Stream Communities Research Articles

The role of habitat features in patterns of population connectivity of two Mediterranean amphibians in arid landscapes of central Iberia

ContextMediterranean wetland ecosystems are in continuous decline due to human pressure. Amphibians are key elements of biotic communities of Mediterranean temporary ponds and streams, and their persistence depends on the availability and inter-connectivity of breeding sites.ObjectivesWe investigated the role of different factors potentially driving functional connectivity patterns in two amphibian species at the landscape and local scales. We focused on two Mediterranean endemic pond-breeding amphibians inhabiting semi-arid landscapes of central Spain, the common parsley frog (Pelodytes punctatus) and the common midwife toad (Alytes obstetricans).MethodsWe genotyped 336 individuals of P. punctatus and 318 of A. obstetricans from 17 and 16 breeding populations at 10 and 17 microsatellite loci, respectively. We used remotely sensed vegetation/moisture indices and land use/cover data to derive optimized resistance surfaces and test their association with estimates of gene flow and migration rates across populations.ResultsWe found evidence for higher population connectivity in common midwife toads than in common parsley frogs, with a strong effect of water availability in patterns of population connectivity of both species. However, the two species differ in the role of landscape features on population connectivity, with the distance and spatial distribution of artificial land-use types positively influencing connectivity in A. obstetricans and meadows/pastureland favouring P. punctatus. This is in line with reported breeding site preferences for the two species, with A. obstetricans successfully breeding in artificial water bodies that P. punctatus generally avoid.ConclusionsThis study highlights the importance of assessing species–habitat relationships shaping connectivity when developing and implementing conservation and management actions to benefit fragmented amphibian populations in the Mediterranean region. Our results show that amphibian species respond differently, even contrastingly to landscape features and thus require alternative, complementary strategies to improve population connectivity and ensure long-term viability.

Mercury Contamination of Fish and Their Prey Across a Riverine Food Web

Lakes and reservoirs are frequently monitored by researchers for elevated mercury concentrations in sportfish. Rivers and streams, especially those of smaller orders, are less frequently monitored for mercury contamination and nonsport fishes and invertebrates, although important components of the food web, are rarely examined. We addressed this gap by surveying mercury levels in a stream community in the Kiamichi River in southeastern Oklahoma, U.S., by sampling fish and macroinvertebrates at ten sites in the river. We found elevated levels of mercury across taxa within the river including individuals of smallmouth bass populations 10–25 cm in length having concentrations (2986 ± 1053 ng/g dry weight) above the U.S. Environmental Protection Agency human limit. Furthermore, we observed high concentrations in darters and logperch (1133 ± 464 ng/g dry weight), nonsport fishes found predominantly in rivers and streams. Our results indicate mercury contamination can reach elevated concentrations in rivers and stream food webs, posing risks to both humans and wildlife.

Diversity and structure of macroinvertebrate communities in permanent small streams and rivers in Eastern Balkans

Diversity and structure of macroinvertebrate communities in permanent small streams and rivers in Eastern Balkans

Elevational patterns of trait composition and functional diversity of stream macroinvertebrates in the Hengduan Mountains region, Southwest China

Stream ecosystems in high-mountain regions are susceptible to rapid environmental change, including warming and increased human activities. Understanding elevational patterns of stream communities and underlying drivers can facilitate the development of efficient conservation and management strategies to mitigate the impacts of these changes. Our study investigated elevational patterns of macroinvertebrate trait composition and functional diversity in six streams in the Hengduan Mountains region, Southwest China, which was recognized as one of the global biodiversity hotspots. We were particularly interested in untangling the effects of watershed human disturbance and instream physicochemical factors on elevational patterns of stream macroinvertebrates. Our results showed clear elevational patterns in both trait composition and functional diversity of macroinvertebrate communities. For trait composition, the results indicated that macroinvertebrate traits associated with mobility, habit, and feeding mode exhibited clear elevational patterns. For functional diversity, functional richness showed a positive correlation with elevation, whereas functional divergence had the opposite trend. No significant elevational pattern was detected in functional evenness and RaoQ. Further analyses found that weak human disturbance was the most important driver shaping trait composition and functional diversity of macroinvertebrates. Meanwhile, instream water temperature, primary productivity, and flow velocity also played considerable roles. Our study emphasizes the influence of watershed human disturbance on elevational patterns of macroinvertebrates in high-mountain streams. It also highlights the potential of trait composition and function diversity of macroinvertebrates as indicators for monitoring the ecological status of high-mountain streams.

