Abstract
The University of Massachusetts Dartmouth School for Marine Science and Technology (SMAST) conducted drop camera surveys to examine the benthic community and substrate in Vineyard Wind 1 LLC’s (Vineyard Wind’s) Lease Area OCS-A 0501 (termed the “VW1 Study Area”) and a Control Area adjacent to the lease area. The primary goal of this project was to collect baseline data for future environmental assessment of wind farm development impacts. Our objectives were to provide:
- distribution and density estimates of dominant benthic megafauna,
- classify substrate types at drop camera stations across the survey domain,
- compare benthic communities and substrate types between the development area, Control Area, and broader regions of the United States (US) Atlantic Outer Continental Shelf (OCS), and
- classify substrate within aliquots sampled by the American Lobster, Black Sea Bass, Larval Lobster Abundance Survey, and Lobster Tagging Study (an associated SMAST trap survey also conducted for Vineyard Wind). These aliquots coincided with a subset of the drop camera stations.
A centric systematic sampling design was used to survey stations with the drop camera in the VW1 Study Area and an adjacent Control Area.1 Stations in the two areas were placed 1.5 kilometers (km) apart following a grid design. At each station, a sampling pyramid was deployed and a high-resolution camera was used to take four quadrat (2.3 square meter [m2 ] images) samples. Both areas were surveyed in May and September 2023 using a commercial scallop fishing vessel to deploy the sampling pyramid. The survey activities occurred while wind farm construction activities were taking place in the VW1 Study Area.
The benthic communities in the VW1 Study Area and Control Area in 2023 continued to be dominated by benthic invertebrates such as sand dollars, hermit crabs, waved whelks (Buccinum undatum, not the commercially harvested channeled whelk, Busycotypus canaliculatus), anemones, crabs (cancer spp.), and burrowing species. The vertebrates included in the dominant benthic community were skates, silver hake, and red hake. The density of the dominant benthic animals found in the VW1 Study Area and Control Area were similar in both seasons except for whelk and squid, which had higher densities in the Control Area in the fall compared to the summer. Most of the taxa recorded as present or absent in a quadrat were observed similarly per station in the VW1 Study and Control Area during the summer and fall surveys. However, holes (burrowing species) were observed more in the Control Area in the fall than in the summer where they were observed more in the VW1 Study Area. Overall, a reduction in some species was observed in the deeper waters of the VW1 Study Area between the summer and the fall in 2023. The confidence intervals associated with the estimates of dominant benthic megafauna prevalence and the ability to detect significant differences show this sampling intensity is adequate for statistical comparison of variance between study and control sites over time.
The drop camera survey results indicated the substrates in the VW1 Study Area and Control Area were dominated by sand with sparse gravel in both the summer and fall in 2023; no cobble or boulders were observed. The benthic communities in the VW1 Study Area and Control Area were most like each other, compared to the selected broader control regions of the US Atlantic OCS in 2023. Benthic communities and substrates became more similar from 2022 to 2023 in the VW1 Study Area and Control Area. The similarity of broader control areas (BCAs) to the VW1 Study Area decreased with increasing distance between the areas. The substrate within designated lobster trap survey aliquots was also assessed by the drop camera and was mostly composed of sand with some sparse gravel in both the summer and fall surveys.