WESTCOUNTRY scientists have discovered that bouts of heavy rainfall could have a significant impact on marine life.

After studying the effects of summer rain in the region, researchers at Plymouth Marine Laboratory have chanced upon a potential consequence of climate change.

A three-man team looked at the nitrogen-rich run-off from the land into the River Tamar.

They found freshwater had been flushed 10 miles out to sea and to one of the laboratory's sampling stations.

As the nutrients found in nitrogen travel through the sea, it fertilises the phytoplankton that live in coastal areas.

With the nitrogen levels raised, the plankton's supply of another enzyme – inorganic phosphorus – is imbalanced, subsequently disrupting the feeding patterns of other species in the ecosystem.

The laboratory is uncertain as to whether the effects damage the environment, saying it is "an unknown thing".

But at worst, it could cause the proliferation of algae blooms that harm fish and human health.

As extreme weather events such as heavy rainfall are a characteristic of climate change, Plymouth Marine Laboratory feels the disruption is likely to happen more often.

The team looked at the effects of the summer of 2007, which saw the heaviest summertime rainfall in Plymouth since records began in 1914.

Dr Andy Rees, lead author of the study and a bio-geochemist at Plymouth Marine Laboratory, said the discovery was "novel" and stumbled across almost by accident when setting an exercise for a Masters degree student.

He said: "Our research has shown positive evidence of extreme rainfall having an ecological effect on the marine organisms in our local coastal waters off Plymouth.

"With climate change scientists predicting an increase in extreme weather events, we could well experience an increase in the frequency and duration of these effects, which could change the way in which our coastal seas function."

Dr Rees added that the research informed a long-running debate in the laboratory over whether river run-off affected the sea. The laboratory plans to use the findings when it researches the north-west African coast and the Atlantic ocean later this year.

Meanwhile, a team from Plymouth Marine Laboratory has been working with Google to help populate the new version of its virtual map.

Google Earth interpretation of the ocean floor includes contributions from scientists at the laboratory.

Dr Stephen de Mora, the laboratory's chief executive, said: "Working with Google has been a pleasure and an honour.

"We look forward to using this application as well as continuing to post research expedition blogs, helping to build a comprehensive overview of the research being undertaken around our planet's oceans."