Benthic Macroinvertebrate Community Structure Research Articles

Rapid assessment implementation in the development of biocriteria and organic enrichment evaluation in the Citarum River, Indonesia

ABSTRACT Socio-economic activities along the Citarum River basin in Indonesia can induce ecological disturbances in the structure of the benthic macroinvertebrate community. This research aims to (1) identify the environmental factors responsible (2) describe the ecological disturbances using biological measurements; (3) and to develop local biocriteria using a multi-metric conceptual approach. An inventory of benthic macroinvertebrates was carried out at eight stations over a sampling period of 3 months, along with water quality monitoring. The results confirm the change in the structure of benthic macroinvertebrate communities, explained by seven environmental parameters: dissolved oxygen (DO), ambient habitat quality, turbidity, nutrient enrichment, conductivity, temperature, and embeddedness percentage. The changes were then assessed using six biological measurements. Only four have been shown to be capable as alternatives to existing biocriteria. Their implementation enabled the development of local biocriteria compatible with the multimetric concept known as the cumulative biotic index (CBI).

Assessing benthic macroinvertebrate communities’ spatial heterogeneity in Mediterranean transitional waters through eDNA metabarcoding

Transitional waters are important habitats both for biodiversity and ecological functions, providing valuable natural resources and relevant ecosystem services. However, they are highly susceptible to climate changes and anthropogenic pressures responsible for biodiversity losses and require specific biomonitoring programs. Benthic macroinvertebrates are suitable as ecological indicators of transitional waters, being affected by biological, chemical, and physical conditions of the ecosystems about their life cycles and space-use behaviour. The advent of high-throughput sequencing technologies has allowed biodiversity investigations, at the molecular level, in multiple ecosystems and for different ecological guilds. Benthic macroinvertebrate communities’ composition has been investigated, at the molecular level, mainly through DNA extracted from sediments in marine and riverine ecosystems. In this work, benthic macroinvertebrate communities are explored through eDNA metabarcoding from water samples in a Mediterranean transitional water ecosystem. This research highlighted the validity of eDNA metabarcoding as an efficient tool for the assessment of benthic macroinvertebrate community structure in transitional waters, unveiling the spatial heterogeneity of benthic macroinvertebrate communities correlated to the measured environmental gradients. The results suggest that peculiar features of transitional water ecosystems, such as shallow waters and limited currents, facilitate the assessment of benthic macroinvertebrate communities through environmental DNA analysis from surface water samples, opening for more rapid and accurate monitoring programs for these valuable ecosystems.

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.

Community Structure and Water Quality Assessment of Benthic Macroinvertebrates in Hongze Lake.

This study investigated the species, density, biomass and physicochemical factors of benthic macroinvertebrates in Hongze Lake from 2016 to 2020. Redundancy analysis (RDA) was used to analyze the relationship between physicochemical parameters and the community structure of macroinvertebrates. Macroinvertebrate-based indices were used to evaluate the water quality conditions in Hongze Lake. The results showed that a total of 50 benthic species (10 annelids, 21 arthropods and 19 mollusks) were collected. The community structure of benthic macroinvertebrates varied in time and space. The dominant species were Limnodrilus hoffmeisteri (L.hoffmeisteri), Corbicula fluminea (C.fluminea), Nephtys oligobranchia (N.oligobranchia). In 2016, arthropods such as Grandidierella sp. were the dominant species of benthos in Hongze Lake while annelids and mollusks dominated from 2017 to 2020, such as L.hoffmeisteri, N.oligobranchia, C.fluminea. The benthic fauna of Chengzi Lake and Lihewa District were relatively abundant and showed slight variation, while the benthic macroinvertebrates of the Crossing the water area were few and varied greatly. RDA showed that changes in benthic macroinvertebrate structure were significantly correlated with dissolved oxygen (DO), Pondus Hydrogenii (pH) and transparency (SD). The Shannon Wiener, Pielou, and Margalef indices indicate that Hongze Lake is currently in a moderately polluted state. Future studies should focus on the combined effects of various physicochemical indicators and other environmental factors on benthic communities.

