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) Lease Area OCS-A 0501 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 Lease Area OCS-A 0501 (termed 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 2021 and May 2022 using a commercial scallop fishing vessel to deploy the sampling pyramid.
The benthic community of the VW1 Study Area and Control Area in 2021 and 2022 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 was similar in both years except for hermit crabs, which had a higher density in the VW1 Study Area in 2021 and a higher density in the Control Area in 2022. By contrast, most of the taxa recorded as present or absent in a quadrat were observed in more quadrats per station in the VW1 Study Area in 2021 and 2022 (aside from bryozoans, hydrozoans, and anemones). Overall, there was an increase in the amount and frequency of all animal taxa from 2021 to 2022. 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 in 2021 with sparse gravel; no cobble or boulders were observed. By 2022, the substrates were still dominated by sand, but some gravel, cobble, and boulders were observed. The benthic community of 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 both 2021 and 2022. Benthic communities and substrates became more similar from 2021 to 2022 in the VW1 Study Area and Control Area. The similarity of control areas to the VW1 Study Area decreased within increasing distance between the areas. The substrate within designated lobster trap survey aliquots was also assessed by the drop camera and was entirely comprised of sand in 2021 and sand, gravel, or cobble in 2022.