Glyphosate Sequestration and Acetylcholinesterase Response in the Invasive Asiatic Clam (Corbicula fluminea) and Environmental Risk Assessment of Glyphosate in Aquatic Systems

Abstract

Glyphosate based herbicides (GBH), such as Roundup are among the most widely used agrochemicals globally, leading to frequent detection in surface waters through runoff and erosion. This raises concerns regarding their impact in aquatic ecosystems. Although formerly regarded as safe to non-target organisms, glyphosate and its commercial formulations can pose toxicological hazards to aquatic organisms. This study evaluates both organism level effects and watershed exposure risk. Chapter one tested whether the invasive Asiatic clam (Corbicula fluminea) can reduce dissolved glyphosate and whether Roundup exposure produces neurotoxic effects in the clams, using Acetylcholinesterase (AChE) as biomarker. Glyphosate reduction was tested with three densities of clams in 2 Liter jars over a 1-week period, with full formulation Roundup (7.2 mg/L glyphosate). Glyphosate concentrations in the water were significantly reduced in multiple treatments, with a negative linear relationship between final glyphosate concentration and treatment biomass. Significant AChE inhibition was observed in the high-density treatment. Chapter two applied a probabilistic risk assessment using USGS monitoring data from Sope Creek, GA, USA and EPA species sensitivity thresholds. Environmental concentrations did not exceed species benchmarks, though a significant increasing trend of glyphosate concentrations raises concerns for the future. These studies emphasize the role bivalves can have in contaminant mitigation while also underlining the potential toxicological side effects.