The effects of hydrocarbons on the setting of the American oyster,Crassostrea virginica,in intertidal habitats in Southeastern North Carolina

Effects of petroleum covered substrate on intertidal oyster spat (Crassostrea virginica) set were measured at three intertidal elevations in a southeastern North Carolina estuary.Mercenaria mercenaria shells were coated with Bunker C crude oil or a 40∶1 mixture of gasoline: 2-cycle engine oil and placed intertidally for seven 13-d periods. Spat densities were significantly lower on oil treatments versus control and gas-treated shells in the high intertidal zone. This was principally attributed to an increased sediment coat on oiled shells. Maximum spat size was smaller on oil-treated shells at all elevations when compared to gas and control shells, indicating that setting may be delayed on oiled shell. For all experimental 13-d periods in the low intertidal zone and for three periods in the mid-tidal zone, barnacle densities (primarilyBalanus improvisus andB. eburneus) were significantly greater on oiled shells than on control shells.