INTENSITIES OF DRILLING PREDATION ON BIVALVES AROUND OIL PLATFORMS IN THE SOUTHERN PERSIAN (ARABIAN) GULF
For this study we examined 2073 individuals belonging to four bivalve taxa, comprising two epifaunal (Pteria sp., Septifer forskali) and two infaunal species (Timoclea cf. arakana, Ervilia purpurea).The frequency of drilled shells, of incomplete drill holes and the prey effectiveness (number of incomplete drill holes divided by the total number of drills attempted) were evaluated.
On average we observed a drilling frequency of 0.82 and 0.005 of incomplete drill holes. Drilling frequencies vary significantly from only a few percent to over 50% drilled shells in some samples. Preliminary data suggests that in general predation frequencies seem to increases in mid distance from the oil rigs, but Spearman rank correlation coefficients between drilling frequency of complete and incomplete drill holes and distances to oil rigs were not statistically significant; thus, predation frequencies seem not to be correlated to distance from the rigs; prey effectiveness also shows no significant correlation with distance from the platforms.
More data is needed to corroborate this observation such as other prey species, which will provide a more comprehensive picture of prey-predator interactions in areas disturbed by oil extraction.