Benthos Research Articles

Biodiversity of Benthic Macroinvertebrates and water quality as a tool to the ecological study of three forest streams in the littoral zone (Cameroon)

A study of the community dynamics of benthic macroinvertebrates in relation to physicochemical water quality was conducted from December 2022 to December 2023 in the Lepp-Nyock, Ndog-Bissolo, and Ngwei streams within the tropical littoral forest area of the Guinean Gulf (Edéa). Physicochemical analyses were performed and Benthic Macroinvertebrate identified following classical method. The results indicate that those waters are well-oxygenated (73.72±12.48%), slightly acidic (pH 6.87±0.42 CU) and contain very low concentrations of nitrogen compounds and heavy metals (0.29±0.28 mg/l Cu, 0.8±0.54 mg/l Zn, 0.45±0.27 mg/l Mn, 1.32±0.47 mg/l Fe, 0.81±0.38 mg/l Al, 0.18±0.2 mg/l Cd, and 0.49±0.52 mg/l Cr). Biological analysis revealed a total of 8,699 Benthic Macroinvertebrates belonging to 4 Phyla, 5 Classes, 12 Orders, 55 Families and 117 Genera. Arthropods were the most abundant, accounting for 86.67% of the total, with the insect Class (86,56%) being dominant (8 Orders, 42 Families, and 68 Genera). Gastropods (13,27%) were the second most abundant group, represented by 2 Orders, 5 Families, and 16 Genera. The Atyidae family was particularly dominant within the benthic community, with Caridina africana identified as the most prevalent species. The Shannon-Weaver diversity index (H') and Piélou equitability index (J) indicated low taxonomic diversity, while the Organic Pollution Index (OPI) suggested a less disturbed environment. Together, these findings reflect the good ecological quality of the water in the studied streams.

Spatio-temporal pollution assessment of Kulfo River using CCME-WQI and pollution tolerance index by benthic macroinvertebrates, Arba Minch, Ethiopia.

In developing nations, the biggest threat to public health is the quality of the water. The Kulfo River provides the majority demand of the domestic water and irrigation along its course; however, it is observed that wastes from anthropogenic and natural activities enter the river. Therefore, this study aimed to examine the pollution status by integrating conventional methods with benthic macroinvertebrates. One hundred twenty samples were collected for 15 water quality parameters from five sampling sites during dry and rainy events. The mean concentration of DO, TSS, BOD5, COD, ortho-phosphate, and turbidity did not meet the standard limits in five sampling sites during the rainy season. Benthic macroinvertebrates were collected from the left, middle, and right sides of the river for each sampling site and examined using the Benthos Biomonitoring Protocol Network Manual. CCME index and PTI index of benthic macroinvertebrates were used to examine the pollution status of the river. According to CCME index result, S2 (39.79), S3 (38.90), and S4 (37.71) are classified under poor pollution status during the rainy season and S1 (92.13) and S5 (95.70) are categorized as good and excellent pollution status in the dry season, respectively. On the contrary, based on the PTI index result, S2 (7.0), S3 (9.0), S4 (9.0), and S5 (9.0) are classified under poor pollution status during the rainy season, whereas S2 (14.0), S3 (10.0), and S4 (15.0) are categorized under fair, and sampling sites S1 (21.0) and S5 (20.0) have good pollution status in the dry season. Based on study findings, the Kulfo River is contaminated by pollutant intrusion, resulting in a decrease in its quality. Therefore, management of solid, liquid, runoff, and domestic activities is critical in upstream tributaries and Arba Minch town to prevent river water quality deterioration.

Invasion of temperate riparian forests by Acacia dealbata affects macroinvertebrate community structure in streams

