Benthic Invertebrate Communities Research Articles

Response of macroinvertebrates to industrial warm discharges: the River Shannon case study (Ireland)

ABSTRACT Warm discharges from industrial processes have the potential to impact benthic invertebrate communities and undermine river functioning as well as inform climate change impacts. We evaluated the effects of heated cooling waters from 2 power plants across 2 River Shannon locations (Ireland) in summer and in winter. The overall multivariate community composition differed significantly between heated and unheated river sections in both seasons. In summer, overall invertebrate taxon richness and diversity were significantly lower in heated than in unheated sections. This finding was coupled with a striking decrease in Ephemeroptera, Plecoptera, and Trichoptera (EPT) abundance, taxon richness, and diversity in heated sections. Furthermore, aerial taxon richness and diversity were significantly lower in the heated sections. We also observed that the abundance of grazers was lower in heated sections. Winter patterns were similar to summer, but with lower invertebrate community abundance and decreased functional representation of shredders, gatherers, and predators in heated sections. Such impacts likely have strong implications for river functioning, including depressed connectivity with riparian habitats, and may impair the performance of eutrophication biomonitoring tools that rely on EPT taxa. Our results highlight the impact of warming of thermal plumes and other ubiquitous triggers of heating and may indicate climate change-driven trajectories.

Benthic invertebrate communities in the water areas of the Volgograd reservoir near the villages Akhmat and Zolotoye as one of the characterization of conditions for commercial fish reproduction in 2020

The main factor affecting the success of the reproduction of limnophilic fish is the level height and duration of the spring flood with uniform heating of the water. However, the efficiency of fish reproduction also depends on other factors, for example, on the development of the food supply for early juveniles. In 2020, in the water area of the Volgograd reservoir near the villages Akhmat and Zolotoye, according to the results of catches of fry net, developed very unfavorable conditions for the reproduction of commercial fish. The values of production indicators (net primary production and the rate of respiration of the plankton community) in 2020 turned out to be minimal. The dynamics of the abundance, and especially the biomass of benthic invertebrate communities, turned out to be very similar for both water areas in 2018 and very different in 2020. In terms of abundance, among benthic invertebrate communities, in the water area near the village Zolotoye in July 2020, was dominated by oligochaetes and chironomids, and oligochaetes in terms of biomass. At the station near the village Akhmat in July was dominated by chironomids in terms of numbers, and oligochaetes in terms of biomass. In August and September, both in terms of abundance and biomass, oligochaetes dominated in both water areas. There is a correlation between the state of production processes and the state of benthic invertebrate communities in the reservoir. However, the efficiency of fish reproduction correlates, first of all, with the level and temperature regimes of the reservoir during the spawning and feeding period. The decrease in the proportion of underyearlings of crucian carp and perch feeding on benthic invertebrate communities in the catch of fry net in 2020 may be due to both an unfavorable level regime and a drop in the feeding capacity of the water areas.

Responses of benthic macroinvertebrate communities to a Bti-based insecticide in artificial microcosm streams

Bioinsecticides based on the bacterium Bacillus thuringiensis subsp. israelensis (Bti) are increasingly being applied directly into aquatic compartments to control nuisance mosquitoes and blackflies and are generally considered environmentally friendly alternatives to synthetic insecticides. Bti-based insecticides are considered highly selective, being Diptera-specific, and supposedly decompose rapidly in the environment. Nevertheless, their safety to non-target species and freshwater ecosystems has been questioned by recent studies, which in fact document possible indirect effects in aquatic food webs such as the decrease of prey availability to predators. This work aimed to evaluate the potential effects of a Bti-based insecticide (VectoBac® 12AS) on a freshwater macroinvertebrate community and on stream ecological functions by using artificial microcosm streams. Artificial microcosm streams were colonized with a macroinvertebrate community plus periphyton collected in a stream together with Alnus glutinosa leaf packs. They were exposed for 7 days to different Bti treatments (0, 12, 120, 1200 μg/L), which are within the recommended concentrations of application in aquatic compartments for blackfly and mosquito control. Besides invertebrate community structure and abundance, effects were evaluated regarding leaf decomposition and primary production as measures of ecosystem functioning. Community structure was significantly altered in all Bti treatments after 7 days of exposure, mostly due to a decline in chironomids, followed by oligochaetes, which both belong to the deposit-feeders’ functional group. Direct effects on oligochaetes are surprising and require further research. Also, reductions of leaf decomposition due to Bti-induced sublethal effects on shredders (reduced feeding) or mortality of chironomids (that can also feed on coarse organic matter) observed in our study, represent potential indirect effects of Bti in aquatic ecosystems. Our short-exposure experiment evidenced some negative effects on stream benthic invertebrate communities and on ecosystem functioning that must be considered whenever Bti is used in water bodies for blackfly or mosquito control programs.

