Ill 



Buzzards Bay is not surprising because documentation in most areas was 

 poor, and observations during the wasting disease were made from the 

 surface, nearshore. Local observers noted at the time that living 

 shoots occasionally washed from offshore areas (e.g. Lewis and Taylor, 

 1933). Little significance was attached to these observations, but in 

 Buzzards Bay, these offshore beds were equally important in facilitating 

 the recovery of eelgrass populations after the disease. In general, the 

 onset of colonization of bare substrate was dependant on the distance 

 from these refuge populations. 



Cause of the wasting disease and the temperature hypothesis 



Labarynthula causes all symptoms of the wasting disease (Short, 

 pers. comm) , but it is always present in eelgrass populations; diseased 

 plants are common, but normally do not reach epidemic proportions. 

 Therefore, what conditions in 1931-1932 led to the outbreak of the 

 wasting disease? One possibility is that more virulent strains of 

 Labarynthula may arise (Short, pers. comm). The transmission of a 

 virulent agent, as Rasmussen (1977) points out, cannot explain the near 

 instantaneous appearance of the disease throughout North America. 



As stated earlier, the most popular hypothesis concerning the 

 onset of the wasting disease is that abnormally high summer water 

 temperatures and mild winter temperatures somehow made eelgrass more 

 susceptible to a parasite (Rasmussen, 1977). Bulthuis (1987) rejected 

 the supposition that temperature stresses eelgrass, because recent 

 research has shown that eelgrass is so eurythermal, and an elevation of 

 several degrees is insignificant. Also, water temperatures were not 



