A Third of Reef Fish Face Extinctions from Climate Change - Oceana USA
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February 18, 2011

A Third of Reef Fish Face Extinctions from Climate Change

When you picture the impacts of climate change, what animal comes to mind? Is it a polar bear floating on a thin chunk of ice, or maybe another cold climate species losing habitat like a walrus or a penguin?

Add butterflyfish to your thoughts about climate change, because a new study predicts that they, along with one-third of all coral reef fish, are losing reef habitat and are locally threatened with extinction from climate change.

Coral reefs are threatened by two aspects of carbon dioxide emissions, ocean acidification and climate change. Corals are susceptible to sustained periods of warmer water temperatures due to climate change, which causes them to bleach when they expel algae, turning them white.

Prolonged periods of bleaching can kill corals and disturb this important marine habitat. Ocean acidification, caused by carbon dioxide emissions entering the oceans, limits the availability of important carbonate ions, and slows the growth of some coral skeletons. Acidification and climate change threatens corals, but also the one-quarter of all marine life that depends on them for food, shelter and nurseries. 

A recent study entitled Extinction Vulnerability of Coral Reef Fishes by Nicholas Graham and others, ranks fish that live on coral reefs based on their vulnerability to climate change. This vulnerability depends on the fish’s dependence on threatened corals and its susceptibility to overfishing. Species that rank high on the vulnerability index, like butterflyfish, are very dependent on corals because they feed exclusively on live corals. These species of fish that eat live corals are called obligate corallivores, and many of them may become extinct as a result of climate change.

The authors of the study also examine the complex ecological interactions of both fishing pressure and climate change. They determined that fishing pressure eliminates some of the most important fish species from a reef, and this disrupts the ecosystem putting the entire community of fish at greater risk from climate change. Luckily, these risks can be reduced by better managing local fisheries, which could serve as a useful climate change adaptation strategy to help coral reef ecosystems.

The solution to climate change is to shift to clean energy sources like offshore wind, and we need to tap into these sources and aggressively transition ourselves into a clean energy economy. Otherwise, we risk losing coral reefs and many magnificent fish species that depend on them.

As we look back at the year 2010, which tied for the hottest year on record, we must also start protecting the butterflyfish and others that we care about from unavoidable future changes. We can alleviate some of the impacts of climate change and protect marine resources if we stop overfishing and shift to a clean energy future.

You can help — tell Congress to reduce CO2 emissions to help stop ocean acidification and climate change today.