Reefs on the northern part of the Red Sea are being threatened by intensive recreational SCUBA diving from the dive tourism trade.
According to the results of a study by Hasler and Ott, which is due to be published shortly in the journal Marine Pollution Bulletin, sites with high levels of recreational diving had significantly lower levels of coral cover than un-dived areas.
The study examined the reefs of Dahab, South Sinai, Egypt, which include some of the world's most heavily dived sites with over 30,000 dives per year, and compared them to sites with little or no diving.
The findings showed that areas subject to intensive SCUBA diving showed significantly higher levels of broken and damaged corals, as well as reduced coral cover.
The coral communities of the reef crest areas were significantly more affected that the reef slope dive sites, with 95% of the branching corals broken.
Diving didn't appear to have had an effect on the abundance of coral-eating (corallivorous) or herbivorous fishes, but the authors said that fish too may be at risk if coral cover decline continued.
There were also problems with sedimentation on some sites - an indication that bottom detritus was being regularly stirred up by divers.
Hasler and Ott have suggested that ecologically sustainable dive plans need to be introduced for individual sites, and that the number of dives per year needs to be reduced to help reefs recover.
They also emphasise the importance of educating both dive guides and divers to help conserve the "ecological and aesthetic qualities of the reef."
For more details see the paper: Hasler H and JA Ott (2008) - Diving down the reefs? Intensive diving tourism threatens the reefs of the Northern Red Sea. Marine Pollution Bulletin, 2008 Aug.