138 



Today, eelgrass grows as far north in the West Branch as Judy's 

 Island and Upper Spectacle Island on the East Branch. These limits 

 probably do not correspond to the lower limits of salinity tolerance in 

 eelgrass because shellfish such as Mercenaria are found north of these 

 areas (D. Roach, pers. comm.), and eelgrass grew further north in the 

 past (Chapter Four). Instead, the upper limit estuarine limit of 

 eelgrass growth may be due to nutrient loading. 



For example, eelgrass beds in the north end of the West Branch 

 have more conspicuous algal epiphytes, and drift algae accumulates among 

 shoots. Drift and attached algae were especially prevalent in bed 

 WEWBl, and eelgrass is sparse here and other poorly flushed areas in the 

 upper estuary, and cover less than 40% of the outlined areas. Light 

 availability to eelgrass diminishes as one proceeds north into the 

 estuary: eelgrass grows below 1.8 m MLW near the mouth, 1.2 m at Whites 

 Flat, 0.9 m north of Great Flat, and less 0.6 m around Hicks Cove. 

 There is much farmland in the drainage basin of this estuary, as well as 

 homes along shore that may be contributing nutrients to this estuary, 

 and may account for these trends. 



All together, there was approximately 180 ha of eelgrass in the 

 West Branch (adjusted for percent cover) in 1984. The East Branch has 

 60% greater subtidal area than the West Branch, but because eelgrass is 

 largely absent from the top quarter of the estuary, eelgrass bed area, 

 for production calculations, was conservatively estimated to be 100 ha. 



Off Horseneck Beach and Gooseberry Pt., considerable wave action 

 reduces water clarity and makes interpretation of photographs difficult. 

 Eelgrass grows to 3.6 m MLW on the outer coast of Dartmouth, with 



