Ocean Acidification: Will Cold Water Corals be Affected?

By June 4, 2013Ocean News

The tendency in ocean conservation, and really news in general tends to be pretty depressing. It seems like every day a new species is at risk of extinction, a new global threat will imminently have massive effects on the planet, etc. If you’re a regular reader of this blog or any number of others you know what I’m talking about.

So today I’ve decided to write about some of the good news. Researchers in France recently found that contrary to the prevailing hypothesis the calcification rates of cold-water corals in the Mediterranean is not likely to be affected by rising CO2 levels in the next 100 years.

Deep Water Coral

Bubblegum coral at 1257 meters water depth

First off a bit of background because a lot of that sentence might not make any sense. So believe it or not there is such a thing as cold-water corals. They have been found in most of the worlds oceans, and provide vitally important ecosystem services such as habitat for juvenile and adult fish (similar to what more common warm water corals do).

The second thing to know is that increasing CO2 in the atmosphere leads to decreasing pH (so increasing acidity) in the oceans (through the processes in the image to the right). This is a problem because Ocean Acidificationcalcium carbonate (the chemical that coral skeletons are made of) dissolves into water at higher acidities. This means that as the acidity of the ocean increases corals are making new skeletal structure more slowly making them more at risk to other environmental impacts (bleaching, storm damage, etc.).

The discovery that the cold water corals in the Mediterranean don’t show a reduction in growth rate under higher CO2 conditions is fantastic news because now it looks like these corals will be able to survive as the acidity of the oceans continues to increase (as we continue to burn fossil fuels at ever increasing rates). Now it doesn’t mean these corals are safe they are still going to have to deal with bottom trawling, and other anthropogenic factors that impact the life of a coral, but at least on this front they might get a reprieve.

The physiological reasons why these corals might be able to avoid the worst of ocean acidification is still unknown. The authors propose some possible explanations such as, they already have a significantly reduced growth rate or it may be because they may maintain a higher pH level inside their body cavity than tropical corals.

Deep Sea coral garden

Deep-sea coral in New Zealand

These corals and really all corals are important to the world’s oceans because they are one of the main species that provide habitat for other species. These other species use to coral for food, somewhere to lay eggs, somewhere to hide from predators, and countless other reasons that make the entire community possible. In areas that have had drops in coral cover there have been measurable decreases in fisheries yield, decreased biodiversity and many other ecosystem services. So conserving corals is an important step to conserving the balance of nature in the oceans and in this one instance it looks like there is some hope.

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