OFFSHORE WIND ENERGY and BENTHIC HABITAT CHANGES Lessons from Block Island Wind Farm
Total Page：16
File Type：pdf, Size：1020Kb
SPECIAL ISSUE ON UNDERSTANDING THE EFFECTS OF OFFSHORE WIND ENERGY DEVELOPMENT ON FISHERIES OFFSHORE WIND ENERGY AND BENTHIC HABITAT CHANGES Lessons from Block Island Wind Farm By Zoë L. Hutchison, Monique LaFrance Bartley, Steven Degraer, Paul English, Anwar Khan, Julia Livermore, Bob Rumes, and John W. King 58 Oceanography | Vol.33, No.4 ABSTRACT. The Block Island Wind Farm (BIWF), situated offshore of Block Island, We first provide a contextual overview Rhode Island, is the first commercial offshore wind farm (OWF) in the United States. of benthic ecology and related fish pat- We briefly review pre-siting studies, which provide contextual information about the terns in the broader area of Block Island benthic habitats and fish in the Block Island Sound area before the BIWF jacket foun- Sound (BIS). We then briefly describe dations were installed in 2015. We focus on benthic monitoring that took place within the RODEO benthic monitoring effort at the BIWF. This monitoring allowed for assessments of spatiotemporal changes in sed- the BIWF and highlight benthic changes iment grain size, organic enrichment, and macrofauna, as well as the colonization of observed. These changes and their poten- the jacket structures, up to four years post-installation. The greatest benthic modifica- tial ecological importance are discussed tions occurred within the footprint of the foundation structures through the develop- with respect to their cascading effects ment of mussel aggregations. Within four years, changes in benthic habitats (defined as and relevance to managed species. The biotopes) were observed within the 90 m range of the study, clearly linked to the mussel- overarching lessons learned from the dominated colonization of the structures, which also hosted numerous indigenous implementation of the RODEO benthic fish species. We discuss the evident structural and functional effects and their ecolog- monitoring effort provide insights that ical importance at the BIWF and for future US OWFs, drawing on similarities with can guide recommendations for future European studies. While reviewing lessons learned from the BIWF, we highlight the efforts. We conclude by drawing paral- need to implement coordinated monitoring for future developments and recommend a lels with European OWF environmen- strategy to better understand environmental implications. tal monitoring regimes, providing pos- sible paths forward for future US OWF INTRODUCTION Time Opportunity for Development monitoring efforts. Offshore wind has proven to be a valu- Environmental Observations (RODEO) able source of clean energy, particularly program in 2015. Thus, evaluation of the BENTHIC ECOLOGY OF in Europe, where over 75% of the global effects of early OWFs can inform man- BLOCK ISLAND SOUND capacity is installed (GWEC, 2019). In agement about how to avoid or mitigate BIS is an ecologically and socioeconomi- 2019, China and the United States were impacts of future facilities and how to cally important area, and to help select an the greatest contributors of new wind prioritize future monitoring efforts. The appropriate site for the BIWF, the Rhode installations (onshore and offshore com- BIWF provided the first opportunity in Island Ocean Special Area Management bined), and with 15 offshore leases, the the United States to evaluate the inten- Plan (OSAMP; CRMC, 2010) was devel- United States has potential as a strong sity, duration, and spatial scale of per- oped. As part of this multidisciplinary contributor to the future offshore wind ceived impacts. During the construction effort, the benthic ecology, habitats, and industry (BOEM, 2019; GWEC, 2019). and/or operational phases, assessments of fishery resources of BIS and Rhode Island Located 4.5 km from Block Island, sediment disturbances, sound emissions, Sound (RIS) were characterized (Malek Rhode Island, the Block Island Wind visual disturbances, and effects on the ben- et al., 2010; LaFrance et al., 2014). We Farm (BIWF) is the first commer- thic environment were made (e.g., HDR, briefly review the knowledge gained, cial offshore wind farm (OWF) in the 2019, 2020a,b). Here, we focus on the focusing on the benthic ecology and United States. The BIWF consists of five RODEO benthic monitoring effort during demersal fish of BIS to provide context for jacket- foundation turbines (150 m tall, the initial operational phase and report on the broader BIS area prior to the BIWF. 15,000 tons, 150 m rotor diameter, 30 MW the effects of the BIWF on benthic ecol- The pre-siting OSAMP study mapped total capacity) spaced approximately 1 km ogy within four years post-construction benthic habitats within a 138.6 km2 area apart. The foundations were installed