Macroinvertebrate Composition Research Articles

Does non-native black locust afforestation affect soil biodiversity at the regional scale? Case study of soil macroinvertebrates across the Chinese Loess Plateau

Land-use changes have a profound impact on species diversity and distribution. Although soil fauna contribute substantially to global biodiversity and ecosystem functioning, the responses of soil fauna to land-use changes at the regional scale remain poorly understood. Non-native Robinia pseudoacacia (black locust, BL) has been widely planted on abandoned cropland to control soil erosion on the Chinese Loess Plateau (CLP). Here, we investigated the effects of BL plantations (<15 years, 15–25 years, >25 years) on the abundance, richness and community composition of soil macroinvertebrates at six sites along a 500-km transect across the CLP. Overall, the mean abundance and richness of macroinvertebrates were greater in the BL plots than in the control plots, regardless of the plantation age. These differences were mainly attributed to the changes in the abundance and richness of predators and phytophages but not of detritivores and omnivores. We also found that the abundance and richness of overall macroinvertebrates decreased with latitude in the BL plots, while no latitudinal trend was found in the control plots, which led to a decrease in the afforestation-induced positive effect with latitude. Additionally, the community composition of macroinvertebrates was similar between the control and BL plots but significantly varied with latitude, which was explained by climate factors and geographic distance. The results indicated that the positive effects of BL afforestation on macroinvertebrate diversity depend on functional groups and the community composition at a large spatial scale was shaped by climate factors and geographic distance rather than BL afforestation. If afforestation has biodiversity objectives, then BL afforestation is more suitable in the south than in the north of the CLP because of the decrease in afforestation-induced positive effects with latitude.

Ethanol eDNA Reveals Unique Community Composition of Aquatic Macroinvertebrates Compared to Bulk Tissue Metabarcoding in a Biomonitoring Sampling Scheme

Freshwater ecosystems provide essential ecosystem services and support biodiversity; however, their water quality and biological communities are influenced by adjacent agricultural land use. Aquatic macroinvertebrates are commonly used as bioindicators of stream conditions in freshwater biomonitoring programs. Sorting benthic samples for molecular identification is a time-consuming process, and this study investigates the potential of ethanol-collected environmental DNA (eDNA) for metabarcoding macroinvertebrates, especially for common bioindicator groups. The objective of this study was to compare macroinvertebrate composition between paired bulk tissue and ethanol eDNA samples, as eDNA could provide a less time-consuming and non-destructive method of sampling macroinvertebrates. We collected benthic samples from streams in Ontario, Canada, and found that community composition varied greatly between sampling methods and that few taxa were shared between paired tissue and ethanol samples, suggesting that ethanol eDNA is not an acceptable substitute. It is unclear why we did not detect all the organisms that were preserved in the ethanol, or the origin of the DNA we did detect. Furthermore, we also detected no difference in community composition for bioindicator taxa due to surrounding land use or water chemistry, suggesting sites were similar in ecological condition.

Influence of climate seasonality on the effectiveness of the use of aquatic macroinvertebrates in urban impact evaluation in central Amazonia

Natural fluctuations in ecosystems, such as those associated with climate, are a fundamental factor structuring macroinvertebrate assemblages. Given that macroinvertebrates are widely used in biomonitoring of aquatic systems, it is necessary assess the potential effects of seasonality on this group to avoid confusing its effects with the effects of anthropogenic impacts. In the present study, the richness, assemblage composition, and abundance of macroinvertebrates of Amazonian streams (n = 23) were compared among four periods—the start and apex of dry period, and the start and apex of rainy period. For these comparisons, were considered the conditions of the streams in three categories: (i) pristine, (ii) impacted by deforestation, and (iii) impacted by deforestation and pollution with raw sewage. The results indicate no significant variation among periods in the richness (p = 0.397), abundance (p = 0.420), and assemblage composition (p = 0.274) of the macroinvertebrates, which respond to anthropogenic impact irrespective of the seasonal period. Given this, representative samples can be obtained during any given period of the year, reducing field costs and sample processing time, enabling the reliable and rapid diagnosis of streams.

