Macroinvertebrate Composition Research Articles

Cost-effective alternatives to facilitate biomonitoring and bioassessment of neotropical streams.

A reliable response of bioindicators to environmental variation is a cornerstone for effective bioassessment and biomonitoring. Fish and aquatic macroinvertebrates are widely used as bioindicators of different human impacts in freshwater ecosystems, but the cost-effectiveness of their usage can be improved through the use of surrogates. We investigated congruence patterns between using different taxonomic and numeric resolutions for aquatic macroinvertebrates and fish to assess community-environment relationships. We also tested whether dataset characteristics (e.g., area sampled, species pool) could explain the variation in the effectiveness of using different taxonomic and numerical resolutions. We used a Brazilian nationwide database encompassing multiple datasets with a gradient of riparian deforestation each. Our findings suggest that families and genera can effectively represent macroinvertebrate genera and fish species, respectively, when using community matrices for assessing community-environment relationships, with an acceptable loss of information. EPT (Ephemeroptera, Plecoptera, and Trichoptera) and Characiformes or Siluriformes may be used as a surrogate, in some cases, for the entire assemblages of macroinvertebrates and fish, respectively, but their use may result in higher loss of information. Presence-absence data also presented a minimal loss of information compared to abundance data, for both macroinvertebrates and fish. The variation in congruence levels among macroinvertebrate datasets was less predicted by dataset characteristics than fish. Across distinct resolutions, on average, 10% and 19% of the variation in community composition of macroinvertebrates and fish, respectively, was explained by broad-scale environmental variables, and the effect size was negatively affected by the dataset's sample size and spatial extent for fish. Whereas identification at species (fish) and genus (macroinvertebrates) level and quantification of all individuals still provide the best scenario, we provide evidence that coarser taxonomical resolution and presence-absence data can be used as cost-effective alternatives to facilitate biomonitoring and bioassessment of freshwaters in the Neotropical region impacted by deforestation.

Characteristics of the macroinvertebrate community structure and their habitat suitability conditions in the Chishui River

IntroductionAs an important tributary of the upper Yangtze River without dams, the study of the macroinvertebrate community structure and habitat suitability conditions in the Chishui River holds significant implications for water ecological conservation and restoration.MethodsIn order to explore the species composition, community characteristics and their ecological needs of macroinvertebrates in the Chishui River, 26 sampling sites were deployed in the Chishui River in this study in March (dry season), July (wet season), and November (normal season) of 2023 and performed community structure analysis.ResultsA total of 153 macroinvertebrate taxa were identified, with 62 taxa recorded in the dry season, 46 in the wet season and 115 in the normal season. The assemblage was predominantly composed of aquatic insects from the EPT group (Ephemeroptera, Plecoptera and Trichoptera). The results of ANOSIM analysis indicate that the species composition of macroinvertebrates varies significantly across different water periods. The Shannon-Wiener diversity index and Margalef index were significantly higher during the normal season compared to the dry and wet seasons. In contrast, the Pielou index and Simpson index remained relatively stable, suggesting a higher level of evenness in community structure across the different water periods. Based on the habitat suitability curves, Corbicula fluminea and Heptagenia prefer environments with high flow velocities and substrate particle sizes (D50) smaller than 300 mm. Hydropsyche sp.1 and Baetis thrive in environments with medium to low water depths, high flow velocities, and D50 ranging from 100 to 300 mm. Caridina favor deeper waters, low flow velocities, and larger substrate particles. The GAM fitting results revealed that the number of macroinvertebrate taxa increased with rising pondus hydrogenii (pH) and electrical conductivity (EC) levels. Species richness initially declined and then rose within certain thresholds of total nitrogen (TN) and total phosphorus (TP) concentrations. The optimal conditions for macroinvertebrate communities in the Chishui River were determined to be a DO concentration of 9.8 mg/L and an NH3-N concentration of 0.12 mg/L.DiscussionOverall, the macroinvertebrate community structure in the Chishui River is significantly influenced by factors such as water quality, flow velocity, and substrate particle size, and it demonstrates strong adaptability to seasonal variations.

