49). The aquatic fauna is abundant and includes some species rare in Belarus and Europe.     

A trait-based approach to assess the vulnerability of European aquatic insects to climate change

Aquatic insects are the dominant taxon group in most freshwater ecosystems. As temperature is the main driver of their life cycle development, metabolic activity, and geographic distribution, these macroinvertebrates are particularly suitable for large scale and comparative studies of freshwater community responses to climate change. A dataset of bio-ecological traits of 1,942 Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa was used to analyze (1) the relationships among traits, (2) the potential vulnerability of EPT species to climate change, and (3) the geographical occurrence patterns of these potentially endangered species at the scale of European ecoregions. By means of a fuzzy correspondence analysis (FCA), two gradients emerged: (1) a longitudinal gradient, describing successive upstream–downstream features, and (2) a biogeographical gradient, separating endemic and micro-endemic species from widely distributed taxa. Moreover, aquatic insects of southern European ecoregions emerged as those most endangered in terms of potential vulnerability to climate change. Comparative multi-taxon studies provide important new insights into freshwater ecosystem functioning and responses to climate change, and could be the first step toward developing integrative monitoring or assessment tools (e.g., trait-based indicators at the species level) by means of non-arbitrary statistical methods.     

Are Water Beetles Good Indicators of Biodiversity in Mediterranean Aquatic Ecosystems? The Case of the Segura River Basin (SE Spain)

Water beetles were examined for use as potential biodiversity indicators in continental aquatic ecosystems in a semiarid Mediterranean region, the Segura river basin (SE Spain). The indicator value of water beetles was investigated by examining the degree to which their species richness patterns was correlated with other groups (Plecoptera, Trichoptera, Mollusca, Heteroptera and Ephemeroptera), and the efficiency of water beetle area networks (selected by complementarity) in conserving overall groups richness. The species richness patterns of Coleoptera, Ephemeroptera, Plecoptera and Trichoptera were significantly correlated with the Remaining Richness value (RR), defined as the total number of species found at a site (of all six groups examined) minus the number of species belonging to the considered indicator group. Area networks for Coleoptera selected by complementarity represented the highest RR percentage (84.46%) and contained more than 78% species of each group. Furthermore, water beetles meet most of the criteria proposed in the literature for choosing biodiversity indicator taxa. In our study, the correlation values and the percentage of species represented by family, genus and species complementary networks were similar and we suggest that the higher taxa of water beetles (genera or families) can be used as biodiversity surrogates for cost-effective practical surveys.     

Vulnerability of alpine stream biodiversity to shrinking glaciers and snowpacks

Climate change poses a considerable threat to the biodiversity of high latitude and altitude ecosystems, with alpine regions across the world already showing responses to warming. However, despite probable hydrological change as alpine glaciers and snowpacks shrink, links between alpine stream biota and reduced meltwater input are virtually unknown. Using data from the French Pyrénées, we demonstrate that taxonomic richness and total abundance of stream macroinvertebrates increase significantly as meltwater (snow melt and glacier melt) contributions to river flow decrease. Macroinvertebrate species showed a gradation of optimum meltwater conditions at which they persist. For example: Habroleptoides berthelemyi (Ephemeroptera), Perla grandis (Plecoptera) and Rhithrogena spp. (Ephemeroptera) increased in abundance when meltwater contributions to streamflow decrease, whereas in contrast, Rhyacophila angelieri (Trichoptera) and Diamesa latitarsis spp. (Diptera) decreased in abundance. Changes in alpine stream macroinvertebrate community composition as meltwater contributions decline were associated with lower suspended sediment concentration, and higher water temperature, electrical conductivity and pH. Our results suggest α diversity (at a site) of streams presently fed by meltwaters will increase with future meltwater reductions. However, β diversity (between‐sites) will be reduced as snow melt and glacier melt decrease because the habitat heterogeneity associated with spatiotemporal variability of water source contributions will become lower as meltwater contributions decline. Extinction of some endemic alpine aquatic species (such as the Pyrenean caddis fly R. angelieri) is predicted with reduced meltwater inputs, leading to decreases in γ diversity (region). Our identification of significant links between meltwater production and stream macroinvertebrate biodiversity has wider implications for the conservation of alpine river ecosystems under scenarios of climate change induced glacier and snowpack loss.     

