Short‐term effects of linear alkylbenzene sulfonate on freshwater plankton studied under field conditions

Abstract

AbstractThe toxic effects of linear alkylbenzene sulfonate (LAS) on several planktonic freshwater organisms were studied over a 5‐d period using small in situ enclosures. The experimental setup, an unreplicated regression design, made it possible to calculate no effect concentrations (NEC), an environmental risk assessment. The NEC varied several orders of magnitude between the different groups of organisms, with ciliates and heterotrophic nanoflagellates being the most sensitive groups (NEC as low as 0.02 mg LAS/L). The high sensitivity of the protozoans makes their exclusion from most ecotoxicological studies questionable, and this must be reconsidered in the future. Most other planktonic organisms were only affected at concentrations higher than normally found in aquatic habitats. Exceptions to this general trend were the photosynthetic activity of the phytoplankton and cryptophyte abundance, which both were nearly as sensitive parameters as the protozoan abundance. The toxicity of LAS was generally higher in the present investigation, compared with the vast majority of laboratory‐derived results, indicating a limited relevance of the latter and the need for field experiments in order to determine impacts of xenobiotics in the aquatic environments.