Browsing by Author "Wood, Paul J."
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Item Open Access Extreme low flow effects on riverine fauna: a perspective on methodological assessments(Wiley, 2022-03-29) White, James C.; Aspin, Thomas; Picken, Jessica Louise; Ledger, Mark E.; Wilby, Robert L.; Wood, Paul J.River flow regimes face increasing pressure from human activities including water resource management operations and climate change. Consequently, extreme hydrological events are becoming more severe and commonplace, and there is a pressing need to understand and manage their ecological effects. Extreme low-flows (ELFs) – those displaying significantly greater magnitudes and durations than typical low-flow conditions – are being increasingly experienced globally. Fish and macroinvertebrate responses to ELFs have been more widely researched relative to other organism groups in riverine environments, although such studies have employed variable methodological techniques. In this perspective piece, we identify field-based assessments and controlled experiments as two key research paradigms used to examine riverine faunal responses to ELFs. Field-based assessments are often explorative and can benefit from utilising large-scale and long-term datasets. Alternatively, controlled experiments typically employ more hypothesis-driven approaches and can establish strong cause and effect linkages through high replication and control over potentially confounding parameters. Each paradigm clearly possesses their respective strengths, which we highlight and discuss how these could be better harnessed to optimise scientific advancements. To date, studies examining faunal responses to ELFs in these two research paradigms have largely been undertaken in parallel. Here, we argue that future research should seek to develop closer synergies to optimise the quality and quantity of evidence to better understand riverine faunal responses to ELFs. Such scientific advances are of paramount importance given the vulnerability of riverine fauna, and the ecosystems they comprise, as they face a new era of ELFs in many global regions.Item Open Access Macroinvertebrate and diatom community responses to thermal alterations below water supply reservoirs(Wiley, 2021-12-29) Krajenbrink, Hendrik J.; White, James C.; Dunbar, Michael J.; Wood, Paul J.River impoundments have transformed river ecosystems globally due to the modification of various abiotic and biotic factors. This study provides rare evidence quantifying how water supply reservoirs alter water temperature regimes and its effects on macroinvertebrate and diatom communities over a 4-year period. We obtained near-continuous water temperature measurements upstream and downstream of three reservoirs and analysed thermal variables in association with macroinvertebrate and diatom community indices (including taxonomic richness, proportion of Ephemeroptera, Plecoptera and Trichoptera taxa [%EPT] and diatom ecological guilds). Reservoirs typically decreased downstream thermal variability, with reduced summer temperatures and increased winter temperatures, and a delayed timing of annual temperature extremes. Marked differences in thermal regime modifications between reservoirs were observed, including evidence of inter-annual variation associated with inter-basin water transfers downstream of one reservoir. Biomonitoring indices showed associations with thermal indices that differed between site types (regulated versus non-regulated) and seasons (spring vs. autumn). Various macroinvertebrate and diatom indices capturing community diversity elements and sensitivities to different environmental pressures were associated with higher maximum summer temperatures and lower minimum winter temperatures, suggesting ecological effects of reduced thermal variation downstream of reservoirs. Different ecological responses to thermal indices were observed between seasons, likely due to organism life-cycle effects and intra-annual thermal variations. Contrasting macroinvertebrate and diatom communities were observed between regulated and non-regulated sites, which may be driven by differences in the thermal regime and other abiotic factors at regulated sites, including nutrient, sediment and flow regimes. Long-term continuous water temperature monitoring of both multiple regulated and non-regulated river systems is necessary to better understand the environmental and ecological effects of river impoundments. Given the extent to which river impoundment has modified stream temperatures globally, the inclusion of thermal regime data in environmental flow studies alongside hydrological information may guide the implementation of mitigation measures on impounded waterbodies.Item Open Access Pond ecology and conservation: research priorities and knowledge gaps(Wiley, 2021-12-09) Hill, Matthew J.; Greaves, Helen M.; Sayer, Carl D.; Hassall, Christopher; Milin, Melanie; Milner, Victoria S.; Marazzi, Luca; Hall, Ruth; Harper, Lynsey R.; Thornhill, Ian; Walton, Richard; Biggs, Jeremy; Ewald, Naomi; Law, Alan; Willby, Nigel; White, James C.; Briers, Robert A.; Mathers, Kate L.; Jeffries, Michael J.; Wood, Paul J.Ponds are among the most biodiverse and ecologically important freshwater habitats globally and may provide a significant opportunity to mitigate anthropogenic pressures and reverse the decline of aquatic biodiversity. Ponds also provide important contributions to society through the provision of ecosystem services. Despite the ecological and societal importance of ponds, freshwater research, policy, and conservation have historically focused on larger water bodies, with significant gaps remaining in our understanding and conservation of pond ecosystems. In May 2019, pond researchers and practitioners participated in a workshop to tackle several pond ecology, conservation, and management issues. Nine research themes and 30 research questions were identified during and following the workshop to address knowledge gaps around: (1) pond habitat definition; (2) global and long-term data availability; (3) anthropogenic stressors; (4) aquatic–terrestrial interactions; (5) succession and disturbance; (6) freshwater connectivity; (7) pond monitoring and technological advances; (8) socio-economic factors; and (9) conservation, management, and policy. Key areas for the future inclusion of ponds in environmental and conservation policy were also discussed. Addressing gaps in our fundamental understanding of pond ecosystems will facilitate more effective research-led conservation and management of pondscapes, their inclusion in environmental policy, support the sustainability of ecosystem services, and help address many of the global threats driving the decline in freshwater biodiversity.