The large brown kelps of the genus Laminaria are known as the world’s most effective bio-accumulators of iodine, an important element for thyroid function in humans. The chemical speciation and biological role of iodine in kelp had, however, remained enigmatic until now.

A scientific paper which has just been published in the Proceedings of the National Academy of Sciences of the USA (PNAS) identifies that iodine is stored in the form of iodide - single, negatively charged ions - which acts as the first known inorganic (and, in fact, the most simple) antioxidant in any living system.

“When kelp experience stress, for example when they are exposed to intense light, desiccation or atmospheric ozone during low tides, they very quickly begin to release large quantities of iodide from stores inside the tissues. These ions detoxify ozone and other oxidants that could otherwise damage kelp, and, in the process, produce molecular iodine” explains lead author, Dr Frithjof Küpper from the Scottish Association for Marine Science. “Our new data provide a biological explanation why we can measure large amounts of iodine oxide in the atmosphere above kelp forests. These chemicals act as condensation nuclei around which clouds may form.” Similarly, large amounts of iodide are released from kelp tissues into sea water as a consequence to the oxidative stress during a defence response against pathogen attack.

Kelps thus play an important role in the global biogeochemical cycle of iodine and in the removal of ozone close to the Earth’s surface.

This interdisciplinary and international study - with contributions from the United Kingdom, the Netherlands, Germany, France, Switzerland, the European Molecular Biology Laboratory (EMBL) and the USA - comes almost 200 years after the discovery of iodine as a novel element - in kelp ashes.

www.fishupdate.com is published by Special Publications. Special Publications also publish FISHupdate magazine, Fish Farmer, the Fish Industry Yearbook, the Scottish Seafood Processors Federation Diary, the Fish Farmer Handbook and a range of wallplanners.

Printer friendly version

Email this article to a friend