Benthic Invertebrate Communities Research Articles

Comparison of Recruitment Patterns of Sessile Marine Invertebrates According to Substrate Characteristics.

A community of benthic invertebrates, including sessile adult-stage invertebrates, can negatively effect corrosion, deformation, and increased fuel consumption by attaching to artificial structures, a phenomenon known as marine biofouling. Investigating the relationship between benthic communities and artificial structures or substrates (to which the organisms attach) can help clarify the factors influencing marine biofouling. Therefore, in our study, natural (stone) and artificial (rubber, tarpaulin, and iron) substrates were installed in three harbors (Mokpo, Tongyeong, and Busan), and the structures of the communities attached to each substrate were compared. The total study period was 15 months (September 2016 to December 2017), and field surveys were performed at 3-month intervals. The three survey sites had significant differences in the structure of the sessile community present. In particular, Tongyeong was significantly different from Mokpo and Busan due to the continuous dominance of Cirripedia. When comparing natural and artificial substrate by sites, significant differences were observed in the community structure in all three surveyed sites. In Mokpo and Busan, colonial ascidians were dominant on natural substrate rather than artificial substrates; post-summer, Cirripedia coverage was higher on artificial substrates than natural substrate due to corrosion. Tongyeong showed a different pattern from that of Mokpo and Busan. After the summer, Bivalvia dominated on natural substrate over artificial substrates, affecting the differences between natural and artificial substrates. Our results demonstrate the recruitment patterns of sessile marine invertebrates according to substrate characteristics and can be used as basic information for biofouling management in marine environment.

Partitioning of benthic biodiversity in boreal streams: Contributions of spatial, inter‐annual, and seasonal variability

Abstract Studies on biodiversity patterns should optimally relate different scales of temporal community variability to spatial variability. Although temporal biodiversity variability is often negligible compared to spatial variation, it may still constitute a substantial source of overall community variability in stream ecosystems. Boreal streams exhibit seasonally recurring environmental periodicity, which can be expected to induce synchronous dynamics of abiotic variables among sites, and consequently, to produce spatial synchrony of deterministically controlled biological communities with higher intra‐ than inter‐annual community variability. We sampled benthic macroinvertebrates in 10 near‐pristine boreal streams on three different seasons (spring, summer, autumn) across 4 consecutive years in northern Finland. We aimed to identify the relative contributions of spatial, inter‐annual, and seasonal variability to overall benthic biodiversity; and relate variation in benthic invertebrate communities to key environmental factors, particularly in‐stream habitat diversity. Among‐site spatial variability was clearly the most important source of variation for both species richness and community dissimilarity. Of the two temporal scales, inter‐annual variability contributed more to variation in taxonomic richness and seasonal variability slightly more to variability in community composition. Only inter‐annual variation differed systematically from random expectation, indicating strong stability (low variability) of stream macroinvertebrate communities across years, with less variation at sites with higher substrate heterogeneity. Considering the distinct seasonality of the boreal stream environment, seasonal variability accounted for an unexpectedly low amount of total community variability. Although differences between seasons were small, autumnal sampling is likely to be the least susceptible to climatic vagaries, thus providing the most consistent and predictable conditions for benthic sampling in boreal streams, particularly for bioassessment purposes. Exceptional climatic conditions are becoming more frequent in northern Europe, probably causing substantial and largely unpredictable changes in benthic community composition. As a result, the importance of temporal (relative to spatial) community variability may increase.

Effects of bottom trawling and hypoxia on benthic invertebrate communities

Marine benthic habitats in continental shelf regions are increasingly impacted by hypoxia caused by the combination of eutrophication and climate warming. Many regions that have the potential for hypoxic conditions are being fished by mobile bottom-contacting fishing gears. The combined effects of trawling and hypoxia may be synergistic and disproportionally impact benthic fauna, or they may act antagonistically, leading to smaller trawl impacts in hypoxic areas. Yet, few studies have quantified how bottom trawling and hypoxia interact to affect benthic communities. Here we examine these combined effects on benthic community biomass and abundance, the number of large organisms, the longevity distribution of the community and the vertical position of fauna in the sediment in the southern Baltic Sea. We find large declines in benthic biomass and abundance that co-occur with declines in near-bed oxygen concentrations from 5.8 to 0.8 ml O2 l-1. Conversely, no relationships and weak positive relationships are found between bottom trawl disturbance and benthic community biomass and abundance. No interacting effects between hypoxia and trawling are detected. Our findings therefore highlight a low likelihood of synergistic impacts of bottom trawling and hypoxia on the benthic communities studied. These results suggest that management may prioritize benthic protection from fishing in regions that are not in a state of oxygen stress.