Assessment of the Biodiversity Value of Benthic Macroinvertebrates in the Tuojiang River Basin, Chengdu

Benthic macroinvertebrates are crucial to the health of river ecosystems. However, their conservation status is often overlooked. Due to their limited mobility and sensitivity to habitat changes, their survival is threatened. Given the current lack of research on their value composition and evaluation, this study refers to the total economic value (TEV) framework to preliminarily construct a systematic evaluation framework for freshwater benthic macroinvertebrates. Through field surveys, questionnaires, and market survey data, the value composition of benthic macroinvertebrates in the Tuojiang River Basin of Chengdu was systematically clarified. The total value was monetized using methods such as the market price method, substitute market method, and simulated market method. The main conclusions are as follows: (1) The biodiversity value of benthic macroinvertebrates in the study area ranges from 6.36 × 108 to 12.76 × 108 CNY/a, accounting for 0.17–0.34% of the region’s 2019 GDP. The various values in order of proportion are as follows: non-use value > direct service value > Direct Material value > indirect use value. This indicates that this biological group has enormous potential value and significant conservation importance. (2) The proportions of the value amounts of various species in the total value differ. The proportions of Viviparidae, Odonata, Ephemeroptera, and Palaemonidae are relatively high, reaching 9.8–23.8%. The proportions of Atyidae, Semisulcospiridae, and Bithyniidae are about 5%. The proportions of Unionidae, Corbiculidae, and Aillpullaridae are less than 3%. These differences are mainly influenced by factors such as species population numbers in the region, public value perception, aesthetic preferences, and dietary habits. This evaluation framework scientifically and comprehensively assesses the biodiversity value of regional benthic macroinvertebrates, providing a reference for the value assessment of other biological groups within the region and offering a scientific basis for the conservation and sustainable utilization of the target biological groups.

Urban parks affect soil macroinvertebrate communities: The case of Tehran, Iran.

Land use change represents a significant environmental transformation on a global scale, profoundly impacting natural ecosystems. The conversion of rangelands into urban parks can adversely affect soil characteristics and biodiversity. This transformation may lead to alterations in soil properties and invertebrate communities, subsequently influencing ecosystem functioning and resilience. This study aims to investigate the diversity of soil macroinvertebrates and examine the impacts of land use changes on their communities. Therefore, sampling was conducted at three locations in Tehran (Chitgar, Lavizan, and Darakeh), where rangelands surround by urban parks. Two sites were selected within each region, and 72 quadrats surveyed the study area. In total, 1517 samples were collected and classified into 267 morphological operational taxonomic units (MorphOTUs). Our findings indicate that the total abundance of macroinvertebrates is higher in rangeland habitats, with a count of 872, compared to 645 in urban parks. Additionally, rangelands demonstrate a greater diversity of MorphOTUs than urban parks. Specifically, Chitgar, Lavizan, and Darakeh reported 162, 141, and 190 MorphOTUs, respectively, while urban parks reported 152, 122, and 118. Univariate and multivariate statistical analyses were employed on abundance, diversity, and macroinvertebrate communities to examine the impacts of changing rangelands to urban parks. Our research indicates that land use change from rangelands to urban parks can significantly (p-value < 0.05) affect the abundance and community composition of macroinvertebrates, as these groups are sensitive to land use changes. Beta diversity analysis indicated turnover happened between them (Chitgar=0.986; Lavizan=0.983; Darakeh=0.983). The SIMPER analysis showed that several MorphOTUs have contributed to this dissimilarity in every location. Furthermore, the Shannon-Wiener diversity index values for Araneae, Hemiptera, and Orthoptera were slightly higher in the rangeland than in the urban park. Our results also exhibited a diverse range of species in urban parks highlighting their important role in supporting biodiversity. Given that these parks have been established for many years, they have had ample opportunity to recover and enhance their ecological value. This study emphasizes that attention to soil organisms is essential for addressing conservation issues. Therefore, studying macroinvertebrate groups as biological indicators can assist in monitoring the effects of land use changes and will contribute to ecosystem management.

