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Chapter 4 



Historical Changes in eelgrass {Zostera marina L.) abundance in Buzzards 

 Bay: Long term patterns and twelve case histories 



Introduction 



During the 1930's, the "wasting disease" destroyed virtually all 

 eelgrass {Zostera marina L.) along the coasts of eastern North America 

 and Europe (Rasmussen, 1977) . Recovery by eelgrass populations from 

 this catastrophic disturbance was slow and took 30 or more years in most 

 areas (den Hartog, 1987) . Superimposed on this long term cycle of 

 collapse and recovery are more recent, local, short and long-term losses 

 of eelgrass due to declining water quality, storms, dredging, 

 shellf ishing, and other sources (Orth and Moore, 1983b, Kemp et al., 

 1983; Thayer et al., 1975). Too often, documentation of declines and 

 recolonization of eelgrass have been qualitative and this has hindered 

 an understanding of the mechanisms or relative importance of different 

 disturbances on eelgrass distribution and abundance. To understand or 

 predict the impact of these disturbances, it is necessary to have data 

 of present-day eelgrass cover, historical changes, or data from 

 comparable areas. 



The main objective of this paper is to document long-term changes 

 in eelgrass abundance in areas of Buzzards Bay that have had different 

 histories of anthropogenic and natural disturbances. From this 

 information, inferences can be made on the relative impact and return 