Revealing the influence of hyporheic water exchange on the composition and abundance of bottom-dwelling macroinvertebrates in a temperate lowland river

We studied distributions and abundances of macroinvertebrates in relation to hyporheic water exchange (HWE) patterns of the upper Biebrza − a small, lowland, low dynamic European river located in Northeast Poland. On a 6-km stretch of the river; we determined the variability of water exchange in the hyporheic zone by using direct field measurements of the pressure gradient to determine groundwater–surface water interactions. We identified locations with upwelling and downwelling fluxes of HWE as well as ambiguous hydraulic contact between groundwater and surface water along the river. In these locations, we sampled bottom-dwelling macroinvertebrates. In total, 627 individuals of benthic macroinvertebrates of 34 taxa were identified. We revealed that bottom-dwelling macroinvertebrate fauna is more abundant and diverse in river stretches where water from the river infiltrates the hyporheic zone. Results also show higher taxonomic richness and abundances of benthic macroinvertebrates in stretches with diagnosed infiltrating conditions (downwelling flux in a hyporheic zone) compared to in stretches where the river drained groundwater (upwelling flux in a hyporheic zone), but the recorded differences were not statistically significant.

Elevation and land use as drivers of macroinvertebrate functional composition in Afromontane headwater streams

Macroinvertebrates play a unique role in aquatic ecosystems by acting as processors of nutrients and organic energy from allochthonous and autochthonous sources. Within East Africa, and especially Kenya, anthropogenic influences on streams and rivers as a result of deforestation and the expansion of agricultural lands are pervasive. This study investigated land use v. altitudinal shifts in the functional composition of macroinvertebrates within the Mount Elgon catchment in western Kenya. A total of 20 sampling sites in 12 streams, 10 sites each within forested and agricultural areas, located in 3 elevation categories were sampled for physicochemical water parameters and macroinvertebrates. Significant (P &lt; 0.05) spatial variation was observed in total suspended solids, coarse particulate organic matter, temperature and electrical conductivity between forested and agricultural sites. Shredder biomass and abundance was higher in forested streams at higher elevations. There was a significant increase in the abundance (of shredders, predators, collector filterers and gatherers), taxon richness (of shredders, predators and scrapers) and biomass (of shredders, collector filterers and gatherers) of functional feeding groups with increasing elevation. Data of near-natural sites are urgently needed to disentangle altitude and land use influences on the diversity and composition of aquatic communities in high-elevation streams in the tropics.

Macroinvertebrados dulceacuícolas del Parque Nacional Yendegala, Chile: Resolviendo brechas de conocimiento sobre la biodiversidad de la Reserva de la Biosfera Cabo de Hornos

The Yendegaia National Park, located to the south of Tierra del Fuego and at the eastern margin of the Darwin Mountain Range, forms part of the Cape Horn Biosphere Reserve (CHBR) and lies in the Magellanic sub-Antarctic ecoregion. This national park in the extreme south of Chile comprises an extensive valley surrounded by mountain ranges that give rise to glacial and rain or snow-melt streams. The present study provides the first inventory of freshwater macroinvertebrates within the park, further comparing the species composition of three rivers with contrasting riparian vegetation. One river has a riparian vegetation dominated by Coihue de Magallanes (Nothofagus betuloides), an evergreen species. The river with riparian vegetation dominated by lenga presented a significantly higher diversity of macroinvertebrates than in the rivers with riparian vegetation dominated by nirre and coihue. The community composition of macroinvertebrates presents some affinities with that reported for other areas within the reserve with similar vegetational composition, such as Navarino Island or the Alberto de Agostini National Park. The influence of riparian vegetation and other environmental variables must be studied through other approaches. In this way, the need for studies that complement the inventory presented here emerges, contributing to a characterization that allows the evaluation of ecological patterns of aquatic macroinvertebrates. In this way, it will be possible to identify generalities and singularities of the freshwater biological communities and their environmental relationships in the southern tip of Chile.

