Within this study, the non-model organism Myriophyllum spicatum was used to evaluate ecotoxic modes of action at the gene expression level. M. spicatum was exposed to low-effect concentrations of bentazone and atorvastatin in a shortened and modified version of the OECD guideline test No. 239, followed by RNA extraction of the shoot tip tissue and a subsequent RNA-seq analysis utilizing a de novo assembly of the transcriptome. While the herbicide bentazone is an inhibitor of photosynthesis, the widely spread pharmaceutical atorvastatin acts as an inhibitor of the hydroxymethylglutaryl-CoA reductase and thus the isoprenoid biosynthesis. The aim of this study was to determine molecular fingerprints and biomarkers distinguishing these distinct modes of action at a molecular level.