VITAL SIGNS

Although assessments based on community ecology are good at exposing severe pollution events, they are less useful at providing subtle warning signs that an ecosystem is coming under pressure. “They can only tell you that you've had a major impact after the event,” says Matthiessen. But combining ecological observations with chemical measurement of pollutants accumulated by animals and plants can provide a much more sensitive and predictive analysis.

Marine scientists have led the way. In Europe, their work was stimulated by the 1992 Convention for the Protection of the Marine Environment of the North-East Atlantic, known as the OSPAR Convention, to which most European nations are signatories. The OSPAR Convention covers the northeast Atlantic, North Sea and parts of the Arctic Ocean and Mediterranean. Its signatories have pledged to “take all possible steps to prevent and eliminate pollution”.

A requirement to monitor the effects of pollutants — including heavy metals, industrial and agricultural chemicals, radioactive waste — and the activities of the oil and gas industries on marine organisms is written into the OSPAR Convention. But as measurements began to accumulate over the 1990s, it became apparent that the diversity of methods used was preventing useful comparisons.

In 1998, the year in which the OSPAR Convention came into force, the European Union set up a project called Biological Effects Quality Assurance in Marine Monitoring, or BEQUALM, to standardize marine biological monitoring. By the time this project wraps up in October, a network of laboratories in Britain, Norway, Sweden and Germany should have hammered out about half-a-dozen standardized measures. These include the activity levels in fish of enzymes that process trace metals and organic pollutants; pathological analysis of fish livers; and community analysis of planktonic plants and invertebrates living in the seabed. Given the range of techniques involved, the progress towards consensus is no mean achievement, says Matthiessen.

Researchers working on other aspects of biomonitoring are similarly standardizing. “There was a period of total anarchy, when every scientist had his or her own methods,” says Pier Luigi Nimis, a botanist at the University of Trieste in Italy who uses lichens to monitor air pollution. He now believes the best methods are emerging “by a process of natural selection”.

Italian lichenologists have adopted a dual approach. They have devised an index of lichen biodiversity, and the sampling methods to calculate it, as an indicator of the atmospheric levels of sulphur dioxide and oxides of nitrogen. Coupled with this, the accumulations of 17 trace metals are measured in a single species in each area.

Governments are starting to take notice. ANPA, the Italian environment agency, has launched a lichen-mapping project. And the influential Association of German Engineers intends to submit a slightly modified version of the Italian protocols to the European Committee for Standardization in Brussels for adoption at a pan-European level.