Composition and Distribution of Macroinvertebrates Associated with the Sponges Lubomirskia baikalensis (Spongillida, Lubomirskiidae) during the Ecological Crisis in Lake Baikal

Composition and Distribution of Macroinvertebrates Associated with the Sponges Lubomirskia baikalensis (Spongillida, Lubomirskiidae) during the Ecological Crisis in Lake Baikal

Comparative analysis of habitat structure and macroinvertebrate assemblages in headwater streams of Odzi sub-catchment, Chimanimani District, Zimbabwe, post Cyclone Idai-induced flooding

Flooding results in short and long-term modifications of aquatic ecosystem structure and biodiversity. Cyclone Idai, which ravaged through Zimbabwe in 2019, had devastating consequences on aquatic ecosystems. However, the extent of habitat modification and consequent biodiversity shifts are unknown. This study focuses on the comparative analysis of (i) habitat structure and (ii) macroinvertebrate assemblages in headwater streams of the Odzi sub-catchment, Chimanimani District, Zimbabwe, specifically examining the conditions post-Cyclone Idai-induced flooding. Field sampling was conducted in the dry season (September−November) 2019 and wet season (January−March) 2020. Headwater streams of the Murare (first order), Umvumvumvu (first and second order) and Nyanyadzi (first and second order) rivers were sampled. Habitat assessment was done following the Benthic Macroinvertebrate Monitoring Protocol Implementation Plan. Selected water variables were measured using appropriate probes. Macroinvertebrate assemblage data were collected using the South African Scoring System (SASS 5) protocol. Spatiotemporal variations in water quality, habitat structure and macroinvertebrate metrics were assessed using two-way ANOVA, ANOSIM and SIMPER. Significant spatiotemporal heterogeneity (p < 0.05) was detected in temperature, turbidity, conductivity and total dissolved solids, velocity and depth regimes, channel flow status, sediment deposition, channel alteration and frequency of riffles for the three rivers. Habitat quality ascending hierarchical order was: Umvumvumvu > Murare > Nyanyadzi after Cyclone Idai induced flooding. The highest macroinvertebrate composition diversity was detected in Murare River, the least flood-affected stream. The largest dissimilarity (ANOSIM, 75.3%) was between the Umvumvumvu and Nyanyadzi rivers. Macroinvertebrate community structure differed significantly because of species uniqueness and heterogenous tolerance to changes in environmental conditions after flooding. Flooding intensity and duration induces dissimilar environmental tolerances and persistent macroinvertebrates communities in lotic systems across local catchment scales. Long-term assessment of water quality impairment, resilient functional feeder groups and rifflescale physical habitat structure are imperative for optimised micro-scale conservation of macroinvertebrates in headwater streams prone to flash flooding.

Spatial distribution and composition of benthic macro-invertebrate in upper Awash River, below and upper Ginchi town, West Shoa Zone, Ethiopia

The composition and distribution of macro-invertebrates of benthic species can be influenced by water quality. The primary objective of this study was to understand the spatial distribution and composition of macro-invertebrates of benthic nature in the upper Awash River below and above Ginchi Town. The study was carried out for a period of three months from February 2020 to April 2020, and macro-invertebrates samples were collected from three stations using Surber sampler with 500 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m/mesh size and 25 cm × 25 cm (0.0625 m2) of sampling area coverage. The present study showed that, in the study area, there was a low density of macro-invertebrates and species richness in general with a comparative difference between the pool riffle habitats in density and family richness. And the total abundance of benthic macro-invertebrates showed a positive correlation with NO3-N, dissolved oxygen, and total phosphorus, while a negative correlation with all the other physicochemical parameters measured during the study period. Spatial and monthly variations in the diversity and richness of benthic macro-invertebrates were attributed to the effects of human action and changes in environmental factors. So, the water shade management system should be applied to control pollution factors that can affect the macro-benthic fauna community.

