Aim: We hypothesized that mechanisms underlying beta diversity in rivers would differ between gradients where (1) natural Stressors result in progressive species turnover with high specificity and ...(2) anthropogenic Stressors result in the loss of specialist taxa thus giving rise to nestedness. Location Great Britain, the Iberian Peninsula and the Himalayan Mountains. Methods: We analysed five dataseis describing benthic macroinvertebrates sampled along natural (elevation, salinity) and anthropogenic (acidity, metals, land use) stress gradients. Predictions were tested by fitting models relating species richness and beta-diversity components (total, turnover and nestedness dissimilarities) to putative stress intensity (i.e. the degree to which a particular environmental constraint filters species occurrence). Results: Stress intensity accounted for most of the variability in species richness (r² = 0.64-0.93), which declined with increasing stress. Dissimilarity in community composition between locations increased with the difference in stress intensity for all datasets. For natural Stressors, beta-diversity patterns mainly reflected species turnover, whilst for anthropogenic stressors beta diversity mainly reflected nesting of subsets of species as stress intensity increased. Main conclusions: Our results support the hypothesis that natural and anthropogenic Stressors generate contrasting patterns in beta diversity that arise through different mechanisms.
Understanding temporal changes in the composition of species communities over spatial and temporal scales relevant to conservation management is crucial for preventing further biodiversity declines. ...Here, we assessed patterns and potential drivers of taxonomic and functional temporal β diversity over 26 years (1991–2016) of 64 river macroinvertebrate communities, and the length of New Zealand (37°00'N, 46°00'S). We further examined changes in population size and range shifts of species pools, and related these to taxonomy and functional traits. We found increasing climate and land‐use driven differences in both the taxonomic and functional composition of communities over time, coupled with poleward species colonisations and increasing extirpations in northern locations. Increases in population and species range size were more prevalent than decreases in population and range size. Species shifted their ranges towards higher latitudes on average by 50 km per decade. Despite little to no relationship with taxonomy, we uncovered distinct relationships between functional traits and population trends and latitudinal species range shifts. Species with a high number of reproductive cycles per year and long‐life duration of adults tended to increase their population size, while larger size species with a high number of descendants per reproductive cycle tended to shift their range towards more southern latitudes. Our results suggest that the intensity of disturbances, the geographic location of individuals and communities, and species ecological and functional characteristics, are major determinants of riverine biodiversity reorganisation in the Anthropocene.
Biological invasions pose a rapidly expanding threat to the persistence, functioning and service provisioning of ecosystems globally, and to socio‐economic interests. The stages of successful ...invasions are driven by the same mechanism that underlies adaptive changes across species in general—via natural selection on intraspecific variation in traits that influence survival and reproductive performance (i.e., fitness). Surprisingly, however, the rapid progress in the field of invasion science has resulted in a predominance of species‐level approaches (such as deny lists), often irrespective of natural selection theory, local adaptation and other population‐level processes that govern successful invasions. To address these issues, we analyse non‐native species dynamics at the population level by employing a database of European freshwater macroinvertebrate time series, to investigate spreading speed, abundance dynamics and impact assessments among populations. Our findings reveal substantial variability in spreading speed and abundance trends within and between macroinvertebrate species across biogeographic regions, indicating that levels of invasiveness and impact differ markedly. Discrepancies and inconsistencies among species‐level risk screenings and real population‐level data were also identified, highlighting the inherent challenges in accurately assessing population‐level effects through species‐level assessments. In recognition of the importance of population‐level assessments, we urge a shift in invasive species management frameworks, which should account for the dynamics of different populations and their environmental context. Adopting an adaptive, region‐specific and population‐focused approach is imperative, considering the diverse ecological contexts and varying degrees of susceptibility. Such an approach could improve and refine risk assessments while promoting mechanistic understandings of risks and impacts, thereby enabling the development of more effective conservation and management strategies.
Biological invasions increasingly threaten global ecosystems and socio‐economic interests, advancing through mechanisms like natural selection that enhance survival and reproductive traits. Our study focuses on population‐level analyses of non‐native European freshwater macroinvertebrates to better understand their spread and impact. We found significant variability in invasion dynamics across populations and regions, suggesting that current species‐level risk assessments may overlook crucial population‐specific factors.
Summary
Trait‐based approaches are increasingly being used to test mechanisms underlying species assemblages and biotic interactions across a wide range of organisms including terrestrial arthropods ...and to investigate consequences for ecosystem processes. Such an approach relies on the standardized measurement of functional traits that can be applied across taxa and regions. Currently, however, unified methods of trait measurements are lacking for terrestrial arthropods and related macroinvertebrates (terrestrial invertebrates hereafter).
Here, we present a comprehensive review and detailed protocol for a set of 29 traits known to be sensitive to global stressors and to affect ecosystem processes and services. We give recommendations how to measure these traits under standardized conditions across various terrestrial invertebrate taxonomic groups.
We provide considerations and approaches that apply to almost all traits described, such as the selection of species and individuals needed for the measurements, the importance of intraspecific trait variability, how many populations or communities to sample and over which spatial scales.