The riparian forest determines many of the stream characteristics such as physicochemical variables and the availability and quality of food resources for aquatic communities. In central Portugal, native mixed deciduous forests are being heavily invaded by Acacia dealbata, which is an evergreen and nitrogen-fixing tree species, but effects on stream benthic macroinvertebrate communities are unknown. We assessed invasion effects on macroinvertebrate communities by comparing streams flowing through native forests (native streams) and streams flowing through forests heavily invaded by A. dealbata (invaded streams), in central Portugal. We did not find major differences in macroinvertebrate abundance, total taxa richness or diversity between native and invaded streams, due to high variation among native streams. However, taxonomic structure of macroinvertebrate communities differed between stream types, with invaded streams showing lower percentage of sensitive taxa. Macroinvertebrate communities structure based on functional feeding groups also differed between stream types, with a tendency for higher abundance of shredders and scrapers/grazers and lower abundance of filter feeders in native than invaded streams, probably due to altered composition of leaf litter inputs and canopy cover within invaded streams. Our findings suggest that invasion by A. dealbata affect macroinvertebrate community mostly in terms of taxonomic and functional structure. Since A. dealbata is rapidly spreading in all southern Europe, this study highlights the importance of enhancing the comprehension of its impact on aquatic communities to identify ecological risks and formulate effective mitigation strategies.

Retrospective trend analysis of biocides in suspended particulate matter of major German rivers

BackgroundDue to their intrinsic biological activity biocides can pose an unintended threat to various aquatic organisms. Monitoring data on the spatial distribution and temporal trends are needed to evaluate potential risks and the effectiveness of mitigation measures, but these are scarce for biocides in aquatic environments. In particular, even though many biocides tend to sorb to particles, there are only few studies investigating the contamination of suspended particulate matter (SPM). The aim of this study was to obtain an overview of the temporal trends of selected biocides in SPM using German rivers as an example. For this purpose, SPM from the German Environmental Specimen Bank was used for a retrospective trend assessment of a broad spectrum of biocides in integrated SPM samples (yearly composite) in six large German rivers between 2008 and 2021.ResultsOverall 16 of 23 analyzed biocides were found, whereof 10 substances were detected in all samples. Highest concentrations were found for quaternary ammonium compounds (QACs, the sum of four analyzed QACs were up to 8.7 µg/g) and methyl-triclosan (up to 280 ng/g), a transformation product of the bactericide triclosan. Considerably lower concentrations in the range of 0.08 to 88 ng/g and < 0.03 to 13 ng/g were detected for azoles and triazines, respectively. The pyrethroid permethrin, which is highly toxic to aquatic organisms (invertebrates: NOEC = 0.0047 µg/L; fish: NOEC = 0.41 µg/L) as well as to sediment-dwelling organisms (Chironomidae: LC50 = 2.1 mg/kg and NOEC 0.1 mg/kg), was detected at several sampling sites (up to 11.2 ng/g). Concentrations of the other analyzed pyrethroids were below the respective quantification or detection limits. In general, for most compounds, concentrations were higher for locations with higher wastewater proportion, but overall no clear differences in biocide concentration pattern between the different sampling locations were observed. For cybutryne and triclosan significant decreasing concentration trends were observed. This is consistent with regulatory use restrictions and confirms their effectiveness. For benthic organisms a toxicological risk from the individual azole fungicides and QACs seems to be low.ConclusionsExplicit differences between sampling sites and temporary changes in local concentrations indicate regional variations of biocide emissions which hamper identification of long-term concentration trends. Moreover, time trends could be affected by remobilization of legacy contamination from contaminated sites. Hence, for biocides a continuous long-term monitoring is crucial to identify the effectiveness of recent restrictions and mitigation measures.

Benthic macroinvertebrate diversity and function in an agricultural constructed wetland affected by agrochemical pressure (Seine-et-Marne, France).

Constructed wetlands (CWs), originally designed to mitigate chemical water pollution, often host noticeable aquatic fauna. However, little is known about the impact of the contaminants circulating within CWs on this local fauna, questioning the role of CWs as ecological refuges or traps. We aimed to assess the potential of an agricultural CWs in northern France to act as an ecological trap for aquatic fauna and the potential consequences on wetland functioning. We made faunistic inventories of benthic macroinvertebrates, using litterbags, from March to June 2022 in two zones within the CWs with contrasting levels of agrochemical contamination and in one unpolluted comparison pond. We calculated community diversity and sensitivity indices (e.g., species at risk, SPEARpesticides index). We measured wetland functioning by monitoring the leaf-litter breakdown. Results showed that pesticide fluxes were related to community composition changes and had negative effects on taxonomic diversity (Shannon index) and functional traits (shredder/scraper feeding mode). The negative link between pesticides and the leaf-litter breakdown was less clear, mainly because of the high level of integration of this response. This study reveals that CWs under agrochemical pressure may act as potential ecological traps for benthic macroinvertebrates and highlights the relevance of studying this group as an early-warning indicator of chemical risk in nature-based solutions.

