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Using Nuclear Techniques to Monitor the Health of Coral Reefs


Nuclear techniques allow scientists to monitor the multiple stressors affecting the health of coral reefs. (Photo: J.L. Teyssie/IAEA)

Pollution and climate change pose a serious threat to coastal and marine environments. Coral reefs, the diverse underwater ecosystems that provide valuable habitat and serve as a spawning ground for a large variety of species, are particularly vulnerable to changes in the marine ecosystem. This, in turn, could have major repercussions for populations around the globe that rely on healthy coastal and marine ecosystems as a vital source of food.

“Reef organisms are subject to multiple stressors, such as pollution, rising temperatures, over-fishing and ocean acidification,” said Marc Metian, a radioecologist at the IAEA Environment Laboratories.

Speaking at the 13th International Coral Reef Symposium (ICRS) in Hawaii from 19 to 24 June, which gathered close to 2500 participants from around the world, Metian said nuclear applications are a tool to study such stressors and quantify them, including, “assessing the variation of metal accumulation in marine species under a changing environment with higher temperatures or higher acidity.”

The IAEA provides expertise to Member States on the use of radiotracers in laboratory experiments to study how metals like silver, cadmium, cobalt and manganese are taken up and expelled by corals and marine organisms. Radiotracers have a distinct signature that scientists can accurately use to trace the movement of contaminants in the environment and in organisms.

Corals, fishing and tourism

Coral reefs supply food to millions of people around the world and are a big source of revenue and employment through fishing and tourism. They also act as storm barriers and protect islands and land along the coast. Studies on coral reefs have shown they can be particularly sensitive to variations in their environment, and, in recent years, there have been several incidences of coral “bleaching”, where the reefs expel the algae that give them their characteristic colour and whiten. Coral reefs can recuperate from mild bleaching, but with the increase in frequency and intensity of such episodes, combined with other stressors, the reefs and associated ecosystems can be threatened.

In some archipelagos in the South Pacific, run-off from the nickel mining industry releases pollutants and by-products into the environment which are absorbed by corals and can reach critical concentration levels. IAEA activities cast light on the processes involved and can provide valuable information on the health of coral reefs and the organisms that populate them.  This research can also be used by Member States to locate sources of pollution, a prerequisite for the implementation of remediation activities.

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