Ecological quality of the Jucusbamaba River, a high Andean urban river in northeastern Peru

The Jucusbamaba River, located in the northeastern region of Peru, flows through two towns that use its waters for agricultural activities. However, these activities generate waste discharged back into the river, which is additionally polluted by untreated domestic wastewater discharges. The main objective was to evaluate the ecological quality of this lotic system, analyzing biotic and abiotic parameters during two seasons. The biotic parameters included microinvertebrates and fecal coliforms, while the abiotic parameters encompassed temperature, pH, dissolved oxygen, electrical conductivity, turbidity, total dissolved solids, and biochemical oxygen demand. Six sampling points were established where physicochemical and microbiological parameters were analyzed. Simultaneously, quantitative sampling of macroinvertebrates was carried out at the same points to evaluate their diversity using Shannon- Wiener, Margalef and Simpson indices. The Andean Biotic Index (ABI) and the Biotic Family Index (FBI) were calculated to determine the ecological quality of the river using macroinvertebrates. Finally, the spatio-temporal variation of macroinvertebrate composition and physicochemical and microbiological parameters were analyzed. Very high concentrations of BOD, total dissolved solids, and electrical conductivity were obtained in the dry season, while in the rainy season, they were pH, dissolved oxygen, and turbidity. 12548 individuals from 6 classes, 11 orders, and 26 families were collected. The greatest richness of macroinvertebrate families was found at points 1 and 2, with Trichoptera, Ephemeroptera and Plecoptera individuals predominating. There was evidence of temporal variation in physicochemical and microbiological parameters, as well as in macroinvertebrate composition. It was concluded that the ecological quality of the Jucusbamba River decreases as it follows its course due to anthropic disturbances. This research can be used to develop management plans, awareness-raising, and sanitation measures to ensure the protection and conservation of the Jucusbamaba River.

Effects of weir‐induced habitat fragmentation on the diversity and community composition of benthic macroinvertebrates in an agricultural stream

Effects of weir‐induced habitat fragmentation on the diversity and community composition of benthic macroinvertebrates in an agricultural stream

Assessment of Macro-Invertebrates of Gubi and Waya Dams in Bauchi State, Nigeria

This study assessed the diversity, abundance, and composition of macro-invertebrates in the Gubi and Waya Dams in Bauchi State. Macro-invertebrates were collected fortnightly from different locations in the upper and lower parts of the dams using a D-frame net with a mesh size of 250 µm. Samples were preserved in 10% formaldehyde and identified. In Gubi Dam, 62 individual macro-invertebrates belonging to 7 orders and 9 families were identified, while Waya Dam had 108 individuals from 8 orders and 10 families. Both dams had Coleoptera with three families, followed by Odonata with two families, and other orders with one family each. In Gubi Dam, the most abundant macro-invertebrates were Psephenus spp. (24.1%), Paragomphus genei (17.74%), and Phaon camerunensis (16.13%). In Waya Dam, Paragomphus genei (29.63%) and Phaon camerunensis (25.93%) were the most abundant. Gubi Dam had a Shannon-Wiener index of 2.00, a Margalef’s index of 1.99, Pielou’s evenness index of 0.91, and a Simpson’s index of 0.86. Waya Dam had a Shannon-Wiener index of 1.88, a Margalef’s index of 1.92, an evenness index of 0.82, and a Simpson’s index of 0.81. The study concluded that both dams provide stable and moderate aquatic environments for the growth and survival of macro-invertebrates as well as other aquatic organisms. Continuous monitoring of the water bodies, especially Waya Dam, using water indices and pollution indicator macro-invertebrates to obtain vital information on ecological status is recommended.

