ENVIRONMENT: Acidic Seawater Endangering Marine Life

By Julio Godoy Reprint | | Print |

Julio Godoy

PARIS, Jun 16 2006 (IPS) - Carbon dioxide emissions have led to a substantial increase in seawater acidity, endangering marine life, leading scientists say.

“Since the beginning of the industrial revolution in the late 18th century, some 120 billion tonnes of carbon dioxide have been absorbed by seawater, thus blocking the development of calcium carbonate, indispensable for many forms of marine life,” says Jean-Pierre Gattuso, researcher at the French National Centre for Scientific Research (CNRS).

Gattuso is also member of Eur-Oceans, a network of scientists spanning 60 research institutes and universities in Europe.

Acidity has risen 26 percent since 1800, according to recent calculations. By the end of this century it could double, scientists say.

“The species most affected are those which need to build an exoskeleton, such as coral reefs, crustacean, and molluscs,” Gattuso told IPS. The exoskeleton is the protective shell of many animals.

One of the instances of damage cited by Gattuso is the bleaching of coral reefs due to rising seawater temperatures as a result of global warming. Carbon dioxide mainly resulting from the burning of fossil fuels for power generation and transport is considered the main emission provoking global warming.

Coral reefs are considered vital for the conservation of marine biodiversity, and are frequently referred to as “the tropical rainforest of the oceans.” Coral bleaching “also represents the destruction of the habitat and feeding of numerous species of marine fauna,” Gattuso said.

If carbon dioxide emissions continue at present levels, Gattuso said, seawater will corrode aragonite, a form of limestone used by organisms to build protective shells.

Some scientists believe that further global warming could lead to a total destruction of reefs.

The phenomenon has been observed mostly in the Indian Ocean and on the shores of Australia, especially the Great Barrier Reef, the world’s largest coral string. In 1998 and again in 2002, Australian scientists detected widespread coral bleaching.

Single-cell marine plants called the coccolithophores are threatened in the sub-polar regions of the North Atlantic, says James Orr, head of the French Climate and Environmental Sciences Laboratory, who has been studying the effects of acidification of seawater along with Gattuso.

“Due to the acidification of seawater, coccolithophores, which under the effect of solar light thrive during the spring in the North Atlantic, cannot fully develop, or bloom deformed,” Orr said.

Given the importance of corals in preserving marine biodiversity, their loss is seen as a major disturbance of the oceans’ ecosystems. In addition, corals, as well as forms of plankton such as the coccolithophores provide habitat for many commercially important fish species.

Corals also harbour several species of sponges that have been used to produce anti-cancer and other medicinal substances. Their disappearance would mean a major setback for the environment and for human needs.

These concerns were taken up at a workshop on sea level rise and variability organised in Paris Jun. 6 to 9 by the United Nations Educational, Scientific and Cultural Organisation (Unesco). Both Orr and Gattuso participated in the workshop.

The workshop organised jointly with the World Climate Research Programme (WCRP) brought together about 200 biologists and oceanographers from all over the world researching climate change and its effects on marine ecology. The workshop in Paris was a part of a WCRP study over 2005-2015 called the Coordinated Observation and Prediction of the Earth System (COPES).

The WCRP which studies the extent to which climate can be predicted, and human influence on climate, also explores the effect of climate change on the sea.