Distribution pattern of macroinvertebrate community and its relationships with environmental factors in the Yongding River Basin

Human disturbances have altered global stream ecosystems in multiple ways. Understan-ding spatio-temporal dynamics of aquatic organism composition and their relationships with environmental factors play an important role in revealing changes in the structure and function of river ecosystems. The macroinvertebrates and environmental parameters were sampled in the Yongding River Basin at spring (March), summer (July), and autumn (November) in 2017. The results showed that chironomids were the dominant group in the Yongding River Basin, including Orthocladius, Chironomus, Glyptotendipes, and Polypedilum. Results of the cluster analysis showed significant spatial variations of macroinvertebrate community. Sampling sites were clustered into two groups based on the similarities of macroinvertebrate composition in the Yongding River. Sampling sites belonging to group 1 mainly located in the Sanggan River and Dongyang River, with Orthocladius sp.being the dominant species. Sampling sites belonging to group 2 mainly located in the Yang River, Guishui River and main section of the Yongding River, with Glyptotendipes sp. being the dominant species. The biomass, Shannon index, Margalef index, Pielou evenness index and taxa richness of group 2 were significantly higher than those of group 1. Higher values of biological indices indicated better ecological condition of the stream ecosystem. The density, biomass and diversity indices of summer were significantly lower than those of both spring and autumn. Results of Canonical correspondence analysis (CCA) showed that the spatio-temporal distribution of macroinvertebrate in the Yongding River was mainly influenced by water temperature, ammonium, pH, dissolved oxygen, and total phosphorus. From the perspective of hydrological characteristics, flow velocity and flow capacity were significantly correlated. The significant positive correlations between hydrological parameters of velocity and capacity and biological indices of density and EPT% in group 2 indicated the preference of fast flow to sensitive taxa of EPT (Ephemeroptera, Plecoptera, and Trichoptera). The negative correlations between flow capacity and biodiversity indices implied the adverse effects of high flow on macroinvertebrate biodiversity. Our results confirmed that the composition and biodiversity of macroinvertebrate were affected by both water environment and hydrology, which reflected the multiple human activities in aquatic ecosystems of the Yongding River. It is important to control water contamination and sustain environmental flow at the specific reaches for the restoration of Yongding River.

Aquatic Macroinvertebrate Indicators in the Zawgyi Irrigation Channels and a River in the Central Dry Zone of Myanmar

Rivers and wetlands in Myanmar provide essential services to people in terms of transportation, agriculture, fisheries and a myriad of other ecosystem services, all of which are dependent on a healthy ecosystem. Irrigation channels are also an important part of the infrastructure for daily water use in Myanmar. The objective of this research is to describe the aquatic ecosystem of irrigation channels using aquatic macroinvertebrate communities. The research focused on the taxonomic composition of the aquatic macroinvertebrates of the Zawgyi River and the associated irrigation channels in central Myanmar, east of the city of Mandalay. Significant differences between the river and channels, and among individual channels, were shown using an analysis of similarity: Bray–Curtis similarity, a multivariate equivalent of the univariate statistical method of analysis of variance: ANOSIM and an analysis of similarity percentages: SIMPER by Plymouth Routines in Multivariate Ecological Research: PRIMER v6 software. The initial findings suggest that there is a clear separation between macroinvertebrate communities at the morpho-species level of identification between river and irrigation channels, while there is less separation between functional feeding groups (FFG) between them. The lower taxonomic level of discrimination at the family level using a water quality index showed no significant difference between river and channels. The preliminary field results indicate that a recently modified biomonitoring index method could be applied in Myanmar to assess the ecological water quality of the modified river, as well as human-made channels.

