Experimental studies of competition in salt marsh juvenile fish (Fundulus heteroclitus Linnaeus) and shrimp (Palaemonetes pugio Holthuis) in laboratory microcosms

The presence and significance of interspecific interactions between larval killifish (Fundulus heteroclitus Linnaeus) and postlarval grass shrimp (Palaemonetes pugio Holthuis) were studied in laboratory microcosms. Densities and species combinations were manipulated in microcosms containing salt marsh sediments and naturally occurring metazoan food resources. Shrimp exhibited reduced growth in the presence of fish, but fish survival and growth were unaffected by the presence of shrimp, indicating an asymmetrical competitive interaction. Negative effects on shrimp growth were evident when the ratio of fish to shrimp was 2:1, but effects were not apparent at a 1:1 ratio. The results of the laboratory studies provided useful baseline information for the design of subsequent field experiments on size-dependent interactions between larval fish and shrimp in a salt marsh environment. (C) 1997 Elsevier Science B.V.