expansion occurred during the 1950 's and 1960's. Most available 

 substrate was saturated by the 1980' s, but eelgrass is still increasing 

 in some areas. 



Superimposed on the regional pattern of catastrophic decline and 

 gradual recovery are local changes in eelgrass abundance driven by 

 anthropogenic and natural disturbances. Hurricanes, ice scour, and 

 freezing periodically destroy eelgrass beds in shallow bays or exposed 

 coasts. Eelgrass beds generally recover from these events in 3 to 10 

 years. 



In contrast, more permanent losses of eelgrass habitat have 

 resulted from human perturbation. Considerable amounts of eelgrass 

 habitat areas have been permanently destroyed because of construction or 

 dredging nearshore. Greater and more widespread losses of eelgrass have 

 resulted from water quality decline. For example, eelgrass populations 

 never recovered from the wasting disease or showed new declines in 

 recent years in some poorly flushed, developed bays, with evident or 

 documented declining water quality (New Bedford; Apponaganset Bay, So 

 Dartmouth; Little Bay, Fairhaven; Wareham River; upper Westport Rivers, 

 areas of Sippican Harbor, Marion; and Waquoit Bay on Cape Cod). 



In most of these areas, nutrient loading or sediment resuspension 

 from boat activity are implicated as the cause of eelgrass decline. 

 Because the distribution of eelgrass is light limited, eelgrass beds may 

 disappear in enriched areas because increased algal epiphytes and 

 phytoplankton absorb light reaching eelgrass leaves, slowing eelgrass 

 growth or causing death. Sediment resuspension, caused by dredging or 

 power boats, contributes to this pattern of declining light availability 



XI 



