Stressed seaweed contributes to cloudy coastal skies, study suggests

Scientists at The University of Manchester have helped to identify that the presence of large amounts of seaweed in coastal areas can influence the climate.

A new international study has found that large brown seaweeds, when under stress, release large quantities of inorganic iodine into the coastal atmosphere, where it may contribute to cloud formation.

A scientific paper published online today (Monday 6 May 2008) in the Proceedings of the National Academy of Science (PNAS) identifies that iodine is stored in the form of iodide – single, negatively charged ions.

When this iodide is released it acts as the first known inorganic – and 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,” explains lead author, Dr Frithjof Küpper from the Scottish Association for Marine Science.

“These ions detoxify ozone and other oxidants that could otherwise damage kelp, and, in the process, produce molecular iodine.

“Our new data provide a biological explanation why we can measure large amounts of iodine oxide and volatile halocarbons in the atmosphere above kelp beds and forests. These chemicals act as condensation nuclei around which clouds may form.”