By Alex Kirby
BBC News website environment correspondent
Crabs' urine and changes in snails' sex hormones are helping UK scientists to monitor the health of the environment.
Crabs are a practical way of giving the environment a proper health check
They are among new research tools being developed by the Environment Agency, as part of its first science strategy.
The agency's priorities for research include climate change, environment and human health, and flood-risk science.
It also wants to identify problems in the future, for instance the possible risks of nanotechnology and the sorts of controls the industry may require.
The agency, responsible for environmental protection in England and Wales, says its science strategy is the result of "a significant culture change" which has set new research priorities.
Professor Mike Depledge, its head of science, said the crabs and snails were "biomarkers", a practical way of giving the environment a proper health check.
In human terms, he said, it was the equivalent of counting the rise in the numbers of people with asthma, not just measuring air quality.
He said using urine and blood from creatures like these showed their responses to hydrocarbons, exposure to trace metals, and to pesticides, especially organophosphates.
A demonstration project was starting in the Ribble river catchment in north-west England, looking at molluscs, worms and fish.
Sampling crabs was a simple matter, Professor Depledge explained: "They have two apertures between their eyes, and you just stick a hypodermic needle in there and take the urine."
The new science strategy involves day-to-day advice to operational staff, and recommendations to policy teams.
Over three to five years the agency will also develop several themes: climate change impacts, the environment and human health, integrated catchment and flood risk science, and the sustainable use of resources.
It will engage in "horizon scanning" over the next decade and beyond, to develop planning for problems that lie ahead.
A fourth element is what it calls "breakthrough projects", designed to improve its own operations: examples are the use of satellite data and solar-powered radio transmitters to send data from rivers.
One new research area involves the Erica project (Environmental Risk from Ionising Contaminants: Assessment and Management), which brings together more than 50 scientists from seven countries.
Dr David Copplestone of the agency said it would be using the exclusion zone round the former Soviet nuclear reactor at Chernobyl as a field station.
In 2005 it would be monitoring frogspawn there, and would also be studying the sand dunes at Drigg, near the Sellafield nuclear plant in north-west England.
Dr Copplestone said: "We're targeting chronic low-level exposures to ionising radiation, where we have much less knowledge than for acute exposures."
Professor Rob Wilby, the agency's climate change science manager, said continuous rainfall records dating back more than 200 years showed the English Lake District had undergone a 20-year drought in the 1840s and 50s.
He said: "Those mega-droughts then were more persistent and more severe than we're used to today - and they were pre-industrial, so it was just Nature that caused them."
He told the BBC: "Future climate will have three components: human-induced change, the natural variability caused by volcanoes, the Sun and so on, and this internal variability in the system caused by the oceans and the atmosphere.
"You can't just focus on one of the three and say that natural variability alone explains what's happening today."
The agency is sponsoring research to see how a 19th-Century "mega-drought" would affect society today.