PNNL

Abstract

Marine energy devices generate energy from the movement of water in the oceans or large rivers, such as waves and tides, and from ocean gradients. Marine energy is a predicable source of renewable energy that can help combat climate change while providing energy security and employment to coastal communities. Most marine energy devices must be attached to the seafloor by anchors or foundations, with transmission cables connecting to shore. The physical presence of these structures, like any manmade structure on the seafloor, leads to changes in benthic environments. Small seafloor areas will be lost under the footprint of devices and anchors, and local water flow around the structures may flush the finest sediments and create scour depressions. But careful seafloor characterization enables proper siting and avoidance of critical habitats, such as eelgrass beds or corals. Marine energy devices may act as artificial reefs, providing new habitat for mobile and sedentary organisms, with the possibility to enhance the biodiversity and biomass around devices. In addition, deployment areas may function as marine reserves if fishing activities are limited around devices, with potential spillover of marine organisms to surrounding areas. Monitoring around marine energy devices is usually required to survey potential changes in benthic environments and provide information to help understand cause-effect relationships. More information on the environmental effects of marine energy and offshore wind can be found on the Tethys website.