PNNL

Abstract

Large-scale marine energy arrays, harvesting oceans’ wave and tidal energy, need to enter the portfolio of renewable energy to successfully contribute to mitigating global climate change. However, with large-scale arrays come potential environmental effects not seen at the scales of single devices and small arrays. The risk of displacing marine animals from their preferred habitat or their migration routes increases with the size of arrays. Many marine animals may be susceptible to some level of displacement once large marine energy arrays are increasingly integrated into the seascape, including large migratory animals, non-migratory pelagic animals with large home ranges, and benthic and demersal mobile organisms with more limited ranges, among many others. Yet, research around mechanisms and effects of displacement has been hindered by the lack of clarity within the international marine energy community regarding the definition of displacement, the mechanisms that cause displacement, as well as the consequences, species of concern, and methods to investigate the outcomes. This review paper leveraged lessons learned from other industries, especially marine, to establish a definition of displacement in the marine energy context, explore which functional groups of marine animals may be affected and in what way, and identify pathways for investigating displacement through modeling and monitoring. In the marine energy context, we propose to define displacement as the outcome of one of three mechanisms (i.e., attraction, avoidance, and exclusion) triggered by an animal’s response to one or more stressors acting as a disturbance, with various consequences at the individual through to population levels. The knowledge gaps highlighted in this study will help the regulatory and scientific communities prepare themselves for mitigating, observing, measuring, and characterizing displacement of various animals around marine energy arrays in order to prevent irreversible consequences.