Water‐level fluctuations and nutrient enrichment interact to alter ecosystem structure in distinct ways at different water depths

Abstract Aquatic ecosystems are often impacted by several human‐derived pressures simultaneously. A key challenge for ecologists is to develop mechanistic understanding of the cumulative effects of multiple stressors on freshwater biodiversity. We established an outdoor mesocosm experiment to examine the individual and combined effects of two key stressors on lake ecosystems globally—nutrient enrichment and amplified water‐level fluctuations—on benthic algal and macroinvertebrate assemblages along a gradient in littoral water depth. We found that nutrient enrichment and water‐level fluctuations not only altered the structure of littoral communities when acting individually, but also interacted to dynamically alter biomass and community structure in different ways at different depths. As expected, enrichment increased benthic algal biomass significantly in very shallow waters. Yet, when enrichment co‐occurred with water‐level fluctuations, this pattern was reversed, with algal biomass increasing significantly in deeper waters, but not in the shallows that were exposed to fluctuating water levels. This pattern occurred across all algal groups that we examined except for green algae. Green algae biomass increased with nutrient enrichment, was greatest in the shallows, and remained unaffected by fluctuating water levels. Water‐level fluctuations modified the functional feeding group structure of benthic macroinvertebrate communities, reducing relative densities of collector‐gatherers and increasing those of predators. However, these changes occurred only in the shallow‐most regions exposed directly to fluctuating water levels. Our results reveal how two globally important stressors of standing water systems can interact in different ways in different ecological contexts and show how stressors can combine to have unanticipated impacts that vary in space. Our findings underscore the potentially highly multifaceted and complex nature of stressor combinations that present a major and growing challenge to ecosystem management, particularly in light of accelerating global environmental change.

Linking physico‐chemical parameters and macroinvertebrates for water quality assessment of Kakamega and the East Usambara montane ecosystems in Kenya

AbstractSub‐Saharan freshwater biodiversity is impacted by changes in land use and climate change. To evaluate the relationship between physico‐chemical variables and macroinvertebrate community assemblages in Kakamega and the East Usambara Mountains forests, we explored benthic macroinvertebrate community structure in relation to physico‐chemical conditions of the water along an anthropogenic stress gradient. Sampling was done in six selected streams during the rainy and dry seasons between April 2017 and November 2019. At Kakamega, 367 macroinvertebrate individuals were identified belonging to 22 families, while at Usambara, 456 individuals belonging to 25 families were identified. Spearman's correlation revealed significant interactions in species diversity, evenness, and richness between macroinvertebrates and several physico‐chemical parameters (pH, conductivity, total dissolved substances, salinity and temperature). At Usambara, species richness, evenness and diversity was significantly negatively correlated with conductivity, tds, salinity, temperature and pH. We demonstrated that macroinvertebrate indices can be used as a quick evaluation tool of water quality in response to stream systems in the region as well as help in pointing out early warnings to help mitigate and reduce threats to stream biodiversity from anthropogenic activities.

Water quality shapes the community structure of zoobenthos in rivers but only has a minor effect on the fatty acid composition of zoobenthos and salmonids

AbstractMany river ecosystems in the boreal zone have faced remarkable changes due to intensive human activities, including land‐use changes in the catchments and channelization. Recently, restoration efforts have increased, hoping to restore a more natural hydromorphology. We studied the community structure of benthic macroinvertebrates (zoobenthos) in seven rivers in Eastern Finland, using samples that covered pre‐ and post‐restoration periods, to examine how environmental metrics relate to the zoobenthos community structure, and the fatty acid (FA) composition and content of Ephemeroptera, Plecoptera, and Trichoptera nymphs and larvae. We also analyzed the FA composition and content of land‐locked salmon (Salmo salar m. sebago) in three of the rivers and brown trout (Salmo trutta) in two of the rivers. Zoobenthos communities differed significantly among most of the rivers: 24% of the differences between the zoobenthos communities were driven by water quality parameters related to the loading of terrestrial organic matter (water color, pH, and iron concentration). Temporal changes in zoobenthos communities could not be fully attributed to restorations. The FA composition of zoobenthos was mostly explained by phylogenetic origin (47%). However, especially mayfly Heptagenia sulphurea (Ephemeroptera: Heptageniidae) had variable FA composition and content among the rivers suggesting an environmental quality indicator role for this species. FA composition and content of salmonids were mostly size‐dependent (24%), but river identity also influenced their FA composition (22%). Our results indicate that water quality affects the availability of essential FAs for consumers by altering the zoobenthos community structure and their FA composition and content.