Benthic macroinvertebrate communities of intermittent streams in the middle reaches of the Guadiana Basin (Portugal)

The Guadiana River has an irregular hydrological regime, with severe droughts and floods, but little is known about how aquatic fauna respond to these natural events. Macroinvertebrate data and environmental information were collected at seven sites from three tributaries in the middle reaches of the Guadiana River, approximately every 3 months from April 1995 to April 1997. Despite considerable annual variation in discharge (related to duration of flood and drought periods), the number of macroinvertebrates found was consistently high. Diptera represented the major proportion of the benthic fauna (73.2%) followed by Ephemeroptera (10.3%), Coleoptera (4.1%) and Trichoptera (3.1%). Canonical correspondence analysis (CCA) was used to evaluate the relationships between taxa density and habitat variables. Generally, Plecoptera and Ephemeroptera were found in the upstream sampling sites. Wider and deeper sites were associated with the presence of Diptera and were least diverse. High values for both the Shannon-Wiener diversity index and the average score per taxon were usually found at upstream sites where Ephemeroptera and Plecoptera predominated. The data suggest that macroinvertebrates have a great capacity to recover rapidly from severe drought periods, both in terms of taxonomic diversity and number of individuals.     

Aligning indicators of community composition and biogeochemical function in stream monitoring and ecological assessments

Reliable and inexpensive indicators of ecosystem function are essential for accurately monitoring and describing ecosystem integrity. Currently, most state and federal assessments of aquatic ecological integrity rely on structural indicators and assume tight coupling of structure and function. We used fluorescent composition of dissolved organic matter as a metric for certain ecosystem functions and compared the resulting index of autochthonous microbial dissolved organic matter (DOM) to macroinvertebrate indicators and classifications of water quality attainment reported by the Maine Department of Environmental Protection (Maine DEP) at 142 stream sites. We observed that metrics of sensitive insect orders such as relative Plecoptera generic richness, relative Ephemeroptera abundance, and generic richness of EPT (Ephemeroptera, Plecoptera, and Trichoptera) were negatively correlated with higher values of metrics based on autochthonous microbial DOM sources. At the same time we observed an increase in the Hilsenhoff Biotic Index with increasing microbial DOM. We compared the abundance of this microbial DOM component to Maine DEP measured attainment classes and found that microbial DOM generally separated sites with high biological integrity from sites where the biotic community was highly degraded. This highlights that measures of biogeochemical ecosystem function complement measures of structure in biological assessments.     

Distribution of macroinvertebrates in relation to physical and biological variables in the littoral zone of nine New Zealand lakes

Macroinvertebrates play a key role in the littoral zone of lakes. Macroinvertebrate community composition is closely linked to habitat conditions. To date, there have been few attempts to relate macroinvertebrates to habitat factors in lakes. In this study, nine mainly oligotrophic lakes from throughout New Zealand were surveyed for macroinvertebrates. The lakes were selected to represent a range of suspended sediment loading and lake level regimes. Within each lake, several sites were selected to provide a range of exposure to wave action. A multiple regression approach was taken to relate macroinvertebrate community composition and habitat characteristics. The results of the analysis suggest that the littoral zone of the lakes we studied could be divided into four general habitats. The first is the wave wash zone characterised by coarse substrates and macroinvertebrate taxa usually associated with lotic environments, such as Ephemeroptera and Plecoptera. The second habitat is associated with macrophytes and is limited at the top by wave action and at depth by light attenuation. In this zone, the snail Potamopyrgus antipodarum is dominant, along with Trichoptera and Odonata. At the base of the macrophytes is the detrital habitat characterised by fine, organic rich sediments and dominated by chironomids, oligochaetes and Trichoptera. At depths below the macrophyte zone, fine sediments are found, and bivalves such as the freshwater mussel Hyridella menziesi are common. While macroinvertebrate abundance can be highly variable, some general predictions of community structure can be made based on a few key environmental factors. Abundance of snails Odonata and Trichoptera was positively related to macrophyte biomass. Some macroinvertebrate groups such as oligochaetes, chironomids, snails and bivalves were more common in fine substrates, while Ephemeroptera were characteristic of coarse substrates. Detrital biomass was important for most of the macroinvertebrate groups studied showing a positive relationship for oligochaetes and Trichoptera and a negative relationship for Ephemeroptera and Plecoptera.     

