Global warming threatens marine life

Posted: 17 January 2002

Global warming could seriously threaten seafood staples such as cod, herring and haddock, as well as other marine creatures like the Baleen whale, warn marine scientists.

Over fishing may not be the only cause of the decline in cod and herring in recent years as previously thought. Scientists now believe that global warming could be upsetting the delicate marine food chain which will have as big an impact on marine life as it has on terrestrial animal and plant life.

Scientists have discovered that the levels of zooplankton - the tiny microscopic animal plankton which live in the upper layers of the sea - have undergone dramatic declines. As a result, sea creatures which depend on zooplankton as a source of food face widespread death and starvation.

The problem threatens the whole of the food chain since fish such as capelin which feed on zooplankton are also eaten by other predators, such as dolphins. "Removing the bottom link in the food chain could have profound and unpleasant results," for marine life rising up the food chain, warns Dr Phil Williamson, marine biologist, at East Anglia University.

A 1963 study of zooplankton levels showed that the tiny shrimp-like creatures were fairly common across the Atlantic. But in December (2001), scientists funded by the Natural Research Council, found that levels of Calanus finmarchicus, the main type of Atlantic zooplankton had dramatically declined from 50,000 per square column of water to only about 5,000-10,000. Their 800 samplings were taken at different water levels from eight main sites 1,000 miles south of Iceland.

"That is an order-of-magnitude and indicates something very serious may have occurred," said Williamson. The researchers believe that warming sea temperatures could be having a damaging impact on the life of zooplankton and that, in other oceans, other similar species may also be affected. "We don't know why zooplankton numbers have plummeted, though global warming looks like the best candidate," said Willliamson.

Source. The Independent (United Kingdom), December 2, 2001.Related link: