Cod egg osmoregulation seems unaffected by oil exposure

Abstract

The developing embryo of the cod ( Gadus morhua) is hyposmotic to seawater and depends strictly on the integrity and low permeability of the surface membrane in order to maintain its water and solute balance. 1 This dependency on a low permeability surface membrane should make the cod embryo vulnerable against oil pollution since the oil hydrocarbons are quickly taken up by the cod eggs, 2 accumulate in lipid tissues and structures of the body, 3 and, at least in mammals, results in dysfunction of transport tissues like the central nervous system and the kidneys. 3 Our studies on the osmotic regulation of the developing cod embryo, however, show that exposure to the water-soluble fraction of Ekofisk and Statfjord B crude oils at concentrations of 50–150 ppb does not significantly affect the surface membrane permeability or body fluid solute concentrations during the egg stage. The tested concentration range covers even heavily industrialised estuaries. 4