The long term effects were very significant. There was no shoreline cleanup, essentially, over the 800 kilometers that the oil – - in Saudi Arabia. And so when we went back in to do quantitative survey in 2002 and 2003, there was a million cubic meters of oil sediment remained then 12 years after the spill.... ()he oil penetrated much more deeply into the intertidal sediment than normal because those sediments there have a lot of crab burrows, and the oil penetrated deep, sometimes 30, 40 centimeters, you know a couple of feet, into the mud of these tidal flats. There’s no way to get it out now. So it has had long term impact.

The study demonstrated that, in contrary to previously published reports e.g. already 1993 by UNEP, several coastal areas even in 2001 still show significant oil impact and in some places no recovery at all. The salt marshes which occur at almost 50% of the coastline show the heaviest impact compared to the other ecosystem types after 10 years. Completely recovered are the rocky shores and mangroves. Sand beaches are on the best way to complete recovery. The main reason for the delayed recovery of the salt marshes is the absence of physical energy (wave action) and the mostly anaerobic milieu of the oiled substrates. The latter is mostly caused by cyanobacteria which forms impermeable mats. In other cases tar crusts are responsible. The availability of oxygen is the most important criteria for oil degradation. Where oil degrades it was obvious that benthic intertidal fauna such as crabs re-colonise the destroyed habitats long before the halophytes. The most important paths of regeneration are the tidal channels and the adjacent areas. Full recovery of the salt marshes will certainly need some more decades.