Biochemical characteristics and demography of the marine calanoid copepod Calanus finmarchicus during spring in Icelandic waters

Abstract The chemical composition of Calanus finmarchicus was analyzed at 21 stations from three regions where 12 transects were sampled from 0 to 50 m depth, including stage composition analysis at the Siglunes and Selvogsbanki transects in relation to the effects of different water masses, during a survey in Icelandic waters during 11–29 May 2018. The stage composition of C. finmarchicus at the northern transect of Siglunes was mostly made up of copepodites CI–CIII, around 76%, whereas older copepods CV–CVI dominated, around 64%, at the southern transect of Selvogsbanki. The dry weight (dw) and lipid content of C. finmarchicus were overall highest in the southwest (160 ± 60 μg dw ind−1 and 60 ± 20 μg lipids ind−1) and lowest in the east (120 ± 20 μg dw ind−1 and 30 ± 10 μg lipids ind−1). Total astaxanthin content ranged from 0.14 to 0.27 μg mg−1 dw. Chitin made up 2–4% of the dw. The diatom marker C20:5n3 was prolific in the copepods southwest of Iceland, while the dinoflagellate markers C18:4n3 and C22:6n3 dominated in the copepods east of Iceland. The results indicate that C. finmarchicus found in the south of Iceland developed faster than those in the north, with the variation in chemical composition and developmental time highly influenced by hydrographic regions.