VITAL SIGNS

VITAL SIGNS

The science of biomonitoring, which uses living organisms as 'sensors' to track environmental pollution, seems to be coming of age. John Whitfield considers its potential.

In the early 1980s, an illegal battery-disposal operation in Hong Kong's Junk Bay was releasing large amounts of polychlorinated biphenyls, lead and zinc into the water. But the crime did not go unwitnessed. The barnacles and mussels living in the bay concentrated the pollutants in their tissues. The evidence they gave up to local researchers and their colleagues at the Natural History Museum in London helped the authorities shut the law-breakers down.

The idea that studies of living organisms can provide information about environmental hazards is not new: before the advent of modern safety equipment, miners kept an eye on the health of caged canaries to warn them of dangerous gas build-ups. But as researchers have concentrated on their own favoured techniques, rigorous standardized methods for biological monitoring have been slow to emerge — success stories like the Hong Kong example are still rare.

Enthusiasts for biomonitoring argue that their field is now coming of age, however. They point to the recent development of protocols that can do much more than simply provide general markers of ecosystem health. In many cases, researchers are now combining ecological studies with analytical chemistry to produce information on the effects of pollution on living organisms, the identity of the chemicals involved, and even where they came from. “In the past few years there's been a considerable drive on the part of the main regulatory bodies to integrate biological and chemical monitoring,” says Peter Matthiessen, an ecotoxicologist and director of the UK Natural Environment Research Council's Centre for Ecology and Hydrology in Windermere, Cumbria.

Biomonitoring has long been the poor relation to the straightforward chemical analysis of water, air and soil. Chemical sensors can provide highly accurate readings of environmental pollution. But in some regards, say the proponents of biomonitoring, this precision is spurious. Instruments can quantify the amount of a pollutant present in the environment. But if a pollutant is not taken up by organisms, it may cause little damage to an ecosystem — and the extent to which it is taken up may depend on a range of factors, including climate and acidity. Also, chemical sampling of the environment can only provide a snapshot of what may be a highly dynamic situation, whereas some organisms preserve a continuous record of the environment throughout their lives.

Community values

In the early years of the last century, two German biologists, Richard Kolkwitz and Maximilian Marsson, realized that some freshwater invertebrates were more sensitive to pollution than others — which means that the community of species found at a particular site says much about its cleanliness. In Britain, this technique is used to monitor 7,000 river sites across the country.