The approaches outlined here provide a means to improve the reliability and predictive power of functional traits to explain community assembly, species diversity patterns and ecosystem processes and services within and across taxa and trophic levels, allowing comparison of studies and running meta‐analyses across regions and ecosystems.
This handbook is a crucial first step towards standardizing trait methodology across the most studied terrestrial invertebrate groups, and the protocols are aimed to balance general applicability and requirements for special cases or particular taxa. Therefore, we envision this handbook as a common platform to which researchers can further provide methodological input for additional special cases.
A lay summary is available for this article.
Lay Summary
According to the first Croatian check-list (Čerba et al. 2020), a total of 239 Chironomidae species has so far been recorded from the country. In the present paper we report the finding of two new ...taxa from the mountain stream Šumetlica, eastern Croatia, namely Boreoheptagyia legeri (Goetghebuer, 1933) and Diamesa cf. insignipes Kieffer, 1908. Šumetlica in the Psunj Mountain is about a 27 km long stream that rises near the highest mountain peak in this area, Brezovo Polje. Macroinvertebrate samples were collected at 415 m a.s.l. in June 2020 and May 2021 according to the AQEM standard multi-habitat protocol. Physico-chemical water parameters were measured in situ. Isolation and identification of macroinvertebrates were carried out in the laboratory. A total of 79 macroinvertebrate taxa were recorded, of which 26 were Chironomidae. The most abundant Chironomidae taxa were, Tvetenia calvescens, Conchapelopia agg. and Brillia bifida in the first sampling period, and Polypedilum convictum in the second. The species Boreoheptagyia legeri was collected with the abundance of 24 individuals per m2 in 2020, while 30 individuals per m2 Diamesa cf. insignipes larvae was recorded in 2021. Representatives of Diamesinae subfamily are usually found in cool, oxygen rich mountain or glacial streams. Diamesa larvae inhabit springs and streams in the mountain region, mainly on stones and gravel, especially those covered with moss cushions, while species of the genus Boreoheptagyia prefer a constant trickle of water. Both inhabit higher elevation mountainous regions, but occasionally Diamesa species are found in the foothills. Boreoheptagyia legeri is the only species of the genus that has been recorded outside the highest mountainous regions, in temperate elevations, under 500 m a.s.l. Our findings contribute to the knowledge of ecology and distribution of Diamesinae representatives.
Despite introduction of legislation such as the EU Nitrates and Water Framework Directives (Directives 91/676/EEC and 2000/60/EC respectively), agricultural practices are often still regarded as a ...major factor in poor water quality across many EU member states. Elevated inputs of nutrients, organic matter and agro-chemicals to receiving waters from agricultural lands in particular are now widely recognised as potentially major causes of deteriorating water quality. Such inputs may emanate from diffuse sources such as agricultural fields, and small point- or intermediate-sources, including farmyards and farm trackways. However, while inputs from these latter intermediate sources may be substantial, their overall contribution to catchment-wide water quality at high temporal or spatial resolution is still largely unknown. In this study, we surveyed water chemistry throughout the multiple natural and artificial watercourses within a single drainage network at high spatial resolution in a predominantly dairy farming area in Southern Ireland. We found that most headwaters at the time of study were impacted by organic inputs via drainage ditches emanating from the vicinity of farmyards. These farmyard drains were found to have elevated concentrations of ammonium, phosphorus, potassium, suspended sediment and biochemical oxygen demand above background levels in the study catchment. Concomitant assessment of macro-invertebrate communities at study sites indicated that the ecological quality of headwaters was also impaired by these inputs. The individual and aggregate contributions of farmyard drains to water quality within a single catchment, when mapped at high spatial resolution, indicates that they constitute a major contribution to catchment scale ‘diffuse’ agricultural inputs. However, our data also suggest that engineering farmyard drains to maximise their retention and attenuation function may prove to be a cost-effective means of mitigating the effects of point source farmyard inputs.
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•Water quality in an Irish dairy catchment was monitored at high spatial resolution.•Nearly 75% of catchment farmyards had a direct hydrological connection to streams.•The majority of headwaters were impacted by inputs from these connections.•Greater management of these inputs would improve water quality in dairy catchments.
Anthropic activities are one of the main drivers of change in the environmental characteristics of streams and the diversity of aquatic macroinvertebrates. We evaluated the influence of an anthropic ...gradient (varying degrees of impact) on the genera level alpha and beta diversity of the Ephemeroptera, Plecoptera, and Trichoptera (EPT) in 48 eastern Amazonian streams. These insects were sampled using a dipnet, and the anthropic gradient was represented by the activities observed in the channel and the catchment of each stream. We found that increasing anthropic impact reduced the alpha diversity of the EPT. The Total Beta Diversity (BD
Total
) showed a moderate degree of variation in streams. The streams with the greatest Local Contribution to Beta Diversity (LCBD) had the lowest alpha diversity of EPT, while the genera with the greatest Species Contribution to Beta Diversity (SCBD) were the most abundant and widely distributed among the streams. Thus, the increase in anthropic impacts reduced the alpha diversity of the EPT and indirectly influenced the uniqueness, emphasizing the importance of using different components of the diversity to understand the effects of anthropic impacts on Amazonian streams.