Different refuge types dampen exotic invasion and enhance diversity at the whole ecosystem scale in a heterogeneous river system

Refuges that result from environmental heterogeneity within ecosystems have an important yet under-appreciated role in maintaining native community diversity in face of exotic invasion. The objective of our study was to determine if different refuge types constrain invasion impacts on native biodiversity at the whole ecosystem-scale of the Upper St. Lawrence River. We focused on the voracious round goby fish as a sentinel exotic species whose spatial distribution within this ecosystem is also representative of the species distributions of several other Ponto-Caspian invaders. We first explored if wetlands were acting as unknown refuges in reducing the local abundance of the round goby fish. We then tested the relative influence of a known broad-scale conductivity gradient compared with local wetlands on structuring the composition, diversity, and abundance of native macroinvertebrate and fish communities inside and outside each of these refuge types. We found that the two types of refuges, broad-scale conductivity gradient and local wetlands, limited round goby abundances at the whole ecosystem scale, and structured macroinvertebrate and fish community diversity. The broad-scale conductivity refuge was twice stronger than wetlands in limiting round goby abundance. Although wetlands were effective in constraining round goby abundance, the direct effect of wetlands rather than their indirect effects through limiting round goby abundance, were more powerful in explaining maintenance of macroinvertebrate and fish community diversity in invaded high conductivity waters. Our findings underscore the important role of environmental heterogeneity in producing different types of refuges that buffer invasion effects in freshwater ecosystems, and we advocate the preservation of wetlands as a part of this process.

Correlation between physical and chemical parameters of water and biotic indices: The case study the White Drin River basin, Kosovo

The major impacts on aquatic ecosystems worldwide caused by land use lead to changes in their natural conditions and limitation of water use for various needs. This paper presents the results of the study of the physical and chemical parame-ters and macroinvertebrate assemblage in the White Drin River (or: the Drim River, Alb. the Drini i Bardhë River) basin, the largest in Kosovo. Macroinvertebrate sampled at 11 sites in the river resulted in 5946 collected benthic organisms, which in taxonomic terms belong to 12 orders and 51 families. Of the total number of organisms, 72.28% were Insects, 25.39% Amphipoda crustaceans and 2.33% were Annelide worms and Mollusk. The used biotic indices Biological Moni-toring Working Party (BMWP), Ephemeroptera, Plecoptera, and Trichoptera (EPT), average score per taxon (ASPT) and Stroud Water Research Center (SWRC) classify water quality in excellent category in the sampling site S1 near the source of the White Drin River, whereas in other sampling sites, as a result of pollution, water quality varies on category II–IV. The Pearson's correlation analyses shown that the physical and chemical parameters affect the water quality and the com-position of macroinvertebrates. Our results show that the parameters that adversely affect the BMWP, EPT and ASPT bio-tic indices as well as the Shannon–Wiener, Mergalef and Menhinik diversity indices are: pH, electrical conductivity (EC), total suspended solids (TSS), nitrates (NO3–) and chlorides (Cl–). We can conclude that the anthropogenic impact on White Drin basin affects the physical, chemical and biological parameters of the water therefore these parameters should be con-stantly included in Biomonitoring and Management plans for water resources in Kosovo.

Density and diversity of macroinvertebrates in Colombian Andean streams impacted by mining, agriculture and cattle production.

