Nemo and the Zombie Anemone

Clouds of fish in the British Indian Ocean Territory, Photograph by Anderson Mayfield

Comparing a bleached anemone to the undead may be a bit of a stretch, but it is fair to say a bleached anemone is hovering somewhere between life and death and depending on what happens next, it can go either way.

We got a closer look at the phenomenon of bleached anemones earlier this year during a research mission in the British Indian Ocean Territory. When we arrived in this massive Marine Protected Area (MPA) we saw thousands of corals competing for reef space in the shallow water. Sponges dotted the nooks and crannies of the reef clinging to the small space they had claimed, anemones filled large parts of open reef with their tentacles dancing back and forth with the waves and thousands upon thousands of glittering fish filled the surrounding blue water. It was the kind of reef we had dreamed of seeing during our Global Reef Expedition.

Clouds of fish in the British Indian Ocean Territory, Photograph by Anderson Mayfield

Warm, sunny days with little wind made the diving easy, but the hot temperatures and calm seas we were enjoying belied their real impact. The ocean began to heat up. For stationary creatures of the reef, like corals and anemones, there is no escape from the rising temperature and excess light. In response, they begin to transform.

Bleached anemones on the reef in the British Indian Ocean Territory. Photograph by Philip Renaud

Coral bleaching may be more familiar than anemone bleaching, but these two processes are nearly identical. Some anemones host algae inside their bodies which gives them their color, both the anemone and the algae benefit from their partnership. The anemone provides the algae with carbon dioxide and other nutrients that they need to live, and in —> Read More