Assessment of the ecological state of small rivers of St. Petersburg according to the benthic macroinvertebrates indicators in 2019-2021

The work is devoted to the topical issue of assessing the state and changes of river ecosystems located within the boundaries of large cities and industrial agglomerations. The paper presents the results obtained during hydrobiological studies on small rivers of St. Petersburg (Russian Federation) in 2019-2021. The application of bioindication methods is substantiated in order to assess long-term changes in aquatic ecosystems under conditions of increasing anthropogenic load. Various characteristics of the community of benthic invertebrates are used as biological indicators of the state of hydroecosystems. Benthos samples were taken on eight small watercourses of the city, which are both tributaries of the Neva River of various orders (the Okhta, Slavyanka, Chernaya Rechka, Lubya, Okkervil, Volkovka rivers) and delta watercourses (the Smolenka and Karpovka rivers). The paper provides a brief description of the studied water bodies and sampling sites. A number of biotic metrics and biotic indices used for bioindication purposes both in Russia and abroad have been identified. It is noted that the unstable hydrochemical regime and low flow velocity in the small watercourses of the Neva River delta contribute to the intensification of the accumulation of sediments with high concentrations of ecotoxicants, which negatively affects both quantitative and qualitative characteristics of biocenoses. In some watercourses re is a complete absence of bottom invertebrates, which can be assessed as an ecological disaster. When assessing water quality by quantitative and qualitative characteristics of communities of benthic invertebrates (Mayer index, BMWP index, some biotic metrics), it can be concluded that Okkervil River, Chernaya Rechka River and Volkovka River should be attributed to watercourses whose ecological state is extremely unfavorable. The ecological state of the rivers Karpovka River, Slavyanka River, as well as the estuaries of Okhta River and Smolenka River should be considered unfavorable. And finally, the situation in Lubya River, the source of Smolenka River and in the middle reaches of the Okhta River can be considered close to satisfactory (low quality according to BMWP or moderately polluted water according to IM).

Invertebrate communities on shipwrecks in Stellwagen Bank National Marine Sanctuary

Shipwrecks serve as island-like habitats on the seafloor and can be conceptualized as unplanned, unprepared, and unintentional artificial reefs. Most artificial reef studies have been restricted in scope and duration, but we have leveraged a dataset of 18 shipwrecks ranging from 15 to 155 yr old and at 24 to 140 m depth in Stellwagen Bank National Marine Sanctuary (SBNMS; Massachusetts, USA) to investigate the factors influencing benthic invertebrate communities on shipwrecks. Classical ecological relationships between species richness and composition and shipwreck size and age (e.g. a log-linear relationship between species richness and shipwreck size) were not observed. Our hypotheses for turnover in species composition with shipwreck age and a significant influence of shipwreck material (i.e. metal, wood) on species composition were also not supported. Rather, our results showed turnover in species composition with shipwreck size, as larger shipwrecks supported dense populations of sessile species such as sponges and anemones. We also observed a high level of patchiness and a significant influence of depth on shipwreck invertebrate communities. These results highlight the importance of shipwrecks as habitats in SBNMS. High-profile shipwrecks in particular support dense invertebrate populations, but the degradation of wooden shipwrecks reduces this effect over time. Our study has implications for future artificial reef management, showing that larger shipwrecks are more valuable habitats, and that reef placement has a strong influence on the resulting species composition.

Восстановление макрозообентоса после дноуглубительных работ на озере Манжерокском (Республика Алтай)

Dredging is the activity of excavating soil and performing other soil operations in order to expand and increase the depth of water bodies. Under conditions of increased pollution, dredging operations may cause certain damage to aquatic ecosystems in general and to particular aquatic species. The changes in the composition and structure of benthic invertebrate communities have been studied in Lake Manzherokskoe in different periods: before dredging (2007), two weeks after the dredging has been started (2018), and 3 years after the dredging activities have been finished (2021). In 2021, there was an increase in species diversity and quantitative indicators of the development of benthic communities comparing to the period of dredging completion. Our data indicated the restoration of macrozoobenthos community in the lake to a certain extent. Later, this process may end in complete restoring with an increase in the water level in the lake and a significant decrease in the technogenic load on bottom communities.

