Herbicide indirectly reduces physiological condition of a benthic grazer

Abstract

Freshwater ecosystems are polluted with various environmental chemicals. For example, pesticides enter the aquatic environment via spray drift or surface runoff from catchment areas used for industrialised agriculture. In the present study, we investigated the response of the grazer−aufwuchs interaction when exposed to the herbicide terbutryn in a microcosm experiment. Terbutryn induced a trophic cascade with negative effects on grazers by inhibiting growth of primary producers. We determined a no-observed-effect concentration (measured as particulate organic carbon, NOEC POC ) of 0.21 µg l −1 for aufwuchs biomass and a lowest-observed-effect concentration (LOEC POC ) of 2.01 µg l −1. Furthermore, a shift in the aufwuchs community was detected in all terbutryn treatments nearly 4 wk after exposure, and this shift persisted until the end of the experiment in the treatment with the highest terbutryn concentration. In addition, reduced energy stores (triglycerides, TG) of the grazer Rhithrogena semicolorata (Heptageniidae: Ephemeroptera) were found (NOEC TG = 0.03 µg l ), which was interpreted as an indication of moderate starvation during the experiment. While starvation did not result in reduced larval growth as might have been expected, the ob served reduction of TG content in larvae (24%) is consistent with results from a separate experiment in which starvation alone induced a 15% reduction of TG content as well as reduced emergence, reduced size at emergence, and reduced egg production.

Mixed messages from benthic microbial communities exposed to nanoparticulate and ionic silver: 3D structure picks up nano-specific effects, while EPS and traditional endpoints indicate a concentration-dependent impact of silver ions

“…Phosphorous was added 11 days (d −11 ) and 6 days (d −6 ) prior to test start to reach a final concentration of 0.046 mg/L. Harvesting and transfer of biofilms on tiles (d −11 ) is also described in detail by Rybicki et al ( 2012 ).…”

Planning Across Freshwater and Terrestrial Realms: Cobenefits and Tradeoffs Between Conservation Actions

“…Moreover, fencing can generate financial benefits to private business (e.g., preventing cattle from straying into, and possible getting stuck in muddy zones- Ross et al 2011), which in turn can improve social acceptability (and cost-effectiveness) of conservation actions (hereafter, actions) that benefit both terrestrial and freshwater ecosystems. Although examples of cobenefits are more common (e.g., Robins 2002;Bohle et al 2008), there are examples of tradeoffs, such as the construction of artificial wetlands that likely benefit freshwater species while altering the composition of terrestrial communities (e.g., Ernst & Brooks 2003), or the use of herbicides for terrestrial weed control that have detrimental impacts on aquatic fauna (Rybicki et al 2012).…”

Direct and indirect effects of pesticides on a benthic grazer during its life cycle

“…The first experiment performed in autumn/winter investigated the effects of environmentally relevant concentrations of the herbicide terbutryn. In previous studies, it was already shown that terbutryn affects the quantity and quality of aufwuchs [ 12 , 52 ]. Moreover, negative impacts affecting the physiological fitness of the grazer R. semicolorata were found, due to indirect effects [ 52 ].…”

“…In previous studies, it was already shown that terbutryn affects the quantity and quality of aufwuchs [ 12 , 52 ]. Moreover, negative impacts affecting the physiological fitness of the grazer R. semicolorata were found, due to indirect effects [ 52 ]. The present study increased the complexity of the experimental design by including further environmental stressors like stream velocity and further endpoints like grazer drift into the effect analysis.…”