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peat mats, and although they change the chemistry and biological 

 components of the sediments (Orth, 1973, 1977), the time to create an 

 eelgrass habitat after initial colonization is shorter than the time to 

 create a mature salt marsh community. Furthermore, the range of 

 habitats that eelgrass can colonize is more diverse and expansive than 

 the habitats available to salt marshes. Some eelgrass beds are seasonal 

 or may appear on marginal habitat only intermittently. 



Given these characteristics of eelgrass beds, the rr.ain priority in 

 regulating physical disturbances should be to prevent alterations to the 

 environment that permanently eliminates eelgrass habitat. Dredging and 

 construction in shallow, poorly flushed bays is especially critical 

 because water transparency in these areas is usually poor, and channels 

 dredged for boats are often so deep and so disturbed that eelgrass can 

 never grow there, and habitat area is lost. Construction of a single 

 private boat channel may result in the removal of only 5% or less of 

 existing eelgrass cover in a bay, but permitting channels to be dredged 

 to every private dock may result in intollerably large losses. 



Small physical disturbances like eelgrass removal during shellfish 

 harvesting with rakes or tongs are probably unimportant for bed survival 

 under low intensity (Costa, 1988, and in prep.), but high intensity 

 shellfishing efforts, or continued dredging from boats can remove large 

 areas of eelgrass beds, as well as increase sediment resuspension and 

 decrease water transparency. 



Past declines of eelgrass due to physical removal, however, have 

 been less important in Buzzards Bay as a whole, than losses due to 

 general declines in water quality. This is understandable because 



