Long-term effects of a catastrophic insecticide spill on stream invertebrates.

Accidental spills or illegal discharges of pesticides in aquatic ecosystems can lead to exposure levels that strongly exceed authorized pesticide concentrations, causing major impacts on aquatic ecosystems. Such short-term events often remain undetected in regular monitoring programs with infrequent sampling. In early spring 2015, we identified a catastrophic pesticide spill with the insecticide cypermethrin in the Holtemme River, Germany. Based on existing pre-event macroinvertebrate community data, we monitored the effects and recovery of the macroinvertebrate community for more than two years after the spill. Strong short-term effects were apparent for all taxa with the exception of Chironomidae and Tubificidae. Effects could also be observed on the community level as total abundance, taxa number and biomass strongly decreased. Total abundance and taxa number showed a fast recovery. Regarding long-term effects, the total biomass remained substantially below the pre-contamination level (76%) until the end of the study. Also the abundances of three taxa (Gammarus, Leuctra, Limnius Ad.) did not return to levels prior to the spill even after 26 months. This lack of the taxon-specific recovery was likely due to their long generation time and a low migration ability due to a restricted connectivity between the contaminated site and uncontaminated stream sections. These factors proved to be stronger predictors for the recovery than the pesticide tolerance. We revealed that the biological indicators SPEARpesticides and share of Ephemeroptera, Plecoptera and Trichoptera (EPT) are not suitable for the identification of such extreme events, when nearly all taxa are eradicated. Both indicators are functioning only when repeated stressors initiate long-term competitive replacement of sensitive by insensitive taxa. We conclude that pesticide spills can have significant long-term effects on stream macroinvertebrate communities. Regular ecological monitoring is imperative to identify such ecosystem impairments, combined with analytical chemistry methods to identify the potential sources of spills.

Validating buccal swabbing as a minimal-invasive method to detect pesticide exposure in squamate reptiles.

The use of enzymatic biomarkers constitutes a widely used approach in ecotoxicology. However, standard sampling procedures are invasive, requiring tissue, organ or blood extraction. This leads to concerns regarding conservation practice, animal welfare and restrictions in study design. New techniques are needed to avoid these problems, but still generate reliable data. Here, we aimed at validating the use of buccal swabs as a reliable method to detect pesticide exposure in reptiles. Common wall lizards (Podarcis muralis) were divided into control, dermal and oral treatment groups and exposed to different pesticide formulations. Subsequently, buccal swabs were taken and enzymatic activity was analyzed. We were able to confirm the suitability of the method to detect effects of pesticide exposure on the enzymatic level. While exposure to the formulation Roundup Ultramax® didn't match when compared to effects previously observed in situ when compared to other glyphosate based formulations, effects could still be detected. This can be seen as a strong indicator that the active ingredient of a formulation may not always be the mian driver for ecotoxicological effectsat the enzymatic level. At the same time, exposure towards the single formulation Vivando® didn't result in any effects. However, individuals residing in agricultural landscapes will mostly be exposed to pesticide mixes containing different formulations. Our results strongly advocate that buccal swabbing is a reliable minimal invasive method to generate samples for detecting effects of pesticide exposure in reptiles. Due to its easy handling, we believe it will provide new opportunities concerning study designs.