Potential environmental effects of deepwater floating offshore wind energy facilities

Over the last few decades, the offshore wind energy industry has expanded its scope from turbines mounted on foundations driven into the seafloor and standing in less than 60 m of water, to floating turbines moored in 120 m of water, to prospecting the development of floating turbines moored in ~1,000 m of water. Since there are few prototype turbines and mooring systems of these deepwater, floating offshore wind energy facilities (OWFs) currently deployed, their effects on the marine environment are speculative. Using the available scientific literature concerning appropriate analogs, including fixed-bottom OWFs, land-based wind energy facilities, wave and tidal energy devices, and oil and gas platforms, we conducted a qualitative systematic review to estimate the potential environmental effects of deepwater, floating OWFs during operation, as well as potential mitigation measures to address some of the effects. We evaluated six categories of potential effects: changes to atmospheric and oceanic dynamics due to energy removal and modifications, electromagnetic field effects on marine species from power cables, habitat alterations to benthic and pelagic fish and invertebrate communities, underwater noise effects on marine species, structural impediments to wildlife, and changes to water quality. Our synthesis of 89 articles selected for the review suggests that many of these potential effects could be mitigated to pose a low risk to the marine environment if developers adopt appropriate mitigation strategies and best-practice protocols. This review takes the necessary first steps in summarizing the available information on the potential environmental effects of deepwater, floating OWFs and can serve as a reference document for marine scientists and engineers, the energy industry, permitting agencies and regulators of the energy industry, project developers, and concerned stakeholders such as coastal residents, conservationists, and fisheries.

Chironomid assemblage changes and chitin degradation in response to ~ 1700-years of seabird population fluctuations at the world’s largest colony of Leach’s Storm-Petrels (Atlantic Canada)

Seabirds are prominent biovectors whose guano and other wastes are an important source of nutrients that can eutrophy terrestrial and aquatic environments surrounding their breeding and nesting habitats. When these ornithogenically derived nutrients are introduced to waterbodies, they alter aquatic conditions, resulting in shifts in benthic invertebrate communities. In this paleolimnological study, we examined subfossil Chironomidae (non-biting midge) assemblages to assess the impacts of changes in the colony size of the Leach’s Storm-Petrel in three ponds on Baccalieu Island (Newfoundland and Labrador, Canada) over the past ~ 1700 years. Our results indicate that chironomids tracked the growth of the storm-petrel colony (determined by five additional paleolimnological proxies) starting in the early-1800s, and the decline of the colony in the 1980s. Given the shallow nature of the study ponds, assemblage changes likely occurred due to a combination of fluctuations in pH, metal concentrations, and bottom-water oxygen. In the ponds influenced by storm-petrels, we observed a poorly described form of degradation in subfossil chironomids that we attribute to chitinolytic processes mediated by bacteria and/or fungi that thrive on organic matter in productive aquatic systems. This study provides complementary proxy data regarding bottom-water habitats for use alongside other established paleolimnological methods to determine the long-term population dynamics of seabirds.

