http://www.nature.com/news/pesticides-spark-broad-biodiversity-loss-1.13214
Agricultural pesticides have been linked to widespread invertebrate
biodiversity loss in two new research papers.
Pesticide use has sharply reduced the regional biodiversity of stream
invertebrates, such as mayflies and dragonflies, in Europe and Australia,
finds a study published today in the Proceedings of the National Academy of
Sciences1<http://www.nature.com/news/pesticides-spark-broad-biodiversity-loss-1.13214#b1>
.
Previous research has shown similar decreases in individual streams, but
the study by Mikhail Beketov, an aquatic ecologist at the Helmholtz Centre
for Environmental Research in Leipzig, Germany, and his colleagues analysed
the effects of pesticides over broad regions.
The team examined 23 streams in the central plains of Germany, 16 in the
western plains of France and 24 in southern Victoria, Australia. They
classified streams according to three different levels of pesticide
contamination: uncontaminated, slightly contaminated and highly
contaminated.
The researchers found that there were up to 42% fewer species in highly
contaminated than in uncontaminated streams in Europe. Highly contaminated
streams in Australia showed a decrease in the number of invertebrate
families by up to 27% when contrasted with uncontaminated streams.
Moreover, the authors say that diversity decreased at pesticide
concentrations that European regulations deem environmentally protective.
"It shows our risk assessments don't work," says Beketov. "I think we
should care about this because invertebrates are an important part of the
food web."
Emma Rosi-Marshall, an aquatic ecologist at the Cary Institute of Ecosystem
Studies in Millbrook, New York, says that she finds the results compelling.
"We are at a crisis point, with species loss on a global scale, especially
in freshwater ecosystems. Considering pesticides along with other known
threats to biodiversity may be crucial for halting species declines," she
says.
But toxicologist Keith Solomon of the University of Guelph in Ontario,
Canada, says he has concerns about the study's sample size. "It begs the
question as to what is happening in all the other streams out there," he
says. "If these streams are representative of the worst case, then the
effects may only be confined to these types of scenarios and not apply to
the entire environment."
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