Effects of land use change on inter‐species and intra‐guild trophic interactions of fish communities in tropical headwater streams

Abstract Freshwater ecosystems are subjected to a broad range of anthropogenic threats. Understanding the responses of aquatic biota to these threats and identifying potential mitigating actions presents a major challenge for ecologists and natural resource managers. Here, we investigated the responses of fish communities to land use change at different scales. We assessed patterns of food web structure of fish across a gradient of human impacts in the Atlantic Forest ecoregion of southeast Brazil. We analysed stomach contents of fish and evaluated the response of five food web metrics to variation in land use change. We also calculated four metrics for intra‐guild comparisons in the omnivore, insectivore, and algivore–insectivore guilds. The proportional abundance of omnivores increased as temperature increased and canopy cover decreased. Food web specialisation decreased in deforested streams with higher nutrient input, suggesting higher resource sharing by those fish communities. Fish in the algivore–insectivore guild consumed fewer types of macroinvertebrates in streams with low canopy cover. The opposite pattern was observed within the insectivore guild with individuals consuming a larger variety of prey in impacted streams. Deforestation, and increases in water temperature and nutrient input, influenced inter‐species and intra‐guild trophic interactions in fish communities in these Atlantic Forest streams, even though the richness of fish community and composition of intra‐guild species remained unchanged. Some food web metrics were sensitive to the direct and indirect effects of disturbance on these fish communities. Our study has shown that assessments of trophic interactions can detect the effects of land‐use disturbance on fish communities that may not be evident from simple measures of species richness and composition. This approach provides direct insights into the functional integrity of fish communities and should be considered for monitoring the success of programmes aimed to protect and, where necessary, restore freshwater ecosystems.

Identifying Key Stressors Driving Biological Impairment in Freshwater Streams in the Chesapeake Bay Watershed, USA

Biological communities in freshwater streams are often impaired by multiple stressors (e.g., flow or water quality) originating from anthropogenic activities such as urbanization, agriculture, or energy extraction. Restoration efforts in the Chesapeake Bay watershed, USA seek to improve biological conditions in 10% of freshwater tributaries and to protect the biological integrity of existing healthy watersheds. To achieve these goals, resource managers need to better understand which stressors are most likely driving biological impairment. Our study addressed this knowledge gap through two approaches: 1) reviewing and synthesizing published multi-stressor studies, and 2) examining 303(d) listed impairments linked to biological impairment as identified by jurisdiction regulatory agencies (the states within the watershed and the District of Columbia). Results identified geomorphology (i.e., physical habitat), salinity, and toxic contaminants as important for explaining variability in benthic community metrics in the literature review. Geomorphology (i.e., physical habitat and sediment), salinity, and nutrients were the most reported stressors in the jurisdictional impairment analysis. Salinity is likely a major stressor in urban and mining settings, whereas geomorphology was commonly reported in agricultural settings. Toxic contaminants, such as pesticides, were rarely measured; more research is needed to quantify the extent of their effects in the region. Flow alteration was also highlighted as an important urban stressor in the literature review but was rarely measured in the literature or reported by jurisdictions as a cause of impairment. These results can be used to prioritize stressor monitoring by managers, and to improve stressor identification methods for identifying causes of biological impairment.

