In the lab, in the field and in between: The Centre for Environmental Research on Pesticides takes a multi-faceted approach

A meandering stream in Southern Ontario has become an outdoor laboratory for the scientists of Fisheries and Oceans Canada (DFO). Twenty Mile Creek winds its way through farming landscapes, travelling for a far longer distance than its name implies. Over its 79 km length, it collects run-off from the agricultural fields – and that drainage makes it an ideal study environment for researchers from the Centre for Environmental Research on Pesticides (CERP).

Pesticides are an integral part of agricultural practice in Canada, and new varieties are being developed every year. DFO scientists need to keep close tabs on how these pesticides are affecting our lakes and rivers, through detailed experiments in CERP laboratories. But the lab work is just part of the equation. The scientists also study wild fish, invertebrates and fish habitat in the field, where pesticides are applied. They are collecting the scientific information which Canada's regulators depend on, to set regulations that will protect fish and their habitat.

At selected locations along Twenty Mile Creek, researchers have been collecting golden shiners for analysis. Credit: Photo provided by Christopher L. Baron, Physical Scientist, Centre for Environmental Research on Pesticides, DFO.

A real world model

Since 2003, CERP scientists have used Twenty Mile Creek as a model system. Since the creek travels through a mixture of agricultural lands, many different types of pesticides are used. The creek "receives quite a mix of pesticide inputs," says CERP Physical Scientist Chris Baron. This allows the CERP researchers to study a wide variety of situations, by utilizing information provided by fellow scientists from Environment Canada. These Environment Canada scientists monitor the creek at several locations, to determine the particular concentrations of various pesticides in each stretch of water.

Once they know pesticide levels in various parts of the creek at different periods, DFO can design its studies accordingly. For example, it is important to know when pesticide levels peak. Then, the scientists can time their collection of fish for sampling to coincide with these peaks.

Examining the golden shiner

In monitoring the reproduction and growth of wild fish and aquatic invertebrates in each area, researchers have been using the golden shiner as a "sentinel" species. The golden shiner is a small fish that inhabits slow moving areas of rivers and streams. Fishermen know the shiner well: it is widely used as bait by anglers. Through detailed study of the shiner, researchers can draw broader implications for other species and the ecosystem as a whole.

Laboratory facilities at the Centre for Environmental Research on Pesticides in Winnipeg allow scientists to expose fish to pesticides in a carefully controlled setting. Credit: Photo provided by Christopher L. Baron, Physical Scientist, Centre for Environmental Research on Pesticides, Freshwater Institute, DFO.

Already scientists have found evidence that elevated pesticide concentrations in parts of the creek have reduced the potential growth of the fish population. For example, some areas tested during peak pesticide application periods showed a lack of young-of-the-year fish. Although the work is on-going, this preliminary finding may mean that young fish hatching at peak application times do not survive. The researchers have also found year-to-year variations in pesticide levels in Twenty Mile Creek. Clearly, continued monitoring is essential to allow CERP scientists to estimate the likely effects of long-term exposures.

Regulations depend on sound science

CERP is just one of 12 DFO centres of expertise which focus on the health of Canada's aquatic environments. The centres explore a wide variety of subjects. They do research on marine mammals, study the environmental effects of oil and gas development, assess aquatic animal health, and monitor the impacts of hydropower on fish and fish habitat, for example. CERP's focus on pesticides is critical to their role as advisor to Health Canada's Pest Management Regulatory Agency (PMRA), which develops federal regulations on pesticide use.

In consultation with the PMRA and other federal departments, the scientists identify high priority research needs. They may review pesticides that are new or re-examine those already in use as part of an ongoing process of updating environmental and safety regulations. In this way, DFO feeds into the legal regulatory process that decides which pesticides may be used and under what conditions.

An artificial environment – on wheels

Of course, the information from field work at Twenty Mile Creek and other wild sites is strengthened by highly controlled laboratory experiments and analysis. And now, CERP has something new in mind. It's called a mesocosm – a research apparatus that combines some of the benefits of working in nature with the flexibility of working in the lab. A mesocosm simulates real-life conditions as closely as possible, while allowing scientists to manipulate specific environmental factors in a controlled manner.

In this case the mesocosm is, in essence, an artificial stream. It is "a trailer with fish tanks, pumps and all kinds of controls for adjusting exposure of fish to water at a study site," says Chris Baron. Now under construction, the mesocosm will let the scientists closely approximate the actual conditions in Twenty Mile Creek while being able to control factors such as the size and age of fish, and flow rates of the water. The device should be ready to roll in time for the summer 2009 field season.

Monitoring the situation

The mesocosm studies and field work will be further complemented by lab research, to be done by CERP researchers at the Freshwater Institute in Winnipeg. The Winnipeg contingent will study different pesticide concentrations, simulating conditions during years with different precipitation patterns.

It is this joint cooperation, both among CERP scientists and partners like the PMRA and Environment Canada that will help ensure the safety of the agricultural chemicals we use.