Characteristics of community structure and niche analysis of benthic macroinvertebrates in the upper reaches of Jinsha River

Characteristics of community structure and niche analysis of benthic macroinvertebrates in the upper reaches of Jinsha River

COMMUNITY STRUCTURE AND DIVERSITY OF BENTHIC MACROINVERTEBRATES IN ALAM KANDUNG WATERFALL TULUNGAGUNG REGENCY

This research aims to determine the profile of the community structure and diversity of benthic macroinvertebrates in Alam Kandung Waterfall. Sampling was carried out at six stations of ± 100 individuals or stations that use surber net and hand net. Data collection for each station includes the composition and density of each species which is used to calculate taxa richness, abundance, IVI (Important Value Index), and diversity index (H'). The results showed that 37 taxa from 11 classes were found and varied at each station. At the first station, the highest taxa were found with a total of 19 taxa, and the lowest taxa at the second station with 7 taxa. The highest abundance is known at the first station and the lowest at the sixth station. The IVI results show that the first and second stations are dominated by the type of Sulcospira testudinaria which is sensitive to pollutants, and the third station and fourth are dominated by Tarebia granifera and Vellidae. The fifth station was dominated by Corixidae, while Thiara scraba and Atyidae were found in all stations. The results of the diversity index show that the first and fourth are lightly polluted, the second station is moderately polluted and the rest are not polluted. It can be concluded that the quality of waterfalls in Alam Kandung is still in a good category, reflected by the diversity of taxa and the presence of riparian vegetation.

Benthic macroinvertebrate community structure in nutrient‐rich, spring‐fed streams recently invaded by non‐native New Zealand mud snails

Abstract Ecological roles of non‐native species can vary over space and time due to abiotic factors and characteristics of the invaded communities. For instance, nutrient availability, temperature, and flow regime can influence invasion outcomes in freshwaters. This variability makes it challenging to predict non‐native species' effects in newly introduced areas. New Zealand mud snails (Potamopyrgus antipodarum; NZMS) are among the most widespread aquatic invasive species globally and have recently been detected in highly productive, spring‐fed streams in the upper mid‐west U.S.A. that are important trout fisheries. We hypothesised that the nutrient‐rich, thermally stable groundwater‐fed streams would provide favourable conditions for NZMS populations, potentially amplifying their effects on native communities. We surveyed benthic macroinvertebrate community structure at 10 streams representing a gradient of NZMS densities in the Driftless Area of southern Wisconsin. At five of the streams, we quantified temporal variation in NZMS and other benthic macroinvertebrates over three seasons. NZMS populations varied considerably across sites and over time, ranging from a few hundred to over 70,000 snails/m2. NZMS numerically represented as much as 97% of the invertebrate community at the highest density sites. At two sites, NZMS increased in population density by 50‐fold and 22‐fold over the survey duration, while at other sites their densities were relatively constant. Based on a principal components analysis summarising stream environmental variables, NZMS densities were negatively associated with stream discharge and positively associated with nitrogen and phosphorus concentrations. The total density and biomass of all benthic invertebrates, and Ephemeroptera and Amphipoda in particular, were negatively associated with NZMS density and biomass. Based on multivariate analyses, overall benthic community composition differed based on NZMS invasion status, as well as across seasons. These results suggest that the environments of southern Wisconsin spring‐fed streams provide favourable conditions for NZMS populations, allowing them to dominate some benthic communities. NZMS effects are likely to vary strongly across streams and over time within streams, highlighting the importance of future work to mechanistically test biotic and abiotic factors influencing their abundance.

