Effects of wave energy extraction on intertidal species of extremely exposed rocky shores

Ecological responses to nearshore extraction of wave energy are expected to be most evident at the shore, where much of this energy would otherwise be expended. Extremely exposed shorelines are the best place to look for such responses, given that these are likely to be adjacent to the highest wave energy resources. Using survey data for the west coast of Mainland Orkney together with modelled wave height data from the EcoWatt 2050 project, we develop statistical models for the abundance of intertidal species characteristic of high exposure levels. Significant relationships with wave height are apparent for many species, even though all sites are at the high end of the spectrum of exposure, and shore topography is shown to be an important modifying factor. These models are projected for scenarios of future wave climate, demonstrating that climate change is expected to be the dominant driver of change in intertidal species. Both losses and gains are projected in response to extraction of wave energy, but these effects are relatively small. We discuss these findings in relation to uncertainties about other environmental drivers, and consider implications for acceptable levels of energy extraction.