Adaptations of Strongylocentrotus droebachiensis for survival on barren grounds in Nova Scotia

The majority of sea urchin species are primarily herbivorous. There are numerous examples where urchin grazing has brought about great changes in the abundance and community composition of marine plant species (North 1974; Breen &Hann 1976a,b; Foreman 1977; Paine 1977; Estes et al., 1978; Simenstad et al. 1978; Vance 1979; Duggins 1980. 1981; Price & John 1980; Sivertsen &Bjorge 1980; Wharton &Mann 1981; further references in Lawrence 1975; Vance 1979). In many of these instances urchins have overgrazed, eradicating virtually all fleshy macrophates from extensive areas. These areas, denuded of macro algae and supporting large numbers of sea urchins have been termed 'urchindominated barren grounds' (Lawrence 1975).