DOI: 10.5061/dryad.3r2280gr8
title: Human impacts mediate freshwater invertebrate community responses to and recovery from drought

description: Drought is an increasing risk to the biodiversity within rivers—ecosystems
 that are already impacted by human activities. However, the long-term
 spatially replicated studies needed to generate an understanding of how
 anthropogenic stressors alter ecological responses to drought are lacking.
 We studied aquatic invertebrate communities in 2500 samples collected from
 179 sites on rivers emerging from England’s chalk aquifer over three
 decades. We tested two sets of alternative hypotheses describing responses
 to and recovery from drought in interaction with human impacts affecting
 water quality, fine sediment, water temperature, channel morphology, flow,
 and temporal change in land use. We summarized communities using taxa
 richness, an index indicating tolerance of anthropogenic degradation
 (average score per taxon, ASPT), and deviation from the average
 composition. Responses to drought were altered by interactions with human
 impacts. Poor water quality exacerbated drought-driven reductions in taxa
 richness. Drought-driven deviations from the average community composition
 were reduced and enhanced at sites impacted by flow augmentation (e.g.
 effluent releases) and flow reduction (e.g. abstraction), respectively.
 Human impacts altered post-drought recovery. Increases in richness were
 lower at sites impacted by water abstraction and higher at sites with
 augmented flows, in particular as recovery trajectories extended beyond 3
 years. ASPT recovered faster at sites that gained woodland compared to
 urban land, due to their greater recovery potential i.e., their lower
 drought-driven minimum values and higher post-drought maximum values. We
 show that communities in river ecosystems exposed to human impacts—in
 particular poor water quality, altered flow volumes, and land-use
 change—are particularly vulnerable to drought. These results provide
 evidence that management actions taken to enhance water quality, regulate
 abstraction, and restore riparian land use could promote ecological
 resilience to drought—in groundwater-dominated rivers such as globally
 rare chalk streams and other rivers of the Anthropocene—as they adapt to a
 future characterized by increasing climatic extremity.
description: Data was collected from several databases from the Environment
 Agency. Data was mostly processed in R.
description: # Human impacts mediate freshwater invertebrate community responses to and
 recovery from drought
 [https://doi.org/10.5061/dryad.3r2280gr8](https://doi.org/10.5061/dryad.3r2280gr8) ## Description of the data and file structure The data is divided into two sheets, one containing the biological response variables and the other one containing environmental predictors (including hydrological and human impact variables). The first column (A) of each sheet has a unique sample ID which can be used to link both sheets. A unique Site ID (Column C) and sample date (Column B) are also provided in both sheets. Rows represent unique samples. **In the sheet "Biological responses"**: Column D: Richness i.e., the number of invertebrate families in each sample Column E: distance to the community centroid as described in the main manuscript Column F: abundance-weighted ‘WHPT’ average score per taxon (ASPT): WHPT-ASPT, a biomonitoring index that reflects responses to organic pollution and general environmental degradation. Column G: Hill diversity index **In the sheet "Environmental predictors"**: Columns D and E include geographical coordinate information for each sampling site given in the UK National Grid system (EPSG:27700) Column F = distance from the sampling site to the river source in km Columns G and H = hydrological variables described in the main manuscript, including the Low Flow anomalies (unitless) and the Time Since Drought (days) Column I-AC includes the human impact variables described in the main manuscript: I: The channel resectioning index (unitless) J: The percentage of fine sediments on the river substrate (%) K: The water temperature anomaly (unitless) L: Flow alteration value (unitless)  M-Q: The concentration of ammonia, nitrate, phosphate, and dissolved oxygen (DO) in mg L-1 and the biological oxygen demand in mg DO L-1 Columns R-U indicate the distance from the biological site to the temperature, water quality, hydrological, and Channel resectioning index site (meters) In addition, upstream catchment percentage land-use can be derived from the Centre for Ecology and Hydrology land-use data available at https://www.ceh.ac.uk/services/land-cover-change-1990-2015