by (late 2016 to late 2019). This relatively of BIS (LaFrance et al., 2014). Water mid-2015, and the facility became oper- short-term monitoring aimed to evaluate depth in this area ranges from 13–44 m. ational in late 2016, primarily supplying near-field spatiotemporal changes in sed- The seafloor was found to be a hetero- power to Block Island, with excess power iment grain size, organic enrichment, and geneous environment, consisting of five transmitted to the mainland via a 34 km benthic macrofauna due to the presence glacial depositional environment types subsea export cable (HDR, 2019). of the BIWF foundations. This effort later (moraine shelf, inner shelf moraine, delta To understand the environmental expanded to evaluate the benthic changes plain, alluvial fan, lake floor basin) and effects of OWFs, the US Department occurring closer to and under the foun- a range of seabed types (flat/ featureless of the Interior Bureau of Ocean Energy dation structures and the colonizing com- areas, sheet sands, sand waves, small Management (BOEM) initiated the Real- munity on the structures. dunes, boulder fields). The area was gen- erally described as a coarse sediment FACING PAGE. The University of Rhode Island team preparing to deploy the benthic grab sampler environment with medium to very coarse in the Block Island Wind Farm. Photo credit: Monique LaFrance Bartley sands dominating, though areas of finer Oceanography | December 2020 59 sediments were recorded. Generally, ben- used to describe biological and phys- terns (Malek et al., 2010; Kritzer et al., thic macrofauna communities were dom- ical characteristics and to define hab- 2016). Both the demersal fish assem- inated by amphipods, polychaetes, and itats referred to as biotopes (FGDC, blage and stomach contents of fish were bivalves. The macrofauna community 2012). Within the OSAMP BIS study dependent on the geographical loca- composition in BIS was influenced by area, 12 distinct biotopes were identified tion and benthic habitat where fish were mean water depth, benthic surface rough- (Figure 1, which also identifies the BIWF caught (Malek et al., 2010). Compared to ness, geological features, and sediment site; LaFrance et al., 2014). the neighboring RIS, BIS had lower fish types at fine and/or broad scale resolu- The pre-siting OSAMP study also species abundance and biomass possibly tions (LaFrance et al., 2014). The Coastal highlighted that the benthic habitat het- due to lower primary production; how- and Marine Ecological Classification erogeneity and associated prey species ever, BIS had greater species diversity, Standard (CMECS; the US standard) was played a role in driving demersal fish pat- likely due to greater habitat complexity (Malek et al., 2010; Nixon et al., 2010). In addition to benthic habitat heteroge- neity, the demersal fish community was influenced by water depth (Malek et al., 2010). Generally, communities with more even species distribution and greater abundance and biomass were found in deeper waters, while lower density yet more diverse communities occurred in shallow waters. Overall, the heteroge- neous benthic habitats of BIS support a rich diversity of fish species important to both recreational and commercial fishing communities (Malek et al., 2010). POST-CONSTRUCTION RODEO MONITORING STRATEGY AT THE BIWF The Monitoring Effort The RODEO benthic monitoring pro- gram was completed over three sampling years spanning four calendar years after the BIWF foundations were installed (from late 2016 to late 2019). This pro- gram was initially designed in 2015 based on strategies and key findings from mon- itoring programs and studies in Europe. At that time, there was some evidence of sediment fining, organic enrichment, and benthic macrofaunal changes close (<15 m) to gravity devices and monopiles (Wilhelmsson et al., 2006; Coates et al., 2014). However, information regarding effects surrounding jacket structures was more limited (Schröder et al., 2006; Krone et al., 2013). Observations of epifouling FIGURE 1. Benthic biotopes within the Block Island Sound study area (138.6 km2). Twelve biotopes on gravity, monopile, and jacket turbine were identified during preparation of the Rhode Island Ocean Special Area Management Plan foundations (Schröder et al., 2006; Emu (LaFrance et al., 2014). The inset, with turbine positions shown, delineates the Block Island Wind Limited., 2008; De Mesel et al., 2015) sug- Farm (BIWF) study area for the benthic monitoring that took place as part of the US Department of the Interior Bureau of Ocean Energy Management monitoring program called Real-Time Opportunity gested considerable quantities of addi- for Development Environmental Observations (RODEO). tional biomass could be introduced to 60 Oceanography | Vol.33, No.4 offshore areas. Foundations were pro- BOX 1.