Sample collection
Specimens were derived from ethanol samples, which were collected during
diverse monitoring programs or field campaigns and from a copepod
culture (Fig. 1, Supplement table 1). Age and storing conditions varied
between samples, samples were stored at 4°C from 2018 onwards. Adult
female copepods were identified morphologically to species level and
stored in ethanol until further processing at 4°C. In total 752
specimens from 32 species and 13 different regions were used for
proteomic fingerprinting analyses. Selected samples from the North Sea
have been part of the pilot study on using MALDI-TOF MS for species
discrimination of North Sea copepods (Laakmann et al., 2013).