Differential use of multiple food sources at a bathyal benthic ecosystem in the central Sagami Bay revealed by amino acid nitrogen isotopic compositions

The nitrogen isotopic composition (δ15N) of amino acids can be used to estimate the trophic position of organisms with high precision compared to bulk tissue analyses, and shed light on potential food sources and food webs. Sagami Bay, Japan, is located at the tectonic plate boundary and have complex bottom topography, making multiple sources of organic matter to bathyal deep-sea ecosystems. Here, we applied this method to benthic animals (meiofauna, macrofauna, and megafauna) living at 1430 m deep in the central Sagami Bay, Japan. The δ15N value of phenylalanine (δ15NPhe) reflects the value of primary producers and was used to estimate the food sources of organisms, while the difference between δ15N value of glutamic acid (δ15NGlu) and δ15NPhe shifts between food source and consumer and was thus used to estimate the trophic position (TPGlu/Phe). The data obtained were interpreted together with previously reported values from benthic foraminifera of the same site for a holistic understanding of the food web. The trophic positions of organisms from the central Sagami Bay ranged mostly from 2.2 to 3.6, except hydrozoans (up to 4.3). Organisms with similar bulk tissue δ15N values sometimes exhibited different TPGlu/Phe values. The observed δ15NPhe varied greatly among benthic organisms in the central Sagami Bay (− 8.3‰ to 21.1‰), suggesting a wide variety of food sources exhibiting different δ15NPhe values. Given the location of the study site at the central part of the deep basin, various organic matter from terrestrial, planktic, coastal, upper bathyal, and perhaps chemosynthetic origins can be expected to accumulate and become available for bathyal benthic organisms. Furthermore, the cross-plot of δ15NPhe values and bulk tissue δ13C values, another indicator of food source, suggested that macro–megafauna examined rely on different organic matter than metazoan meiofauna and foraminifera, which rely on particulate organic matter and bulk sediments. Despite living in the same habitat, organisms of these two size classes may belong to independent food webs due to differences in feeding ecology.

Short‐term response of an abyssal macrofaunal community to a simulated phytodetrital pulse in the Cabo Verde Abyssal Basin, Northeast Tropical Atlantic Ocean

AbstractAbyssal ecosystems comprise more than 50% of the Earth's area and constitute an important reservoir in the global carbon cycle. With ocean productivity expected to decrease due to global warming, these ecosystems could face significant impacts in the coming decades. Benthic macrofauna are a key component of the seafloor carbon and nitrogen cycles, but limited in situ measurements result in high global uncertainty on the rates of metazoan C assimilation at abyssal depths. We sampled the macrofaunal community at the Cabo Verde Abyssal Basin (CVAB), finding a higher abundance of macrofaunal organisms (polychaetes and crustaceans) compared to other abyssal basins of the Atlantic Ocean. We assessed their short‐term response to a simulated phytodetrital pulse during a two‐day tracer in situ experiment at 4200 m depth. 13C and 15N‐labeled diatoms were used as a food source, and the uptake of these elements by the macrofaunal community was quantified. Results showed that surface deposit feeding polychaetes contributed the most to the biomass (75%) and C and N uptake (70% and 83%), revealing their importance to organic matter cycling in the abyss. Enrichment was modest in most macrofauna; however, the uptake of labeled diatoms by some organisms was detected after 48 h. Our findings suggest that CVAB might receive more pelagic input than other abyssal basins underlying oligotrophic regimes. This study establishes a baseline for both macrofauna characterization and benthic ecosystem functioning in abyssal sediments around Cabo Verde and underscores the crucial role of macrofaunal‐sized benthic organisms in C uptake and assimilation within the tropical abyssal Atlantic.

Characterizing Stream Condition with Benthic Macroinvertebrates in Southeastern Minnesota, USA: Agriculture, Channelization, and Karst Geology Impact Lotic Habitats and Communities.