Towards a functional assessment of stream integrity: A first large-scale application using leaf litter decomposition

• Litter decomposition exhibits large variability at the regional scale (83 streams). • Litter decomposition does not correlate with the European WFD structural indicators. • Functional and structural indicators are complementary. • A grid is given to translate decomposition rates into functional quality classes. There is increasing recognition that indicators of ecosystem functioning are needed to improve current stream monitoring schemes. However, to date, no attempt has been made to include functional metrics in large-scale routine monitoring programs under the European Water Framework Directive (WFD). One reason is the uncertainty if functional indicators really carry new and independent information about stream status or, to the contrary, remain broadly redundant with existing indicators of biological stream quality (based on stream communities). A second reason is that, despite increasing scientific knowledge on how anthropogenic pressures influence ecosystem process rates, no ‘ready for use’ tool is available to translate them into stream ecosystem status. Litter decomposition probably ranges among the most documented stream ecosystem processes, and its potential for bioindication has been repeatedly demonstrated during the past decade. Here we report an extensive comparison of routine French structural indicators (I 2 M 2 , IBGN, IBD) with alder litter (microbial and total) decomposition rates in 83 streams located in south-western France. Expectedly, microbial decomposition rates were positively correlated with fungal biomass and activity (conidial production rate), while total and invertebrate-driven decomposition rates increased together with detritivore density and diversity in litter bags. By contrast, correlations between litter decomposition rates and routine structural indicators were clearly weak (Spearman’s ρ < 0.20), providing evidence that functional indicators bring new information. We devised a new interpretation grid to translate litter decomposition rates into stream ecological quality in a WFD-compatible design. This system considers the litter decomposition rates measured in both coarse (total decomposition) and fine (microbial decomposition) mesh bags as uncorrelated metrics of ecosystem functioning ( P = 0.898). Streams are considered functionally impaired when total and/or microbial decomposition rates are either higher or lower than in a reference condition. Applying our classification system to the 83 study sites allowed to assign them to 5 functional quality classes: bad (4 streams), poor (26), fair (29), good (21) and high (3). This classification did not match the classes obtained by conventional WFD structural indicators, reflecting that both functional and structural indicators are needed to obtain a comprehensive assessment of stream ecosystem integrity.

Meta‐ecosystem dynamics drive the spatial distribution of functional groups in river networks

The meta‐ecosystem concept provides a theoretical framework to study the effect of local and regional flows of resources on ecosystem dynamics. Meta‐ecosystem theory has hitherto been applied to highly abstract landscapes, and meta‐ecosystem dynamics in real‐world landscapes remain largely unexplored. River networks constitute a prime example of meta‐ecosystems, being characterized by directional resource flows from upstream to downstream communities and between the terrestrial and the aquatic realm. These flows have been thoroughly described by the River continuum concept (RCC), a seminal concept in freshwater ecology, stating that observed spatial variations in the relative abundances of invertebrate functional groups reflect systematic shifts in types and locations of food resources, which are in turn determined by the physical attributes of river reaches. Hence, the RCC represents a solid conceptual basis for determining how changes in landscape structure and resource flows will translate into local and regional changes in community composition. Here, we develop and analyse a riverine meta‐ecosystem model inspired by the RCC, which builds upon a physically‐based landscape model of dendritic river networks. We show that the spatial distributions and regional biomass of invertebrate functional groups observed in stream communities are determined by the spatial structure and scaling attributes of dendritic river networks, as well as by specific rates of resource flows. Neglecting any of these aspects in modelling river meta‐ecosystems would result in different community patterns. Moreover, we observed that high rates of resource flow, for example due to river anthropization, have a negative effect on the regional biomass of all functional groups studied, and can lead to cascading extinctions at the meta‐ecosystem scale. Our work paves the way for the development of physically‐based meta‐ecosystem models to understand the structure and functioning of real‐world ecosystems.

Convergence of biofilm successional trajectories initiated during contrasting seasons.