Razor clam (Pinna bicolor) structural mimics as drivers of epibenthic biodiversity; a manipulative experiment

Shellfish ecosystems facilitate important ecological functions and communities, but overexploitation and mismanagement have contributed to their decline worldwide. Within recent decades, coastal management efforts have increasingly sought to understand and reinstate valuable ecological functions provided by habitat-forming bivalves including oysters, mussels and pinnids. However, many bivalve species are critically understudied, limiting restoration and ecological engineering opportunities. Pinnids, specifically, are an underappreciated bivalve group, with razor clams (Pinna bicolor) forming dense aggregations, and potentially supporting important ecological functions. This study, conducted in an urban Australian estuary, was a manipulative experiment that investigated whether artificial razor clam shells could facilitate beneficial ecological functions through the provision of structural habitat. Specifically, we investigated the influence of intertidal benthic structures, including the micro-habitat influences of surface structure associated with mortality status (open or closed shell), and the short-term response of the benthic and epifaunal communities. Within 12 weeks, the structural razor clam mimics rapidly changed the aboveground ecological community, relative to the bare habitat controls. Both open and closed artificial shells provided a settlement surface for epiphytic organisms and supported enhanced epifaunal biodiversity. Contrastingly, the artificial structures did not significantly alter sediment characteristics or infaunal macroinvertebrate composition in the surrounding benthos. These results provide important insights into the rapid ecological response to the installation of intertidal pinnid structures in dynamic estuarine ecosystems. Furthermore, we provide a case study for understanding the ecological functions of an understudied habitat-forming species, which could be used to inform future restoration and management efforts.

The assessment of water quality by macroinvertebrate and water quality indices in small reservoir (Damsa, Türkiye)

AbstractThe composition and spatial distribution of macroinvertebrates in the Damsa reservoir have been analysed. Also, reservoir water was evaluated with water quality index (WQI). Damsa reservoir is significant for both biodiversity and recreation in the region. Except for the winter season, the lake water is of good quality for WQI. There is pollution in the lake in terms of phosphorus, especially for winter. In terms of phosphate, all of the stations are mezotrophic for the OECD; however, Stations 4 and 5 are eutrophic for the Türkiye Surface Water Quality Management Regulation (the others are mezotrophic). Community variation and status of benthic macroinvertebrate were evaluated with Ecological Status Class Assessment Tools (ESCATs) indices which have been widely used in the literature. In the present study, 1062 individual benthic macroinvertebrates from 11 orders and 17 families were collected. A total of 46 macroinvertebrates taxa were identified. The first three dominant groups are Oligochaeta (42.66%), Hemiptera (Micronecta scholtzi, 23.07%) and Chironomidae (19.67%).

Quantification of large-spatial scale and in-stream factors affecting the structure of benthic macroinvertebrate communities in mountain streams

