Submarine canyons are dominant features of the outer continental shelf and slope of the US East coast from Cape Hatteras to the Gulf of Maine. Click image for larger view and image credit.
The Science of Deep-water
Submarine canyons are dominant features of the outer continental shelf and slope of the US East coast from Cape Hatteras to the Gulf of Maine. There are 13 major canyons in the Middle Atlantic Bight (MAB) region, and minor canyons are abundant. The canyons vary in size, shape, and morphological complexity; some were scoured by the flow of rivers during past low sea level periods, but most formed via other erosional processes, such as mud-slides, debris flows, and turbidity currents.
Target study areas
Cutting deeply into the bottom and linking the shelf to the deep sea, canyons are conduits that funnel anthropogenic pollutants, organic carbon, and sediments from shallow to deeper waters. The most southerly of these canyons (just north of Cape Hatteras) occurs in an extremely dynamic and productive area known as “The Point”. The Point has been characterized as one of the hottest fishing spots on the east coast, apparently fueled by upwelling generated by the collision of several major currents over complex bottom topography. Further north, large canyons (e.g., Norfolk, Baltimore, Washington, Hudson, Lydonia) occur at regular intervals.
The geology of these features has been well-studied; however, despite their well-known biological productivity, biological data are quite limited (particularly deeper than 200 m). While there are studies on fishes at The Point and a few of the canyons to the north, there is very little information on the benthic invertebrate communities of the slope. We know that vulnerable and productive habitats such as deep-sea corals and hydrocarbon seeps occur in and around some of these canyons, yet these habitats are poorly explored. The canyons between Cape Hatteras and Cape Cod are less well-known than those further north, and yet these are the subject of potential oil exploration, intensive fisheries, and are possible National Marine Sanctuary (NMS) candidates. Some of the areas around the Mid-Atlantic canyons, have been designated as Essential Fish Habitat by the Fishery Management Councils.
The middle Atlantic includes some of the most historically significant waters in the US. The approaches to Chesapeake and Delaware Bays have a long history of exploration, warfare, commerce, fishing, and recreation, leaving a rich, but poorly understood, repository of cultural material on the seafloor. This diversity and intensity of human activity along the middle Atlantic region has created an important submerged cultural landscape. The ocean floor is marked by fishing vessels (and their gear), warships, military experiments and ammunition, and the remnants of commercial shipping dating back 400 years. While the area is historically significant and archaeologically sensitive, gaps in our knowledge are extensive and much of the reported information about shipwreck locations is incorrect and/or inaccurate.
These canyon ecosystems are important targets of study for the following reasons:
- Canyons are productivity hotspots and support different communities compared with non-canyon habitats; however, there is very little information available on the biology and ecology of the mid-Atlantic canyons.
- These canyons harbor the only known deep-sea coral communities in the mid-Atlantic region.
- An earlier study indicated the presence of a cold seep community in Baltimore Canyon; this is the only known cold seep north of Cape Hatteras, NC.
- The mid-Atlantic canyons have several sites of cultural historical interest, such as shipwrecks and ancient human population centers.
- The canyons and surrounding shelf areas support many valuable fisheries species and are sites of intense recreational and commercial fishing activity.
- Sensitive fauna within the canyons may be impacted by human activities, such as fishing and energy industry activities.
- There is currently little habitat protection in the study canyons; however, the regional fisheries management councils are discussing establishing protection. Establishment of effective marine protection requires good ecological information.
The Mid-Atlantic Deepwater Canyons project is co-funded by the Bureau of Ocean Energy Management (BOEM) and NOAA’s Office of Ocean Exploration and Research (which provides the ship and ROV for research cruises). The project is managed by Continental Shelf Associates, and includes scientific partners from several academic institutions and the US Geological Survey.
Our first research cruise was in June 2011 using the NOAA ship Nancy Foste; the primary objective of this expedition was to conduct multibeam sonar mapping of major canyons and potential shipwreck sites in the study region. This was a successful cruise, which resulted in nearly 1,400 sq. km of high resolution maps of the seafloor, nine new shipwreck targets, 32 hydrographic profiles to describe the water column environment and a shipboard outreach effort to communicate our scientific findings to the public.
Our next research cruise aboard the NOAA ship Nancy Foster this summer will use the Kraken II ROV (University of Connecticut) to conduct video and photo transects, collect samples of invertebrates and fishes for various biological studies, deploy instruments to collect long-term environmental data and survey several archaeological sites. We will have a strong education and public outreach component to the cruise which will enable the public to follow our progress as we explore these little known ecosystems.
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