Prior to implementing watershed-wide projects to reduce the impacts of agriculture on regional streams and rivers, stream habitats and benthic aquatic macroinvertebrate communities were assessed at 15 sites on the South Branch Root River and its major tributaries in southeastern Minnesota, USA. Triplicate kick-net samples were collected from each site during three time periods (1998, 1999, 2006/2008) and stream habitats were inventoried within 150 m long sections at each site. In total, 26,760 invertebrates representing 84 taxa were collected and used to rate stream sites using a regional multi-metric benthic index of biotic integrity (BIBI). BIBI scores were significantly correlated with total invertebrate taxa richness. BIBI ratings improved from poor and very poor at headwater sites in channelized stream sections draining agricultural lands to fair to good to excellent in downstream sections flowing through natural channels in largely forested lands. Fifty percent of samples rated stream sites as poor or very poor. Over 85% of stream habitat assessments indicated the presence of fair to good habitats, although stream sites were relatively wide and shallow and dominated by fine sediments that also embedded coarser substrates. BIBI metrics and scores were strongly positively correlated with pool area, riffle spacing-to-stream width ratios, and silt-free substrate, and negatively correlated with width-to-depth ratios. Most stream sites had few Ephemeroptera, Plecoptera, Trichoptera, and Diptera taxa and too few intolerant taxa. It is expected that benthic invertebrate communities should improve as more riparian buffers are added along all streams. However, on-going channel maintenance activities in headwater stream sections, mandated to encourage drainage of adjacent agricultural fields, will continue to negatively impact headwater habitats and biotic communities.

From plankton to fish: The multifaceted threat of microplastics in freshwater environments.

The detrimental impact of emerging pollutants, specifically microplastics (MPs), on the ecological environment are receiving increasing attention. Freshwater ecosystems serve as both repositories for terrestrial microplastic (MP) sources and conduits for their subsequent entry into marine environments. Consequently, it is imperative to rigorously investigate the toxicological effects of MPs on freshwater ecosystems. This article provides a comprehensive analysis of the ecological toxicity effects of MP pollution, both in isolation and in combination with other pollutants, on freshwater aquatic organisms, including plankton, benthic organisms, and fish. The review elucidates potential mechanisms underlying these effects, which encompass oxidative stress, metabolic disorders, immune and inflammatory responses, dysbiosis of the gut microbiota, DNA damage, and cell apoptosis. This paper advocates for the integrated application of multi-omics technologies to investigate the molecular mechanisms underlying the toxicity of MPs to freshwater aquatic organisms from interdisciplinary and multifaceted perspectives. Additionally, it emphasizes the importance of enhancing research on the compounded pollution effects arising from various pollution modes, particularly in conjunction with other pollutants. This study aims to establish a foundation for assessing the ecological risks posed by MPs in freshwater ecosystem and offers valuable insights for the protection of aquatic biodiversity and ecosystem stability.

Investigation of benthic macroinvertable fauna and some environmental variables in Sızır Waterfall (Gemerek-Sivas)

In this study, the benthic macroinvertebrate fauna of Sızır Waterfall, which is located in Sivas Province (Türkiye) and has an important place in recreational activities, and some environmental variables (velocity speed, water temperature, pH, conductivity, dissolved oxygen, total hardness of water, Ca, Mg, Cl, salinity, total amount of dissolved matter, PO4, SO4, NO2-N, NO3-N contents) that may be effective in their distribution were investigated. Also, some elements (Li, B, Na, Al, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Cd, Sb, Ba, Tl, Pb) and a total of 181 types of pesticides were investigated in the studied area. During the wet and dry seasons of 2022, samplings were made from a total of 3 stations: at the beginning of the waterfall (upstream), inside the waterfall (waterfall) and at the exit of the waterfall (downstream). While individuals belonging to Oligochaeta (Potamothrix sp.), Gastropoda (Physa sp.), Amphipoda (Gammarus pseudosyriacus), Ephemeroptera (Baetis sp.), Plecoptera, Trichoptera, Coleoptera, Diptera and Odonata were determined. Also the physicochemical analysis results were evaluated in terms of water quality. The physicochemical and biological data of the sampling stations were examined statistically, and based on the similarity obtained, the effects of environmental variables on the distribution of macroinvertebrates were evaluated. The relationship between physicochemical data was analyzed using Pearson Correlation Analysis.

Biodiversity spatial distribution of benthic macroinvertebrate assemblages is influenced by anthropogenic disturbances at multiple spatial extents.

