Sea anemones, which provide shelter for clownfish and 27 other fish species, are facing the same worldwide threat as coral reefs – bleaching and loss due to rising water temperatures, an international team of scientists has found.
"Our study showed that at least seven of the ten anemone species suffer from bleaching when water temperatures get too high," said Dr Ashley Frisch of the ARC Centre of Excellence for Coral Reef Studies at James Cook University, a co-author of the report which has highlighted a potential crisis for two of the world's most popular marine species.
"Importantly, we found bleaching of anemones occurring wherever we looked – from the Red Sea and Indian Ocean to the Indo-Australian region and the Pacific. Sometimes it was on a massive scale," said Frisch.
The bleaching appears to be due to the same cause as coral bleaching – loss of the anemone's symbiotic algae, which supply an important part of its nourishment. This happens when the surrounding water becomes too warm.
It also involves the loss of the brightly coloured fishes which the anemone protects – and which in turn protect it. The result is a collapse in the delicate three-way partnership between algae, anemone and fish.
"Bleaching causes the loss of anemonefish, like nemos, which have nowhere to hide and without the anemones to protect them are quickly gobbled up by predators," said Frisch.
"Also, because the fish appear to perform useful services for the anemone like protecting them from grazing fish, it may also be that the loss of anemonefishes following a bleaching event means the anemones themselves are much less likely to recover," said Frisch.
The researchers, from Australia, Saudi Arabia and the US surveyed nearly 14000 anemones worldwide and found 4 percent were bleached. However, bleaching rates ranged from 20-100 percent, following five major bleaching episodes.
They conclude that in some areas, anemone "population viability will be severely compromised if anemones and their symbionts cannot acclimatize or adapt to rising sea temperatures.


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