Refining stream ecosystem evaluation: A novel approach using the family ecological index (FEIS)

The use of ecological indices based on benthic macroinvertebrate population for streams ecosystem quality assessment receives great attention. Streams in general have high variability characteristics; thus, using a single index used for the whole stream stretch renders less accurate readings. Therefore, this study was conducted to produce an ecological index using benthic macroinvertebrates as a bioindicator for a clean stream ecosystem. In this study, 42 recreational streams throughout Peninsular Malaysia were sampled and 663 units of water and benthic macroinvertebrates samples were analysed. Three phyla, 19 orders, 117 families and 55,410 macroinvertebrate individuals were recorded. Benthic macroinvertebrate data were analysed using existing indices such as Shannon Diversity Index (H’), biotic indices (BMWPTHAI and FBI) and WQI to analyse water quality. Canonical Correspondence Analysis (CCA) was used to evaluate the strength of water quality and physical habitat in determining benthic macroinvertebrate community structure. Next, Principal Component Analysis (PCA) was used to produce new weights. Based on the similarities and dissimilarities of each family in their ecological functions, the components were truncated into only three significant groups with respective weights and a new ecological index, namely Family Ecological Index for Streams (FEIS). From the FEIS values calculation, three scales which are 2.11 to 3.00 (first class: excellent ecosystem), 1.36 to 2.10 (second class: healthy ecosystem), and 0.00 to 1.35 (third class: moderately healthy ecosystem) were obtained. It is found that FEIS is capable of exhibiting variations in stream quality even within clean streams and able to detect early deterioration in streams which is highly useful for management stakeholders to manage recreational streams in Malaysia. The new data-driven approach in the development of FEIS in this study can be applied to other rivers and the difference in the weights determination as well as formulation obtained can be observed.

Influence of the Hydrological Variability on Water Quality and Benthic Macroinvertebrates in a Chilean Estuary During a Megadrought

The climate crisis has accelerated the frequency and intensity of droughts in the Mediterranean areas, impacting the hydrology and the ecology of their basins. Maule River is the largest watershed in the Chilean Mediterranean Zone. The growing anthropic and environmental pressure has led to changes in the structure and function of its terrestrial ecosystem. However, little is known about its influence on aquatic ecosystems. The effect of the recent extreme drought on the streamflow and its influence on water quality and the benthic macroinvertebrate community structure were evaluated in the Maule River’s lower section. Beyond temporal and spatial fluctuations, healthy and permanently well-oxygenated waters prevailed in the study area. However, during the megadrought period, evidenced by a significant decrease in both precipitation and river streamflow, a greater salt wedge influence was observed, at least, in the last 7 km of the river. Although with certain asynchrony, a change in the structure of the benthic macroinvertebrate community was observed in the upstream stations. This marinization reveals an increase in the domain of marine taxa associated with the Polychaeta group and a clear decrease in typical freshwater Oligochaeta individuals. This modification in the structure of the benthic community is expected to affect the function of this estuarine system. The results presented here highlight the importance of considering the variability associated with biological components for the management of water resources and related ecosystem services, considering that one of the main problems associated with changes in land use and the pressures caused by the climate crisis is the decrease in the quality and availability of water in this and other Mediterranean basins globally.

Spatial variation in the community structure and response of benthic macroinvertebrates to multiple environmental factors in mountain rivers

