Effects of settlement and early post-settlement predation on the recruitment of juvenile echinoderms in Bocabec Cove, Bay of Fundy, Canada

Recruitment patterns can set up patterns of abundance and distribution of adults and can be affected by settlement and early post-settlement events. This thesis examined if recruitment patterns of echinoderms were influenced by settlement and early post-settlement predation on rocky subtidal sites in Bocabec Cove, Bay of Fundy, New Brunswick, Canada. Settlement patterns of sea urchins Strongylocentrotus droebachiensis, sea stars Asterias spp. and sea cucumbers Psolus fabricii and Cucumaria frondosa were found to vary over small spatial (1.5 km) and temporal scales (1 year) but did not exhibit a strong relationship to abundances of pre-recruits (<10 mm). Size-frequency distributions showed that early post-settlement processes may be important for these echinoderms. Laboratory and field experiments indicated that predation was not a critical source of mortality for sea urchins <10 mm, although may be important for larger juvenile sea urchins (>20 mm). In general, this study suggests that settlement is not the main process affecting recruitment patterns in echinoderms, nor is predation important for pre-recruit sea urchins in Bocabec Cove.