attach to a stable surface. Sedimentary environments are inhabited by animals 

 (e.g., clams and worms) that burrow into the substratum. 



Water currents supply food to the benthos by transporting phytoplankton or 

 detritus. They likewise supply respiratory gases, remove some waste material, 

 and act as a dispersing medium for pelagic larvae. Water areas that have 

 curents have relatively high productivity, probably because of the increased 

 food supply (i.e., more phytoplankton passing by). Large numbers of mussels 

 and associated animals usually are found in these high energy areas. 



Relatively high summer temperatures in areas exposed during low tide sometimes 

 cause desiccation, particularly if strong winds are blowing. Ice formation 

 (see "Climatology" above) sometimes suffocate, dislodge, freeze, or displace 

 benthic animals. Some intertidal animals (clams and worms) survive short 

 periods of freezing. 



Fog and sunlight have opposite effects. Since areas facing south receive more 

 solar energy than those facing north, they are likely to be warmer and drier. 

 Heavy fog (see "Climatology" above) sometimes protects animals from 

 desiccation. 



Waves are a factor in determing the penetration of animals into the intertidal 

 subsystem. During periods of heavy waves, areas higher in the intertidal 

 subsystem are wetter than during calm seas (see "Climatology" above and 

 "Introduction to Subtidal and Intertidal Subsystems," below). Waves also 

 carry floating debris which can grind across the shore and dislodge animals. 



The physical nature of the bottom influences the distribution and abundance of 

 animals. For example, benthos that live in intertidal sediments are protected 

 somewhat from desiccation because sediments with finer consistencies (see 

 table 5-3) retain more water in their interstitial spaces at low tide. 

 Cracks, crevices, undersides of rocks, and tidepools also are areas that are 

 less subject to drying. These areas support more diverse animal life than the 

 more exposed surfaces. 



The angle of a beach-like shoreline determines not only how far up the beach a 

 wave will surge before its energy is dissipated but also how quickly the water 

 will drain from it. The water drains off flat, wide, sandy or muddy shores 

 very slowly and this lessens the threat of desiccation. Tidal area also 

 affects animal abundance and distribution. Large tides in the northeastern 

 coastal region of the characterization area (see "Hydrography," page 4-11 in 

 chapter 4) create larger intertidal zones and potentially higher benthic 

 diversity than those in southwestern coastal Maine. 



Decomposers 



Temperature strongly influences microbial processes. Even though bacteria 

 have been shown to function at 32 F (0 C; Ingraham 1962), their growth and 

 metabolic activity at low temperatures is extremely slow. Seasonal cycles of 

 microbial activity are pronounced, with most of the activity occurring during 

 spring, summer, and fall. The largest phytoplankton populations usually occur 

 in spring but the abundance of decomposers peaks somewhat later (Novitsky and 

 Passman, unpublished ) . Bacterial and fungal decomposers generally are able to 

 function at lower temperatures than phytoplankton. 



5-72 



