Abstract
The Bureau of Ocean Energy Management (BOEM) is responsible for oversight and management of the development of offshore energy resources on the outer continental shelf (OCS). A large proportion of the Atlantic OCS blocks deemed likely suitable for energy development is located offshore of North Carolina (NC). Prior to making OCS blocks available for lease, BOEM must satisfy criteria of the Outer Continental Shelf Lands Act, of which Section 1346 mandates the conduct of environmental and socioeconomic studies to assess and manage any environmental impacts on the human, marine, and coastal environments anticipated by construction, development, or operational activities. Offshore energy development, such as installing wind turbine infrastructure and using seismic surveys to explore for oil and gas deposits, introduces noise to the marine environment. Knowledge of how these noises influence fish in their natural environments is limited but understanding possible impacts has important management implications (Popper and Hastings 2009, Popper et al. 2014, Nowacek et al. 2015). Hardbottom reefs that occur on the NC continental shelf support a diverse community of fishes and present an opportunity to test how underwater sound affects reef fish. These hardbottom reefs are defined as Essential Fish Habitat (EFH) by the Magnusson-Stevens Fisheries Conservation and Management Act (1996) because they function as nursery, foraging, and spawning grounds, as well as refuge and nearshore connectivity corridors for fishery species (Deaton et al. 2010). Hardbottom reefs include natural hard substrate of exposed rock and consolidated sediments, as well as architecturally unique man-made structures, such as shipwrecks and artificial reefs. Natural reefs include flat pavements, rubble fields, and substantial ledge systems with up to several meters of vertical relief that are subject to dramatic state changes due to sediment dynamics and other physical processes (Riggs et al. 1996, Renaud et al. 1996, 1999). Artificial reefs and shipwrecks vary in architecture, as these man-made structures range from piled concrete pipes to large sunken ships. There is a particularly high concentration of shipwrecks in NC coastal waters, which are commonly referred to as the ‘Graveyard of the Atlantic,’ because they form the resting grounds for thousands of shipwrecks from the past 500 years that were casualties of changing barrier island geomorphology, as well as war (Stick 1989). In addition to shipwrecks, the state of NC intentionally sinks man-made structures, such as ships, bridge rubble, airplanes, boxcars, concrete pipes, and numerous other items to enhance habitat for fish and invertebrates as part of the NC Artificial Reef Program (North Carolina Department of Natural Resources and Community Development - Division of Marine Fisheries 1988).
Natural hardbottom and artificial reefs, henceforth jointly referred to as hardbottom or temperate reefs, serve as living resources because they, with the exception of shipwrecks, form federally designated EFH for reef associated fishes, as well as habitat for invertebrates and macroalgae. These reefs draw recreational and commercial fishers, as well as divers to these areas (Parker Jr. 1990, Parker Jr. and Dixon 1998, Whitfield et al. 2014). Fish in the snapper-grouper complex that use hardbottom are of particular concern because of their recreational and commercial value and their depressed numbers for several exploited populations in the region (Deaton et al., 2010). Benthic invertebrates and macroalgae, where they occur, may provide important biogenic habitat structure and prey for fishes on hardbottom (Peckol and Searles 1983, 1984, Renaud et al. 1997, 1999). Temperate reefs of NC are not only ecologically valuable but are also important to coastal
economies and cultures.