Quantitative modelling of fish habitat in a large regulated river in a changing climate

Abstract

AbstractThe expansion of hydropower in combination with the already existing infrastructure and a changing climate are significantly influencing the world's rivers. The resulting alteration in flow regimes is expected to strongly affect fish habitat and associated fish communities both spatially and temporally. Using habitat modelling, this study identified habitat bottlenecks during the critical summer low flow period and fish assemblages that will be most susceptible to regulated and predicted future flow regimes in the Saint John River downstream the Mactaquac Generating Station. Expert knowledge‐based habitat models were applied at the meso‐scale to evaluate the influence of alternative future flow regimes on habitat suitability indices of fish assemblages. Dam renewal and removal scenarios predicted low habitat suitability for rheophilic fish species, particularly during prolonged low flow periods in dry years. Limnophilic and eurytopic fish assemblages were not expected to be limited in habitat conditions. Overall, the proposed modelling approach represents a promising tool to support the development of environmental flows in large regulated rivers that face challenges with ageing infrastructure and a changing climate.