Bifenthrin Causes Trophic Cascade and Altered Insect Emergence in Mesocosms: Implications for Small Streams

Abstract

Direct and indirect ecological effects of the widely used insecticide bifenthrin on stream ecosystems are largely unknown. To investigate such effects, a manipulative experiment was conducted in stream mesocosms that were colonized by aquatic insect communities and exposed to bifenthrin-contaminated sediment; implications for natural streams were interpreted through comparison of mesocosm results to a survey of 100 Midwestern streams, USA. In the mesocosm experiment, direct effects of bifenthrin exposure included reduced larval macroinvertebrate abundance, richness, and biomass at concentrations (EC's ranged from 197.6 to 233.5 ng bifenthrin/g organic carbon) previously thought safe for aquatic life. Indirect effects included a trophic cascade in which periphyton abundance increased after macroinvertebrate scrapers decreased. Adult emergence dynamics and corresponding terrestrial subsidies were altered at all bifenthrin concentrations tested. Extrapolating these results to the Midwestern stream assessment suggests pervasive ecological effects, with altered emergence dynamics likely in 40% of streams and a trophic cascade in 7% of streams. This study provides new evidence that a common pyrethroid might alter aquatic and terrestrial ecosystem function at the regional scale.

Bioaccumulation and Toxicity of Cadmium, Copper, Nickel, and Zinc and Their Mixtures to Aquatic Insect Communities

“…These indirect effects can be as significant as or more significant than the direct toxic effects of a contaminant (Fleeger et al 2003). When potential direct and indirect effects are strongly correlated, teasing them apart is difficult (Gardham et al 2014; Rogers et al 2016; Van Regenmortel et al 2018). The uncertainty around the mechanisms of direct and indirect effects of metals on aquatic insect communities presents an obvious line of inquiry for further study.…”

“…Such assumptions may not always be correct. For example, metamorphosis is a stressful life‐stage transition, and metal‐exposed insects may show reduced emergence even when effects on larvae were not detected (Nebeker et al 1984; Schmidt et al 2013; Wesner et al 2014; Rogers et al 2016).…”

Historical changes in fish communities in urban streams of the south‐eastern United States and the relative importance of water‐quality stressors

“…Solid line represents smooth; dashed lines represent 95% confidence bands applications made near surface water involve effects on algae, and noted that if algae are adversely affected by tebuthiuron, indirect effects on aquatic invertebrates and fish could be detrimental due to a decrease in available food. However, evidence from mesocosm studies suggests that pesticides in streams can create trophic cascades, altering phytoplankton productivity and invertebrate diversity (Rogers et al, 2016;Temple et al, 1991). Durkin (2016) further noted that extreme caution should be used when applying tebuthiuron near surface water, consistent with current product labelling.…”

“…The hydrophobic pesticide bifenthrin was examined as a water-quality stressor because it is known to frequently occur in streams, persist in bed sediments (Hladik & Kuivila, 2012) and negatively affect aquatic biota (Moran et al, 2017;Rogers et al, 2016).…”

A Uniform Practice for Conceptualizing and Communicating Food‐Energy‐Water Nexus Studies

“…Resource scarcity issues will likely become increasingly prevalent, given that humans have already appropriated more than 50% of available renewable freshwater, converted more than 50% of arable land to crops or pasture, and tripled extraction of natural materials in the last 40 years (Crowther et al, 2015;Schandl et al, 2016;Srinivasan et al, 2016;Vitousek et al, 1997). In the United States alone, more natural resources are currently being used both totally and on a per capita basis than ever before (Rogich et al, 2008a). The changing climate has also prompted concerns about our current practices, including certain waste disposal practices (e.g., Barnett et al, 2008;Colgan et al, 2016) that may no longer be stable.…”