First Report on the Benthic Invertebrate Community Associated With a Bronze Naval Ram From the First Punic War: A Proxy of Marine Biodiversity

Historical traces of organisms on the seafloor, such as shells and tubes, constitute the ecological memory of ancient benthic assemblages and serve as an important resource for understanding the assembly of modern communities. Archeological shipwrecks are particularly interesting submerged substrata for both their archeological and biological implications. For the first time, we studied the species composition and life-history traits of dominant organisms in the benthic assemblage on a bronze Carthaginian naval ram, which sank more than two thousand years ago in the Southern Tyrrhenian Sea. By comparing the species composition of the ram assemblage with those of the surrounding habitats, we inferred possible colonization patterns for the ram and discussed the informative role of the shipwreck as a proxy of marine biodiversity. The ram assemblage was rich in species, including both sessile (bryozoans, serpulid polychaetes, and few bivalves) and motile (gastropods) species. Sexual reproduction with free-spawning fertilization and long-duration larvae characterized most species. The long submersion time of the ram, together with the reproductive strategies, growth forms, and motility of the dominant species were key factors shaping the community of the ram. The ram itself offers an archeological artifact of inestimable value, but our analysis revealed it to be an effective collector of fauna from the surrounding seabed. The ram community hosted species from a range of nearby natural habitats (mostly coralligenous, detritic bottoms, and zoosteracean meadows) and thus served as a proxy for marine biodiversity on the surrounding seabed. We conclude that the presence of many species on the ram that commonly occur in adjacent habitats of great environmental value was informative and highlight the important marine biodiversity in the area of the Aegadian archipelago.

Distributions of microplastics and larger anthropogenic debris in Norfolk Canyon, Baltimore Canyon, and the adjacent continental slope (Western North Atlantic Margin, U.S.A.)

Anthropogenic debris has been reported in all studied marine environments, including the deepest parts of the sea. Finding areas of accumulation and methods of transport for debris are important to determine potential impacts on marine life. This study analyzed both sediment cores and Remotely Operated Vehicle video to determine the density and distribution of debris, including both micro- and macroplastics, in Norfolk and Baltimore canyons. The average microplastic density in Norfolk Canyon sediment was 37.30 plastic particles m−2 within the canyon and 21.03 particles m−2 on the adjacent slope, suggesting that microplastics could accumulate within submarine canyons. In video transects from both Norfolk and Baltimore canyons, the largest amounts of macroplastic were recorded near the canyon heads. Our findings contribute to a growing evidence base that canyons and their associated benthic invertebrate communities are important repositories and conduits for debris to the deep sea.

Decline in niche specialization and trait β-diversity in benthic invertebrate communities of Central European low-mountain streams over 25 years

Biotic homogenization is one of the key aspects of the current biodiversity crisis. Here we analyzed the trends of three facets of niche homogenization, i.e. niche specialization, trait α-diversity and spatial β-diversity, over a period of 25 years (1990–2014) using a large dataset of 3782 stream benthic invertebrate samples collected from central European low-mountain streams. We studied a set of traits describing the ecological niche of species and their functions: body size, feeding groups, substrate preferences, flow preferences, stream zonation preferences and saprobity. Trait composition changed significantly during the study period, and we identified an overall increase in niche homogenization. Specifically, community niche specialization significantly decreased by 20.3% over the 25-year period, with declines ranging from −16.0 to −40.9% for zonation-, flow-, substrate-preferences, body size and feeding traits. Trait diversity did not change significantly, although we recorded significant decreases by −14.2% and −10.2% for flow- and substrate-preference and increases by 5.8% and 22.6% for feeding traits and zonation preference over the study period. Trait spatial β-diversity significantly decreased by −53.0%, with substrate-preference, feeding groups and flow-preference traits declining from −61.9% to −75.3% over the study period. This increased niche homogenization is likely driven by the increase of down-stream typical taxa, which are favored by warming temperatures. Further, it is in apparent contradiction with the recorded increase in abundance (+35.9%) and taxonomic richness (+39.2%) over the same period. Even such increases do not safeguard communities from undergoing niche homogenization, indicating that recovery processes may differ with regard to community taxonomic composition and traits. Our results emphasize the complexity of community responses to global change and warrant caution when founding conclusions based solely on single community metrics.