Habitat diversity plays a crucial role in shaping the structure and distribution of benthic macroinvertebrate communities. However, few studies have investigated the concurrent effects of such drivers operating at different spatial scales in mountain streams. Here, we assessed which environmental factors at different spatial scales, related to stream/river type and substrate, influence the diversity of benthic macroinvertebrate assemblages in mountain streams and rivers. Within the framework of the aquatic investigations of the Biodiversity Monitoring South Tyrol (BMS) – a newly-established, regional-based, long-term biodiversity monitoring program – benthic macroinvertebrates and a set of environmental factors describing water quality, stream/river hydromorphology and in-stream habitat characteristics were collected and analysed. The variation in total density, taxonomic richness, Shannon evenness and % Ephemeroptera–Plecoptera–Trichoptera taxa of stream benthic macroinvertebrates was assessed at multi-scale habitat levels, in 48 sampling sites across the mountainous region of the Autonomous Province of Bolzano/Bozen (Italy). The effects of stream/river type, substrates and different environmental factors on community composition of benthic macroinvertebrates were quantified, using a stepfoward Redundancy Analysis (RDA) and generalized additive models (GAMs). In addition, we performed an Indicator Value analysis to detect taxa that were significantly associated with a specific substrate and/or stream/river type. Overall, we observed significant differences in benthic biological metrics among both stream/river and substrate types. We also found at least one indicator taxa for each stream/river type, with environmental factors acting at reach and large-spatial scale – temperature, stream channel stability, elevation – being the key drivers in shaping macroinvertebrate distribution patterns in the analysed mountain rivers. While significant differences in macroinvertebrate community structures were found among substrates, the influence of stream/river type conditions was particularly evident. Apart from ranking environmental variables worth including in a long-term aquatic biodiversity monitoring program in mountain areas, our study provides a baseline for practical applications. For instance, depending on the desired outcome of habitat heterogeneity restoration, it can suggest the optimal scale (landscape vs. reach vs. patch) for prioritizing in-field interventions.

Influence of seasonal hydrological regimes on benthic macroinvertebrates in two the Brazilian biodiversity hotspots

Global warming has changed climate patterns worldwide causing an increase of extreme weather conditions that have altered annual seasonal hydrological regimes. These extreme climate-driven shifts modify habitat availability and can influence freshwater communities in disruptive ways. Our study investigates how changes in annual seasonal hydrological regimes affect the community structure and the Functional Feeding Groups (FFG) of benthic macroinvertebrates in two Brazilian biodiversity hotspots, the Brazilian Tropical Savannas (a.k.a., Cerrado) and Atlantic Forest biomes. We investigate whether annual variation in precipitation between biomes influence composition, richness, and abundance of benthic macroinvertebrates and their proportions of FFG. We demonstrate that differences in annual precipitation rates affect the composition and abundance, but not richness of benthic macroinvertebrates. Changes in community structure are related to changes in annual precipitation, which modify stream variables. Our findings suggest that annual seasonal changes in hydrological precipitation modify benthic macroinvertebrate communities, especially in Cerrado, where dry seasons are more pronounced. Therefore, annual changes in precipitation rates may disrupt the benthic macroinvertebrate communities in tropical savannas, potentially leading to biodiversity loss.

Zoogeographical composition of macroinvertebrates in low-mountain lakes of the Russian Altai

In 2022 the taxonomic and zoogeographic composition of the macrozoobenthos of six lowland lakes of the Russian Altai: Aya, Beloe, Kireevo, Kolyvanskoe, Koksha and Svetloye was investigated. In the studied lakes 156 species of zoobenthos from 9 classes of invertebrates were identified. The largest number of species is characteristic of the insect class. Chironomids and oligochaetes dominated in terms of frequency of occurrence in the lakes. Of the oligochaetes, the family Tubificidae (68%) was more frequently observed. Tubificidae (68%), chironomids — subfamilies Chironominae (91%) and Tanypodinae (66%). The maximum species diversity of zoobenthos was observed in lakes Beloe (81 species) and Koksha (76 species), the least number of species was found in lakes Aya (41 species) and Kireevo (52 species). Lakes Beloe — Kireevo — Kolyvanskoe and Koksha — Svetloye are the most similar in composition of benthic invertebrates. The most original was the taxonomic composition of the deepest lake Aya. According to the taxonomic composition of the fauna of bottom invertebrates, most lakes (Aya, Beloe, Kireevo, Kolyvanskoe) were closer to plain water bodies, two lakes (Koksha, Svetloe) combined features of both plain and mountain lakes. Zoogeographic analysis of the fauna of benthic invertebrates of foothill lakes revealed 12 types of distribution. Holarctic (39%), Palaearctic (23%) and Western Palaearctic species (21%) were predominant in the lake fauna. Comparative analysis of the fauna of the identified homotopic and heterotopic species showed that the most extensive areas are found only among homotopic primary aquatic archaic taxa. Zoogeographic analysis of the studied lakes indicate their proximity to the border of the Western and Eastern Palearctic.

