61 



Based on Table 1, the years 1938, 1944-1945, 1954, 1960-1961, and 

 1977-1978 had the greatest storm intensity or combination of 

 disturbances that could have impacted eelgrass abundance. Undoubtedly, 

 wind direction, orientation of the shore, path of storm, and local 

 hydrography had a great effect on the local impact of these events, and 

 smaller storms and wave scour define some smaller patterns of eelgrass 

 colonization and patchiness observed as well. 



Declining water quality 



Water quality declines result from pollution by toxic compounds, 

 enrichment by nutrients, and increased suspended sediment loads. 

 Nutrient loading is typically most important over large regions (e.g. 

 Orth and Moore, 1983b) , and is caused by human and livestock waste 

 disposal, and fertilizer applications. Increased suspended sediment 

 loading may result from dredging, topsoil runoff, shellf ishing, and 

 boating. Pollution by toxic compounds is generally localized. 



Nutrient loading and sediment resuspension can have profound 

 effects on eelgrass abundance. The lower limit of eelgrass growth is 

 determined by the duration of light intensity above compensation 

 (Dennison, 1987; Dennison and Alberte, 1985,1986). Hence, in a 

 fundamental way, the distribution of eelgrass is determined by factors 

 that affect water transparency and epiphyte densities (Sand-Jensen and 

 Borum, 1983) . Nutrient loading increases phytoplankton and algal 

 epiphyte abundance, which in turn shade eelgrass, causing lower growth 

 and recruitment, or death (Borum, 1985; Bulthuis and Woerkerling, 1983; 

 Kemp et al., 1983; Sand-Jensen and Borum, 1983). Eelgrass beds often 