Shifts in Estuarine Macroinvertebrate Communities Associated With Water Quality and Climate Change

The present work aims to identify changes in the macroinvertebrate community of the Tagus estuary (Portugal) due to improvements in water quality and to climate change. Data was collected over a period of 16 years (1998–2014) from different sites located along the estuarine gradient. The AZTI Marine Biotic Index (AMBI) was used to assess the ecological quality status based on benthic invertebrate communities and identify possible variations associated with changes in water quality. The overall distribution of each species was examined to detect possible changes associated with climate, based on species’ affinity for more temperate or subtropical climates. Results demonstrate that there was an overall improvement of AMBI scores during the assessment period. The analysis of the geographical distribution of benthic species seems to indicate that there has been an increase of species which prefer subtropical climates in the shallower waters of the estuary, whereas in the deeper estuarine sections the propensity is for species that prefer temperate climates.

The fauna of aquatic invertebrates in the river impacted by wastewaters from the pulp and paper industry (Komi Republic).

BackgroundInvertebrates are important elements of aquatic ecosystems and play a crucial role in the transformation of matter and energy in continental water bodies. Communities of aquatic invertebrates are characterised by high sensitivity to pollution by nutrients and toxic substances and acidification of water bodies; they serve as good bioindicators of the quality of the aquatic environment and impacts on hydroecosystems. All hydrobionts participate in the processes of self-purification of water bodies.The presented dataset provides information on the aquatic invertebrate community of a large northern river. During 2018-2020, we collected data on changes in the quantitative indicators of the development of benthic and planktonic communities, as well as the species diversity of their fauna. The dataset combines information about the occurrence and abundance of benthic and planktonic invertebrates and summarises data of aquatic invertebrate species found in the Vychegda River in the zone of influence from the pulp and paper mill.New informationThe presented dataset is part of a monitoring programme of the river ecosystems in the production area of Mondi Syktyvkar JSC (the European North-East of Russia, Komi Republic). The dataset describes the structure of benthic invertebrate and plankton communities in the Northern Dvina River Basin. The data on the finding and abundance of large taxa of aquatic invertebrates and species of some groups: Oligochaeta, Cladocera, Copepoda, Rotifera, Ephemeroptera, Plecoptera and Trichoptera are presented. In total, the resource includes 8720 findings of invertebrates, of which 6041 are for zoobenthos organisms and 2679 for zooplankton organisms.

Assessment of benthic invertebrate diversity and river ecological status along an urbanized gradient using environmental DNA metabarcoding and a traditional survey method

Benthic invertebrate diversity is one of the most commonly used bioindicators for assessing aquatic ecosystem health in river systems. Although an increasing number of studies have focused on assessing benthic invertebrate diversity using environmental DNA metabarcoding and traditional survey methods, benthic invertebrate diversity and ecological status assessments performed across different landscapes within river systems have not been well documented. Here, the diversity and ecological status of benthic invertebrates and the influence of water quality on the invertebrate assemblage distribution along an urbanization gradient in rivers from the Jingjinji (JJJ) region, China, were investigated using eDNA metabarcoding and the traditional method. With the combination of the two methods, 395 benthic invertebrates from 6 phyla, 27 orders, 94 families, and 222 genera were identified. The species richness of the benthic invertebrate community in the mountain area was significantly higher than that in the urban and agricultural areas. Compared to the traditional results, eDNA metabarcoding obtained a significantly greater number of species from every sampling site (P = 0.000) and detected a notably higher abundance in Annelida (P = 0.000). Furthermore, the nonmetric multidimensional scaling (NMDS) and permutational multivariate analysis of variance (PERMANOVA) based on the Bray-Curtis dissimilarity index indicated that the benthic invertebrate communities from the different habitats were discriminated more accurately and easily using eDNA metabarcoding (P = 0.038) than with the traditional method (P = 0.829). Additionally, the assemblages identified by eDNA metabarcoding were more closely linked to water quality and could be realistically used to assess the ecological status of rivers. Our findings highlight that eDNA metabarcoding could represent a rapid and reliable method for estimating benthic invertebrate diversity and ecological status in river systems.