Biofilm communities play a major role in explaining the temporal variation of biogeochemical conditions in freshwater ecosystems, and yet we know little about how these complex microbial communities change over time (aka succession), and from different initial conditions, in comparison to other stream communities. This has resulted in limited knowledge on how biofilm community structure and microbial colonization vary over relevant time scales to become mature biofilms capable of significant alteration of the freshwater environment in which they live. Here, we monitored successional trajectories of biofilm communities from summer and winter in a headwater stream and evaluated their structural state over time by DNA high-throughput sequencing. Significant differences in biofilm composition were observed when microbial colonization started in the summer vs. winter seasons, with higher percentage of algae (Bacillariophyta) and Bacteroidetes in winter-initiated samples but higher abundance of Proteobacteria (e.g., Rhizobiales, Rhodobacterales, Sphingomonadales, and Burkholderiales), Actinobacteria, and Chloroflexi in summer-initiated samples. Interestingly, results showed that despite seasonal effects on early biofilm succession, biofilm community structures converged after 70 days, suggesting the existence of a stable, mature community in the stream that is independent of the environmental conditions during biofilm colonization. Overall, our results show that algae are important in the early development of biofilm communities during winter, while heterotrophic bacteria play a more critical role during summer colonization and development of biofilms.

Wastewater microorganisms impact microbial diversity and important ecological functions of stream periphyton

Effluents of wastewater treatment plants can impact microbial communities in the receiving streams. However, little is known about the role of microorganisms in wastewater as opposed to other wastewater constituents, such as nutrients and micropollutants. We aimed therefore at determining the impact of wastewater microorganisms on the microbial diversity and function of periphyton, key microbial communities in streams. We used a flow-through channel system to grow periphyton upon exposure to a mixture of stream water and unfiltered or ultra-filtered wastewater. Impacts were assessed on periphyton biomass, activities and tolerance to micropollutants, as well as on microbial diversity. Our results showed that wastewater microorganisms colonized periphyton and modified its community composition, resulting for instance in an increased abundance of Chloroflexi and a decreased abundance of diatoms and green algae. This led to shifts towards heterotrophy, as suggested by the changes in nutrient stoichiometry and the increased mineralization potential of carbon substrates. An increased tolerance towards micropollutants was only found for periphyton exposed to unfiltered wastewater but not to ultra-filtered wastewater, suggesting that wastewater microorganisms were responsible for this increased tolerance. Overall, our results highlight the need to consider the role of wastewater microorganisms when studying potential impacts of wastewater on the receiving water body.

Cover Image

The cover image is based on the Original Article Structure and functional composition of macroinvertebrate communities in coastal plain streams across a precipitation gradient, by Fernando R. Carvallo et al. https://doi.org/10.1111/fwb.13968.

Breeding phenology of amphibians in a Mediterranean ephemeral stream (Ardèche, France)

We present the results of the monitoring of breeding phenology of an assemblage of eight species of amphibians in a Mediterranean ephemeral stream, located in the Ardèche department, France. For most species, during 11 consecutive years, phenology was rather constant from year to year, which is rather unusual in Mediterranean temporary ponds. The occurrence of summer breeding was not rare for three species: Pelobates cultripes (Cuvier, 1829), Pelodytes punctatus (Daudin, 1803) and Hyla meridionalis Böttger, 1874. Breeding occurrence is linked to rewetting events caused by active karst resurgences, fuelled by periods of intense rainfall episodes called “cévenol” episodes. We document for the first time a triannual breeding occurrence (spring, summer, and autumn), and an in situ record of a short tadpole development period, concerning particularly P. cultripes. The ecological factors which can explain this species richness and these unusual observations are outlined. In conclusion, we encourage the conservation and monitoring of amphibian communities in ephemeral streams, as the natural and scientific interests for this type of habitat are often underestimated.

