The "wrack line" forms at the uppermost tide line of the marine intertidal gravel/sand beach. Here marine algae, eelgrass, shells, and other debris, are deposited at high tide. Since plants and seaweeds cannot grow in the unstable wash zone of the beach, numerous shorebirds and other animals rely on the wrack line as a food source.
Maintain dynamic beach and dune processes, prevent recreational overuse (driving on the beach is particularly destructive) and encourage the public to carry away all of their trash. Ensure connectivity landward to maritime beaches and dunes, and offshore toward the open ocean that allows plants and animals to freely move between these habitats. Remove shoreline armoring to increase overland sediment input; improve water quality by reducing or eliminating sewer and stormwater discharge and pesticide application; restore tidal regime by removing culverts, dikes, and impoundments, plugging ditches, and replacing static flow restriction devices with those that are calibrated for local tidal hydrology.
Minimize or eliminate hardened shoreline and avoid dumping dredge spoil onto marine intertidal beaches. This community is best protected as part of a larger ocean shoreline ecosystem. Protected areas should encompass nearshore marine communities, such as marine rocky intertidal and marine eelgrass meadows if present, as well as onshore maritime communities, such as maritime beach, dunes, and bluffs if present. Connectivity should be maintained in both directions, on- and offshore. Connectivity between these habitats is important not only for nutrient flow and seed dispersal, but also for animals that move between them seasonally. Similarly, fragmentation of linear beaches should be avoided. Bisecting roads and developments significantly disrupt biota and alter physical beach processes.
This community ranges along the Atlantic Coast from southern Maine to North Carolina
The marine intertidal gravel/sand beach is a community washed by rough, high-energy waves, with sand or gravel substrates that are well-drained at low tide. These areas are subject to high fluctuations in salinity and moisture, but generally the sand is noticeably wetter than the adjacent maritime beach sand. A relatively low diversity community, it is perhaps best characterized by the benthic invertebrate fauna including polychaetes (Spiophanes bombyx, Pygospio elegans, Clymenella torquata, Scoloplos fragilis, Nephtys incisa), amphipods (Protohaustorius deichmannae, Acantho¬haustorius millsi), and mole crabs (Emerita spp.). This community provides feeding grounds for migrant shorebirds, such as sanderling (Calidris alba) and semipalmated plover (Charadrius semipalmatus), and breeding shorebirds, such as piping plover (Charadrius melodus).
These areas are subject to high fluctuations in salinity and moisture, but generally the sand is noticeably wetter than the adjacent maritime beach sand and located below the wrack line.
Known examples of this community have been found at elevations between -1 feet and 9 feet.
Marine intertidal gravel/sand beaches are scenic year-round! Enjoy a visit in the middle of the summer when the ocean is warm for swimming.
amphipod (Acantho¬haustorius millsi)
amphipod (Protohaustorius deichmannae)
mole crabs (Emerita spp.).
polychaete (Clymenella torquata)
polychaete (Nephtys incisa)
polychaete (Pygospio elegans)
polychaete (Scoloplos fragilis)
polychaete (Spiophanes bombyx)
This figure helps visualize the structure and "look" or "feel" of a typical Marine Intertidal Gravel/Sand Beach. Each bar represents the amount of "coverage" for all the species growing at that height. Because layers overlap (shrubs may grow under trees, for example), the shaded regions can add up to more than 100%.
Edinger, G. J., A. L. Feldmann, T. G. Howard, J. J. Schmid, E. Eastman, E. Largay, and L. A. Sneddon. 2008. Vegetation Classification and Mapping at Gateway National Recreation Area. Technical Report NPS/NER/NRTR—2008/107. National Park Service. Northeast Region. Philadelphia, PA.
Edinger, G. J., D. J. Evans, S. Gebauer, T. G. Howard, D. M. Hunt, and A. M. Olivero (editors). 2014. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke’s Ecological Communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation, Albany, NY. http://www.dec.ny.gov/docs/wildlife_pdf/ecocomm2014.pdf
Edinger, G. J., E. S. Runnells, and T. G. Howard. 2019. Montauk Point, Marine Rocky Intertidal Monitoring, Year One 2018 Baseline Results. New York Natural Heritage Program, Albany, NY.
Edinger, Gregory J., D.J. Evans, Shane Gebauer, Timothy G. Howard, David M. Hunt, and Adele M. Olivero (editors). 2002. Ecological Communities of New York State. Second Edition. A revised and expanded edition of Carol Reschke's Ecological Communities of New York State. (Draft for review). New York Natural Heritage Program, New York State Department of Environmental Conservation. Albany, NY. 136 pp.
New York Natural Heritage Program. 2020. New York Natural Heritage Program Databases. Albany, NY.
Reschke, Carol. 1990. Ecological communities of New York State. New York Natural Heritage Program, New York State Department of Environmental Conservation. Latham, NY. 96 pp. plus xi.
This guide was authored by: Gregory J. Edinger
Information for this guide was last updated on: May 15, 2020
Please cite this page as:
New York Natural Heritage Program. 2020. Online Conservation Guide for Marine intertidal gravel/sand beach. Available from: https://guides.nynhp.org/marine-intertidal-gravelsand-beach/. Accessed June 7, 2020.