Consistent but Delayed Timing of Precipitation Affects Community Composition of Prairie Pothole Birds and Aquatic Macroinvertebrates, but not Wetland Plants

Consistent but Delayed Timing of Precipitation Affects Community Composition of Prairie Pothole Birds and Aquatic Macroinvertebrates, but not Wetland Plants

Ecological importance of low-order streams to macroinvertebrate community composition in Afromontane headwater streams

Low-order streams contribute to the abiotic and biotic character of large rivers and are renowned for harboring unique forms of aquatic flora and fauna. However, most studies on headwater streams mainly focus on the mainstems and overlook the contribution of the tributary systems. Moreover, low-order streams are generally overlooked in legislation and bioassessment programs, and consequently not protected in many countries. To contribute to the recognition of the ecological importance of low-orders streams, this study focused on determining whether river network characteristics and associated physico-chemical parameters can be used to effectively predict the variabilities in macroinvertebrate assemblage characteristics between first-order and second-order streams in the headwaters of the Nzoia River Basin, Kenya. The study quantified the structural and functional community composition, diversity, similarity, and richness of macroinvertebrate communities between the two river systems. Dissolved oxygen, coarse particulate organic matter, conductivity, stream width, depth, discharge and flow velocity were the main predictors of the diversity and distribution of macroinvertebrates in the first order and second-order streams. The first order streams recorded higher abundance of macroinvertebrates than the second-order streams. Taxa from families Ephydridae, Elmidae, Gomphidae, and genera Euthraulus, Neoperla, Orthothrichia and Prosopistoma were limited to the second-order stream sites while families Ceratopogonidae, Pisuliidae, Dytiscidae and genus Trichosetodes occurred exclusively in the first-order stream sites. Collector-filterers and collector-gatherers were the most abundant functional feeding groups (FFGs) in the two river systems. Scrapers were abundant in the second-order stream while shredders were abundant in the first order streams. The distinctness in the structural and functional composition of macroinvertebrates between the two river systems suggests that linkages among streams in a network as exemplified in the Nzoia River Basin, support and foster biodiversity.

Macroinvertebrates beta diversity and responses of functional traits to water environmental factors in the Qingyijiang River, China

AbstractThe diversity of functional traits of macroinvertebrates in freshwater ecosystems is one of the current research hotspots in the field of biodiversity. Understanding the functional trait composition of macroinvertebrates and their factors can make the study of watershed beta diversity and river ecological security patterns more effective. Based on two field surveys conducted in September 2020 and July 2021 in the Qingyijiang (QYJ) River, the longest tributary on the south bank of the lower Yangtze River in China, we explored the functional trait compositions of macroinvertebrates and relationships between functional traits and water environment factors using functional diversity indices, beta diversity decomposition, R‐mode linked to Q‐mode, and fourth‐corner analysis methods. Our results showed that water environmental factors affected the distribution of macroinvertebrates traits, and the degree of effect was reflected by the correlation between water environmental factors and the abundance of species traits. Physical factors like flow velocity and water depth were significantly correlated with biological traits of species such as body size and swimming ability. In counterparts, some nutrient indicators significantly affected species ecological traits, such as total phosphorus, ammonia nitrogen, and chemical oxygen demand, which affected species habits and functional feeding group traits. At the same time, we also found a high turnover rate between communities in the river, reflecting the strong dispersal ability of the species. This will be an important guide for the conservation of macroinvertebrates diversity in the river. Local governments can take measures such as conducting quarterly monitoring of macroinvertebrates species; restoring riparian vegetation; limiting hardening of riverbanks and dredging of rivers; controlling wastewater discharges from residential areas on both sides of the river; controlling the use of pesticides in agricultural lands, and so on. These will become the key directions for the conservation of macroinvertebrates diversity.

