Match/Mismatch between the Abundance of Marine Fish Eggs and Invertebrate Predators: An Analysis of Calliopius laeviusculus (Amphipoda: Gammaridae) Population Growth Relative to the Seasonal Spawning Cycle of Capelin (Mallotus villosus)

Abstract

The amphipod Calliopius laeviusculus actively preys on the intertidal eggs of capelin (Mallotus villosus). From samples collected in 1988, we found that the patterns of changes in C. laeviusculus biomass closely matched changes in capelin egg biomass throughout the capelin egg development period. Calliopius laeviusculus and capelin egg biomass exhibited pronounced and overlapping peaks in mid June. Endogenous reproductive patterns influenced by exogenous seasonal stimuli in both C. laeviusculus and capelin could facilitate yearly biomass coupling between these two species. Calliopius laeviusculus exhibited a semiannual life cycle, overwintering adults releasing young in April, May and July. Cohorts released in April and May reached sexual maturity within the summer, reproduced and produced a second maximum in amphipod biomass at the beginning of August. This second abundance peak appeared to be a numerical response to predation on capelin eggs by the adult C. laeviusculus present in mid-summer. Given this response and the reported quiescence of C. laeviusculus during the winter, we speculate that amphipod biomass in spring may be strongly linked to feeding conditions in the previous year. The implications of this coupling for capelin egg survival are considered.