EFFECT OF SPILLS OF DISPERSED AND NON-DISPERSED OIL ON INTERTIDAL INFAUNAL COMMUNITY STRUCTURE

ABSTRACT The effect of two nearshore discharges of Murban crude oil on community structure in intertidal benthic communities was studied. One discharge consisted of 250 gallons of Murban crude only. Following the discharge, no measurable amount of Murban crude could be found in sediments exposed to the cloud of dispersed oil. Significant amounts were found in the test plot exposed to untreated oil. In the area exposed to untreated oil, more oil was found in the upper intertidal zone than lower down. Effects on infaunal communities mirrored the analytical results. There was no evidence of adverse effects on infaunal community structure from exposure to dispersed oil. There is clear evidence that exposure to untreated oil did adversely affect community structure. Some indigenous species were reduced in number or eliminated; there were blooms of opportunistic polychaetes. The changes in community structure brought about by the untreated oil are consistent with results observed at real-world oil spill sites.