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Coral reefs and pollution: 27% at high risk

Reef corals are [...] sensitive to many pollutants. Unstressed reefs grow fast enough to withstand erosion by wave action and boring organisms and keep pace with sea level rise, but relatively small changes in calcification can shift the balance from growth to decline.

According to the most recent estimate [in 1998], reefs have been damaged in 93 of the 110 countries where they occur and some 27% of the world's reefs are at high risk of degradation.

Globally, the greatest threats to coral reefs from human activities are sediment mobilization, eutrophication, overfishing and destructive fishing, aggregate extraction and direct physical destruction.

Mass coral bleaching and the possibility of increasing frequencies of coral diseases have recently emerged as issues of concern . Elevated sediment input damages reefs both by increasing turbidity and by directly smothering corals. Coral recruitment may be reduced on sediment sur-faces and sedimentation can alter coral community structure.

For coral reefs in Indonesia, [it was estimated in 1996 that] the societal costs of a number of activities that result in reef damage to be up to 50 times the private benefits obtained (using 10% discount rate over a 25 year term).

Intervention in this case would be reef management including, inter alia, restriction on access to reefs and the costs would be those of the implementation of the required management measures and the foregone individual benefits.