Meta-analysis contrasting freshwater biodiversity in forests and oil palm plantations with and without riparian buffers.

The expansion of oil palm plantations has led to land-use change and deforestation in the tropics, which has affected biodiversity. Although the impacts of the crop on terrestrial biodiversity have been extensively reviewed, its effects on freshwater biodiversity remain relatively unexplored. We reviewed the research assessing the impacts of forest-to-oil palm conversion on freshwater biota and the mitigating effect of riparian buffers on these impacts. We searched for studies comparing taxa richness, species abundance, and community composition of macroinvertebrates, amphibians, and fish in streams in forests (primary and disturbed) and oil palm plantations with and without riparian buffers. Then, we conducted a meta-analysis to quantify the overall effect of the land-use change on the 3 taxonomic groups. Twenty-nine studies fulfilled the inclusion criteria. On average, plantations lacking buffers hosted 44% and 19% fewer stream taxa than primary and disturbed forests, respectively. Stream taxa on plantations with buffers were 24% lower than in primary forest and did not differ significantly from disturbed forest. In contrast, stream community composition differed between forests and plantations regardless of the presence of riparian buffers. These differences were attributed to agrochemical use and altered environmental conditions in the plantations, including temperature changes, worsened water conditions, microhabitat loss, and food and shelter depletion. On aggregate, abundance did not differ significantly among land uses because increases in generalist species offset the population decline of vulnerable forest specialists in the plantation. Our results reveal significant impacts of forest-to-oil palm conversion on freshwater biota, particularly taxa richness and composition (but not aggregate abundance). Although preserving riparian buffers in the plantations can mitigate the loss of various aquatic species, it cannot conserve primary forest communities. Therefore, safeguarding primary forests from the oil palm expansion is crucial, and further research is needed to address riparian buffers as a promising mitigation strategy in agricultural areas.

Fatty-acid based assessment of benthic food-web responses to multiple stressors in a large river system

Rivers are often exposed to multiple stressors, such as nutrients and contaminants, whose impacts on the river food webs may not be distinguished by sole assessment of biological community structures. We examined the benthic algal assemblages and the fatty acids (FA) of benthic macroinvertebrates in the lower Athabasca River in Canada, aiming to assess the changes in algal support and nutritional quality of the benthic food web in response to cumulative exposure to natural bitumen, municipal sewage discharge (hereafter, “sewage”), and oil sands mining (“mining”). Data show that the decline in water quality (increases in nutrient concentrations and total suspended solids) was associated with decreases in benthic diatom abundance, and was driven mainly by sewage-induced nutrient enrichment. Responses in nutritional quality of benthic macroinvertebrates, indicated by their polyunsaturated FA (PUFA) concentrations, were taxon- and stressor-specific. Nutritional quality of the larval dragonfly predator, Ophiogomphus, decreased nonlinearly with decreasing benthic diatom abundance and was lowest at the sewage-affected sites, although exposure to natural bitumen also resulted in reduced Ophiogomphus PUFA concentrations. In contrast, the PUFA concentrations of mayfly grazers/collector-gatherers were not affected by natural bitumen exposure, and were higher at the sewage and sewage+mining sites. The PUFA concentrations of the shredder Pteronarcys larvae did not change with cumulative exposure to the stressors. Sediment metal and polycyclic aromatic compound concentrations were not associated with the macroinvertebrate FA changes. Overall, we provide evidence that sewage induced reduction in trophic support by PUFA-rich diatoms, and was the predominant driver of the observed changes in FA composition and nutritional quality of the benthic macroinvertebrates. Fatty-acid metrics are useful to untangle effects of concurrent stressors, but the assessment outcomes depend on the functional feeding guilds used. A food-web perspective using multiple trophic levels and feeding guilds supports a more holistic assessment of the stressor impacts.