go to: USFWS Gulf of Maine Watershed Habitat Analysis

We used substrate information for modeling habitats for coastal fishes, the horseshoe crab, and waterfowl. Available digital information identified intertidal and subtidal benthic sediments such as rock, gravel, sand, and mud. These form the structure to which invertebrates may attach, or into which they may burrow, and which can offer cover or spawning habitat for a number of fish species.

Primary information sources were Maine Surficial Geology (Bardhardt et al. 1996), USGS Surficial Sediment Polygons for Greater Gulf of Maine (Poppe et al. 1989), and a Map of Sedimentary Environments of Cape Cod Bay (Knebel et al. 1996). The data from the latter 2 coverages and other supplementary information were re-coded to correspond to classes of the surficial geology coverage. More detailed inshore features were derived from photo-interpreted information: Maine Geologic Survey Coastal Geologic Environments, USFWS National Wetlands Inventory, and detailed surveys of Great Bay (Armstrong 1974, Capuzzo and Anderson 1973, displayed in Nichols 1993). Digital data was not available for the upper St. Croix River or Merrimac River; these were screen-digitized from NOAA nautical chart notation; other slivers (from discrepancies between larger and smaller scale sources) were filled in by expanding the data from the higher resolution sources. A 30 m cell size grid was constructed with the following substrate classes:


Value Descriptive

0 land

1 gravel

2 gravel/mud

3 gravel/rock

4 gravel/sand

5 mud

6 mud/gravel

7 mud/rock

8 mud/sand

9 rock

10 rock/gravel

11 rock/mud

12 rock/sand

13 sand

14 sand/gravel

15 sand/mud

16 sand/rock


Armstrong, P. 1974. Copper, zinc, chromium, lead, and cadmium in the unconsolidated sediments of Great Bay Estuary, New Hampshire. M.S. Thesis. University of New Hampshire, Durham. 85p.

Barnhardt, W.A., D.F. Belknap, A.R. Kelley, J.T. Kelley and S.M. Dickson. 1996. Surficial Geology of the Maine Inner Continental Shelf. Digital Data provided through Maine Office of GIS.

Capuzzo, J.M. and F.E. Anderson. 1973. The impact of chromium accumulation in an estuarine environment. Ph.D. Dissertation. University of New Hampshire, Durham. 170p.

Knebel, H.J., R.R. Rendigs, J.H. List and R.P. Signell. 1996. Sea floor environments in Cape Cod Bay, a large coastal embayment: Marine Geology, v. 133, p. 11-33.

Nichols, M.M. 1993. National Estuarine Inventory: Supplement. Sediment Characterization of North Atlantic Systems, New England. Coastal Resources Foundation, Gloucester VA 23061 33p.

Poppe, L.J., J.S. Schlee, B. Butman and C.M. Lane. 1989. Map showing distribution of surficial sediment, Gulf of Maine and Georges Bank. Miscellaneous Investigations Series Map, I-1986-A, 1 sheet.