ABIOTIC FEATURES 



Abiotic factors are forcing functions that influence the biotic components of 

 the ecosystem. This section addresses the geology, hydrography, and climate 

 of nearshore areas. 



Geology 



Geology has a primary role in shaping the ecology of the marine system. The 

 biological communities that comprise the marine system are often related to 

 substrate types. NWI categories are often defined by substratum 

 characteristics (figure 4-2) . Since the marine system is composed of many 

 varieties of deposits, the descriptions of the geologic substrata are found in 

 the class level discussions below. The size distribution of substratum 

 particles by habitat is given in figure 4-3. The composition and formation of 

 the substrata in the marine system, and the primary abiotic forces affecting 

 it, are summarized in table 4-2. A general discussion of coastal marine 

 geology is contained in "Geology," page 2-35 in Chapter 2. 



In coastal Maine, human activities may affect the marine system by altering 

 the marine geology and associated erosion and sedimentation rates. Coastal 

 developments in and adjacent to the marine system and dredging and filling are 

 activities that could alter the marine geology. For a discussion of the 

 extent of these activities and their potential impacts, see chapter 3, "Human 

 Impacts on the Ecosystem." 



INTERTIDAL 



BEACH/BAR 



SAND 

 GRAVEL 

 COBBLE 



ROCKY SHORE 



BOULDER 



FLAT 



SUBTIDAL 



SAND 

 MUD 



UNCONSOLIDATED 

 BOTTOM 



AQUATIC BED 



< •- 



^-•- 



-SAND- 



-MUD- 



-KELP BEDS- 



EEL GRASS BEDS- 



Figure 4-3. 



Size distribution of sediment particles in marine habitats of 

 coastal Maine. Dots indicate dominant size; arrows indicate 

 range. 



4-7 



10-80 