Back to Ecology: Reference Conditions as a Basis for Assessment, Restoration and Sustainable Management of Large Rivers

Under the EU Water Framework Directive, ecological assessment and management are based on type-specific reference conditions. In the EU it may be difficult to find sites in large rivers with at least near-natural conditions, though this is not the case in southeast Europe, where stretches of large rivers still exist with at least near-natural conditions, meaning that there is little or no disturbance from hydromorphological alteration, water quality, land use in the catchment and alien species. We examined benthic invertebrate assemblages in 45 samples collected from near-natural sites of several large rivers: Sava, Drava, Mura, Kupa and Una. The near-natural benthic invertebrate assemblages of large rivers contained several rare or remarkable species, especially among stoneflies, e.g., Marthamea vitripennis, Xanthoperla apicalis. We compared benthic invertebrate communities in river sections with fine and coarse substrates and in three eco-hydromorphological (ECO-HM) types of large rivers, reflecting habitat heterogeneity: lowland-deep, lowland-braided and intermountain. Multivariate analysis of variance (PERMANOVA) was used to statistically evaluate similarities among assemblages. It was found that the composition of benthic invertebrate assemblages varied by both ECO-HM types and substrate category. Similarity percentage (SIMPER) analysis showed that the average dissimilarity of benthic invertebrate assemblages was high between all ECO-HM type pairs and between fine and coarse substrate. We found that habitat heterogeneity and substrate independently influenced benthic invertebrate assemblages. To achieve ecological goals in the management of large rivers, in addition to functionality, a holistic view with at least near-natural assemblages, including the names of the taxa present, should also be considered.

A survey of benthic invertebrate communities in native and non-native seagrass beds in St. John, USVI

Halophila stipulacea, a seagrass native to the Indian Ocean, spread to the Caribbean in 2002. Few studies have explored the spatiotemporal distribution of H. stipulacea throughout the Caribbean and whether native invertebrates utilize this non-native seagrass as habitat. We surveyed the shallow, nearshore subtidal zones of four bays in St. John, US Virgin Islands over a two-year period to assess the abundance of both H. stipulacea and native seagrass species. We then surveyed macroinvertebrate communities in one bay with large areas of H. stipulacea, native seagrasses, and bare substrate to assess how macroinvertebrate species composition varied in these habitats. Our survey of the benthic macroinvertebrates revealed that: (1) native invertebrate species utilize H. stipulacea beds and (2) the density and richness of invertebrates was significantly higher in H. stipulacea beds compared to both native seagrass beds and bare substrate. Our results show that H. stipulacea is a common component of nearshore communities in St. John, USVI and that native invertebrates use H. stipulacea beds as habitat — results that agree with findings from other recent studies. While these findings indicate that native macroinvertebrate species can be abundant in non-native seagrass, further investigation, including experimental manipulations, preference tests, and surveys across broad spatial scales, are required to develop a robust understanding of the ecological impacts of this non-native grass.

Microplastics in freshwater sediments: Effects on benthic invertebrate communities and ecosystem functioning assessed in artificial streams

The high levels of microplastics (MPs) found in freshwaters, particularly in riverine sediments, may impose a threat to the macroinvertebrate communities with possible consequences at ecosystem-level. The present study aimed to assess the effects of a mixture of different sizes of polyethylene microplastics (PE-MPs) on the composition and structure of macroinvertebrate communities and key-functions, such as primary production and leaf litter decomposition. MPs were mixed in the sediment at three different concentrations (0.1, 1, and 10 g kg-1) already found in freshwater sediments to enhance the relevance of the work. After eight days of exposure to PE-MPs, the observed changes in macroinvertebrate community structure were mostly due to the reduction in the abundance of deposit-feeders and grazers that were reduced by ca 31-50% and 34-39%, in the two highest MPs concentrations respectively, in comparison with the control treatment after 8 days of exposure. MPs internal concentrations were detected only in organisms exposed to plastic particles within artificial streams with chironomids and mayflies presenting higher MPs internal levels (average of 115 particles/individual found in chironomids, 166/individual for Baetis sp. and 415 particles/individual for Ephemerella sp.) suggesting higher ingestion of plastic microparticles. Nevertheless, the alterations in the community structure did not translate into impairments in the functional endpoints analysed, leaf litter decomposition and primary production, that were expected due to possible sub-lethal effects (e.g., feeding inhibition) on detritivores and grazers.This study represents one of the few assessments of MPs effects on freshwater benthic macroinvertebrate community structure and the first that simultaneously considered ecosystem-level functional endpoints. Further research combining different microplastics and longer exposure periods are needed to raise knowledge on potential ecological consequences of MPs to freshwaters.