BackgroundMining, agriculture and cattle production are activities that threaten the quality and quantity of water resources in the Colombian Andes. However, many drainage basins in this region have not been subjected to simultaneous evaluation of the impact these activities have on the density, diversity and composition of aquatic macroinvertebrates (AMI). The first two of these ecological variables are expected to decrease drastically from zones with no apparent impact towards areas with anthropogenic activity, which areas with mining will present the most impoverished AMI community.MethodsWe evaluated the density, diversity and composition dissimilarity of AMI in streams impacted by gold mining, agriculture and cattle production. Two reference streams were also studied. Six benthic samplings were conducted bimonthly (Feb 2014–Feb 2015) using a Surber net. Water samples were taken in order to make environmental evaluation among the aforementioned streams, including hydrological, physicochemical and bacteriological parameters (HPCB). Diversity was evaluated as the effective number of RTUs—recognizable taxonomic units—by comparing the richness, typical diversity, and effective number of the most abundant RTUs. Compositional dissimilarity was examined with nMDS and CCA analysis.ResultsA total of 7,483 organisms were collected: 14 orders, 42 families and 71 RTUs. Our prediction regarding the density and diversity of AMI (Reference > Cattle production > Agriculture > Mining) was partially fulfilled, since the agriculture-dominated stream presented a more impoverished AMI community than that of the gold mining stream. However, these streams presented lower diversity than the cattle production and reference streams, and the AMI density only differed significantly between one reference stream and the agriculture stream. The AMI composition in the agriculture-dominated stream clearly differed from that of the other streams.DiscussionThe observation of a more impoverished AMI community in agricultural production areas compared to those with mining or cattle production may reflect the importance of the remaining riparian vegetation, which was scarce at the stream with agricultural activity. Moreover, the low diversity, and mainly the reduced AMI richness, in the agriculture stream coincided with the absence of insect genera are intolerant to deterioration of the biological and physicochemical conditions of the water (e.g. Anacroneuria).ConclusionsThe results suggest that the local impact of agricultural activities may be of equal or greater magnitude than that of mining in terms of AMI density, diversity and composition, in the Colombian Andean riverscape. Future studies should systematically evaluate, throughout the annual cycle, the relative effects of the productive land use, the remaining native vegetation cover and the consequent changes in the HPCB parameters of the water on AMI communities in Colombian Andean basins.

Long-term ecological changes in fishes and macro-invertebrates in the world's warmest coral reefs

The Arabian Gulf is a natural laboratory for examining the consequences of large-scale disturbances due to global warming on coral reef ecosystems because of its extreme temperature regime. Using a coral reef monitoring time series extending from 1985 to 2015, we examined the long-term ecological changes in fish and macro-invertebrate communities as these habitats suffered heat shocks. We used a GLMM modelling framework to obtain clean annual signals in community indicators from noisy data. We also visualized temporal change in the taxonomic composition of fishes and macro-invertebrates. A phase shift from predominantly reef-building corals to barren grounds occurred between 1996 and 2000. Macro-invertebrates responded rapidly, and most of associated indicators recovered to pre-shift levels in 15 years. Fishes generally had lagged responses to the phase shift and had shifted to a new state with lower abundance, as well as different species composition. Increased levels of herbivory first by macro-invertebrates, mostly sea urchins, and then fishes, could have suppressed macro-algae expansion and consequently led to the dominance of barren ground. When the phase shift occurred, most of the 14 fish families declined in abundance while macro-invertebrate groups increased. Fish families able to utilize non-coral habitats appeared more resilient to the disturbances and subsequent coral degradation. Unlike other regions, we observed high resilience of the coral-dependent butterflyfishes to coral loss, possibly due to local migration from other less-impacted coral reefs. We hypothesized a top-down control mechanism mediated by predation by fishes has contributed to shaping the temporal and spatial patterns of the macro-invertebrates. Our results also revealed differences in spatial preferences among fishes and macro-invertebrate groups, which could be used to set priorities and develop effective conservation and management strategies.

Spatial and Temporal Patterns of Macroinvertebrate Assemblages in the River Po Catchment (Northern Italy)

In the last decade, large scale biomonitoring programs have been implemented to obtain a robust understanding of freshwater in the name of helping to inform and develop effective restoration and management plans. A comprehensive biomonitoring dataset on the macroinvertebrate assemblages inhabiting the rivers of the Po Valley (northern Italy), comprised a total of 6762 sampling events (period 2007–2018), was analyzed in this study in order to examine coarse spatial and temporal trends displayed by biotic communities. Our results showed that macroinvertebrate compositions and derived structural and functional metrics were controlled by multiple environmental drivers, including altitude and climate (large scale), as well as habitat characteristics (local scale). Altitude proved to be the primary geographic driver, likely due to its association with thermal and precipitation regimes, thus explaining its overriding influence on macroinvertebrate assemblages. Significant temporal variations were observed across the study period, but notably in 2017, the overall taxonomic richness and diversity increased at the expense of Ephemeroptera, Plectoptera and Trichoptera taxa during an unprecedented heatwave that occurred across southern Europe. The detail of this study dataset allowed for important environmental attributes (e.g., altitude, habitat characteristics) shaping biotic communities to be identified, along with ecologically vulnerable regions and time periods (e.g., extreme climatic events). Such research is required globally to help inform large-scale management and restoration efforts that are sustainable over long-term periods.

