Abstract
Novel environments and biological communities created by the large-scale deployment of Marine Renewable Energy Devices (MREDs) have the potential to promote the spread of non-native species (NNS). Knowledge of how community composition resident on MREDs is shaped by geography, local hydrodynamics and the duration of deployment, will clarify how these technologies will interact with natural habitats, including the provision of suitable habitat for NNS. A network of navigation buoys was used to study biofouling communities in areas proposed for MRED deployment. Significant differences in community structure were observed in different geographic areas. A significant reduction in number of taxa present and community wet-weight was observed where buoys were deployed in greater tidal flow rates. However, overall community composition was not significantly different between ‘high’ (>1 ms-1) and ‘low’ (<1 ms-1) flow areas and for buoys deployed for different time durations (1-7 years). These finding have important implications for the longevity of devices and their interaction with natural habitats, including proposed ‘artificial reef’ effects. In total five non-native species were identified on the buoys sampled, supporting the need to monitor MREDs as the industry grows. Hydrodynamic and biotic features of the epibenthic communities were used to predict the presence of the most prevalent NNS, the amphipod Caprella mutica, in addition to other native amphipod species. Caprella mutica presence was found to be significantly affected by increasing flow speed compared with the native amphipod Jassa herdmani. Behavioural flume studies investigating flow-related processes governing the presence of non-native amphipods supported these findings. This study details how the hydrodynamic and biological environments created by MREDs determine their suitability for the establishment of self-sustaining populations, and therefore their dispersal potential for NNS. These findings inform design criteria and management options to minimise the biosecurity risk that these structures will pose as the industry expands.