Exploring the response between benthic community changes and environmental variables has significance for restoring the health of river ecosystems. However, little is known of the impact on communities of interactions between multiple environmental factors, and frequent changes in the flow of mountain rivers are different from those in the flow of plain river networks, which also impact differently the benthic community. Thus, there is a need for research on the response of benthic communities to environmental changes in mountain rivers under flow regulation. In this study, we collected samples from the Jiangshan River in the dry season (November 2021) and the wet season (July 2022) to investigate the aquatic ecology and benthic macroinvertebrate communities in the watershed. Multi-dimension analyses were used to analyze the spatial variation in the community structure and response of benthic macroinvertebrates to multiple environmental factors. In addition, the explanatory power of the interaction between multiple factors on the spatial variation of communities, and the distribution characteristics of benthic community and their causes were investigated. The results showed that herbivores are the most abundant forms in the benthic community of mountain rivers. The structure of benthic community in Jiangshan River was significantly affected by water quality and substrate, whereas the overall community structure was affected by river flow conditions. Furthermore, nitrite nitrogen and ammonium nitrogen were the key environmental factors impacting the spatial heterogeneity of communities during the dry and wet season, respectively. Meanwhile, the interaction between these environmental factors showed a synergistic effect, enhancing the influence of these environmental factors on community structure. Thus, controlling urban and agricultural pollution and releasing ecological flow would be effective strategies to improve benthic biodiversity. Our study showed that using the interaction of environmental factors was a suitable way to evaluate the association between environmental variables and variation in benthic macroinvertebrate community structure in river ecosystems.

Community structure and diversity of benthic macroinvertebrates as bioindicators of water quality in some waterfall ecosystems, Bawean Island, Indonesia

Abstract. Retnaningdyah C, Arisoesilaningsih E, Vidayanti V, Purnomo, Febriansyah SC. 2023. Community structure and diversity of benthic macroinvertebrates as bioindicators of water quality in some waterfall ecosystems, Bawean Island, Indonesia. Biodiversitas 24: 370-378. Bawean Island is a small island with a fairly dense population, so the need for water resources is quite high. On Bawean Island, several waterfalls have been found that have a hydrological function capable of supplying water continuously for drinking water, raw materials, agricultural irrigation functions and other daily activities that are very important for the people of Bawean Island. However, the quality of the waterfall ecosystem on Bawean Island has never been studied. This study aims to evaluate the water quality of some waterfall ecosystems on Bawean Island using the community structure and diversity of benthic macroinvertebrates as a complement to water physicochemical monitoring. This study used the Ex Post Facto method. The research was conducted at 6 waterfalls found on Bawean Island. The physicochemical quality of the water observed included air temperature, water temperature, pH, Dissolved Oxygen (DO), conductivity, Biochemical Oxygen Demand (BOD), nitrate, and Total Phosphate (TP). The quality of the benthic macroinvertebrate that had been monitored included Importance Value Index (IVI), taxa richness, total density, Shannon-Wiener Diversity Index (H’), and an ecological index, namely the Family Biotic Index (FBI). The monitoring data then be used to analyze the interaction between water quality profiles and macroinvertebrates profiles by conducting Principal Component Analysis (PCA). Based on the results obtained, the water quality in the Bawean Island waterfall, according to the FBI index categorized as Good-Excellent. According to Indonesian government regulation (PP. No. 22 of 2021), some parameters of water quality in Putri and Suwari waterfall were classified as class 2, which can be used for water tourism infrastructure, fish farming also agriculture and the others are categorized as class 3 which is only used for fish farming and agriculture. To maintain good water quality, the waterfall manager needs to control human activities around the waterfall’s ecosystem.

Ecological structure of aquatic macroinvertebrate communities in the Hauts Plateaux of Northeast Algeria.

Aquatic macroinvertebrates are integral parts of functioning wetlands, inhabiting a diversity of aquatic ecosystems where communities are spatially structured. Macroinvertebrates of some Mediterranean regions such as North Africa are still not well studied. Here, we study the community structure of benthic macroinvertebrates in four different types of lotic and lentic wetlands in the semiarid Haut Plateaux of Northeast Algeria. Macroinvertebrates and 06 physicochemical parameters were sampled in 12 sites belonging to four types of habitats (lotic river, lentic river, dams, and sebkha [saline lentic water body]) during January-December 2021. Eventually, the character lentic-lotic was the most important variable affecting the affecting invertebrate communities in the Mediterranean region. The results revealed that sebkha and dams had a lower Shannon index than lentic and lotic rivers. Non-metric multidimensional scaling analysis showed a strong overlap between the community composition in lotic and lentic sites . Howeverin the three types of aquatic groups lentic river, dam and lotic habitats showed a strong overlap between the community whereas sebkha was markedly separated. Redundancy analysis showed that water velocity and pH, were the main drivers of community structure of macroinvertebrates, revealed a strong effect with pH (F1,8=4.15, P = 0.001) and water velocity (F1,8= 3.22, P = 0.002) , separating lotic communities from those that inhabited dams, lentic rivers, and sebkhas. As conclusion, this study contributes to the better understanding of the community structure of macroinvertebrates in semiarid North Africa where wetlands have been experiencing high anthropogenic disturbance.

