Networks in aquatic communities collapse upon neonicotinoid-induced stress

Freshwater ecosystems worldwide are under pressure from neonicotinoid
insecticides. While recognized that communities of species are responsible
for ecosystem functioning, it remains unknown if neonicotinoid-induced
community transformations negatively affect ecosystem functioning.
Therefore, we employed an experimental approach with 36 naturally
established freshwater ecosystems exposed to increasing field realistic
concentrations of the neonicotinoid thiacloprid. Upon exposure, we found
severe degradation of ecosystem functioning in the form of loss of organic
matter consumption and dramatic shifts in primary productivity. This
functional decline coincides with strongly eroded species co-occurrence
networks to the point that these are indistinguishable from randomized
assemblages of species. Together, these findings show how current
environmental concentrations of a neonicotinoid can strongly disrupt
freshwater ecosystem functioning via degradation of the invertebrate food
web. Since this dramatic ecosystem degradation occurs below nearly all
identified ecotoxicological risks, we call here for the reconsideration of
the use of these insecticides.