A new survey of coral reefs along Madagascar's southwestern coast found massive damage from coral bleaching caused by rising sea temperatures, researchers announced.
However, the survey team, funded by Conservation International and led by the conservation groups Blue Ventures and the Wildlife Conservation Society, said scientists also discovered several small reefs with corals that appeared to be resilient to rising sea temperatures and that could be used to reseed damaged reefs.
Algae called zooxanthellae live within the coral, give it its brilliant reds, oranges and browns and through photosynthesis provide 98 percent of the coral's food. Warmer sea temperatures block the photosynthesis and cause the coral to shed the algae, leaving the coral white and possibly leading to the death of the coral.
Sea temperatures in many tropical areas have been rising over the past 100 years and coral bleaching has become common.
The survey in southwest Madagascar found that some reefs had lost up to 99 percent of their coral cover.
The scientists said the resilient reefs may provide information about how to protect corals from future damage.
"This survey shows how important it is to locate and protect areas of resilient corals," said Alasdair Harris, research director of Blue Ventures. "As climate change poses an increasing threat to our marine habitats, these resilient areas could hold the key to ensuring the continued existence of coral reefs around the world and the marine species that rely upon them for survival."
The two conservation groups urge the creation of a network of marine protected areas to promote the long-term survival of the reefs.
Madagascar's coastal waters are believed to have some of the highest diversity of marine species in the Indian Ocean. Many marine creatures depend on the reefs for their own survival.
During the survey, scientists recorded 3,865 species of fish along the reefs off southwestern Madagascar. They said 20 of those species had never been recorded in Madagascar. The survey team believes further research may reveal more than 500 fish species living among the reefs.
The team also recorded 164 species of hard coral, including 19 that were previously unknown to inhabit Madagascar's waters. Another four coral species could not be identified and may be new to science.