Flow variability and macroinvertebrate community response within riverine systems

River flow regimes, controlled by climatic and catchment factors, vary over a wide range of temporal and spatial scales. This hydrological dynamism is important in determining the structure and functioning of riverine ecosystems; however, such hydroecological associations remain poorly quantified. This paper explores and models relationships between a suite of flow regime predictors and macroinvertebrate community metrics from 83 rivers in England and Wales. A two-stage analytical approach was employed: (1) classification of 83 river basins based upon the magnitude and shape (form) of their long-term (1980 – 1999) average annual regime to group basins with similar flow responses; and (2) examination of relationships between a total of 201 flow regime descriptors identified by previous researchers and macroinvertebrate community metrics for the whole data set and long-term flow regime classes over an 11-year period (1990 – 2000). The classification method highlighted large-scale patterns in river flow regimes, identifying five magnitude classes and three shape classes. A west–east trend of flow regime magnitude (high-low) and timing (early-late peak) was displayed across the study area, reflecting climatic gradients and basin controls (e.g. lithology). From the suite of hydrological variables, those associated with the magnitude of the flow regime consistently produced the strongest relationships with macroinvertebrate community metrics for all sites and for the long-term regime composite classes. The results indicate that the classification (subdivision) of rivers into flow regime regions potentially offers a means of increasing predictive capacity and, in turn, better management of fluvial hydrosystems

The long-term effects of invasive signal crayfish (Pacifastacus leniusculus) on instream macroinvertebrate communities

Non-native species represent a significant threat to indigenous biodiversity and ecosystem functioning worldwide. It is widely acknowledged that invasive crayfish species may be instrumental in modifying benthic invertebrate community structure, but there is limited knowledge regarding the temporal and spatial extent of these effects within lotic ecosystems. This study investigates the long term changes to benthic macroinvertebrate community composition following the invasion of signal crayfish, Pacifastacus leniusculus, into English rivers. Data from long-term monitoring sites on 7 rivers invaded by crayfish and 7 rivers where signal crayfish were absent throughout the record (control sites) were used to examine how invertebrate community composition and populations of individual taxa changed as a result of invasion. Following the detection of non-native crayfish, significant shifts in invertebrate community composition were observed at invaded sites compared to control sites. This pattern was strongest during autumn months but was also evident during spring surveys. The observed shifts in community composition following invasion were associated with reductions in the occurrence of ubiquitous Hirudinea species (Glossiphonia complanata and Erpobdella octoculata), Gastropoda (Radix spp.), Ephemeroptera (Caenis spp.), and Trichoptera (Hydropsyche spp.); although variations in specific taxa affected were evident between regions and seasons. Changes in community structure were persistent over time with no evidence of recovery, suggesting that crayfish invasions represent significant perturbations leading to permanent changes in benthic communities. The results provide fundamental knowledge regarding non-native crayfish invasions of lotic ecosystems required for the development of future management strategies

An index to track the ecological effects of drought development and recovery on riverine invertebrate communities

© 2017 Elsevier Ltd In rivers, the ecological effects of drought typically result in gradual adjustments of invertebrate community structure and functioning, punctuated by sudden changes as key habitats, such as wetted channel margins, become dewatered and dry. This paper outlines the development and application of a new index (Drought Effect of Habitat Loss on Invertebrates – DEHLI) to quantify the effects of drought on instream macroinvertebrate communities by assigning weights to taxa on the basis of their likely association with key stages of channel drying. Two case studies are presented, in which the DEHLI index illustrates the ecological development of drought conditions and subsequent recovery. These examples demonstrate persistent drought effects months or several years after river flows recovered. Results derived using DEHLI are compared with an established macroinvertebrate flow velocity-reactive index (Lotic-invertebrate Index for Flow Evaluation – LIFE score) and demonstrates its greater sensitivity to drought conditions. Data from a number of rivers in south east England were used to calibrate a statistical model, which was then used to examine the response of DEHLI and LIFE to a hypothetical multi-year drought. This demonstrated a difference in response between sampling seasons, with the spring model indicating a lagged response due to delayed recolonisation and the autumn model differentiating habitat loss and flow velocity-driven responses. The application of DEHLI and the principles which underlie it allow the effects of drought on instream habitats and invertebrates associated with short or long term weather patterns to be monitored, whilst also allowing the identification of specific locations where intervention via river restoration, or revision of existing abstraction licensing, may be required to increase resilience to the effect of anthropogenic activities exacerbated by climate change

The assessment of fine sediment accumulation in rivers using macro-invertebrate community response

