Effects of Incubation in Oiled Sediment on Emergence of Capelin (Mallotus villosus) Larvae

Abstract

Capelin (Mallotus villosus) were incubated in oiled sediment (range of initial concentrations 0–400 ppm total hydrocarbons) from the blastula stage to emergence of larvae. Concentrations of individual and total hydrocarbons in the sediment and interstitial water declined by ≈80–90% over the 28-d exposure period. Larvae from oiled sediment emerged ≈0.5–1 d earlier than did control larvae, and the percentage of larvae emerging was greater in the oiled treatments. Yolk length of exposed larvae after emergence was 10% greater than that of controls; head length (a measure of body size) was 1% less. The emergence behaviour of exposed larvae serves as an adaptive response to stress which enables more larvae to leave the contaminated sediment quickly. The yolk and body size effects would probably not affect survival. Therefore, oiled sediment in the tested range would not significantly affect embryos and larvae prior to emergence. Delayed effects on emerged larvae, which are more sensitive than embryos, may be more important.