Agricultural pesticides derived from nicotine also harm fishing

• Environment: The EU bans three insecticides considered dangerous for bees
• Research Scientists show that pesticides generate 'anorexic' birds

First the insects, then the amphibians, the birds and, now, the fish. The scientific literature on the damage caused by neonicotinoid pesticides continues to accumulate. A study published Thursday in Science shows that the intensive use of these substances was the cause of the sudden collapse of local fish populations in Lake Shinji in Japan.

The analysis of the data accumulated over the last three decades on water quality, plant life and lake catch figures has allowed a group of researchers to reconstruct the ravages caused by pesticides in the aquatic food chain.

The neonicotinoids began to be used in the rice fields surrounding Shinji in 1993. According to the authors, that same year the arthropod populations suffered a dramatic decline, which led in a short time to a reduction in the species that depend on those invertebrates to feed , like eel and smelt. A chain effect that eventually reached the local industry, causing the closure of the fishing factories in the area, as the catches dropped.

"The use of neonicotinoids in this river basin since 1993 coincided with an 83% decrease in zooplankton biomass during the spring, causing collapse of catches of smells from 240 tons to only 22", the authors summarize, which also , consider "likely that this same alteration has occurred in other areas."

Scientists at the University of Tokyo have ruled out that this sharp decrease in biomass is related to other factors, such as nutrient quality, changes in salinity or oxygen concentration in water.

"Arthropods are exceptionally sensitive to neonicotinoids," explains Olaf Jensen, a researcher at the Department of Marine and Coastal Sciences at the University of Rutgers (USA) and author of a second article on the subject in the same issue of Science . "After all, insecticides are designed to kill insects, and the way in which that impact spreads to other species in the food web is now evident."

The damage caused by pesticides in pollinator species (especially bees) has been known for more than a decade. But, in recent years, evidence of its direct and indirect effects on other organisms, including vertebrates, is also accumulating.

"Proponents of chemical-dependent industrial agriculture argue that, although the ideal would be to reduce the use of pesticides, there are too many mouths to feed," argues Jensen. "But this study shows that what is gained in one type of production (agriculture), is lost in another (fishing); fisheries that were sustainable for decades closed a year after they began using neonicotinoids."

At the center of the European debate

In Europe, pesticides are at the center of the current confrontation between the Commission and Parliament. This summer, the Commission decided to postpone the application of new safety tests to protect wild pollinators (bees, bumblebees, butterflies, etc.) from pesticides, thus ignoring the recommendations of the experts of the European Food Safety Authority (EFSA) ).

However, last week MEPs voted for an overwhelming majority (533 in favor, 67 against, 100 abstentions) a resolution demanding a new assessment on the risks of phytosanitary products, since the current one "does not correspond to the latest developments in scientific and technical knowledge. "

In Europe, the three main neonicotinoids (imidacloprid, thiamethoxam and clothianidine) have been banned since the end of 2018. However, with the current approval process, they could be replaced by similar molecules. That is why in 2013 - a year after a report was published detailing the defects of the current tests - the EFSA produced an orientation document on possible harmful effects that must be tested before allowing the entry of a substance in the market.

"Standard laboratory tests on pesticides, which are those required by regulatory agencies, typically focus on the short-term effects of acute exposure to individual model organisms," says Jensen. "But, to understand the long-term impact of pollutants, you have to study entire ecosystems for a long time."

According to the criteria of The Trust Project

• science
• Science and Health

Genetic archeology Being rich or poor was already inherited 4,000 years ago

Astronomy Borisov, the second interstellar comet that visits our solar system

SpaceA former NASA scientist believes life on Mars has already been discovered in the 1970s