Findings: Algae growth uncovered

The scope for damaging growths of algae in seas and rivers may be severely underestimated, according to a chemist who is pioneering alternative ways of analysing sea and river water, writes Martin Ince.

Eric Achterberg, senior lecturer in environmental sciences at the University of Plymouth, said that dense algal blooms that could spread across river estuaries and inshore waters were driven by the presence of large amounts of nitrogen and other nutrients, often the result of pollution from agriculture.

He said: "Methods used by groups such as the Environment Agency miss about half the nitrogen compounds in the water. The methods we are using produce a much more accurate result. It shows what we call the dissolved organic nitrogen that is missed by other techniques."

Dr Achterberg's group uses a method that oxidises the entire sample to reveal all nitrogen. It has been used in the sea off China and Egypt, and in the Plym and Tamar rivers near Plymouth. His group is working on identifying the ways in which pollution is distributed in coastal waters and the stresses it places on animals.

He said: "It is becoming possible to collect data continuously, with an instrument on a buoy or a ship, or to have alerts issued when an accidental discharge is detected. These measurements allow us to look at the stresses placed on animals. We have been looking at the stress markers in algae.

Rivers in the Southwest where there has been metal mining often show severe stress."

Dr Achterberg said that although the Cornish mining industry had closed, metals such as copper would persist for years in rivers such as Restormel Creek.

He said: "Marine algae are showing very high levels of stress in these rivers, and there have been proposals to clean them up. The problem is that there are thousands of channels and the water system is very complex, so it would be impossible to stop up all the routes the polluted water takes."

Dr Achterberg's next paper on this work will be published in the journal Aquatic Geochemistry .