Larval supply of predator and prey: temporal mismatch between crabs and bivalves after a severe winter in the Wadden Sea
Enhanced bivalve recruitment after severe winters is a well known phenomenon in the coastal North Sea. By comparing the bivalve larval abundances after a severe (1995/96), a moderate (1996/97) and a mild (1997/98) winter in the northern Wadden Sea we found no evidence for the hypothesis that high bivalve recruitment after severe winters was caused by enhanced larval supply. Total and peak abundances of all bivalve larvae as well as of the species Ensis americanus, Mytilus edulis, Cerastoderma edule and Mya arenaria were 3 to 6 times lower after the severe than after the mild winter. In Macoma balthica total and peak abundances after the severe winter were only slightly higher than after the moderate winter. The larvae of the epibenthic predator Carcinus maenas appeared in lower numbers and 6 to 8 weeks later after the severe than after the moderate and the mild winter. Since the bivalve larvae appeared without or less delay there was a temporal mismatch between Carcinus and the bivalves, supporting the hypothesis of reduced epibenthic predation being an important factor of high bivalve recruitment after severe winters.