An international team's groundbreaking research has revealed a new approach for better understanding the harmful effects pesticides have on aquatic invertebrates like shrimps and snails.

Aquatic invertebrate species are abundant in European freshwaters. They are important for decomposing organic material, and given that they are towards the bottom of the food chain, they are an important food source for higher level species.

But these some 7,000 species are regularly exposed to and combating toxic pesticides lurking in their waters, the result of spray drift, leaching or run-off from fields.

A team of scientists from the UK, Switzerland and Finland focused on how sensitive different species were to different toxins, as aquatic invertebrates do not respond similarly to various pollutants, past research shows.

"Our study introduces a systematic way of understanding the differences between species' reactions to pesticides," lead investigator Roman Ashauer, from University of York's Environment Department, said in a statement.

They stress the importance of toxicokinetics - biotransformation and distribution of the toxicants - as a means of explaining the variation in sensitivity to chemicals.

The research team looked at the effects of three pesticides - diazinon, imidacloprid and propiconazole - on the aquatic invertebrates Gammarus pulex (freshwater shrimp), Gammarus fossarum (freshwater shrimp) and Lymnaea stagnalis (pond snail). The former two pesticides, for example, are neurotoxic insecticides designed to kill pest insects.

"We produced images of the pesticide distribution within the shrimps and snails to better understand which organs are at risk," Ashauer explained. "It turns out that for some pesticides the distribution in the body matters a lot, whereas for other pesticides it is the organism's ability to detoxify."

Although researchers can now pinpoint the exact location where toxins are concentrated in these invertebrates' bodies, takwaways from thsi research can be utilized to protect aquatic species.

"We need to better understand species' differences, because we want to kill the pests, but not all the other species in our environment."