Influence of oil shale on intertidal organisms: Sensory impairment in the blenny, Blennius pholis L. by oil shale extracts

Abstract

As part of an investigation on the effect of natural oil seeps and oil-bearing substrata on littoral organisms, a study was made on the effect of the presence of freshly exposed Blackstone oil shale from Kimmeridge on the Dorset coast on the behaviour of the common littoral fish the blenny Blennius pholis L. in a simulated rock pool habitat. Plastic test chambers were designed with two compartments, one contained sea water and the other contaminated sea water which had been allowed to equilibrate with pieces of Blackstone oil shale and in some experiments further modified by decreasing the pH to simulate natural CO 2 build up in rock pools. The fish were allowed to enter the sea water in either compartment from one of three types of ramp positioned above the surface. The results showed that against appropriate controls, fish which are able to sample a saturated atmosphere avoid coming into contact with equilibrated shale oil-contaminated sea water. As the shale oil content decreased the aversion decreased but the oil still affected the ability of the fish to detect a decrease in pH. Apparently the presence of shale oil leachings in the sea water interferes with the ability of the blenny to discriminate certain characteristics of the physico-chemical environment which would otherwise be avoided.