Inventory of Physical and Benthic Habitats and Ocean Resources within the Nearshore Boundary of Assateague Island National Seashore

Wells, Darlene; Conkwright, Robert; Ortt, Richard; Van Ryswick, Stephen; Younger, Richard

In order to obtain basic information about the shallow marine environment within the boundary of Assateague Island National Seashore (ASIS), the Seashore contracted the Maryland Geological Survey (MGS) and Versar, Inc. to conduct remote sensing surveys, sediment and benthic sampling along the entire length of Assateague Island. The geophysical and biological data from this project will provide baseline marine information that ASIS can use to identify critical benthic habitat locations. This information will be used to effectively manage these sensitive areas and protect them from destructive commercial fishing practices, and justify these restrictions to the public. The primary objective of this project is to create baseline inventories of submerged marine resources within and immediately adjacent to the Seashore boundary, in order to answer the following questions: 1. What are the types, locations, and extent of subaqueous sediment types and benthic habitats (including gravel and peat outcrops, sand shoals, hard bottom features, and other benthic habitat classifications)? 2. What is the existing bathymetry of the Seashore’s shoreface and nearshore areas, and where are the major geomorphic features (such as shoals and shore attached-bars)? 3. What is the character of the shallow sub-bottom, such as shoreface sand thickness and locations and widths of relict inlets? 4. What benthic communities are found in the nearshore areas of the Seashore, and how do these benthic communities vary between locations and habitat types? The study area includes the nearshore area extending out to 1 km offshore, along the 58-km Assateague Island shoreline. This offshore distance encompasses the jurisdictional boundary of ASIS and major adjoining bathymetric features indicated by regional surveys done farther offshore. A significant portion of project area lies within the closure depth of the nearshore profile, and thus is considered highly dynamic. The Maryland Geological Survey (MGS), part of the collaborative team, conducted remote sensing surveys with ground truthing to address the geological and geophysical task components in fulfilling objectives 1, 2 and 3 for this project. The surveys were conducted during May and June of 2011. The data provided by these surveys were used to select sites to sample for benthic invertebrate inventory (Objectives 4), which was conducted by Versar, Inc. in the fall of 2011. The remote sensing surveys were done onboard the DNR R/V Kerhin. MGS collected sidescan sonar, seismic, bathymetric sounding and magnetometer data, as well as sediment samples and underwater videos. Track lines (boat path) for the surveys ran parallel to the shoreline. Primary instrumentation included: • Side scan sonar - EdgeTech 4200 FS @ 120 and 410 kHz • Seismic profiler – EdgeTech SB 216 @ 2 – 16 kHz, 10ms • Seabed classification system - QuesterTangent QTC 5.5 VIEW @ 200 kHz • Magnetometer – Geometric 881 Marine Magnetometer • Echosounder - Dual Frequency Transducer 200 kHz and 28 kHz with 4 degree beam angle The geophysical framework for the habitat classification are presented in terms of the Coastal and Marine Ecological Classification System (CMECS). Eventually this information will be incorporated with the biological information for resource management by the NPS.

Inventory of Physical and Benthic Habitats and Ocean Resources within the Nearshore Boundary of Assateague Island National Seashore

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