Clownfishes or anemonefishes are colorful saltwater fishes that mainly inhabit coral reefs in the warm and tropical waters of the Indo-Pacific. Clownfishes have a symbiotic and mutually beneficial relationship with sea anemones, which they rely on for shelter and protection from predators. In turn, clownfishes will protect the anemone from anemone-eating fish, as well as clean and fan them. The popular film Finding Nemo is about a clownfish who lives in a secluded sea anemone.
The Red Sea, circled by Middle Eastern deserts, is home to marine life that is accustomed to very warm water – often 85 to 90 degrees during the summer. However, in the past three years marine heat waves have made the Red Sea even hotter. The rising sea temperatures have caused a breakdown in the symbiotic relationship between clownfish and anemones.
Anemones have a symbiotic relationship of their own with the same microscopic algae that pair with coral. Just as is the case with coral, anemones expel the algae from their tissues during periods of high heat, causing them to bleach. Prolonged bleaching can result in the death of the anemone and, in turn, exposes the clownfish to danger.
Researchers from Boston University monitoring three Red Sea reefs over a three-year period found that the marine heatwave in 2023 resulted in the death of 94 to 100% of the clownfish and 66-94% of the anemones. Rising ocean temperatures can be devastating for many sea creatures.
Anemones are not as well-studied as coral, so it is not clear whether their populations can recover, particularly once the clownfish are gone, making them much more vulnerable to their own predators.
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Clownfish and Anemones Are Disappearing Because of Climate Change
Photo, posted March 9, 2016, courtesy of John Voo via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio
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