Information from the NWI on the location and extent of marine habitats is 

 incorporated. Habitat units are mapped at a minimum resolution of about 3 to 

 5 acres (1 to 2 ha) in the NWI (personal communication from R. W. Tiner, U.S. 

 Fish and Wildlife Service, Newton, MA; June, 1978). Thus, habitat areas 

 smaller than 3 acres (1.2 ha) generally were not mapped. A particular marine 

 habitat may contain more than one marine class and a particular marine class 

 may contain areas of other marine classes smaller than 3 acres. For example, 

 an area mapped as a 5-acre (2 ha) flat may consist of a sand or mud flat 

 surrounded by emergent wetland and rocky shore with an aquatic bed or mussel 

 reef in the lower intertidal area. If each of these habitat types (rocky 

 shore, emergent wetland, reef, and aquatic bed) was 3 to 5 acres (1.2 ha to 2 

 ha) or larger they would be mapped as distinct units. Small-scale variations 

 in abiotic factors affecting marine areas may result in several marine classes 

 being found in the same area. These classes may intergrade into one another, 

 adding to the difficulty of precise classification. The NWI provides the user 

 with data on the distribution of marine habitats in the Maine coastal zone. 

 These data provide a baseline against which the future status of marine 

 habitats can be measured. 



Marine classes identified by the NWI include aquatic bed, unconsolidated 

 bottom, open water, and rocky bottom in the subtidal subsystem; and aquatic 

 bed, beach/bar, flat, reef, and rocky shore in the intertidal subsystem 

 (figure 4-2). Marine classes of rock bottom, unconsolidated bottom, and 

 aquatic bed have been mapped mostly as open water, although a few areas have 

 been designated as unconsolidated bottom; and, as much rock bottom is 

 vegetated (principally by kelp), it is therefore classified as aquatic bed. 



In classifying the intertidal zone, the NWI included the splash zone. An 

 estimated 34% of the rocky intertidal acreage (personal communication from J. 

 A. Topinka, Bigelow Laboratory, West Boothbay Harbor, ME; November, 1979) 

 identified by the NWI is above the zone where macroalgae are found. Other 

 intertidal classes include flats, beach/bars, aquatic beds, and reefs. Flats 

 include both sand and mud flats and stream beds crossing the flats. Beach/bar 

 encompasses cobble, gravel, and sand beaches. Both boulder beaches and 

 bedrock are mapped as rocky shore. Intertidal and subtidal aquatic beds are 

 principally eelgrass on mud sediments. Reefs are composed of mussels and 

 usually are found on mud flats. Since many of these subhabitats (e.g., sand 

 vs. mud) are ecologically distinct they will be addressed separately here. 

 Lack of useful data prevents an in-depth discussion of each subhabitat. 



DISTRIBUTION OF THE MARINE SYSTEM 



The eastern regions of the characterization area (regions 4, 5, and 6) have 

 greater areas of marine waters than those in the west (regions 1, 2, and 3; 

 table 4-1). If the area of water to the 300-foot contour were included 

 (rather than just that area enclosed by headlands as calculated by the NWI), 

 the eastern regions would have an even higher percentage of marine waters. In 

 these regions the 300-foot contour is farther offshore. Part of this 

 discrepancy between regions is due to differences in size. Large bays are 

 encompassed in region 1 (Casco Bay) , region 4 (Penobscot Bay) , region 5 

 (Frenchman Bay and Blue Hill Bay), and region 6 (Cobscook Bay), which account 

 for the high acreage of subtidal and intertidal areas in these regions. 

 Regions 2 and 3 encompass smaller segments of the coast and have more acres of 

 estuarine waters than marine waters. 



4-5 



10-80 