The effects of beaver impoundments on montane stream fish communities

Abstract North American beavers (Castor canadensis) are ecosystem engineers that create novel habitats in stream ecosystems. Although driven to the edge of extinction by historical over‐exploitation, beavers are recolonizing much of their former range. In the Southern Appalachian Mountains beavers alter habitats occupied by diverse fish communities across a mosaic of changing forest cover and management priorities. Fishes were sampled from nine streams with active beaver ponds and from seven streams with inactive ponds in the Southern Appalachians during summer 2019. The status of beaver ponds was among the most important factors affecting fish communities; however, both active and inactive beaver ponds affected fish community structure, α‐diversity, and local contributions to β‐diversity (LCBD). Fish α‐diversity was lower in reaches from streams with active ponds and the magnitude of this reduction was dependent on the position relative to a pond. However, both active and abandoned beaver ponds and pond tail races had higher LCBD values compared with free‐flowing reaches. Arcsin‐transformed forest cover did not improve the model fit for any dependent variables. Indicator species analysis found that two species had an association with active beaver ponds, whereas eight species were associated with inactive beaver ponds or free‐flowing reaches. The effects of beaver impoundments on fish communities in Appalachian streams are dependent on the pond activity level and spatial context. Although diversity and species richness may be reduced in individual habitats, beaver ponds contribute to higher biodiversity at a regional spatial scale. An increased understanding of beaver effects on Southern Appalachian fish communities will enable stakeholders to make informed decisions regarding the management of sensitive or economically important fishes. Mitigating conflicts between sensitive resources and these ecosystem engineers will become an increasingly important management concern as beaver populations recover in the Southern Appalachians.

Spatial patterns of benthic biofilm diversity among streams draining proglacial floodplains.

Glacier shrinkage opens new proglacial terrain with pronounced environmental gradients along longitudinal and lateral chronosequences. Despite the environmental harshness of the streams that drain glacier forelands, their benthic biofilms can harbor astonishing biodiversity spanning all domains of life. Here, we studied the spatial dynamics of prokaryotic and eukaryotic photoautotroph diversity within braided glacier-fed streams and tributaries draining lateral terraces predominantly fed by groundwater and snowmelt across three proglacial floodplains in the Swiss Alps. Along the lateral chronosequence, we found that benthic biofilms in tributaries develop higher biomass than those in glacier-fed streams, and that their respective diversity and community composition differed markedly. We also found spatial turnover of bacterial communities in the glacier-fed streams along the longitudinal chronosequence. These patterns along the two chronosequences seem unexpected given the close spatial proximity and connectivity of the various streams, suggesting environmental filtering as an underlying mechanism. Furthermore, our results suggest that photoautotrophic communities shape bacterial communities across the various streams, which is understandable given that algae are the major source of organic matter in proglacial streams. Overall, our findings shed new light on benthic biofilms in proglacial streams now changing at rapid pace owing to climate-induced glacier shrinkage.

Community Composition and Assessment of the Aquatic Ecosystem of Periphytic Algae in the Yangtze River Basin

To explore the periphytic algae community structure in the Yangtze River basin, samples were collected from 130 sampling sites, including the source to the estuary along the mainstream of the Yangtze River, eight primary tributaries, and the tributary of the Three Gorges area. The periphytic algae densities of different areas in the mainstream of the Yangtze River ranked from high to low were the upstream area, source area, middle and lower area, and the Jinsha River. The high periphytic algae density in the upstream area was associated with the shift in nutrition level, and the high periphytic algae density in the source area was associated with human activity. The spatial pattern of the periphytic algae community in the whole main stream from west to east presented the alternating dominance of Bacillariophyta and Cyanophyta; the Bacillariophyta (Navicula) had a competitive advantage in the main stream, and the distribution of the periphytic algae community was driven by total nitrogen, total phosphorus, and pH. For the tributary of the Yangtze River, the periphytic algae density in the Three Gorges tributary area was far higher than those in the eight primary tributaries; the periphytic algae community was dominated by Cyanophyta (Lyngbya), which had a competitive advantage in the tributaries of the Yangtze River. The distribution of the periphytic community was driven by dissolved oxygen and pH. According to the diversity analysis and assessment, the periphytic algae community in the source area showed lower species richness and higher evenness, thus leading to a high α-diversity and good assessment result (mesosaprobic zone). The middle and lower reaches of the Yangtze River also showed the same assessment result, the mesosaprobic zone. However, the community evenness of the middle and lower reaches was significantly lower than that of the source area, thus making the middle and lower reaches of the Yangtze River have a significantly lower α-diversity than that of the source area. All areas of the Yangtze River showed good water quality assessment; however, different areas had different WQI index numbers, and the assessment results of the WQI index were inconsistent with the results of the aquatic assessment. Therefore, a comprehensive assessment of aquatic ecosystem health should use both aquatic assessments and water quality assessments.

