No association between the use of Bti for mosquito control and the dynamics of non-target aquatic invertebrates in French coastal and continental wetlands.

The environmental safety of Bacillus thuringiensis subsp. israelensis (Bti) is still controversial, mainly because most of the previous field studies on its undesired effects were spatially limited and did not address the relationship between community similarity and application time and frequency. No general statement can therefore be drawn on the usage conditions of Bti that insure protection of non-target organisms.

Effect of thiram and of a hydrocarbon mixture on freshwater macroinvertebrate communities in outdoor stream and pond mesocosms: I. Study design, chemicals fate and structural responses.

Higher-tier ecological risk assessment (ERA) in mesocosms is commonly performed in lotic or lentic experimental systems. These systems differ in their physico-chemical and hydrological properties, leading to differences in chemical fate, community characteristics and potential recovery. This raises the issue of the relevance and sensitivity of community-level endpoints in different types of mesocosms.

Effect of thiram and of a hydrocarbon mixture on freshwater macroinvertebrate communities in outdoor stream and pond mesocosms: II. Biological and ecological trait responses and leaf litter breakdown.

Higher-tier ecological risk assessment of chemicals often relies upon studies in dynamic and/or static mesocosms. Physico-chemical and hydrological properties of each type of mesocosm result in specific chemicals fate, community functioning, and potential recovery. In the present study, macroinvertebrate abundance- and biomass-weighted biological and ecological trait matrices were used to assess the effects of a dithiocarbamate fungicide, thiram (35 and 170 µg l(-1)), and of a petroleum middle distillate (0.

Analysing chemical-induced changes in macroinvertebrate communities in aquatic mesocosm experiments: a comparison of methods.

Mesocosm experiments that study the ecological impact of chemicals are often analysed using the multivariate method 'Principal Response Curves' (PRCs). Recently, the extension of generalised linear models (GLMs) to multivariate data was introduced as a tool to analyse community data in ecology. Moreover, data aggregation techniques that can be analysed with univariate statistics have been proposed.

Structural and biological trait responses of diatom assemblages to organic chemicals in outdoor flow-through mesocosms.

The sensitivity of diatom taxonomy and trait-based endpoints to chemicals has been poorly used so far in Environmental Risk Assessment. In this study, diatom assemblages in outdoor flow-through mesocosms were exposed to thiram (35 and 170 μg/L), and a hydrocarbon emulsion (HE; 0.01, 0.

Isotopic niche metrics as indicators of toxic stress in two freshwater snails.

Descriptors of trophic niche and of food web structure and function have been suggested as integrative and sensitive endpoints of toxicant effects. In the present study, carbon and nitrogen stable isotope signatures were used to assess the effects of the dithiocarbamate fungicide thiram (35 and 170μg/L nominal concentrations) and of a petroleum distillate (0.01, 0.

Secondary production of freshwater zooplankton communities exposed to a fungicide and to a petroleum distillate in outdoor pond mesocosms.

Ecological risk assessment of chemicals in mesocosms requires measurement of a large number of parameters at the community level. Studies on invertebrate communities usually focus on taxonomic approaches, which only provide insights into taxonomic structure changes induced by chemicals. In the present study, abundance, biomass (B), theoretical production (P), and instantaneous P/B ratio were used as endpoints to assess the effects of the commercial form of the dithiocarbamate fungicide thiram (35 µg/L and 170 µg/L nominal concentrations) and of the hydrocarbon water accommodated fraction (HWAF) of a petroleum distillate (0.

Structural and functional effects of conventional and low pesticide input crop-protection programs on benthic macroinvertebrate communities in outdoor pond mesocosms.

The impacts of current and alternative wheat crop protection programs were compared in outdoor pond mesocosms in a 10-month long study. Realistic exposure scenarios were built based upon the results of modelling of drift, drainage and runoff of pesticides successively applied under two environmental situations characteristics of drained soils of northern France. Each situation was associated to two crop protection programs ("Conventional" and "Low-input") differing in the nature of pesticides used, number of treatments and application rate.

Effects of repeated field applications of two formulations of Bacillus thuringiensis var. israelensis on non-target saltmarsh invertebrates in Atlantic coastal wetlands.

Bacillus thuringiensis var. israelensis (Bti) is commonly used for selective control of larval populations of mosquitoes in coastal wetlands. A two year-study was implemented to investigate whether repeated treatments with Bti applied either as a liquid (VectoBac® 12AS) or a water-dispersible granule (VectoBac® WG) formulation may affect the abundance and diversity of non-target aquatic invertebrates in saltmarsh pools.

Influence of isolation on the recovery of pond mesocosms from the application of an insecticide. II. Benthic macroinvertebrate responses.

The immediate response and recovery of the macrobenthic communities of nonisolated and isolated freshwater outdoor 9 ml mesocosms following an acute stress caused by the addition of deltamethrin were studied over a 14-month period. To discriminate between internal and external recovery mechanisms, half of the treated ponds were covered by 1-mm mesh lids that restricted aerial recolonization. Both structural (abundance of the different taxonomic groups) and functional (litter breakdown) parameters were monitored.