Understanding the patterns and mechanisms of biodiversity and its organization in space is essential for developing effective conservation strategies. Zeta diversity is an index of how taxa are shared by several sites, providing information on how ecological filters, including anthropogenic disturbances, influence biodiversity distribution. This study documents how anthropogenic disturbances at multiple spatial extents affect the spatial variation of benthic macroinvertebrate assemblages in lotic ecosystems. To test the relation between zeta diversity and anthropogenic disturbances, we used three disturbance metrics. (a) For in-stream disturbances, we used the percentage of fine sediment in the substrate (PCT_FN). (b) For local/riparian disturbances, we used the Local Disturbance Index (LDI). (c) For catchment disturbances we used the Catchment Disturbance Index (CDI). Our results showed that differing anthropogenic disturbances were differently important for spatial biodiversity variation in benthic macroinvertebrate assemblages. Relatively rarer taxa were usually more susceptible to in-stream and local/riparian-scale disturbances or local environmental filters. On the other hand, relatively common taxa were usually more related to catchment-scale disturbances or landscape resistance to dispersal. These results indicate that conservation efforts to maintain headwater ecosystem biodiversity must incorporate multiple spatial extents because relatively rare and relatively common taxa appear to be affected to different degrees by different anthropogenic disturbances at different spatial extents.

Boulder ramps as a restoration measure: Increasing in the resilience of mountain freshwater ecosystems to environmental changes.

Mountain environments, as biodiversity hotspots, are subject to numerous anthropological pressures. In mountain areas, a common threat to stream biocenoses is the timber industry. Timber industry increases the fine sediment input into the mountain rivers; furthermore, timber transport requires the construction of low-water crossings across streams. Transversal barriers (weirs/fords/pipe culverts) may cause excessive erosion downstream and the accumulation of fine sediments upstream, thereby decreasing habitat heterogeneity. Moreover, mountain stream communities are sensitive to climate change; for e.g., climate change may result in increasing water temperature and decreasing flows. Boulder ramps are considered effective restoration measure for rivers; benthic macroinvertebrate community composition is an effective indicator of stream health. In this study, we selected two mountain streams catchment with forest management. The control was a stream without any objects in the streambed related to timber transport. The other stream contained weirs and pipe culverts. We considered an extensive study period that covered the stages before (2009) and after restoration (2014, 2017-2018, 2019). We present the hypothesis that boulder ramps can restore in-stream habitats, improve biodiversity, and increase the resilience of benthic macroinvertebrate communities to future environmental changes. Our study demonstrates the effectiveness of boulder ramps for mountain streams restoration. We indicated, that the habitat potential of the restored stream-reach for rheophilic and lithophilic invertebrates increased substantially. Moreover, the restored riffles allowed the streambed to be cleared of fine sediments, offering the microrefugia, which were beneficial for mountain stream invertebrates, thereby increasing the diversity and resilience of the benthic communities.

Macrozoobenthos of the rivers of North-Eastern Azerbaijan

Between 2020 and 2023, an in-depth analysis was conducted on the species composition of the macrozoobenthos in the Yalama River, including its tributaries Telchay, Mukhtadyrchay, Velmirchay, and Khuraychay, as well as other significant rivers in northeastern Azerbaijan. During this period, a total of 53 species of benthic organisms, representing 14 different taxonomic groups, were identified across the rivers studied. These findings provide important insights into the biodiversity and ecological health of the region's freshwater ecosystems. Among the various groups recorded, mollusks, dragonflies, crustaceans, and chironomid larvae were particularly prominent, both in terms of species richness and their ecological significance within the aquatic habitats. These groups are crucial for understanding the dynamics of the river systems, as they play key roles in nutrient cycling, sediment stability, and the food web. The diversity of these species also reflects the environmental conditions and the unique characteristics of the rivers in this region, which may be influenced by factors such as water quality, habitat variation, and seasonal changes.

Autonomous Reef Monitoring Structures (ARMS) as a tool to uncover neglected marine biodiversity: two new Solenogastres (Mollusca, Aplacophora) from the Gulf of Mexico.