The Interaction Effects of School Location and Teaching Experience on Self-Efficacy Perceived by the Primary Science Teachers Towards Integrated Stream Teaching

Integrated science, technology, engineering and mathematics (STEM) is expanded to integrated STrEAM, where the “r” denotes the amalgamation of reading and writing elements to bridge the gap between STEM disciplines. Since integrated STrEAM is a new approach, it is pivotal to gauge the teachers’ self-efficacy in executing integrated STrEAM teaching. Therefore, this cross-sectional survey design reports on the effect of school location and years of teaching experience on the self-efficacy of primary science teachers towards integrated STrEAM teaching. For this purpose, the STrEAM Teaching Self-Efficacy Scale (STSES) was administered to 200 primary science teachers throughout the nation. The STSES consists of five subscales: STrEAM instructional strategies self-efficacy, STrEAM classroom management self-efficacy, STrEAM community involvement self-efficacy, STrEAM student engagement self-efficacy, and STrEAM outcome expectancy. Data obtained from the STSES survey was analysed using two-way Multiple analysis of variance (MANOVA) to identify the effects of school location and years of teaching experience towards self-efficacy perceived by the primary science teachers towards integrated STrEAM teaching. The findings show that school location and years of teaching experience significantly affect the self-efficacy perceived by the primary science teachers towards integrated STrEAM teaching. School location and years of teaching experience also have a significant interaction effect (Wilks’ lambda = 0.860, F (15, 519) = 1.950, p &lt; 0.005) on primary science teachers towards integrated STrEAM teaching. The finding of this study is resourceful for the STEM stakeholders and policy makers to design the STrEAM teaching materials for training the teachers.

Close to reality? Micro-/mesocosm communities do not represent natural macroinvertebrate communities

BackgroundThe European environmental risk assessment of plant protection products considers aquatic model ecosystem studies (microcosms/mesocosms, M/M) as suitable higher tier approach to assess treatment-related effects and to derive regulatory acceptable concentrations (RAC). However, it is under debate to what extent these artificial test systems reflect the risks of pesticidal substances with potential harmful effects on natural macroinvertebrate communities, and whether the field communities are adequately protected by the results of the M/M studies. We therefore compared the composition, sensitivity and vulnerability of benthic macroinvertebrates established in control (untreated) groups of 47 selected M/M studies with natural stream communities at 26 reference field sites.ResultsSince 2013 the number of benthic macroinvertebrate taxa present in M/M studies has increased by 39% to a mean of 38 families per study. However, there is only an average of 4 families per study that comply with the recommendations provided by EFSA (EFSA J 11:3290, 2013), i.e.: (i) allowing statistical identification of treatment-related effects of at least 70% according to the minimum detectable difference (here criteria are slightly modified) and (ii) belonging to insects or crustaceans (potentially sensitive taxa for pesticidal substances). Applying the criterion of physiological sensitivity according to the SPEARpesticides concept, the number of families decreases from 4 to 2.3 per study.ConclusionsMost taxa established in recent M/M studies do not suitably represent natural freshwater communities. First, because their abundances are often not sufficient for statistical detection of treatment-related effects in order to determine an appropriate endpoint and subsequent RAC. Recommendations are given to improve the detectability of such effects and their reliability. Second, the taxa often do not represent especially sensitive or vulnerable taxa in natural communities in terms of their traits. The uncertainties linked to vulnerable taxa in M/M studies are especially high considering their representativity for field assemblages and the comparability of factors determining their recovery time. Thus considering recovery for deriving a RAC (i.e., ERO-RAC) is not recommended. In addition, this paper discusses further concerns regarding M/M studies in a broader regulatory context and recommends the development of alternative assessment tools and a shift towards a new paradigm.

