© 1986 by The Society for Integrative and Comparative Biology
The Role of Fundulus heteroclitus in Salt Marsh Trophic Dynamics1
University of Georgia Marine Institute Sapelo Island, Georgia 31327
The common mummichog, Fundulus heteroclitus, functions as both predator and prey in the trophic structure of east coast tidal marshes. Although mummichogs are generally considered important to energy transformations within marshes, few studies have convincingly demonstrated that predation by F. heteroclitus affects the abundance of salt marsh benthic invertebrates. Thus far investigations of this type have dealt only with the direct effects of adult mummichogs. The results of recent experiments have suggested that by controlling smaller predators, mummichogs may indirectly have a positive effect on the densities of some infaunal marsh invertebrates. Our current knowledge of larval and juvenile mummichogs in their natural habitat is minimal. Unlike the adults, which can utilize the intertidal zone only when it is flooded, the young remain on the marsh even at low tide, inhabiting shallow puddles of residual tidal water that form between clumps of vegetation and around fiddler crab (Uca sp.) burrows. The importance of F. heteroclitus in salt marsh communities will remain incompletely understood unless future studies consider the role of larval and juvenile mummichogs. Although many species of fishes and wading birds feed on mummichogs, the blue crab (Callinectes sapidus) is probably the major predator of adult F. heteroclitus in the intertidal salt marsh. Predation by adult mummichogs and xanthid crabs (e.g., Eurytium limosum) may contribute to the high mortality of larval and juvenile Fundulus.