The impact of small impoundments and connectivity loss on fishdistribution and abundance in river ecosystems: leveraging cutting edge geospatial model

Rivers are among the world's most threatened ecosystems. Freshwater fisheriesare at risk from multiple stressors including climate change, pollutants and the presence of dams which inhibit fish movement and migration. Globally, only 37% of the world's rivers remain free of dams, butin the UK only 1% of watercourses unimpeded by barriersduelargely tothe UK's industrial heritage.Althoughresearch has demonstrated clear links between large dams and declines in fish populations, there is aclearlack of knowledge on how smaller (but more frequent)historical barriers typical of UK rivers influence fish populations. In thecontextofincreasing need to balance conservation of freshwater ecosystems against the demandforrenewable energy from legacy micro-hydroelectric facilitiesand similar structures, research isthereforeurgently needed to understand how cumulative small historicalbarriers influence fish population dynamics.This study will use eDNA (trace DNA shed from fish, collected via water samples) to quantify the abundance and distribution of fish communities within the Derbyshire Derwent, a catchment with a rich history of historical impoundment. By coupling population-level datawith river connectivity models relating to the presence of historical barriers and key fish habitats, thisprojectwill generate new fundamental understanding of the impacts of small, frequent impoundments on river habitat connectivity and fish population dynamicsand thus provide important information for managing rivers affected by the legacy of industrial development.