Temporal design for aquatic organismal sampling across the National Ecological Observatory Network

Abstract The National Ecological Observatory Network (NEON) is a continental‐scale research platform designed to assess the impacts of climate change, land‐use change and invasive species on ecosystem structure and function at field sites distributed across 20 ecoclimatic domains (or regions) from Alaska to Puerto Rico. Aquatic sites within the NEON network include 24 streams, 7 lakes and 3 rivers among 19 domains. A significant challenge to this effort is defining standardized methodology for sampling at sites with substantially variable geomorphology and hydrology. The aquatic temporal sampling design provides timing windows for seasonal sampling to best assess organismal diversity and abundance. The need to establish a rule set for temporal sampling was addressed via site‐specific seasonal sampling windows, defined using a suite of environmental variables collected from publicly available meteorological data. Variables integrated into the design include stream flow, growing degree days and riparian phenology. Thresholds for these variables were determined using published literature and used to create three sampling windows for each sample site. Sampling windows target biological community diversity and seasonal changes in abundance, and roughly align with spring, mid‐summer and autumn. NEON‐generated organismal data from 2014 to 2021 were analysed for inter‐ and intra‐annual variability to quantify community‐scale variability among seasonal sampling windows and years at each site. Algae, macroinvertebrate and zooplankton community structure was significantly different within sites across sampling windows, supporting the sampling design of three separate windows per year. Moreover, 93% of sampling windows were completed from 2014 to 2021. An analysis of macroinvertebrate data at 14 sites shows that seasonal β‐diversity represents an important attribute of the stream community, even if interannual trends among sites may differ. We conclude that the temporal sampling design for NEON aquatic biological sampling is justified in having three sampling windows per site and is achievable at most NEON aquatic sites. Although sampling windows have been adjusted at a select number of sites, the original sampling windows are used successfully at the majority of NEON aquatic sites. Sampling windows will be updated with NEON continuous sensor data from each site once sufficient (&gt;3 years) data are available.

Structure and functional composition of macroinvertebrate communities in coastal plain streams across a precipitation gradient

Abstract Climate change is expected to alter rainfall and temperature regimes across the world. The hydrology and riparian zone vegetation of lotic ecosystems are tightly linked to rainfall and a mechanistic understanding of the effects of rainfall on lotic ecosystems is needed to forecast the ecological impacts of climate change. However, it is difficult to isolate rainfall effects from other environmental variables that covary across climates. To address this, we leveraged a unique steep rainfall gradient with few covarying changes in elevation, temperature, and geology to evaluate the effects of rainfall on stream invertebrate communities. We surveyed nine streams in the Texas Gulf Coast Prairie distributed along a 550–1,350 mm/year rainfall gradient. Four sites were classified as drier semi‐arid streams (&lt;750 mm annual rainfall) and five sites were classified as wetter sub‐humid streams (&gt;750 mm annual rainfall). A suite of characteristics including benthic invertebrate community metrics, flow conditions, and water quality variables were assessed monthly for 14 months at each site to relate precipitation regime to stream structure and function. Precipitation regime was observed to be a master explanatory variable. As annual rainfall increased, the flow environment became more stable within seasons and predictable across seasons, influencing spatial structure and temporal variability of invertebrate community composition. Wetter streams were dominated by slower growing taxa without adaptions for desiccation resistance and strong dispersal. Wetter sites displayed seasonal variation in community composition and species richness, whereas temporal variation in communities in drier streams was controlled by stochastic variation in flow conditions. These observations show that differences in local annual rainfall correlated with major changes to community structure and functional composition. We hypothesise that this association is related to the connection of rainfall to hydrological stability, particularly the frequency of low flow disturbances, and the subsequent effects on riparian vegetation and temporally available niches to stream invertebrates. Our work adds to evidence that alterations in precipitation patterns associated with climate change have sweeping impacts on lotic fauna.

Dry phase duration and periodicity alter clitellate communities in central European intermittent streams

Dry phase duration and periodicity alter clitellate communities in central European intermittent streams