This report studies the effects of crudes and a chemical oil counteractant on survival, metabolism, and behavior of representative species of Red Sea macrofauna under controlled environmental conditions. Specifically, it examines the action of crude oil from fields in Iran and in the Sinai, a chemical oil dispersant, and oil-dispersant mixtures on juveniles or adults of octocorals, crustaceans, molluscs, echinoderms, and teleosts. The choice of bioassay methodology on response parameters, especially survival, is significant. A comparison of toxicity values derived from tests in large (1,500 Q), deep (2.0 m) tanks under conditions of continuous flow with those performed in small (3 Q) jars under static conditions demonstrated that most assay species were up to 30 times more resistant to almost all toxicants in large tanks. Tank tests also demonstrated a protective effect with increasing depth: organisms confined 1.0 to 1.8 m from the surface exhibited higher survival than those held at shallower depths. Sublethal and latent effects of oils and dispersants on Red Sea biota were reviewed and included reduction in feeding rate and egg case deposition of predatory gastropods, interference with substrate attachment by mussels, liver enlargement and lowered blood hematocrit values in fishes, and bio-accumulation of crude oils in octocorals.

These and other data presented herein suggest that introduction of petroleum into Red Sea ecosystems may disrupt established feeding-predator patterns, reproductive processes, defense mechanisms, and conceivably other systems, and it would constitute a potential threat to population stability.

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Author notes

1Work performed while Visiting Professor, Hebrew University of Jerusalem, Marine Biological Laboratory, Eilat, Israel.