Life-history traits of the copepods Pseudocalanus minutus (Calanoida) and Oithona similis (Cyclopoida) in the Arctic Kongsfjorden (Svalbard) with particular emphasis on seasonality

Abstract

The life-history traits of the copepods Pseudocalanus minutus (Calanoida) and Oithona similis (Cyclopoida) were investigated in the Arctic Kongsfjorden (Svalbard). In November, both species exhibited maximum abundances (P. minutus: 111,297 and O. similis: 704,633 ind m2), whereas minima occurred in June (1,088 and 4,483 ind m2, respectively). High levels of diatom marker fatty acids (16:1(n-7), 16:4(n-1), 20:5(n-3)) as well as high trypsin activities showed that the diatom bloom in spring was of specific importance for adult females and stage V copepodids of P. minutus to fuel final maturation processes and reproduction in May/June. O. similis generally followed an omnivorous feeding mode as indicated by consistently high amounts of the 18:1(n-9) fatty acid and the general predominance of the (dino-)flagellate biomarker 22:6(n-3). The first reproductive peak in June was primarily fueled by lipid reserves (wax esters), whereas the second reproductive peak in August/September co-occurred with energy storage for overwintering.