Louisiana waterthrushes (Seiurus motacilla) and habitat assessments as cost-effective indicators of instream biotic integrity

1. Benthic stream animals, in particular macroinvertebrates, are good indicators of water quality, but sampling can be laborious to obtain accurate indices of biotic integrity. Thus, tools for bioassessment that include measurements other than macroinvertebrates would be valuable additions to volunteer monitoring protocols. 2. We evaluated the usefulness of a stream‐dependent songbird, the Louisiana waterthrush (waterthrush, Seiurus motacilla) and the Environmental Protection Agency Visual Habitat Assessment (EPA VHA) as indicators of the macrobenthos community in headwater streams of the Georgia Piedmont, U.S.A. We sampled macrobenthos, surveyed waterthrushes and measured habitat characteristics along 39 headwater reaches across 17 catchments ranging from forested to heavily urbanised or grazed by cattle. 3. Of the indicators considered, waterthrush occupancy was best for predicting relative abundances of macrobenthic taxa, while the EPA VHA was best for predicting Ephemeroptera–Plecoptera–Trichoptera (EPT) richness. Individual components of EPA VHA scores were much less useful as indicators of EPT richness and % EPT when compared with the total score. Waterthrushes were found along streams with higher % EPT, a lower Family Biotic Index (FBI) values and greater macrobenthos biomass. 4. While macroinvertebrates remain one of the most direct indicators of stream water quality, stream bird surveys and reach‐scale habitat assessments can serve as cost‐effective indicators of benthic macroinvertebrate communities. Using stream‐dependent birds as an early warning signal for degradation of stream biotic integrity could improve the efficacy of catchment monitoring programmes in detecting and identifying perturbations within the catchment.     

The influence of sawmill wood wastes on the distribution and population of macroinvertebrates at Benin River, Niger Delta area, Nigeria

The impact of sawmill wood wastes on the distribution of benthic macroinvertebrates at the Sapele section of Benin River, Niger Delta, Nigeria, was investigated from March 2005 to August 2005. A total of 434 individuals were collected by kick-sampling method, representing 21 taxa of benthic macroinvertebrates. Three stations, 1, 2, and 3, were selected from upstream of the site, receiving wood wastes discharge, the impacted site and its down stream, respectively. Among the water quality variables, conductivity, dissolved oxygen, biochemical oxigen demand (BOD(5)), nitrate-nitrogen, phosphate-phosphorus, transparency, and alkalinity were significantly different (P<0.05) among the stations. Orthogonal comparison by Duncan's multiple range test showed that station 2 (the impacted site) was the cause of the difference. More sensitive species such as Ephemeroptera or Plecoptera were completely absent from station 2, the impacted site. Species abundance was similar in station 1 and 3, indicating that the wood wastes must have adversely affected the distribution of these macroinvertebrates, especially the intolerant species. The wood waste discharge not only altered the water chemistry, but also stimulated the abundance of less-sensitive macroinvertebrate species.     

河湖生态系统生态用水优化研究——以滇池流域为例

生态需水是河流与湖泊生态系统健康的重要基础。湖泊流域的河流与湖泊生态系统之间存在密切的水量联系,目前对流域内生态用水的研究多为单一生态系统生态需水简单相加,忽略了河流和湖泊之间复杂的水量联系。基于河湖复合生态系统之间的水量联系构建了河湖生态系统生态用水优化模型,并以滇池为例分析了河湖生态系统生态用水规律。结果表明：湖泊流域中单一河流或湖泊生态需水计算结果不能满足复合生态系统的生态用水要求,需要综合考虑河流和湖泊之间的水量联系;在当前水质状况下,牛栏江每年的调水量不能满足滇池流域的生态用水要求;滇池流域水体污染对流域内生态用水影响较大,随着水体污染程度的下降,流域生态用水量和调水量呈指数下降,河流生态用水呈线性下降。     

Short-term responses of macroinvertebrate drift following experimental sediment flushing in a Japanese headwater channel

