Effects of Pesticides Monitored with Three Sampling Methods in 24 Sites on Macroinvertebrates and Microorganisms

Abstract

Grab water samples, sediment samples, and 2,2,4-trimethylpentane passive samplers (TRIMPS) were used to determine the exposure to 97 pesticides in 24 southeast Australian stream sites over 5 months. Macroinvertebrate communities and selected microorganisms (bacteria, flagellates, ciliates, amoebas, nematodes, and gastrotrichs) were sampled to detect relationships with pesticide toxicity. Sediment samples had the highest estimated toxicities in terms of toxic units (TU) for Daphnia magna (TUDM) and for Selenastrum capricornutum (TUSC). The pesticide-selective SPEARpesticides and the general SIGNAL index for macroinvertebrates exhibited negative linear relationships (r(2) = 0.67 and 0.36, respectively) with pesticide contamination in terms of log maximum TUDM (log mTUDM), suggesting macroinvertebrate community change due to pesticide exposure. Pesticide contamination was the only measured variable explaining variation in ecological quality. Variation in the densities of several microbial groups was best explained by environmental variables other than log TUs. The log mTUDM values derived from sediment concentrations were most important to establish a link with effects on macroinvertebrates, whereas log mTUDM of grab water samples had only minor contribution. Current-use insecticides and fungicides can affect macroinvertebrate communities and monitoring of sediment and continuous water sampling is needed to detect these effects.

Pesticides reduce regional biodiversity of stream invertebrates

“…The only exceptions are two studies that addressed effects of salinity (8,9). Hence, although chemical contaminants are well known as an important driver for biodiversity loss (1,(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28), there is scarce empirical evidence to support such opinion for the large-scale taxonomic pools.…”

“…Essentially, it remains unknown whether, to what degree, and at what concentrations pesticides cause the species losses at the regional scale. However, there are many investigations showing the effects on the local biodiversityrelated parameters in both freshwater (16)(17)(18)(19)(20)(21)(22)(23) and terrestrial systems (14,15,(24)(25)(26)(27). Thus, the previous studies with freshwater invertebrates reliably measured the aquatic pesticide concentrations and identified local (site-scale) changes in the abundance of the taxa specifically vulnerable to pesticides and structural community alterations, e.g., using the species-at-risk (SPEAR) pesticides indicator (16)(17)(18)(19)(20)(21), or the abundance of separate species (22) (for different taxonomic groups, see ref.…”

“…In the present study, we applied the contaminant category richness to investigate the effects of pesticides on stream invertebrates using the data from Europe [Germany (16) and France (17)] and Australia [southern Victoria (18)]. These data were chosen as they included (i) exposure assessment using methods designed to capture episodic pesticide exposure, (ii) records of stream invertebrates, and (iii) data on the principal environmental factors that may confound the effects of pesticides.…”

Assessment of ecological risks of agrochemicals requires a new framework.

“…This introduces a bias in the monitoring data gathered, as the worst case scenarios that may well be the cause of population declines in some species are ignored. Passive samplers deployed in water or air can obtain integrated measurements of residues over a period of time, including peaks and troughs, so are found to produce better data than simple grab samples [93]. Whatever the case, the monitoring residue data must be evaluated for the highest peaks as well as the average or the median concentrations of residues in the matrices considered, whether plant products (e.g.…”

Scientific Opinion on the effect assessment for pesticides on sediment organisms in edge‐of‐field surface water

“…Studies focusing on retrospective risk assessment employ laboratory tests with microorganisms for evaluating toxicity of polluted sediments (often using various biosensors, e.g. Farré and Barceló, 2003;Girotti et al, 2008) or monitor differences in microbial communities between polluted and unpolluted sediments (de Lipthay et al, 2003;Vezzuli et al, 2003;Schäfer et al, 2011). Information from such studies is useful when establishing sediment quality guidelines and pollutant concentration thresholds.…”