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time of eelgrass populations impacted by disturbances of different scale 

 and intensity. Because the effects of the wasting disease were so 

 longlasting, and because new outbreaks of the disease have been 

 reported, I also reassess the causes and impact of the wasting disease 

 in Buzzards Bay. In particular I examine the relevance of the 

 temperature hypothesis to this and earlier declines in eelgrass 

 populations. 



I have documented changes in eelgrass abundance from aerial 

 photographs, written reports, old charts, observations of local 

 residents, and in a few cases, sediment cores. This approach has been 

 used elsewhere, most notably in Chesapeake Bay, where the loss of 

 eelgrass and other submerged macrophytes in recent years has been 

 documented (Brush and Davis, 1984; Davis, 1985, Orth and Moore, 1983b). 

 I have based my interpretation of the historical record on factors that 

 limit eelgrass distribution and the local history of natural and human 

 disturbances. 



Factors limiting eelgrass distribution 



Eelgrass may be absent from an area because of factors that 

 prevent growth, or because eelgrass has not recovered from disease or 

 other disturbance. The most important factor limiting the geographic 

 distribution of eelgrass is light (Dennison, 1987; Wetzel and Penhale, 

 1983; Sand-Jensen and Borum, 1983). In clear temperate waters, eelgrass 

 grows to 11 m MLW or more, but to less then 1 m MLW in some turbid or 

 enriched bays {Sand-Jensen and Borum, 1983). The deepest reported 

 growth of eelgrass was reported by divers at 45 m in Southern California 



