Amoco Cadiz

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Amoco Cadiz

This shipwreck in March 1978 off the Brittany coast was the first major supertanker accident since the Torrey Canyon 11 years earlier. Ironically, this spill, more than twice the size of the Torrey Canyon, blackened some of the same shores and was one of four substantial oil spills there since 1967. It received great scientific attention because it occurred near several renowned marine laboratories.

The cause of the wreck was a steering failure as the ship entered the English Channel off the northwest Brittany coast, and failure to act swiftly enough to correct it. During the next 12 hours, the Amoco Cadiz could not be extricated from the site. In fact, three separate lines from a powerful tug broke trying to remove the tanker before it drifted onto rocky shoals. Eight days later the Amoco Cadiz split in two.

Seabirds seemed to suffer the most from the spill, although the oil devastated invertebrates within the extensive, 20–30 ft (6-9 m) high intertidal zone. Thousands of birds died in a bird hospital described by one oil spill expert as a bird morgue. Thirty percent of France's seafood production was threatened, as well as an extensive kelp crop, harvested for fertilizer , mulch , and livestock feed. However, except on oyster farms located in inlets, most of the impact was restricted to the few months following the spill.

In an extensive journal article, Erich Grundlach and others reported studies on where the oil went and summarized the findings of biologists. Of the 223,000 metric tons released, 13.5% was incorporated within the water column, 8% went into subtidal sediments, 28% washed into the intertidal zone, 20–40% evaporated, and 4% was altered while at sea. Much research was done on chemical changes in the hydrocarbon fractions over time, including that taken up within organisms. Researchers found that during early phases, biodegradation was occurring as rapidly as evaporation.

The cleanup efforts of thousands of workers were helped by storm and wave action that removed much of the stranded oil. High energy waves maintained an adequate supply of nutrients and oxygenated water, which provided optimal conditions for biodegradation. This is important because most of the biodegradation was done by aerobic organisms. Except for protected inlets, much of the impact was gone three years later, but some effects were expected to last a decade.

[Nathan H. Meleen ]