Survey Reveals French Polynesia Has The World's Healthiest Reefs
The largest-ever survey of coral reefs in French Polynesia reveals them to be some of the healthiest on the planet with live coral cover topping more than 70 per cent of the reef on some sites.
The survey was carried out as part of the Global Reef Expedition and involved a team of 73 international scientists mapping and surveying reefs around 29 islands on 264 dive sites over a period of seven months.
The project is part of a worldwide survey of coral reefs being funded by the Kaled bin Sultan Living Oceans Foundation in an effort to set rigorous benchmarks for the health of coral reefs. They have already carried out surveys in Fiji, the Cook Islands, the Bahamas, across the Caribbean, the Red Sea, Seychelles and the Galápagos Islands.
The average coral cover they found in French Polynesia was 50 per cent. That compares to less than 10 per cent in parts of the Caribbean and 45 per cent in the northern part of the Great Barrier Reef.
'The archipelagos of French Polynesia are home to some of the healthiest and most expansive coral reefs on the planet,' said Dr Sam Purkis, lead author of the study Global Reef Expedition: French Polynesia Final Report, published this week. 'Recent models suggest that French Polynesia might serve as a climate refuge for the survival of reefs in the future.'
Healthy coral coincides with high densities of fish. In some of the French Polynesian sites they found as many as 300 fish per square metre. In the Caribbean that can drop to less than 50 per square metre and the metric for the northern Great Barrier Reef is 220 per square metre.
However, the survey also discovered areas of extensive cyclone damage and reefs badly damaged by crown of thorns infestations particularly in the Society Islands and Austral Archipelagoes. In the worst affected areas, coral cover was as low as five per cent.
The scientists found the healthiest reefs and fish communities were most likely to be found around islands with low elevation and few residents.
One of the key objectives of the research is to establish what makes reefs more resilient to a multitude of stresses such as warming oceans, cyclone damage, and pollution.
The survey revealed, for example, that reefs with a particular type of seaweed — coralline algae — recover faster from high temperatures or predation.
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