ABSTRACT
Between 1980 and 1983, recurrent outbreaks of disease have resulted in mass mortalities of Strongylo-centrotus droebachiensis along the Atlantic coast of Nova Scotia. Mortality has been virtually complete (>99%) over an area spanning ≃400 km of coastline and to a depth of at least 15m; partial mortalities have occurred over another ≃150 km. The estimated loss of biomass exceeds 200,000 tons fresh weight. The elimination of echinoids has enabled an extensive colonization of the rocky substratum by kelp and other fleshy macroalgae. Increases in the number and biomass of macro-algal species are reported for areas where mass mortality of echinoids occurred 1, 3 and 4 years previously.
