requiring warmer temperatures may not be able to survive in abundance in 

 regions 5 and 6. 



Fog. Fog affects the biota by insulating the intertidal organisms from 

 desiccation and allowing less hardy (less adaptable) species to survive in low 

 intertidal areas. Eastport has more fog (1 day in 3) than Portland (1 day in 

 5), which may be one reason why the Cobscook Bay intertidal fauna is richer 

 than that of Portland. 



Atmospheric pressure . Atmospheric "highs" and "lows" cause temporary 

 changes in sea level and may affect the water levels or circulation in 

 estuaries temporarily, through coastal storms or ice formation and movement. 

 The most extreme climatic variations that occur on the Maine coast are 

 extratropical cyclones producing "northeasters," and tropical cyclones 

 producing "tropical storms" and hurricanes. Coastal flooding, habitat 

 destruction, and alteration are often associated with these storms. Mass 

 mortalities of animals and "uprooting" of macroalgae may occur. The flushing 

 action associated with flooding is particularly important in redistributing 

 detritus from the high intertidal area (emergent wetlands and wrack area) and 

 terrestrial system into the marine system. Flooding can also distribute 

 pollutants (e.g., oil) into the high intertidal zone, where emergent wetlands 

 and wrack communities may be impacted. 



Ice formation sometimes has major effects on biota, especially estuarine 

 invertebrates and waterbirds. Ice forms along the shore in protected areas 

 (mostly estuaries) for varying lengths of time each winter. Ice movement may 

 dislodge species such as clams and other burrowing invertebrates. Under 

 extreme conditions, the water can freeze all the way to the bottom and kill 

 all the biota. During years of extensive ice formation, large areas of 

 shallow substratum, containing biota, may be transported in ice rafts. 

 Disturbances during winter (clamming) dislodge animals, making them more 

 susceptible to icing and freezing temperatures. 



The freezing of mudflats may harm waterbirds that traditionally inhabit 

 specific flats in winter. Long periods of icing may result in the starvation 

 of some birds. Where tidal fluctuations are greatest (in eastern Maine, 

 especially Cobscook Bay; region 6), icing is less likely to occur at a given 

 winter temperature because of the relatively forceful tidal currents. 



Additional information on climate parameters is found in chapter 2, under 

 "Climate," page 2-9 . 



BIOTA 



The living components of estuaries may be divided into producers, consumers, 

 and decomposers, based on their function in the food web. These groups, 

 their habitats, and their roles in the estuarine system are discussed below. 

 Communities of organisms found in the specific estuarine subsystem and classes 

 are described. Food web and energy flow interactions between these components 

 are described in subsequent sections of this chapter. 



5-39 



10-80 