We examined short-term responses of macroinvertebrate drift associated with experimental sediment flushing in a headwater. Increases in the drifting abundances of Ephemeroptera and Plecoptera coincided with increases in bed load yield rather than peaks in discharge or suspended sediment concentrations. The approach and arrival of a sediment wave may provide a physical cue that initiates the escape of benthic macroinvertebrates. Because fine bed load sediments, with diameters <4 mm, tended to accumulate on and in the substrate matrix, such sedimentation affected the benthic macroinvertebrates residing on and in the substrate, increasing the number of macroinvertebrates in the drift. Therefore, the decreases observed in the densities of most macroinvertebrate taxa following sediment flushing were probably associated with sediment deposition and the resulting escape of macroinvertebrates from benthic habitats. The magnitudes of the decreases in macroinvertebrate density were lower at sites located 200 m downstream from the sediment sources than at sites located 20 m downstream. The results from this experimental flushing study suggest that bed load movement and resulting sediment accumulation alter macroinvertebrate drift patterns and cause decreases in the abundances of benthic macroinvertebrates in headwater streams.     

Relationship between benthic insects (Ephemeroptera, Plecoptera, Coleoptera, Trichoptera) and temperature in small and medium-sized streams in Germany: A multivariate study

Benthic insect communities (Ephemeroptera, Plecoptera, Coleoptera, Trichoptera) were studied together with water temperature and environmental parameters in streams between June 2000 and June 2001. The sampling area consisted of 20 sites in small and medium-sized streams located in the lower mountainous area of Central Europe. Temperature was recorded nearly continuously and several physicochemical and environmental variables were assessed. Macroinvertebrates were sampled both in spring and summer. Data-sets of species abundance and occurrence were analysed using multivariate techniques and were correlated to the thermal and environmental conditions of the streams. The temperature preferences of the species were compared to published data-sets on their autecological characteristics. Up to 29% of the variability in the Ephemeroptera, Plecoptera, Trichoptera and Coleoptera community was explained by summer temperature variation in the data-sets for both small and medium-sized streams. A smaller, but significant part of the variability in species distribution was explained by conductivity, substratum type, and the percent coverage of local riparian forest. Compared to small streams, temperature was less important for the macroinvertebrate composition in medium-sized streams. This result is likely due to the more tolerant, eurythermic species composition in larger streams. A total of 33 Ephemeroptera, Plecoptera, Coleoptera and Trichoptera taxa were positively correlated and 28 taxa were negatively correlated to summer temperature patterns. The temperature preferences of taxa considered in this study were related to species traits, such as egg dormancies and life cycle plasticity.     

The presence of macrophytes changes the beta diversity of Ephemeroptera,Plecoptera, and Trichoptera (EPT) assemblages in Cerrado streams in Northeastern Brazil

Limnology - In-stream conditions can affect the distribution of the Ephemeroptera, Plecoptera, and Trichoptera orders (EPT) because they require specific food resources and good quality water....     

Groundwater influence on alpine stream ecosystems

1. Spatial and temporal variability of relative snow‐melt, glacier‐melt and groundwater contributions to streams play important roles in shaping alpine freshwater ecosystems. Although meltwater (particularly glacier‐fed) streams have received much attention in recent years, the influence of groundwater on alpine freshwater ecosystems remains poorly understood. 2. This study tested the hypotheses that increased groundwater contributions to meltwater‐dominated alpine streams would yield increases in water temperature, channel stability, electrical conductivity and particulate organic matter (POM) and decreases in suspended sediment concentration (SSC). These more favourable habitat conditions were hypothesised to result in increased macroinvertebrate abundance and diversity. 3. Groundwater contributions, physicochemical habitat variables and benthic macroinvertebrates were sampled throughout the 2002 and 2003 summer‐melt seasons in three streams in the French Pyrénées. 4. Increased groundwater contributions were significantly correlated with higher discharge, water temperature, electrical conductivity, POM and channel stability, but lower SSC. 5. Macroinvertebrate total abundance, taxonomic richness, number of Ephemeroptera, Plecoptera and Trichoptera genera, and per cent Plecoptera all increased significantly with greater groundwater contributions to streamflow. However, beta diversity and Trichoptera relative abundance decreased. 6. Abundance of most macroinvertebrate taxa was highest under groundwater‐dominated conditions but a gradient of optimum groundwater preferences was evident across all taxa. Some taxa were found only where groundwater contributions were low (i.e. in predominantly meltwater‐fed streams). 7. This study provides evidence that water source, physicochemical habitat and stream biota are strongly linked. Therefore, an interdisciplinary approach is necessary for future studies aiming to develop conservation strategies or predict the response of alpine river ecosystems to global climate change.