How Does Mining Salinisation Gradient Affect the Structure and Functioning of Macroinvertebrate Communities?

Elevated salinity creates degrading conditions for the development of aquatic biota in different regions of the world. There is a need for research on freshwater salinisation in order to understand how this stressor alters ecosystem function and to predict changes in biodiversity globally. Such data are missing from Central Europe, and therefore, the presented study was performed in inland anthropogenic ponds with different salinity levels located in the second largest European hard coal basin. The researcher indicated a positive correlation between water salinity and the biomass and density of macrozoobenthos as well as the percentage of shredders and the abundance of alien species, whereas there was a decrease in taxa diversity and richness and the abundance of filtering and gathering collectors and predators along with increasing salinity. The survey showed that a high level of nutrients and organic matter were also significantly correlated with the distribution of the macroinvertebrate taxa and functional feeding groups. The conducted research confirmed that mining salinisation acts as a strong filter that shapes the biodiversity because it affects the composition, abundance, biomass and functional traits of benthic macroinvertebrates and significantly contributes to the invasion of alien species.

Diversity of diatoms, benthic macroinvertebrates, and fish varies in response to different environmental correlates in Arctic rivers across North America

Abstract Climate change poses a significant threat to Arctic freshwater biodiversity, but impacts depend upon the strength of organism response to climate‐related drivers. Currently, there is insufficient knowledge about Arctic freshwater biodiversity patterns to guide assessment, prediction, and management of biodiversity change. As part of the Circumpolar Biodiversity Monitoring Program's first freshwater assessment, we evaluated diversity of diatoms, benthic macroinvertebrates, and fish in North American Arctic rivers. Alpha diversity was assessed in relation to temperature, water chemistry, bedrock geology, and glaciation history to identify important environmental correlates. Biotic composition was compared among groups to evaluate response to environmental gradients. Macroinvertebrate α‐diversity declined strongly with increasing latitude from 48°N to 82°N, whereas diatom and fish diversity peaked around 70°N without a clear latitudinal decline. Macroinvertebrate diversity was significantly positively related to air temperature. Diatom diversity was related to bedrock geology and temperature, whereas fish diversity was related to glaciation history. Fish and macroinvertebrate assemblages differed between sites in western Canada, where invertebrate composition was more variable, and Alaska, where fish composition was more variable. In sites with both diatom and macroinvertebrate data, diatom composition was distinct in Alaska, where richness was highest in former glacial refugia. Macroinvertebrate composition was distinct in lowest‐latitude eastern and high‐latitude western Canadian sites where temperature was highest. Temperature, precipitation, geology, calcium, and substrate size were important environmental correlates for diatoms and macroinvertebrates, although the relative importance of each correlate differed. Diatom taxa were most strongly associated with water chemistry, whereas benthic invertebrate composition related most strongly to precipitation and temperature. This large‐scale study provides the most substantial integration and analysis of river diatom, macroinvertebrate, and fish data from the North American Arctic to date. Findings suggest that macroinvertebrates will show the strongest response to climate‐related shifts in temperature, whereas diatoms and fish are more likely to respond to climate‐induced shifts in nutrients and hydraulic connectivity. However, significant gaps in data coverage limited our ability to reliably evaluate spatial patterns and detect change. These gaps could be reduced by improving collaborative efforts between the U.S.A. and Canada to harmonise future monitoring.

