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Rainforests of the Sea

By: Jill McGrady, Ph. D.

Image courtesy of Gary Bell/Oceanwidelmages.com

Image courtesy of Gary Bell/Oceanwidelmages.com

Scientists have long known the characteristic ‘smell of the ocean’ comes from a compound called demethylsulphoniopropionate (DMSP), produced by the symbiotic algae living inside corals. However, an article published in Nature last month revealed that the coral animal itself also produces DMSP1.  Furthermore, this research indicates that corals may help regulate the Earth’s temperatures – a role that is significantly threatened as coral cover continues to decline worldwide.

Coral reefs account for less than 1% of the entire ocean floor and are in decline because of rising sea temperatures, increased ocean acidity, and powerful storms.

Coral reefs cover less than 1 % of the entire ocean floor but harbor 25% of marine life.  Image courtesy of Hugo Ahlenius, UNEP/GRID-Arendal.

Map depicts the world’s coral reefs which cover less than 1% of the ocean floor.
Image courtesy of Hugo Ahlenius, UNEP/GRID-Arendal.

As the “rainforests of the ocean”, they provide food and shelter to a multitude of marine organisms, harboring more than 25% of all marine life. Now there is another reason coral reefs deserve their nickname. Like terrestrial rainforests, corals may be involved in a regulatory cycle that helps regulate local climates.

Coral production of DMSP increases in response to stress caused by rising water temperatures, basically acting as anti-oxidants for cellular protection. DMSP also serve as cloud-condensation nuclei (CCN) for the formation of water droplets in the atmosphere, aiding in cloud formation. As we know, cloud production is an important climate regulator through reflection of the sun’s heat back into space, keeping Earth’s temperatures down. However, if coral numbers continue to decline, less DMSP would be produced, potentially reducing cloud formation and resulting in less heat being reflected back to space. As a result, fewer clouds mean warmer sea surface temperatures and more stressful conditions for coral colonies.

Graphic courtesy of Graham Jones

(a) Shows how coral may help regulate sea temperatures. Production of DMSP increases in response to stress caused by higher water temperatures. DMSP serves as nuclei for clouds, which cools water temperatures as heat is reflected away.
(b) If corals continue to decline, less DMSP will be produced and without clouds reflecting heat, the water temperatures will increase, causing thermal stress.  For more information read the full report. Graphic courtesy of Graham Jones.

These findings are the first evidence that coral itself may play a role in regulating the local climate in which it lives. Declining coral cover worldwide, and the concomitant reduction in DMSP from coral reefs could further disrupt climate regulation and increase the speed at which coral communities disappear.

This discovery about the regulatory nature of coral reefs shouldn’t come as a surprise. It has long been known that forests play an important role in regulating the earth’s temperatures by storing large quantities of carbon, the main constituent of CO2 – the most significant greenhouse gas. This temperature regulation process has a profound effect on local as well as global climates.

Innovative Solution: Designer corals

Trees and corals (or the lack of them) are key problems that must be tackled if we are to minimize the effects of climate change. Researchers around the world are working on various strategies for saving coral reefs, which are particularly sensitive to the damaging effects of pollution, global warming, and sedimentation. One research team is taking a new approach to the problem. Researchers from the University of Hawaii and the Australian Institute for Marine Science are assuming that climate change is here to stay and preparing to make corals resistant to its effects.

Drawing on genetic selection practices used in agriculture, aquaculture, and forestry, the researchers will pre-condition corals to withstand the stress of future warmer scenarios. Their innovative solution will develop a process of ‘human-assisted evolution’ to build a stock of “super corals” which are resilient to the higher temperatures and acidic conditions created by climate change. These super corals will be used to repopulate dead reef areas and return these highly valued ecosystems to their former grandeur, restoring their potential role in climate regulation.

These “designer corals” could represent a new approach to reduce the adverse effects of climate change. Both our terrestrial and aquatic rainforests play important roles in temperature control and both are threatened by climate change. It is essential that we continue to develop new and innovative approaches to protect and restore our valuable natural resources.

References:

1Jean-Baptiste Raina, Dianne M. Tapiolas, Sylvain Forêt, Adrian Lutz, David Abrego, Janja Ceh, François O. Seneca, Peta L. Clode, David G. Bourne, Bette L. Willis, Cherie A. Motti. DMSP biosynthesis by an animal and its role in coral thermal stress response. Nature, 2013; DOI: 10.1038/nature12677

2 Aoun, Gabriela. Ocean Acidification Has A New Enemy: Super Corals. The Huffington Post. TheHuffingtonPost.com, 21 Oct. 2013.

 

 

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