Assessing land-use impacts on a 5th-order tropical river using multiple environmental indicators

Land-use change, such as agricultural expansion and intensification, and urbanisation, affects river ecosystem health and threatens riverine biological communities in a multifactorial and interactive way. In this study, we compiled the results of several studies carried out in a 5th-order tropical river, the Rio das Mortes in the upper Rio Grande basin (Southeast Brazil). We analysed if a combination of different environmental indicators, such as river water quality, sediment structure, habitat structural integrity, biochemistry of suspended organic matter, and the composition and distribution of the benthic invertebrate community, provides a complementary and more complete assessment of land-use impacts from headwaters to the river mouth than single indicators. Water quality exhibited longitudinal changes along the studied river, especially during the dry season, corresponding to the urbanisation pattern in the river catchment with considerable urbanisation already in the upper catchment, and several urban centres along the river's course. The predominance of saturated fatty acids and bacterial fatty acids in the river water's suspended organic matter at urbanised river segments showed that the biochemistry of suspended organic matter, an important resource for the river's biological community, was a sensitive indicator of catchment urbanisation. In contrast, river sediment structure and habitat integrity showed local impacts, primarily in mid-catchment urbanised river segments, with notable positive effects of local conservation efforts and natural differences in sediment structure. Chironomidae and Oligochaeta were the dominant groups in the river's macroinvertebrate community. Their spatial distribution was mainly determined by sediment structure and river habitat integrity, and thereby, by local impacts on river structure. We argue that integrated assessment approaches rarely applied to larger tropical rivers, combining local structural, habitat and community characteristics with large-scale land use and water quality patterns, are important to understand and manage land-use stress in these systems.

Assessing the Ecological Status of European Rivers and Lakes Using Benthic Invertebrate Communities: A Practical Catalogue of Metrics and Methods

The Water Framework Directive requires that the ecological status of surface waters be monitored and managed if necessary. A central function in ecological status assessment has the Biological Quality Elements—organisms inhabiting surface waters—by indicating human impact on their habitat. For benthic invertebrates, a wide array of national methods are used, but to date no comprehensive summary of metrics and methods is available. In this study, we summarize the benthic invertebrate community metrics used in national systems to assess the ecological status of rivers, (very) large rivers, and lakes. Currently, benthic invertebrate assemblages are used in 26 national assessment systems for rivers, 13 assessment systems for very large rivers, and 21 assessment systems for lakes in the EU. In the majority of systems, the same metrics and modules are used. In the Red Queen’s race of ecosystem management this may be a disadvantage as these same metrics and module likely depict the same stressors but there is growing evidence that aquatic ecosystems are subject to highly differentiated, complex multiple stressor impacts. Method development should be fostered to identify and rank impacts in multi-stressor environments. DNA-based biomonitoring 2.0 offers to detect stressors with greater accuracy—if new tools are calibrated.

Stochastic processes and ecological connectivity drive stream invertebrate community responses to short-term drought.

Community responses to and recovery from disturbances depend on local (e.g. presence of refuges) and regional (connectivity to recolonization sources) factors. Droughts are becoming more frequent in boreal regions, and are likely to constitute a severe disturbance for boreal stream communities where organisms largely lack adaptations to such hydrological extremes. We conducted an experiment in 24 semi-natural stream flumes to assess the effects of local and regional factors on the responses of benthic invertebrate communities to a short-term drought. We manipulated flow (drought vs. constant-flow), spatial arrangement of leaf litter patches (aggregated vs. evenly distributed) and colonization from regional species pool (enhanced vs. ambient connectivity) to test the combined effects of disturbance, resource arrangement and connectivity on the structural and functional responses of benthic invertebrate communities. We found that a drought as short as 1week reduced invertebrate taxonomic richness and abundance, mainly through stochastic extinctions. Such changes in richness were not reflected in functional diversity. This suggests that communities were characterized by a high degree of functional redundancy, which allowed maintenance of functional diversity despite species losses. Feeding groups responded differently to drought, with organic matter decomposers responding more than scrapers and predators. Three weeks were insufficient for complete invertebrate community recovery from drought. However, recovery was greater in channels subjected to enhanced connectivity, which increased taxonomic diversity and abundance of certain taxa. Spatial configuration of resources explained the least variation in our response variables, having a significant effect only on invertebrate abundance and evenness (both sampling occasions) and taxonomic richness (end of recovery period). Even a short drought, if occurring late in the season, may not allow communities to recover before the onset of winter, thus having a potentially long-lasting effect on stream communities. For boreal headwaters, extreme dewatering poses a novel disturbance regime that may trigger substantial and potentially irreversible changes. An improved understanding of such changes is needed to underpin adaptive management strategies in these increasingly fragmented and disturbed ecosystems.