Spatial and temporal variations in the species composition and abundance of benthic macroinvertebrates along the coast of the Eastern Black Sea

ABSTRACT The species composition and abundance of benthic macroinvertebrates in the Eastern Black Sea were determined seasonally, between May 2013 and February 2014. Sediment was collected using a Van Veen grab, at different depths: 5–15 m, 15–25 m, 25–35 m and >35 m. A total of 320 hauls were undertaken at 80 stations, and 90 species were identified, from seven phyla and 47 families. Overall, Mollusca was the most diverse phylum, with 32 species, followed by Annelida (32) and Arthropoda (13). The most abundant species was Chamelea gallina, which accounted for 37% of the total number of individuals, followed by Gouldia minima (25%) and Pitar rudis (10%). Based on seasonal variations, 62 species were identified in winter, 59 in summer, 54 in spring and 46 in autumn. The highest abundance was recorded in summer, representing 37.8% of the total abundance, followed by spring (25.2%). The species with the highest abundance in all four seasons was C. gallina followed by G. minima. Also, C. gallina followed by G. minima was the most abundant species in Samsun, Ordu, Giresun and Trabzon, whereas in Rize and Artvin, the most abundant species was G. minima followed by C. gallina. The results of this study should provide baseline data for future monitoring, to understand the consequences of natural or anthropogenic disturbance on the species composition and abundance pattern of the benthic macroinvertebrate community along the coast of the Eastern Black Sea.

Longitudinal Distribution of Benthic Macroinvertebrates Affected by a Hydropower Plant Cascade in the Mudan River

Hydropower plant operation changes river habitats in various aspects, and thus affects the community composition of the river ecosystem. As a result, the river health is adversely affected. The influence of a hydropower plant cascade on river continuity is even more pronounced. In this study, benthic macroinvertebrates and environmental factors were sampled from the Jingbohu Hydropower Plant to the Shiyan Hydropower Plant, along the Mudan River, and the influence of a hydropower plant cascade on the longitudinal distribution of benthic macroinvertebrates was analyzed. The results demonstrate that the hydropower plant cascade affected several environmental variables and led to changes in the community composition of benthic macroinvertebrates in the Mudan River. Significant differences were observed between sites upstream and downstream of the hydropower plants, with more sensitive species downstream of the hydropower plants. "Run-of-river" hydropower plants exert less adverse influence on benthic macroinvertebrates than dam-type plants. The influence of hydropower plants decreases along the longitudinal direction of the river, with the density and richness of benthic macroinvertebrates increasing.

Assessment of Water Quality Using Benthic Macroinvertebrate Along Sumber Maron River, District of Gondanglegi Kulon, East Java-Malang, Indonesia

Human activities such as agriculture, swimming, livestock, public washing, and the use of latrines around the river are considered as major causes of damage to the river ecosystem, affecting the growth of Macroinvertebrate, and thus assessing the condition of the river. This study aimed to study the composition of Macroinvertebrate and the quality of water health in Sumber Maron River, in the village of Gondanglegi. This research was conducted from March to April 2018. The method used in this research was the quantitative method using primary data. Research stations were identified by considering land-use in nine regions. The sampling technique of total macroinvertebrates was the kicking technique using the manual mesh with a 500 µm applied to the submerged solid substrates. The data were analyzed using a BMWP Index and interpreted by calculating the Average Scores Per Taxon (ASPT). The result of this research represented that there were 20 taxa of macroinvertebrates, which consisted of It belongs to 8 orders (Trichoptera, Coleoptera, Diptera, Tricladida, Decapoda, Odonata, Ephemeroptera, Plecoptera) and four class (Oligochaeta, Hirudinea, Gastropoda, Crustacea). Generally, the lowest taxa groups found in the station A1 (3 taxa), which were the agriculture and toilet (recreation area). Meanwhile, the highest taxa groups were found in station B3, which was the recreation area, by a total of 14 taxa. Macroinvertebrate with the lowest abundance was Gerridae at station A3, which respectively had the number of 1 ind.5m-2. Macroinvertebrate with the highest abundance was Baetidae at the station B3, which is the recreation area, by the number of 549 ind.5m-2. The result of modified BMWP – ASPT analysis showed a value of 3.3 – 5.75, which indicated that the condition of Sumber Maron River was ranging from bad to excellent category. The bad water condition was found in the agriculture and toilet (recreation area), whereas the excellent water condition was found in the swimming pool (recreation area). Canonical Correspondence Analysis (CCA) revealed that environmental variables were significant for an explanation of the variance in the family.

