Over fishing in places like the Philippines and Indonesia has caused the disappearance of many types of fish from entire areas. With out these predators in the area, ‘pests’ like the sea urchin increase in population. Sea urchins kill live coral as they feed on algae, so eventually, algae growth overtakes the coral and can suffocate it. Fishing act ivies were therefore banned in 1997, and consequently diversity of fish in the Philippines is exceptionally high.
Since the 1960's, thousands of fishermen in Asia and Indonesia have been using dynamite fishing to collect live fish for money. It’s a quick and easy way to catch fish because once the dynamite explodes, the fish nearby are stunned and float to the top where they can be caught. However, the dynamite severely damages the coral reefs and affects the biodiversity because, as mentioned earlier, the community is symbiotic and so if parts of the reef are killed, all the algae and polyp will die.
However, tourism plays it’s part in the decrease of reef biodiversity because it encourages activities like scuba diving, which affects it by the tourists taking bits of the coral as a souvenir and then this kills that particular bit of the coral and consequently kills the plant life on it (and could decrease the fish biodiversity because some may consume the plant life on the coral). Another major tourist activity is recreational boating; this can be a threat because anchoring in reef areas damages the reef as well.
Because of the decrease in reefs (and reef biodiversity), the tourist related businesses pressurised the government of some places (e.g. Bermuda) to close the fishing industry in 1990 and consequently the $2m/yr fishing industry has closed but the $9m/yr tourist industry has blossomed. To deal with the anchor problem, the dive tourism industry install anchor buoys to stop anchor damage to reef, and because of these management approaches the diversity of fish has been maintained.
There are also more subtle ways that humans can damage coral reefs, and sometimes they don’t realise it. Deforestation for agricultural or constructional use causes soil erosion and if there is a monsoon or heavy rainfall then this sediment travels to rivers and into the sea, where the coral is. The sediment can pollute the water by blocking the sunlight out and so the coral cannot breathe, or in the worst cases it can smother the coral completely, killing off sometimes the whole organism, not just a little piece. This would have a devastating impact on the diversity because a complete habitat would be lost – 22% of global reef area is affected by pollution like this, it shows it is not a localised problem and the government of the countries affected should tackle this in ways it has tackled the other threats.
The difficulty with worldwide coral problems is that different reefs have different types of pressure and therefore different management issues. Some coral reefs are in LEDC countries and the government may not be able to afford the type of protection Australia can give to its great barrier reef.
