Each species has a certain range of tolerance for each of the ecological factors listed above. Animal life cycles are very complex. At different stages in an organism's growth the tolerance ranges can change significantly. Seasonal climate variations cause drastic changes in marine habitats. For instance, in the winter wave energy increases, light decreases, oxygen availibilty increases, and food supply generally diminshes.
Different habitats tend to support different species.
For instance, the high energy evironment of the surf zone and offshore bars supports a completely different fauna that back barrier bays, tidal flats, and channels. Some species, however can occupy a variety of environments but their abundance will vary from place to place. Spisula solidissima . By far the most abundant shell on area beaches. Ensis directus .