Unravelling the effects of multiple stressors on diatom and macroinvertebrate communities in European river basins using structural and functional approaches

Rivers suffer from more severe decreases in species diversity compared to other aquatic and terrestrial ecosystems due to a variety of pressures related to human activities. Species provide different roles in the functioning of the ecosystem, and their loss may reduce the capacity of the ecosystems to respond to multiple stressors. The effects on diversity will differ based on the type, combination and severity of stressors, as well as on the characteristics of the community composition and tolerance. Multiple trait-based approaches (MTBAs) can help to unravel the effects of multiple stressors on communities, providing a mechanistic interpretation, and, thus, complementing traditional biodiversity assessments using community structure. We studied the relationships between diversity indexes and trait composition of macroinvertebrate and diatom communities, as well as environmental variables that described the hydrological and geomorphological alterations and toxic pollution (pesticides and pharmaceuticals) of three different European river basins: the Adige, the Sava, and the Evrotas. These river basins can be considered representative cases of different situations in European freshwater systems. Hydrological variables were the main drivers determining the community structure and function in the rivers, for both diatoms and macroinvertebrates. For diatom communities, pharmaceutical active compound (PhAC) toxic units were also identified as a very important driver of diversity changes, explaining up to 57% of the variance in taxonomic richness. For macroinvertebrates, river geomorphology was an important driver of structural changes, particularly affecting Plecoptera richness. In addition, PhAC and pesticide toxic units were also identified as stressors for macroinvertebrate communities. MTBA provided a detailed picture of the effects of the stressors on the communities and confirmed the importance of hydrological variables in shaping the functional attributes of the communities.

Freshwater crabs (Decapoda: Pseudothelphusidae) increase rates of leaf breakdown in a neotropical headwater stream

Abstract Freshwater crabs are the largest macroconsumers in many neotropical headwater streams, but few studies have examined their roles in ecosystem processes such as leaf litter breakdown. As omnivorous macroconsumers, freshwater crabs affect multiple trophic levels. They may directly increase leaf breakdown through fragmentation and consumption or indirectly decrease breakdown by consuming other macroinvertebrates, including shredders and detritivores. In a headwater stream in Monteverde, Costa Rica, we conducted an in‐stream experiment with 40 enclosures to quantify the effects of pseudothelphusid crabs on both leaf breakdown and macroinvertebrate colonisation of leaves. Half of the enclosures were randomly selected to contain two crabs (mean carapace width = 30 mm) and half were controls without crabs. We sampled mixed leaf packs from the enclosures on days 11, 19, 28, 34, and 42. We found the leaves of one species (Koanophyllon pittieri) almost completely decomposed by day 28 in both treatments (crab versus no crab). The other two leaf species (Meliosma idiopoda, Quercus brenesii) composed the remaining leaf mass at the end of the experiment. At 42 days, enclosures with crabs had faster rates of leaf breakdown than those without crabs (with crabs: k = −0.020; without crabs: k = −0.016; p = 0.034). This suggests that the magnitude of direct leaf breakdown by crabs, due to fragmentation, consumption, or manipulation of leaves, was greater than any indirect effects on leaf breakdown via crab consumption of other leaf‐consuming species. Macroinvertebrate composition based on taxa abundances or biomasses did not significantly differ between treatments (ANOSIM; p = 0.73 and p = 0.65, respectively). Shredder and detritivore abundances and biomasses increased significantly through time (ANOVA; p ≤ 0.001), but there was no evidence of an effect of crab presence (p &gt; 0.2), nor were there significant interactions between crab presence and time (p &gt; 0.3). This is one of the first studies to quantify the effects of pseudothelphusid freshwater crabs on leaf breakdown rates. Our results suggest that these crabs can play a significant role in detrital processing in neotropical headwater streams. This study has also demonstrated that short‐term enclosure experiments are useful in measuring in‐stream effects of crab activity on leaf breakdown.