ABSTRACT
Herbicides are used extensively in agriculture to protect crop plants by eliminating, modifying, or limiting the growth of weed species. They are highly regulated and undergo evaluations to ensure minimal impacts to freshwater ecosystems when used appropriately. Still, many compounds can be transported to surface water, mainly through run-off events, posing a potential risk to non-target organisms. In an ecological context, herbicides are most likely to impair primary production (algae, macrophyes, periphyton) directly, with indirect effects on higher trophic levels (e.g., via loss of food resources) should the changes be sufficiently adverse in space, time, and magnitude of change. In the field, these effects are a rarely observed, likely a result of both the regulatory oversight that keeps concentrations below adverse effect levels, but also functional redundancy in the systems where exposure occurs. Future work should aim to better characterize and incorporate recovery by primary producers from herbicide exposure in the risk assessment process.
