Abstract:
Predators play an important role in structuring assemblages through direct and cascading indirect effects. While there has been recent interest in how the strength and direction of trophic cascades vary spatially, seasonal variability in trophic links is seldom considered. In North Carolina, recruitment-failure of bay scallops typically occurs following the spring but not the fall spawning despite the presence in each of these seasons of predatory blue crabs. One explanation for this pattern is that in the fall, seasonally abundant predators of blue crabs reduce the foraging efficiency of crabs on scallops and this the overall magnitude of top-down effects.Quantification of bay scallop consumption by blue crabs on scallops in closed mesocosms with or without pinfish supported the hypothesis that seasonally abundant adult pinfish indirectly increase survivorship of bay scallop recruits in fall by reducing predation by blue crabs.
