Offshore wind energy and benthic habitat changes : lessons from block island wind farm

Abstract

The Block Island Wind Farm (BIWF), situated offshore of Block Island, Rhode Island, is the first commercial offshore wind farm (OWF) in the United States. We briefly review pre-siting studies, which provide contextual information about the benthic habitats and fish in the Block Island Sound area before the BIWF jacket foundations were installed in 2015. We focus on benthic monitoring that took place within the BIWF. This monitoring allowed for assessments of spatiotemporal changes in sediment grain size, organic enrichment, and macrofauna, as well as the colonization of the jacket structures, up to four years post-installation. The greatest benthic modifications occurred within the footprint of the foundation structures through the development of mussel aggregations. Within four years, changes in benthic habitats (defined as biotopes) were observed within the 90 m range of the study, clearly linked to the mussel-dominated colonization of the structures, which also hosted numerous indigenous fish species. We discuss the evident structural and functional effects and their ecological importance at the BIWF and for future US OWFs, drawing on similarities with European studies. While reviewing lessons learned from the BIWF, we highlight the need to implement coordinated monitoring for future developments and recommend a strategy to better understand environmental implications.