This research focusses on environmental responses of genes in the context of marine pollutants. Using next-generation mRNA sequencing, genomic responses (e.g. differential gene expression) on different stressors can be evaluated. Here, we focus on marine pelagic copepods from the Belgian part of the North Sea. By studying sexual reproducing species, such as Temora, inferences can be made on population level, a biologically more relevant level, from an ecotoxicological perspective.