Community structure of benthic macroinvertebrates in native and introduced mangroves of northern Beibu Gulf, China: Implication for restoring mangrove ecosystems

Introduced mangroves are widely used to restore mangrove ecosystems in South China. Results of potential impacts on indicative benthic macroinvertebrates are divergent. We explored the community structure of benthic macroinvertebrates in the mangrove ecosystem of northern Beibu Gulf, China across four habitats: native Avicennia marina mangrove, introduced Laguncularia racemosa mangrove, native-introduced mixed mangrove, and unvegetated intertidal flat. Based on the Hill number, community structure was estimated from the dimensions of estimated species richness, diversity, evenness, and species composition similarity. Benthic macroinvertebrates in the unvegetated flat significantly differed from the other three assemblages in mangroves; introduced L. racemosa mangrove had relatively distinct benthic macroinvertebrate assemblage from the native A. marina and the mixed mangroves, with lower species richness and similarity but higher diversity and evenness. Considering the lack of unanimous conclusion of potential impact on benthic macroinvertebrates under complex species interactions, native mangroves should be of top priority in ecosystem restoration.

The Relationship between Benthic Macroinvertebrate Assemblages and Water Quality Parameters in the Sanyati Basin, Lake Kariba, Zimbabwe.

Biological monitoring of reservoirs is important in assessing aquatic health. This study aimed at assessing the structure of benthic macroinvertebrate communities in relation to physicochemical parameters along Sanyati basin shoreline in Lake Kariba, Zimbabwe. Six sites (S1 to S6) characterized by various human disturbances were sampled for physicochemical parameters and benthic macroinvertebrates from January to March 2018. We computed macroinvertebrate metrics and classified them into functional feeding groups (FFGs). A canonical correspondence analysis (CCA) triplot was constructed to assess species-physicochemical relations. Significant differences across the sampling sites were observed for pH, electrical conductivity, turbidity, nitrate-nitrogen (NO3-N), ammonium nitrogen (NH4-N), total nitrogen (TN), phosphate-phosphorus (PO4-P), total phosphates (TP), and dissolved oxygen (DO). The results from CCA highlighted that S1 was generally associated with high pH, NH4-N, and TN, and Oligochaeta, Syrphidae, and Hydrophilidae families. The highest percentage of EPT taxa (39.83%) was recorded at S6, while the lowest was recorded at S1. The taxa were made up of 50% predators, 26% collector-gatherers, 6% scrappers, 6% shredders, and 3% collector-filters with 3 taxa (Chironomidae, Hydropsychidae, and Leptoceridae) having more than two FFGs. Site S1 had a significantly higher mean abundance of collector-gatherers than the other sites. A high correlation between water parameters and SASS and ASPT scores was observed indicating their ability to detect environmental changes. These findings suggest that macroinvertebrate communities are good candidates for delineating the effects of industrial pollution on water quality.

Temporal effects of fine sediment deposition on benthic macroinvertebrate community structure, function and biodiversity likely reflects landscape setting

