National Park Service

Northeast Coastal and Barrier Network (NCBN)

Inventory & Monitoring at
Assateague Island National Seashore

Wild horses of Assateague Island National Seashore
Wild horses of Assateague Island National Seashore

Resource Briefs


Monitoring Products

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NCBN park map
Location of Assateague Island National Seashore in the Northeast Coastal and Barrier Network. Click for larger image.

Assateague encompasses more than 19,000 hectares, more than half of which consists of oceanic and estuarine waters surrounding the Island. Located within a three hour drive of the Washington/Baltimore/Philadelphia metropolitan area, the National Seashore hosts more than 1.8 million visitors every year. Assateague Island consists of three major public areas. Approximately 26,000 acres of this island are located in Maryland. The state of Maryland manages a section of the northern part of the island called Assateague State Park and the NPS manages the remainder of the Maryland portion of the island as Assateague Island National Seashore. The Virginia section of the island is managed by the U.S. Fish and Wildlife Service as Chincoteague National Wildlife Refuge. The northern 10 km of ASIS called the "north end", is managed as a primitive area where public access is limited to foot and boat-in traffic. Vehicle traffic is restricted to NPS beach patrols and authorized research activities. The 3.2 km section of the island immediately south of Assateague State Park is managed by ASIS as a developed recreational area and includes campgrounds, day-use facilities and interpretive trails. The 19 km section south of the developed area to the MD/VA state line is managed as a primitive and traditional recreation area, which permits off-road vehicle (ORV) use, back-country camping and hunting. Off-road vehicle use is restricted to the ocean beach and other designated trails west of the ocean beach.

The park's natural resources include a diverse assemblage of aquatic and terrestrial wildlife, including the free-roaming feral horses for which Assateague is famous. The vegetation communities, geological features and physical processes reflect the complexity of the land/sea interface along the Mid-Atlantic coast. The indigenous plant communities at ASIS reflect the adaptive extremes necessary for survival on a barrier island, where exposure to salt spray, lack of freshwater, and shifting sands create a harsh and dynamic environment.

Changing patterns in land use within the watershed of the coastal lagoons of ASIS threatens park water quality and biotic systems. Although park waters are considered to be in "good" condition at present, nearby estuaries with more extensive development are significantly degraded, primarily due to nutrient enrichment from anthropogenic nutrient inputs. With a projected growth rate of >20% in land development over the next 25 years, the potential for similar degradation of park waters is considered high. The ability to document changing estuarine conditions, including trends in submerged aquatic vegetation, fish, and benthic invertebrate community composition, is considered crucial towards influencing and mitigating local/regional development.

Since 1935, the federal navigation channel at Ocean City, MD has disrupted the natural sediment supply to Assateague Island, resulting in wholesale physical and biological changes. A comprehensive mitigation program has been developed involving both short term (one-time beach nourishment) and long term components (sediment bypassing). Implementation and management of these programs will require the ability tocontinuously evaluate island conditions, (including changes in the distribution and abundance of rare species), relevant physical processes, and the effects of restoration actions in order to optimize outcomes and ensure maximum compatibility with management objectives.

Portions of ASIS provide suitable habitat for a variety of state and federally listed species, both plants and animals. The known and perceived threats to these species vary in intensity, and include a range of causative factors such as; recreational activities, disruptions to natural coastal processes, and interactions with both native and non-native species. Certain high-profile species such as the piping plover are being actively managed, but others remain poorly understood and are largely ignored. In particular, rare resident plant and insect species, and transient bird species lack appropriate levels of documentation (presence/absence, distribution and abundance), threat mitigation, and assessment.

Non-native plant (especially Phragmites and Asiatic sand sedge) and animal species (feral horses, sika deer, nutria) present on Assateague Island are known to be having a significant impact on several of the primary vegetation communities occurring within the park. Documented effects include reduced health and reproductive capacity of certain key plant species, changes in species abundance and community composition, and loss of faunal biodiversity. The development of long-term management programs to mitigate the impacts of these species requires a variety of basic life history, distribution, and relative abundance data to guide decision-making and program implementation/evaluation. The following list include some of Assateague’s current natural resource management issues.

  • Estuarine Water Quality and its affect on the distribution and abundance of submerged aquatic vegetation (SAV's).
  • Altered coastal processes and its affects on early successional, disturbance-driven beach habitat, and associated plant/animals.
  • Exotic Species and their impacts on native species and rare/sensitive habitats
  • Recreational Activities and their impacts on migratory shorebirds using ocean beach as "stopover habitat" as well as the ocean nearshore benthic macroinvertebrate community.
  • Adjacent land use changes and associated water quality issues.

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Last Updated: September 22, 2017 Contact Webmaster