Seaweed to rescue of tiny creatures

SEAWEED could help provide a refuge for small marine animals at risk from ocean acidification, researchers from the Institute for Marine and Antarctic Studies have found.

Dr Fanny Noisette and Associate Professor Catriona Hurd studied the most common kelp in the southern hemisphere, Ecklonia radiata.

Carbon dioxide in the atmosphere dissolves into seawater, lowering the pH and making it more acidic. Kelp and other seaweeds absorb CO2 through photosynthesis and temporarily increase the pH level of seawater.

Using kelp blades from the Tinderbox Marine Reserve, the researchers measured characteristics of the micro-environment under different light and water flow conditions.

Dr Noisette said the study showed that kelp created a microlayer above their blades with much higher pH levels than in surrounding seawater.

“With the increasing risk of ocean acidification, small calcifying organisms such as ... tube-forming worms, small molluscs or crustaceans living on the blades might be able to better cope with this phenomenon,” Dr Noisette said.

“These ... organisms are especially vulnerable to ocean acidification as it prevents them from forming or repairing their shells or skeletons.

“By settling on the blades in their early stages of development, they might be able to temporarily alleviate stress or train for the harsher conditions that await them in the open ocean.”

Professor Hurd said seaweed could help coastal ecosystems adapt to global changes.

“Seaweeds not only influence the pH ... they may also help larger animals including clams, oysters and crabs overcome effects of acidification.”