Edge Effect Display in the Communities of Benthic Invertebrates of the Danube River Delta

Edge Effect Display in the Communities of Benthic Invertebrates of the Danube River Delta

Assisted colonization of a regionally native predator impacts benthic invertebrates in fishless mountain lakes

AbstractThe intentional introduction of native cold‐water trout into high‐elevation fishless lakes has been considered a tool to build resilience to climate change (i.e., assisted colonization); however, ecological impacts on recipient communities are understudied. The purpose of this study was to inform native cold‐water trout recovery managers by assessing potential consequences of translocating a regionally native trout (westslope cutthroat trout; Oncorhynchus clarkii lewisi) into fishless mountain lakes. This study compared littoral benthic invertebrate richness, diversity, community structure and abundance between three groups of lakes (fishless, native trout, nonnative trout) in the Canadian Rocky Mountains. While richness and diversity were preserved across all lake groups, other lines of evidence suggested that the introduction of native westslope cutthroat trout into fishless lakes can alter littoral benthic invertebrate communities in similar ways as nonnative brook trout (Salvelinus fontinalis). The community structure of cutthroat trout lakes resembled brook trout lakes compared to that of fishless lakes. For example, both trout‐lake groups contained a lower density of free‐swimming ameletid mayflies and a higher density of certain burrowing taxa. Risk assessments for trout‐recovery actions should consider the potential for collateral damage to recipient invertebrate communities. Future research should identify possible cascading trophic effects on species subsidized by invertebrate prey.

Rock glaciers and paraglacial features influence stream invertebrates in a deglaciating Alpine area

Abstract Climate change and progressive glacier loss are leading to rapid ecological shifts in alpine aquatic systems. Rock glaciers and paraglacial features such as proglacial lakes, moraines, and taluses can alter the gradients of glacial influence along alpine river networks, but the ecological responses are still understudied. We investigated benthic invertebrate communities of different stream types (upper kryal, lower kryal, glacio‐rhithral, krenal, and rock glacial) within a deglaciating area of the Italian Alps (Solda and Zay sub‐catchments). Alpha‐ (Shannon index and taxa richness) and β‐diversity (i.e. nestedness and turnover), production (abundance, biomass), average body mass of invertebrate taxa, and functional feeding groups were used to analyse the influence of habitat conditions on invertebrate communities in different microhabitats (mineral substrates, bryophytes, Hydrurus foetidus). We defined an index of habitat mildness based on water temperature, channel stability, turbidity, and organic detritus, to measure the difference in community metrics over a gradient of habitat amelioration, driven by the mixing of distinct stream types and their interactions with paraglacial features. While diversity proxies showed an asymptotic behaviour along the gradient, the quantitative metrics peaked at intermediate mildness. Peaks of invertebrate biomass/abundance were recorded at the glacio‐rhithral station below the talus. Highest average body mass occurred at Zay, specifically at the rock glacial stream, and at the lower kryal stations influenced by the lake/moraine and the rock glacier. The moraine outflow showed unexpected high biomass/abundance values of shredders and grazers, that were supported by a high epilithic production. Bryophytes acted as local scale multipliers of mildness as they stored more detritus, and hosted higher biomass/abundance of invertebrates and, in particular, of gatherer–collectors. Beta‐diversity, driven by the turnover component, was positively related to different habitat mildness of the sampling stations. Although influenced by distinct lentic/lotic conditions, rock glacial streams hosted several taxa typical of glacio‐rhithral and krenal stations, alongside large numbers of Diamesa (Chironomidae), a genus typical of kryal habitats. Under progressive deglaciation, rock glaciers and paraglacial features influence the invertebrate communities of alpine river networks. As they host a high number of taxa dwelling in non‐glacial locations, rock glacial streams may act as stepping stones facilitating invertebrate colonisation following glacier retreat. After glacier loss, rock glacial streams may represent climate refugia for cold adapted taxa and/or kryal specialists, because the slow thawing of their ice might sustain cold water conditions for a longer period of time.

