Abstract
There is uncertainty on the ecological effects of tidal stream turbines. Concerns include animal collision with turbine blades, disruption of migratory and foraging behaviour, attraction of animals to prey aggregating around turbines, or conversely displacement of animals from preferred habitat.This study used concurrent ecological and physical measurements to show the predictability of fish school characteristics (presence, school area and height above seabed) in a high energy tidal site across spring/neap, ebb/flood and daily cycles, and how this changed around a turbine structure.The rate of schools and school area per hour increased by 1.74 and 1.75 times respectively around a turbine structure compared to observations under similar conditions without a turbine structure. The largest schools occurred at peak flow speeds and the vertical distribution of schools over the diel cycle was altered around the turbine structure.While predictable attraction or aggregation of prey may increase prey availability and predator foraging efficiency, attraction of predators has the potential to increase animal collision risk. Predictable changes from the installation of turbine structures can be used to estimate cumulative effects on predators at a population level. This study can guide a strategic approach to the monitoring and management of turbines and arrays.
Highlights
With rapid development of marine renewable energy extraction, uncertainty surrounding the environmental and ecological effects of installing and operating tidal stream turbines remains [1]
This study investigates if differences in fish school characteristics in a high energy tidal site can be predicted from spring/neap, ebb/flood and diel cycles, and if these characteristics change with or without the presence of a turbine support structure
This study focuses on two consecutive deployments of the FLOWBEC platform (2 Jun e 15 Jun 2013 and 18 Jun e 5 Jul 2013) at the European Marine Energy Centre (EMEC) Fall of Warness (FoW) tidal site in Orkney, Scotland (Fig. 1) [33], which provides seven grid-connected tidal turbine berths
Summary
With rapid development of marine renewable energy extraction, uncertainty surrounding the environmental and ecological effects of installing and operating tidal stream turbines remains [1]. Species at risk from impacts vary among sites, often including fish, seabirds and marine mammals. Particular focus is given to populations that are protected due to their increased vulnerability to external factors that threaten their viability [2]. Concerns include animal collision risk, disruption of migratory and foraging behaviour, attraction of animals to turbines or to prey attracted to or aggregating around turbines, or displacement from preferred habitat [3]. Changes in behaviour of fish species, in particular those which are common prey of seabirds and marine mammals, could lead to changes in foraging behaviour of their predators as observed at offshore wind turbines [4]
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