Warming and imidacloprid pulses determine macroinvertebrate community dynamics in experimental streams.

Sustainable management of freshwater and pesticide use is essential for mitigating the impacts of intensive agriculture in the context of a changing climate. To better understand how climate change will affect the vulnerability of freshwater ecosystems to chemical pollutants, more empirical evidence is needed on the combined effects of climatic and chemical stressors in environmentally realistic conditions. Our experiment provides the first empirical evaluation of stream macroinvertebrate community dynamics in response to one of the world's most widely used insecticides, imidacloprid, and increased water temperature. In a 7-week streamside experiment using 128flow-through circular mesocosms, we investigated the effects of pulsed imidacloprid exposure (four environmentally relevant levels between 0 and 4.6µg/L) and raised water temperature (ambient, 3°C above) on invertebrate communities representative of fast- and slow-flowing microhabitats. Invertebrate drift and insect emergence were monitored during three pesticide pulses (10days apart), and benthic invertebrate communities were sampled after 24days of heating and pesticide manipulations. All three manipulated factors strongly affected drift community composition. The first imidacloprid pulse and increased temperature had a greater impact on communities in fast-flowing mesocosms, which contained more pollution-sensitive EPT taxa (mayflies, stoneflies and caddisflies). Heating and imidacloprid caused increased emigration by drift, weak reductions in emergence, and negatively affected the benthic community. The combined effect of stressor manipulations and a 10-day natural heatwave drastically reduced relative abundances of EPT and insects overall and caused a shift to oligochaete-, crustacean- and gastropod-dominated communities. Contrary to our hypothesis, the very high yet realistic water temperatures reached in our experiment meant the negative effects of imidacloprid were clearest at ambient temperatures and fast flow. These findings demonstrate the potential combined impacts of imidacloprid contamination and heatwaves on freshwater invertebrate communities under future climate scenarios and highlight the need for more countries to take regulatory action to control neonicotinoid use.

Functionality and Effectiveness of Marine Protected Areas in Southeastern Brazilian Waters for Demersal Elasmobranchs

Ensuring the efficacy of Marine Protected Areas (MPAs) requires that adequate management strategies be implemented according to the MPA’s objectives. Within the scope of species conservation, achieving MPA objectives demands understanding of the role played by MPAs for the target species. In 2014, Brazilian stakeholders and experts set the action plan for elasmobranchs’ conservation, which intended to create new protected areas and expand the existing ones. Nevertheless, more than 65% of Brazilian elasmobranch species are threatened by anthropogenic pressures such as fisheries and habitat loss. In addition, their ecological aspects are not well studied, which might jeopardize the success of the proposed actions. To assess the functionality and effectiveness of two no-take MPAs for sixteen demersal species, the Wildlife Refuge of Alcatrazes (WRA) and the Tupinambás Ecological Station (TES), we evaluated the community structure, space-time variations in functional diversity and changes in fishery indicators. Community dynamics were driven by inshore intrusion and time persistent effects of a cold and nutrient-rich water mass, the South Atlantic Central Water, which increased the relative abundance of species, functional groups, and overall diversity. Spatially, the heterogeneity of benthic habitats, due to the action of stronger waves in specific parts of the MPAs, reflects a diverse community of benthic invertebrates, explaining differences in relative abundance and similarities in space use by the functional groups. Regarding effectiveness, the MPAs make up a key network with the surrounding protection areas to support the ecosystem maintenance on the central and northern coast of the São Paulo state. The establishment of the TES has positively influenced the community throughout the years while the recent creation of the WRA may have promoted some improvements in fisheries indicators for a threatened guitarfish. We propose different functions of the Alcatrazes archipelago for each species and suggest some measures to enhance not only elasmobranch conservation but also the MPAs’ effectiveness.