Hydraulic calculation of fish ladders, Sebesel River, Romania

Sebesel 1 hydropower development is located on the Sebesel River, in the outskirts of Borlova, Caraş-Severin County. The realization of the fish ladder will not influence the flow regime of the surface or groundwater in the neighboring area. The fish ladder is dimensioned so as to allow the migration of the ichthyofauna upstream during the spawning period and the partial transit of the alluviums as well as the downstream provision of a servitude flow Q = 0.059 mc / s. The Sebeşel 1 hydroelectric power plant is a hydropower arrangement by shunt without accumulation lake. The plant has two power groups equipped with Pelton turbines. The power delivered by MHC Sebesel 1 is 876.03 kW. The installed flow rate is 0.90 m3 / s; gross fall: 131 m; capture rate 814 mdMN. The fish ladders are of the technical ladder type with pools. The objectives of the studies were: to describe the qualitative and quantitative structure of benthic invertebrate and fish macro communities; assessment of the ecological status of the rivers in the areas of hydropower development; highlighting the presence of fish species of conservative interest and assessing the status of their populations. The methodology was carried out in accordance with the provisions of the Water Framework Directive, Annex V used took into account the following: Assessment of the status of aquatic communities; description of the structure of fish communities; assessment of the ecological status of the river sectors. The study led to obtaining some essential information for the exploitation and maintenance of the micro-hydroelectric plant as well as the fish ladder.

Re-assessing the degradation of benthos beneficial use impairment in the Toronto and Region Area of Concern

Sediment quality of the Toronto and Region Area of Concern (AOC) waterfront was assessed using a weight of evidence approach following the Sediment Quality Triad, with the addition of contaminant bioaccumulation data, to determine current status following the 2013 re-designation of the “degradation of benthos” Beneficial Use Impairment as “no longer impaired.” Five stations within the AOC were sampled in 2015 and compared to lower Great Lakes nearshore reference areas (n = 22) selected based on similarity of sediment physicochemical properties. Sediment chemistry was comparable except for a localized instance of elevated perfluorinated compounds at one AOC site. Laboratory sediment toxicity bioassays indicated chronic toxicity associated with point sources to the AOC, corresponding to increased invertebrate body burdens measured in laboratory exposures. Diversity metrics and multivariate analysis showed that benthic invertebrate community composition present at the AOC sites was not significantly different from reference conditions of the lower Great Lakes. The weight of evidence from this study indicates benthic invertebrate communities continue to show effects of degraded sediment conditions at sites impacted by point sources. While the 2013 RAP decision was to re-designate the “degradation of benthos” BUI to “no longer impaired,” our results support the notion that life after AOC delisting must continue to prioritize monitoring efforts.

Community characteristics of benthic macroinvertebrates and identification of environmental driving factors in rivers in semi-arid areas – A case study of Wei River Basin, China

The characteristics of the benthic community structure can effectively reflect the health status of the river ecosystem and the quality of the river ecological environment. It is of great significance to identify the limiting factors of benthic community structure for the maintenance of river ecosystem health. As a typical semi-arid ecological fragile area, the eco-environmental problems in the Wei River basin have become increasingly prominent. The benthic community structure is affected by multiple stresses such as habitat degradation and water quality deterioration. In this study, 18 national monitoring stations were selected to investigate the ecological environment and benthic invertebrate community characteristics in the Wei River basin in October 2019. W-statistics, Shannon-Winer index, Pielou index, Margalef index, and B-IBI index were selected to evaluate the community characteristics of benthic macroinvertebrates from three aspects of the community stability, community diversity, and community integrity. Principal component analysis, Pearson correlation analysis, and canonical correspondence analysis were used to analyze the correlation and variability between zoobenthos community index and environmental factors. The results showed that the spatial difference of benthic community structure in the Wei River basin was not significant, and the Sal, NH3-N, Tub, DO in water environment and heavy metals in sediment were the main environmental factors affecting the community structure of benthos. Improving water quality and controlling pollution were the main strategies to improve benthic biodiversity and promote sustainable development in the Wei River basin.