Increased fine sediment deposition and entrainment in rivers can arise from a combination of factors including low flows, habitat modification and excessive sediment delivery from the catchment. Physical and visual methods have traditionally been used to quantify the volume of deposited fine sediment (<2mm in size), but here we propose an alternative, the development and utilization of a sediment-sensitive macro-invertebrate metric (PSI - Proportion of Sediment-sensitive Invertebrates) which provides a proxy to describe the extent to which the surface of river beds are composed of, or covered by, fine sediments. Where suitable biomonitoring data exists, the index can be calculated retrospectively to track trends in fine sediment deposition, and its ecological impact, through time. Furthermore, the utilization of reference condition models such as RIVPACS (River InVertebrate Prediction And Classification System), allows site-specific unimpacted conditions to be defined, opening-up the possibility of standard classification and assessment systems being developed. In Europe, such systems are vital if the Water Framework Directive is to be implemented. Knowledge regarding spatial differences in sediment/flow interdependencies may provide valuable information on diffuse sources of fine sediment to rivers and we illustrate this with an example from the UK (Laceby Beck). Further UK case studies are presented to show a range of applications, including the demonstration of improvements in habitat heterogeneity following river restoration (rivers Chess and Rib) and the detection of fine sediment impacts downstream of an impoundment (Eye Brook). The PSI metric offers a readily deployable, cost-effective and hydroecologically relevant methodology for the assessment of fine sediment impacts in rivers. The technique has potential for application outside of the UK and an adaptation of the methodology for use in the Simandou Mountains (Guinea) is used to illustrate this

How freshwater biomonitoring tools vary sub‐seasonally reflects temporary river flow regimes

Characterizing temporary river ecosystem responses to flow regimes is vital for conserving their biodiversity and the services they provide to society. However, freshwater biomonitoring tools rarely reflect community responses to hydrological variations or flow cessation events, and those available have not been widely tested within temporary rivers. This study examines two invertebrate biomonitoring tools characterizing community responses to different flow-related properties: the “Drought Effect of Habitat Loss on Invertebrates” (DEHLI) and “Lotic-invertebrate Index for Flow Evaluation” (LIFE), which, respectively reflect community responses to habitat and hydraulic properties associated with changing flow conditions. Sub-seasonal (monthly) variations of LIFE and DEHLI were explored within two groundwater-fed intermittent rivers, one dries sporadically (a flashy, karstic hydrology—River Lathkill) and the other dries seasonally (a highly buffered flow regime—South Winterbourne). Biomonitoring tools were highly sensitive to channel drying and also responded to reduced discharges in permanently flowing reaches. Biomonitoring tools captured ecological recovery patterns in the Lathkill following a supra-seasonal drought. Some unexpected results were observed in the South Winterbourne where LIFE and DEHLI indicated relatively high-flow conditions despite low discharges occurring during some summer months. This probably reflected macrophyte encroachment, which benefitted certain invertebrates (e.g., marginal-dwelling taxa) and highlights the importance of considering instream habitat conditions when interpreting flow regime influences on biomonitoring tools. Although LIFE and DEHLI were positively correlated, the latter responded more clearly to drying events, highlighting that communities respond strongly to the disconnection of instream habitats as flows recede. The results highlighted short-term ecological responses to hydrological variations and the value in adopting sub-seasonal sampling strategies within temporary rivers. Findings from this study indicate the importance of establishing flow response guilds which group taxa that respond comparably to flow cessation events. Such information could be adopted within biomonitoring practices to better characterize temporary river ecosystem responses to hydrological variations

Effects of rare kidney diseases on kidney failure: a longitudinal analysis of the UK National Registry of Rare Kidney Diseases (RaDaR) cohort

Individuals with rare kidney diseases account for 5-10% of people with chronic kidney disease, but constitute more than 25% of patients receiving kidney replacement therapy. The National Registry of Rare Kidney Diseases (RaDaR) gathers longitudinal data from patients with these conditions, which we used to study disease progression and outcomes of death and kidney failure.People aged 0-96 years living with 28 types of rare kidney diseases were recruited from 108 UK renal care facilities. The primary outcomes were cumulative incidence of mortality and kidney failure in individuals with rare kidney diseases, which were calculated and compared with that of unselected patients with chronic kidney disease. Cumulative incidence and Kaplan-Meier survival estimates were calculated for the following outcomes: median age at kidney failure; median age at death; time from start of dialysis to death; and time from diagnosis to estimated glomerular filtration rate (eGFR) thresholds, allowing calculation of time from last eGFR of 75 mL/min per 1·73 m2 or more to first eGFR of less than 30 mL/min per 1·73 m2 (the therapeutic trial window).Between Jan 18, 2010, and July 25, 2022, 27 285 participants were recruited to RaDaR. Median follow-up time from diagnosis was 9·6 years (IQR 5·9-16·7). RaDaR participants had significantly higher 5-year cumulative incidence of kidney failure than 2·81 million UK patients with all-cause chronic kidney disease (28% vs 1%; p Background Methods Findings Interpretation Funding</p