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Ecosystem Background
Ecosystem Background

Marine ecosystems are complex and dynamic assemblages of co-evolved species. In this study, we analyzed the distributions and movements of prominent marine wildlife species, and examined the influence of environmental factors (such as productivity, water depth, and salinity) on these distributions.

Download Mid-Atlantic Wildlife Studies: Distribution and Abundance of Wildlife along the Eastern Seaboard 2012-2014. This 32-page summary publication explores aspects of the mid-Atlantic ecosystem; describes our survey and analytical approaches; and presents a range of results, featuring several case studies on specific species or phenomena.

The Executive Summary for the technical report is also available here.

 

Regional Importance

The mid-Atlantic region is used by a broad range of marine wildlife species across the entire annual cycle, including several dozen species that are listed as threatened or endangered at the federal level or state level. The region is important to these species in part because of a relatively high level of primary productivity and because of the area’s central location in a major migratory corridor.
 

Productivity

The region’s highest levels of chlorophyll—a measure of primary productivity—are typically found near the mouths of Delaware Bay and Chesapeake Bay. Year-round mixing of saline and fresh waters in these areas, combined with strong tidal currents, lead to increased primary productivity. Nutrient- and phytoplankton-rich waters flow from these bays and are carried south by the Labrador Current.

Sunlight penetrates a relatively high proportion of the water column in shallow coastal waters, driving phytoplankton growth. The zooplankton species that feed on phytoplankton become food for larger predators, such as small fishes. The Mid-Atlantic Bight is generally rich in forage fish—small, schooling fishes that feed piscivorous predators. The presence of forage fish indicates the productivity of the region; they are likely responsible, in part, for the relatively high density of predators found in the mid-Atlantic.

 

Geography and Seasonal Variation

The Mid-Atlantic Bight stretches from Cape Cod to Cape Hatteras and is characterized by gently sloping, sandy-bottomed continental shelf. The shelf extends to up to 150 km offshore, where waters can reach 200 m deep. Beyond the shelf edge, the continental slope rapidly descends to around 3,000 m.

Most of the mid-Atlantic coastal region is bathed in the cool arctic waters introduced by the Labrador Current flowing down the east coast. Around Cape Hatteras, the cool waters collide with the warmer waters of the Gulf Stream. The region experiences a strong seasonal temperature cycle, with sea surface temperatures spanning 3-30° C. There is also a wide range of salinity, with large volumes of fresh water entering the shelf from the Hudson Estuary, Delaware Bay, and Chesapeake Bay.

 

Regional Context

Our observations of community composition, distribution patterns, movement timing, and behaviors all vary somewhat from other recent baseline studies along the eastern seaboard. This is to be expected based on the different latitudes, bathymetry, and other characteristics of these areas. However, several other studies have found a similar pattern of high overall abundance and species diversity in shallow water areas (which in many cases are coincident with areas closer to shore, though not always).

In several cases, results from these studies have been used to identify areas of high biodiversity and priorities for conservation, ultimately influencing the choice of lease sites for offshore wind development.

 

For More Information

For more information, see Chapters 1 and 2 in the technical report.
 

References

  • www.boem.gov/BOEM-Newsroom/Press-Releases/2012/press05302012.aspx
  • Geo-Marine Inc., 2010. Ocean Wind Power Ecological Baseline Studies Final Report - Volume 2: Avian Studies, Report by Geo-Marine Inc and New Jersey Department of Environmental Protection Office of Science. 
  • Paton, P., Winiarski, K., Trocki, C., McWilliams, S., 2010. Spatial Distribution, Abundance and Flight Ecology of Birds in Nearshore and Offshore Waters in Rhode Island, Report by University of Rhode Island. 
  • Rhode Island Coastal Resources Management Council, 2013. Chapter 11 : The Policies of the Ocean SAMP, in: Rhode Island Ocean Special Area Management Plan (Ocean SAMP), Volume 1. Wakefield, Rhode Island, pp. 1–73.
 
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