Variability in benthic invertebrate community structure near warm water effluents of a power plant in the southern Caspian Sea

Anthropogenic changes to the temperature regime of a water body, including but not limited to climate change and thermal pollution, may influence the community structure of species living therein. Among these, benthic communities, due to their limited movement and long life span, are one of the best biological indicators to reflect the impact of environmental stressors. In this regard, the thermal pollution of Pare-Sar power plant in the southern Caspian Sea was used as a natural laboratory to assess the effects of warming on macrobenthic communities’ biomass, abundance, richness, and structure throughout the year. Water temperature near the effluents of the power plant was on average 1.29 °C higher than the control sites. We observed that warming led to an increase in the abundance and species richness of benthic macroinvertebrates. However, benthos biomass was significantly lower in the impact site rather than the control sites, probably due to the increased proportion of small-bodied taxa and decreased growth rate of biomass determinant taxa. Therefore, our findings may be an indication of potential benthic community response to thermal pollution and may provide a baseline for future projections under global climate change scenarios.

Do changes in temperature affect EU Water Framework Directive compliant assessment results of central European streams?

BackgroundBenthic invertebrate communities are an integral and longstanding component of stream biomonitoring. However, multiple stressors driven by global change threaten benthic invertebrate communities. In particular, climate warming is expected to disrupt freshwater ecosystems. While an increasing number of studies have shown changes in benthic invertebrate community composition in response to climate warming, the effect on stream assessments has rarely been investigated. As several community composition metrics are also used in stream assessments, we predicted that climate warming would worsen stream assessment results. Therefore, we used a comprehensive data set of 2865 benthic invertebrate samples taken between 2000 and 2014 from small central European low mountain streams. We examined the effects of changes in temperature on common community and stream assessment metrics. We used 31 metrics covering composition, richness, tolerance and function of communities, of which many are used in various stream assessment schemes.ResultsAgainst our expectations, we identified a decreasing air temperature trend of − 0.18 °C over 15 years. This trend was accompanied by significant changes in community composition, for example, increases in species richness and decreases in the community temperature index (CTI). Further, we identified slight concomitant improvements of various globally used stream quality assessment metrics, such as a decreasing saprobic index and an increasing BMWP.ConclusionsWhile temperature increased by + 0.9 °C during the past 30 years (1985–2014), our 15-year study period (2000–2014) showed a decrease by − 0.18 °C. Therefore, we regard the concomitant improvement in several assessment metrics as a recovery from prior increasing temperatures. In turn, we assume that increases in water temperature will lead to opposite effects and therefore cause declining assessment results. Water managers should be aware of this linkage that in turn could provide a chance to mitigate the effects of global warming by, for example, planting trees along the rivers and the removal of artificial barriers to increase current velocity to minimize a warming effect.

Effects of riparian deforestation on benthic invertebrate community and leaf processing in Atlantic forest streams

Riparian deforestation may strongly affect stream functioning, with consequences for biodiversity and ecosystem services. These effects can be assessed using bioindicators relating to biotic community structure and ecosystem functioning. We evaluated the effects of riparian deforestation on 1. measures of community structure using aquatic benthic invertebrates, and 2. an aspect of ecosystem functioning, aquatic leaf processing. We selected sites along gradients of riparian land use in four Atlantic rainforest streams and measured physical and chemical properties for their association with riparian deforestation. We sampled benthic invertebrates and calculated metrics of community structure at each site. We measured rates of leaf processing using leaves of a common riparian tree, Guarea guidonia. Riparian deforestation was accompanied by increasing concentration of ammonia, water current and temperature and decreasing nightly oxygen saturation. Invertebrate diversity decreased and community metrics changed with deforestation as expected of negative impacts. Leaf processing decreased with deforestation. Although there were significant differences in physical and chemical measurements among streams, the gradients in community and ecosystem responses were similar, thus suggesting that both types of bioindicators were useful for monitoring changes and relating them to loss of biodiversity and ecosystem function.

