Abstract
- The commercial importance of the hard clam, Mercenaria mercenaria (Linnaeus), as a marketable fishery makes knowledge of its natural predators essential. Laboratory experiments were conducted to determine the potential for significant predation by grass shrimp, Palaemonetes pugio (Holthuis), on Mercenaria mercenaria. Survivorship of juvenile M. mercenaria was monitored in the presence and absence of grass shrimp under three substrate types: no sediment, sand, and silt. Clam size and the presence of sediment significantly affected predation by grass shrimp. Clams escaped predation at an approximate size of 0.8 mm. Substrate offered protection for smaller clams (0.4 mm and 0.6 mm) but there was no difference in predation rates for mud versus sand. These results indicate that size rather than substrate type may be the primary factor for M. mercenaria escaping predation by grass shrimp.