Pesticides are important contributors to the global freshwater biodiversity crisis. Among pesticides, neonicotinoids are the best-selling class of agricultural insecticides and are suspected to ...represent significant risks to freshwater and terrestrial ecosystems worldwide. Despite growing recognition that neonicotinoid impacts may be modified by the presence of additional stressors, there is limited information about their interactions with other agricultural stressors in freshwater ecosystems. We conducted an outdoor pond-mesocosm experiment to investigate the individual and interactive effects of nutrients, fine sediment, and imidacloprid (a neonicotinoid insecticide) inputs on freshwater community structure (density, diversity, and composition of zooplankton and benthic invertebrates) and ecosystem functioning (ecosystem metabolism, primary production, and organic matter decomposition). We hypothesized antagonistic nutrient-imidacloprid, and synergistic sediment-imidacloprid interactions, affecting aquatic invertebrate communities. The three stressors had significant individual and interactive effects on pond ecosystems. The insecticide neutralized the positive effects of nutrient additions on benthic invertebrate richness and mitigated the negative effects of sediment on zooplankton communities (antagonistic interactions). Moreover, we observed compensatory responses of tolerant benthic invertebrates, which resulted in reversal interactions between sediment and imidacloprid. Furthermore, our observations suggest that imidacloprid has the potential to increase net ecosystem production at environmentally relevant concentrations. Our findings support the hypothesis that the impacts of imidacloprid may be modified by other agricultural stressors. This has important implications on a global scale, given the widespread use of these pesticides in intensive agricultural landscapes and the growing body of literature suggesting that traditional pesticide assessment frameworks, based on laboratory toxicity tests alone, may be insufficient to adequately predict effects to complex freshwater ecosystems.
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•Imidacloprid impacts can be modified by nutrients and sedimentation.•Imidacloprid neutralized subsidy effects of nutrient additions.•Compensatory responses of benthic communities to imidacloprid-sediment combination•Weak indirect effects of imidacloprid on freshwater ecosystem metabolism
Macroinvertebrate assemblages often remain depauperate in physically restored urban streams despite efforts to improve habitat conditions and increase species abundance and diversity. The lack of ...biological recovery may be due to a lack of a natural, nearby source of colonists, and this has inspired researchers and practitioners to reintroduce macroinvertebrates in otherwise restored urban streams to jump start the recovery process. However, without standardized guidelines that describe reintroduction best practices, some reintroduction programs may create additional problems (e.g., disease spread, genetic homogenization, population loss). To reduce these risks and limit a potential waste of resources, a cautionary approach is warranted. In this paper we summarize current stream reintroduction knowledge and detail best practices for aquatic macroinvertebrate reintroduction in restored urban streams. We provide criteria that managers can use to determine whether reintroduction is appropriate and demonstrate how researchers can use reintroduction as a tool to test hypotheses regarding factors limiting recolonization. We provide guidance for how to set clear reintroduction goals, select donor sites, determine the number of organisms required, establish reintroduction frequency and timing, and overcome challenges associated with monitoring. This framework can help managers create more successful reintroduction programs that can benefit urban stream restoration.
Summary
DNA metabarcoding holds great promise for the assessment of macroinvertebrates in stream ecosystems. However, few large‐scale studies have compared the performance of DNA metabarcoding with ...that of routine morphological identification.
We performed metabarcoding using four primer sets on macroinvertebrate samples from 18 stream sites across Finland. The samples were collected in 2013 and identified based on morphology as part of a Finnish stream monitoring program. Specimens were morphologically classified, following standardised protocols, to the lowest taxonomic level for which identification was feasible in the routine national monitoring.
DNA metabarcoding identified more than twice the number of taxa than the morphology‐based protocol, and also yielded a higher taxonomic resolution. For each sample, we detected more taxa by metabarcoding than by the morphological method, and all four primer sets exhibited comparably good performance. Sequence read abundance and the number of specimens per taxon (a proxy for biomass) were significantly correlated in each sample, although the adjusted R2 values were low. With a few exceptions, the ecological status assessment metrics calculated from morphological and DNA metabarcoding datasets were similar. Given the recent reduction in sequencing costs, metabarcoding is currently approximately as expensive as morphology‐based identification.
Using samples obtained in the field, we demonstrated that DNA metabarcoding can achieve comparable assessment results to current protocols relying on morphological identification. Thus, metabarcoding represents a feasible and reliable method to identify macroinvertebrates in stream bioassessment, and offers powerful advantage over morphological identification in providing identification for taxonomic groups that are unfeasible to identify in routine protocols. To unlock the full potential of DNA metabarcoding for ecosystem assessment, however, it will be necessary to address key problems with current laboratory protocols and reference databases.
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