Continuous riverine biodiversity changes in a 10‐years‐post‐restoration‐study—Impacts and pitfalls

AbstractEvaluating river restoration effects over several years is the exception rather than the rule. The benthic invertebrate fauna of three small mountain streams was investigated yearly from 2010 to 2019 following remeandering measures. Additionally, upstream near‐natural reaches were studied following a Before‐After‐Control‐Impact (BACI) design. Species richness and Ephemeroptera, Plecoptera and Trichoptera richness decreased strongly immediately after restoration but had positive effect sizes in the following 6 years. Abundances increased in all sites after restoration. These patterns were consistent also in the upstream near‐natural reaches, except for the decrease in richness in the second year, indicating that other factors beside the restoration affected the sites. A large flood event coincided with the implementation of the restoration measures depleting also the near‐natural sites. The similarity between paired reaches showed a sharp decline in the first year after restoration, followed by a direct increase, which indicates fast recolonization from the upstream reaches. Community composition analysis showed a shift of all communities with the time axis, underlining a substantial effect of external factors. Generalized linear mixed effects models exhibited that the percentage of tree cover and riparian vegetation had significant effects on changes in richness and abundance. Clear‐cut logging in the floodplains to restore natural floodplain forest supposedly increased water temperatures because many cold‐adapted upstream species were replaced by species naturally inhabiting more downstream reaches. The results emphasize that multiannual samples and a BACI design are necessary to understand restored systems. Furthermore, floodplain restoration and natural hydrology often shape benthic invertebrate communities more than pure instream restoration measures.

Taxonomic and functional homogenisation of macroinvertebrate communities in recently intermittent Alpine watercourses

Abstract Mountain streams in southwestern European Alps are currently shifting from perennial to intermittent flow due to the combined effects of climate change and local anthropogenic pressures. Given that flow intermittency is a recently documented phenomenon in the Alps, only scattered studies have investigated functional and taxonomical diversity of benthic invertebrate communities in recently intermittent Alpine streams. We used a hierarchical sampling design to investigate patterns in taxonomic and functional diversity of benthic invertebrate communities in 13 recently intermittent Alpine streams in north‐west Italy. in April 2017, we sampled benthic communities in two reaches of each stream with different hydrological conditions: a control reach, with permanent flow; and an intermittent reach, which recently experienced non‐flow periods in summer. We tested for the response of taxonomic richness at multiple spatial scales by partitioning total diversity into the average richness of local communities and the richness due to variation among local communities both within and among reaches. By partitioning total diversity (γ) into its local (α) and turnover (β) components we showed a decrease in local and regional species richness both within and among reaches, whereas variation among communities was significantly lower in intermittent reaches at the reach scale only. The analysis of multidimensional trait space of macroinvertebrate communities in reaches with different hydrological conditions revealed a significant reduction of functional diversity, dispersion, and evenness in intermittent reaches. There was trait overdispersion in intermittent reaches, as these hosted both typical Alpine taxa and organisms adapted to flow intermittency. In particular, we observed the replacement of taxa with aquatic respiration and those preferring medium‐ to fast‐flowing oligotrophic waters by taxa adapted to lentic habitats, air breathing and with larval dormancy phases. These results indicate that recent flow intermittency has caused drastic changes in benthic invertebrate communities in Alpine streams. Our work highlights the importance of integrating taxonomic and functional diversity to thoroughly assess the impacts of flow intermittency.

Carbon Sources Supporting Macro-Invertebrate Communities in Restored Mangrove Forests from Hau Loc, Thanh Hoa, Vietnam

Mangrove forests are important in providing habitats for complex communities of terrestrial and marine fauna. Moreover, they are recognized as highly productive ecosystems in providing nutrients to mangrove food webs or exporting them to nearby coastal waters. In the present study, stable isotopes of carbon and nitrogen were applied to examine the changes in the diets of benthic invertebrate communities following mangrove restoration. The isotope signature of invertebrate tissues varied among the forest ages and locations and ranged from 3.7 ± 1.0 to 13.9 ± 1.1‰ and −26.6 ± 0.5 to −15.0 ± 0.4‰ for δ15N and δ13C, respectively. The results showed that the food source assimilation of macro-invertebrates is slightly altered from a mixture of benthic microalgae and marine phytoplankton in the mudflat to a combination of benthic microalgae and sediment organic matter in the Sonneratia caseolaris and the Kandelia obovata forests. Therefore, the diets of macro-invertebrates varied following forest ages and the position of the forest in the intertidal zone. These insights from the present study are useful for the effective conservation and restoration of mangrove forests in Vietnam and worldwide.