Solenogastres is a group of mollusks with evolutionary and ecological importance. Nevertheless, their diversity is underestimated and knowledge about the distribution of the approximately 300 formally described species is limited. Factors that contribute to this include their small size and frequent misidentification by non-specialists. Recent deep-sea explorations have resulted in the collection of numerous specimens through effective methods such as epibenthic sledges. However, this is a costly, labor-intensive, and destructive methodology. In contrast, Autonomous Reef Monitoring Structures (ARMS) offer a novel, non-destructive approach, by providing a substrate for benthic organism colonization. This study is the first to describe Solenogastres collected using ARMS, demonstrating that they are an effective tool for biodiversity assessment and characterizing rare marine invertebrates. Following an integrative taxonomic approach, two new solenogaster species are described: Dondersiatweedtae Farris, Olson & Kocot, sp. nov. (Dondersiidae) and Eleutheromeniabullescens Cobo, sp. nov. (Pruvotinidae). The diagnosis of the family Dondersiidae is amended and the necessity of reassessing the validity of the current diagnostic characters for Pruvotinidae, and its classification is emphasized. The two newly described species exhibit distinct external characteristics; D.tweedtae sp. nov. has a striking pink color with a bright yellow dorsal keel and E.bullescens sp. nov. has a unique, discontinuous dorsal keel with nearly spherical protrusions. The presence of cnidocytes in the digestive systems of both species indicate that they feed on cnidarians. It is hypothesized that, like in some nudibranchs, their coloration and body features reflect defensive adaptations related to their diet. This study shows that while habitus alone is typically insufficient for accurate identification in solenogasters, it can sometimes simplify the process. For this, live observations and photographs are essential.

Distribution, composition and impact of environmental factors on benthic macroinvertebrates functional feeding groups and ecosystem attributes in river Yaah (East Lekie)

From July 2022 to May 2023, a study was carried out in the Lékié division (Center region) and its objective was to evaluate the composition and distribution of benthic macroinvertebrates functional feeding groups in relation to the characteristics of environmental factors and determine the ecosystem attributes of the Yaah watercourse. For that, in three sampling stations, the collection of water samples for analysis and benthic macroinvertebrates were carried out according to standard methods. The grouping of benthic macroinvertebrates into functional feeding groups was done thanks to the keys and appropriate works. A total of 730 benthic macroinvertebrates belonging to 38 families were identified and the families of Belostomidae (11.51%) and Libellulidae (10.96%) were the most dominant. The 38 families of benthic macroinvertebrates identified were grouped into 5 trophic functional groups, predators (63.29%) and Shredders (22.19%) were largely predominant. The distribution of collectors varied from YA 1 to YA 3. The abundance relative of Shredders decreased from upstream to downstream while that of filters increased earlier and these variations were consistent with the River Continuum Concept. The electrical conductivity was influenced positively the distribution of scrapers and gathering collectors while the suspended solids negatively influenced the distribution of shredders and positively the distribution of predators. The watercourses sampled were heterotrophic, conducive to the development of shredders and dominated by Coarse Particulate Organic Matter and predators.

Community size and disturbance history jointly explain the interplay between stochastic and deterministic community variation in benthic invertebrates

Community ecology has so far struggled to integrate both deterministic and stochastic processes into a global model of community variation. To address this issue, we aimed to characterise the ecological conditions that determine the relative importance of deterministic and stochastic community variation in benthic macroinvertebrates. We sampled macroinvertebrate and algal periphyton communities, and microhabitat conditions at monthly intervals over a five year period in two sampling sites in the regulated Durance River and one site in the Asse River (a natural tributary of the Durance). The relative importance of stochastic and deterministic processes was estimated over time as functional and taxonomic spatial β‐deviation (i.e. β‐diversityobs − mean β‐diversitynull/SD β‐diversitynull) for each sampling date and site. We additionally quantified deterministic variation as the trait–environment relationship and predicted a positive correlation with β‐deviation metrics. We found evidence of overdispersal in both functional and taxonomic β‐diversities compared to null expectations. Spatial β‐deviation was highly variable over temporal scales and was jointly explained by invertebrate community size, disturbance (i.e. flooding), periphyton diversity and to a lesser extent, microhabitat diversity. The key factor that explained β‐deviation was recent river discharge (&lt; 90 days), which had a strong negative effect on community size but was also directly associated with higher β‐deviation, likely related to recolonization processes post‐flood. Lastly, we found that when β‐deviation was high, the hydraulic trait–environment relationship was stronger. This indicates that spatial heterogeneity in hydraulic conditions was the main driver of deterministic variation in invertebrate community structure. This study demonstrates that the importance of stochastic processes can vary greatly over short (~ months) and long (~ years) temporal windows with significant consequences for trait–environment relationships. Our study provides an example of how stochastic community variation can be modelled to better interpret deterministic patterns of community structure in natural communities.