Globally, excessive fine sediment (particles <2 mm) deposition is acknowledged to have deleterious effects on aquatic biodiversity. However, the impacts are often equivocal possibly reflecting landscape context, although this is rarely considered. To address this, we examined the temporal response of macroinvertebrate taxonomic and functional diversity to experimental fine sediment clogging in a prealpine (Italy) and lowland setting (UK). Colonisation devices were installed insitu with either clean or clogged substrates and examined for short (7–14 days), medium (21–28 days) and long (56–63 days) timescales. Clogging resulted in altered taxonomic community composition in both the lowland and prealpine rivers and modified functional community composition in the prealpine river. Nestedness was consistently found to be the dominant process driving differences in taxonomic composition between the clean and clogged substrates in the prealpine environment, with clogged substrates forming a nested community. No dominant component structured lowland taxonomic communities. Functional community composition was driven by nestedness in both environments but was heavily dominant in the case of the prealpine river, possibly reflecting low functional redundancy. Widely employed community richness metrics (EPT, taxa and functional richness) only displayed a response to fine sediment loading in the prealpine environment but taxa characterized as sensitive to fine sediment as well as some functional feeding groups did exhibit differences in both settings. In the prealpine environment, the effects of fine sediment intensified over time for several community metrics. Although further research is required to corroborate our findings and extend our observations across more rivers and typologies, excessive fine sediment is a pervasive stressor affecting macroinvertebrate communities in prealpine and lowland environments. However, the biodiversity facets that responded to clogging differed between the two landscape settings probably reflecting wider environmental filtering. Monitoring and managing fine sediment loading likely requires context specific approaches to maximise ecological benefits.

Habitat quality assessment of Alpine Streams using ARISE: a classification tool for Alpine RIver and Stream Ecosystems in Khunjerab National Park Gilgit, Pakistan

This study is based on detailed multidisciplinary field investigations with the use of the Alpine River and Stream Ecosystems (ARISE) Classification to assess spatial and temporal patterns of benthic macroinvertebrate communities in relation to altitudinal and channel stability gradients. We expected the field validation through the use of an innovative ARISE classification approach of alpine aquatic ecosystems by collecting physicochemical variables and benthic macroinvertebrate community data from various stream locations of Khunjerab National Park (Pakistan). The significant differences in physicochemical habitat structure and altitudinal changes of benthic macroinvertebrate communities (i.e., richness, abundance, and diversity) were observed among the ARISE classification categories. For instance, the early spring categories had high Shannon-Wiener index (1.377) than summer (1.267), while summer season categories had high turbidity (>5NTU). Early spring mercury nival (0.00083 mg/L) and aluminum nivo-kernal (0.25 mg/L) were also found above permissible levels according to the World Health Organization (WHO). The multivariate statistical techniques showed a strong correlation among physicochemical and biological parameters of stream classification categories suggesting the increased applicability of the use of the ARISE classification approach. This study is expected to contribute to the advancement in the method of the stream monitoring program and improve conservation and management of the alpine benthic macroinvertebrate diversity further in Pakistan, the Asian Himalayas, and beyond. HIGHLIGHTS The ARISE categories of alpine streams were evaluated using physicochemical and biological indicators in Khunjerab National Park, Pakistan. The distinctive ARISE classification reflects community composition and structure (density, diversity, evenness, and richness) and additionally biotic and diversity indices. Baseline information is presented to understand the current features for the conservation and management of alpine lotic ecosystems.

Response of sub-Antarctic streams to urbanization: Relevance of assemblage structure and independent reference areas

Andean Patagonia is experiencing sudden changes due to unorganized urban expansion. Despite being known for its wilderness areas, southern Patagonian urban streams have been increasingly studied during the last decade, using reference-impact gradients within urbanizing watersheds. Here, we assess urbanization effects on stream integrity by comparing environmental characteristics on independent reference streams vs. urban streams, and the benthic macroinvertebrate community structure along three stream reaches in an urbanization gradient. In comparison to reference sites, urban streams had higher nutrient concentrations, temperature, turbidity, stream flow, and total primary producer biomass, accompanied by lower dissolved oxygen concentrations, substrate particle size, mainly along mid and downstream areas. These variables were the main factors structuring macroinvertebrate assemblage ordination analysis. Macroinvertebrate assemblages from areas upstream from the urbanization differed from their counterparts in reference streams, but not from downstream reference areas. Environmental characteristics and biotic assemblage structure were altered in urban streams, even in reaches located upstream from urbanization, compared to independent upstream reference reaches. This study highlights the importance of a community and comparative vision towards independent areas with low impact to serve as reference values and establish appropriate goals or baselines when assessing ecological conditions and potential restoration.