Temperature is important to the survival of intertidal animals. High summer 

 temperatures can create stress in the intertidal zone through desiccation, 

 particularly in combination with wind. Maine's winter temperatures can freeze 

 exposed organisms. Ice formation (see "Climate" above) can suffocate, 

 dislodge, or freeze and displace animals. Some intertidal animals survive 

 being frozen. 



Fog and sunlight have opposite effects. Fog (see "Climate" above) protects 

 animals from desiccation. Areas facing south receive more insolation than 

 those facing north and hence are likely to be drier. 



Reduced salinity may limit the development of invertebrate communities. In 

 areas where streams cross the intertidal zone, or where fresh water seeps in 

 from the water table, lowering salinity, those species that cannot tolerate 

 salinity reduction are excluded. 



Waves influence the penetration of animals into the intertidal zone. When 

 waves are present, higher areas of the intertidal zone are wetted than are 

 wetted during calm seas (see "Climate," above and "Class Level Discussions 

 and Intertidal Subsystems" below). Waves also carry floating debris, such as 

 logs that can grind across the shore and dislodge animals. 



The nature of the substrate influences the distribution and abundance of 

 intertidal animals. Sediments with finer consistencies (see table 4-2) have 

 water remaining in the interstitial spaces at low tide and afford a degree of 

 insulation against drying to intertidal animals. Cracks, crevices, undersides 

 of rocks and tidepools are also areas that are less subject to drying. These 

 areas support more diverse animal life than exposed surfaces. 



The angle of the shore determines not only how far upwards a wave will surge 

 before its energy is dissipated, but also how quickly water will drain off it. 

 Water drains off flat wide shores very slowly and this lessens the threat of 

 desiccation. 



The area of tides also affects animal abundance and distribution. Large 

 tides, as are found in the eastern region of the coastal zone, are important 

 because they create large intertidal zones, which are potentially more diverse 

 than smaller intertidal zones. 



Squid . Little is known about the effects of physical and biogeochemical 

 factors on squid. The two species (flying squid and long-finned squid) found 

 in waters of coastal Maine have northern and southern affinities, 

 respectively. The zoogeographic boundary described above (at region A) 

 appears to be applicable for these invertebrate species also. 



Finfish, birds, and marine mammals . Interactions of finfish, waterbirds, 

 and marine mammals with physical and biogeochemical factors are described in 

 chapter 11, "Fishes," chapter 17, "Waterbirds," and chapter 13, "Marine 

 Mammals ." 



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 activity 



4-57 



10-80 



