Editorial

In the early 1 980s, on illegal battery-disposal operation in Hong Kong's Junk' boy 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 helped the authorities shut the low-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 o( caged canaries to warn them of dangerous gas build-ups.

Recently Italian lichenologists hove devised an index of lichen biodiversity, and the sampling methods to calculate if 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.

Although assessments based on community ecology are good o1 exposing, severe pollution events, they are less useful at providing subtle warning signs that on ecosystem is coming underpressure. They con only tell you that you've had a major impact after the event. But combining ecological observations with chemical measurement of pollutants accumulated by animals and plants can provide a much more sensitive and predictive analysis.

Biomonitoring has long been the poor relation to the straight forward chemical analysis of water, air and soil. Chemical sensors can provide highly accurate readings of environmental pollution. But in some regards, soy the proponents of bio monitoring, this precisian is spurious. Instruments can quantify the amount of a pollutant present in the environment. But if a pollutant is not token up by organisms, it may cause little damage to an ecosystem - and the extent to which it is token up may depend on a range of factors, including climate and acidity. Also, chemical sampling of the environment can only provide o snapshot of what may be a highly dynamic situation, whereas some organisms preservs a continuous record of the environment throughout. their lives. Enthusiasts soy biomonitoring is much cheaper than conventional chemical monitoring. Automated chemical sensors are expensive to buy and maintain, also instruments are vulnerable to theft and vandalism.

As biomonitoring slowly gains credence certain 'indicator' species have emerged as stars. In the sea. the undisputed champion is the blue mussel, Mytilus edulis. As mussels filter food from the water they live in, they also retain contaminants, which reach high concentrations in their tissues. Their sedentary lives prevent confusion about where they might hove picked up a chemical. In warmer climes, where M. edulis does not live, Crustacea could become the sentinel organisms of choice. Barnacles in particular, are "phenomenal accumulators of trace metals".

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