Summer population structure of the copepods Paraeuchaeta spp. in the Kara Sea

•Paraeuchaeta spp. (mainly P. glacialis) reached its maximum abundance in the western Kara Sea.•The species reproduced in summer season.•Unimodal size spectra were recorded for most age stages.•Clutch and egg sizes positively correlated with P. glacialis female individual biomass.

High Arctic seas are poorly studied due to difficulties to access and sample seas with extensive sea ice cover. The current study investigated the distribution of the large deepwater copepods Paraeuchaeta spp. (Paraeuchaeta glacialis) in the summer season in the Kara Sea. The total abundance of P. glacialis varied from 10 to 1210 × 10− 2 ind m− 3 sampled with a Juday net and from 2 to 490 × 10− 2 ind m− 3 sampled with a IKS-80 net. The highest abundances were recorded at the deepwater stations. Nauplii dominated the population of Paraeuchaeta spp. comprising 23% of the total abundance. Unimodal size spectra were found for most of the age stages that suggests the presence of one generation during the year. Clutch size and egg size tended to increase with P. glacialis female prosome length and individual biomass.