Assessment of Organic Matter Influence on the Ecological Integrity of Poyang Lake Using O/E Model and Chemical-Biological Indices over the Past Two Decades.

Ecological integrity, encompassing physical, chemical, and biological aspects, is crucial for sustaining ecosystem service functions and stability. As the largest freshwater lake in China, the ecological integrity of Poyang Lake has attracted much attention due to the over-exploitation of its water resources in recent years. In this study, several biological and water quality surveys on water ecological conditions were carried out at 11 sampling points of Poyang Lake from 1998 to 2022, and the ecological health of Poyang Lake was evaluated by use of the O/E (Observation/Expectation) model and the chemical-biological index method according to the status of the water quality and the structure of the benthic fauna in the four seasons, respectively. The results showed that the benthic community structure is simple, and the biodiversity is low, which is mainly dominated by Insecta in Arthropoda and Oligochaeta in Oroidea, accounting for 84.3% and 42.4%, respectively; the results of the O/E index evaluated under the threshold of probability of capture ≥ 0.5 showed that the health grade of all sections was sub-healthy or average, which was consistent with the results of the chemical-biological composite index evaluation. The dual evaluation method of the O/E model and chemical-biological composite index adopted in this study integrates more than twenty years of long-time scale data; this method combined with long time scale data has not been studied before, and its advantage is that it can more objectively show the change in the ecological situation of Poyang Lake for many years. The results of the present study could provide a theoretical basis and technical support for the evaluation of lake water environment quality.

Impact of biotic and abiotic factors on epibiotic communities of the Barents Sea red king crab

Based on a long-term dataset of species composition and infestation levels of associated organisms on the invasive Barents Sea red king crab, a multivariate analysis was conducted to determine the contributions of biotic and abiotic factors to the fouling community structure. Results indicate that host size and exoskeleton age were the most significant factors for diversity indices and infestation intensity. Abiotic factors played a diminished role in the formation of fouling communities. Temperature conditions during the mass molting periods were found to have significant effects, apparently serving as a catalyst for the primary settlement of crab shells by benthic organisms. Our data not only yield new insights into the formation of fouling communities of decapod crustaceans, but also provide valuable information for further studies on the adaptation process of the red crab to the conditions of the Barents Sea.

Editorial: Experiments in benthic ecology: using experimental manipulations to study the effects of pressures on benthic organisms

Editorial: Experiments in benthic ecology: using experimental manipulations to study the effects of pressures on benthic organisms

Heavy metals and microplastics derived from laboratory effluents enhance toxicological risks to the ecosystems of canals in Bangladesh.

The occurrence of chemical effluents in different water bodies is an emerging concern. However, the effect of laboratory effluents on the canal ecosystem in Bangladesh is largely unknown. In this study, we collected 10 components of the canal ecosystem including sediments, water, fish, crabs, snails, phytoplanktons, and weeds specifically from canals that directly receive laboratory effluents. We examined the occurrence of both the essential (Fe, Mn, Cu, and Zn) and toxic (Pb, Cd, Cr, Co, Ni, and As) metals as well as microplastics (MPs). Results explored that laboratory effluents strongly interact with the components of the canal ecosystem and enhance the abundance of toxic metals in the canal hydrosystem. Furthermore, diverse types of MPs including fibers, fragments, and microbeads were observed in all components of the canal ecosystem. Remarkably, our results unveiled that the co-occurrence of pollutants was more severe in benthic organisms like snails or crabs might be due to their omnivorous food habits. The cumulative pollutant accumulation was much higher in all components of the canal ecosystem indicating a greater ecological risk. Although the potential risk index (RI) or hazardous index (HI) from fish ingestion was found within acceptable limits, the biomagnification of pollutants due to repeated ingestions may have strong ecotoxicological impacts even at very low concentrations.