Superimposed on the collapse of eelgrass populations during this 

 century are local patterns of decline and recolonization driven by both 

 natural and anthropogenic disturbances, including storms, ice scour and 

 freezing, and pollution. In Chapter 4, I also document 12 "case 

 histories" of changing eelgrass abundance that involve these processes. 



Because eelgrass beds are ecologically important, and are 

 increasingly affected by anthropogenic perturbations, there is interest 

 in resource management initiatives to protect these communities. In 

 addition, the widespread distribution of eelgrass and its sensitivity to 

 pollution make it a potential indicator species for changes in water 

 quality. I address both these management concerns in Chapter 5. 



There are some excellent reviews of eelgrass biology and ecology 

 available (e.g. Thayer et al., 1984) and certain topics are covered in 

 detail elsewhere in this report, therefore I will outline only the more 

 salient features of eelgrass biology below. 



General biology and ecology of eelgrass. 



Eelgrass is a vascular plant composed of 3-7 strap-like leaves, 

 bound together in a sheath attached to an underground rhizome (Fig. 1) . 

 In this region, the leaves are less than 1 cm wide, and range 20 - 160 

 cm long. The leaves are adapted to the marine environment in several 

 ways. The leaf cuticle is thin and multiperf orate and allows the uptake 

 of nitrogen, phosphorus, and inorganic carbon through the leaf surface 

 (McRoy and Barsdate, 1970; Penhale and Thayer, 1980; Thursby and Harlin, 

 1982). Air compartments (lacunae) extend throughout the leaves and keep 

 them buoyed in the water. Most chloroplasts are located in epidermal 