Ecological consequences of consecutive river damming for three groups of bioindicators

We studied three commonly used bioindicator groups: phytoplankton, phytobenthos and benthic invertebrate communities’ structure patterns in transitions between lotic and lentic habitats as consequences of two consecutive large dams constructed in the early twentieth century on the intermediate reach of a lowland river in Normandy (NW, France), the Selune. According to sampling station position along the river, including two in the two reservoir lakes, we defined three sorts of transitions, from upstream to downstream: lentic to lotic transition (hereafter len-lot), lentic to lentic transition (hereafter len-len), within the two reservoir lakes, and lentic to lotic transition (hereafter len-lot).Lot-len transition, imposed by damming, and the recovery of lotic character of the river afterward dams, promoted different diversity patterns for the studied organisms’ groups. Phytobenthos’ α diversity significantly incresed in the len-lot transition, and the highest β diversity score was observed in the lot-len. Both, habitat conditions and spatial controls drove phytobenthos community structure. Benthic invertebrate community was mainly shaped by habitat conditions. Invertebrate’s α diversity significantly changed in the lot-len and len-lot transitions, with the β diversity score being the highest in the lot-len transition. Community’s traits composition of invertebrates best fitted predictions on lotic- and lentic- type communities. Phytoplankton’s α diversity remained unchanged in the transitions and subsequently β diversity scores were low.According to the results, we proposed three classes of organisms based on their response to river damming: i) organisms indifferent or tolerant to dams effect, like phytoplankton communities in this study, that were neither hampered by changes in water flow velocity, and did not display dispersal limitation neither; ii) organisms sensitive to habitat conditions shift but not limited in their dispersal capacity by the dam, like benthic invertebrates and phytobenthos in this study. Benthic invertebrate community and phytobenthos communities differed in their response likely due to their differential dispersal capabilities and niche breadth; iii) organisms limited in their dispersal by the dam, not represented in this study.Riverine organisms best tracked transitions, while β diversity assessment revealed as the most useful metric to disentangle the relative contribution of dispersal limitation or habitat modification provoked by multiple dams.

Evidence of Taxonomic and Functional Recovery of Macroinvertebrate Communities Following River Restoration

River ecosystems have been heavily degraded globally due to channel hydromorphological modifications or alterations to catchment-wide processes. Restoration actions aimed at addressing these changes and restoring ecological integrity are increasing, but evidence of the effectiveness of these actions is variable. Using a rare 7-year before-after-control-impact (BACI) study of restoration of a lowland groundwater-fed river in England, UK, we explore changes in the macroinvertebrate community following the removal of impoundments and channel narrowing to aid restoration of physical processes. Restoration activity prompted significant taxonomic and functional responses of benthic invertebrate communities in the 4 years post-restoration. Specifically, significant gains in taxonomic and functional richness were evident following restoration, although corresponding evenness and diversity measures did not mirror these trends. Restoration activities prompted a shift to more rheophilic taxa and associated traits matching the physical changes to the channel and habitat composition. Temporal changes were clearer for taxonomic compositions compared to the functional properties of macroinvertebrate communities, indicating a functional redundancy effect of new colonists inhabiting restored reaches following restoration. The results highlight the value of long-term BACI studies in river restoration assessments, as well as project appraisals incorporating both taxonomic and functional observations. We highlight the urgent need of such studies to provide evidence to inform effective river restoration strategies to address future changes such as adaption to climate change and the biodiversity crisis.

Hydrobiological and ichthyological features of the Shirokovsky Reservoir

The characteristic of Shirokovsky Reservoir by communities of phytoplankton, zooplankton, benthic invertebrates, and fish is given. It is the first investigation of the reservoir since the building time of 1948. All levels of the ecosystem are impoverished as species compositions as functional groups. A considerable part of all communities is presented by riverine oxyphilous species. Any invasion species of algae, invertebrates, and fish haven’t registered. The maximal species richness and quantitative parameters of phytoplankton have been registered in the upper riverine part of the reservoir and were determined by Bacillariophyta (primarily centric species). The zooplankton complexes’ dominants were Bosmina longirostris, Daphnia galeata, and Mesocyclops leuckarti. Maximal quantity of zooplankton has been shown in the middle part of the waterbody. The species of oligochaetes Limnodrilus hoffmeisteri and chironomids Parakiefferiella coronata were the most important in benthic communities’ structure. Benthofauna species richness and quantity of benthic invertebrates have been maximal in the lower part of the reservoir. The most common fish species at the current period are dace, perch, and Siberian roach. The fish quantity has been the richest in the middle part of the reservoir with lots of shallow areas. Assessing the quantitative values, the Shirokovsky Reservoir was classified as an oligotrophic waterbody at present.