Detecting responses of rocky shore organisms to environmental change following wave energy extraction

Abstract

The highly energetic waters surrounding Orkney have recently attracted attention as a renewable resource to generate electricity. While the importance of wave exposure to littoral assemblages is well known, the ecological consequences of industrial-scale extraction of marine energy have not been directly studied on rocky shores. The aim of this study was to examine the potential consequences of wave energy extraction and other long-term forcing agents, such as climate change, to rocky shore assemblages. Baseline surveys were conducted in areas not previously described in scientific detail to serve as ‘before’ and ‘control’ sites in a BACI-style design. Composition and abundances of biological assemblages were compared with topographic measurement of coastal features expected to modify exposure through dissipation of incoming wave energy. Observed variation in assemblages between sites was explained by differences in exposure and topography, particularly substrate complexity. Rocky shore species were selected for monitoring long-term changes using a paired-species monitoring method, including key structuring organisms on high exposure shores. Monitoring and experimental manipulation identified species which respond to changes in wave energy extraction and temperature. This research will assist in elucidating ecological responses that might occur following removal of wave energy, amid warming seas.