Diatom – lipid – copepod nexus under threat by global change: Database on copepod wax ester composition

This dataset originates from experimental studies investigating the influence of diet and temperature (5°C and 7°C) on lipid storage and wax ester composition in the calanoid copepod Calanus finmarchicus. The dataset contains the relative composition of 75 wax ester compounds, together with indices characterizing the saturation and carbon chain length of the wax ester pool at the conclusion of the feeding experiment. Furthermore, the dataset includes measurements of mean developmental stage, body length, and oil sac volume of copepods across treatments. The experiment was initiated with copepods at the C1 copepodite stage. Individuals were maintained under controlled conditions and fed ad libitum with one of three monospecific algal diets: the cryptophyte Rhodomonas salina (RS), the diatom Thalassiosira weissflogii (TW), or the dinoflagellate Heterocapsa triquetra (HT). Experimental treatments were terminated when individuals within a cohort had reached the C4 and C5 copepodite stages. For each treatment, copepods were sorted into groups of 5–6 individuals and placed in 2 mL tapered glass vials. Samples were flushed with nitrogen (N₂) gas to minimize lipid oxidation and stored at −80°C until wax ester analysis. Wax ester composition was determined using supercritical fluid chromatography coupled with electrospray ionization tandem mass spectrometry (SFC–ESI–MS/MS) on an Acquity UPC² system (Waters, Milford, MA, USA). A detailed description of the analytical procedures and methodology is provided in Jónasdóttir et al. (2026).