Early life stages of the Arctic copepod Calanus glacialis are unaffected by increased seawater pCO2

As the world's oceans continue to absorb anthropogenic CO2 from the atmosphere, the carbonate chemistry of seawater will change. This process, termed ocean acidification, may affect the physiology of marine organisms. Arctic seas are expected to experience the greatest decreases in pH in the future, as changing sea ice dynamics and naturally cold, brackish water, will accelerate ocean acidification. In this study, we investigated the effect of increased pCO2 on the early developmental stages of the key Arctic copepod Calanus glacialis. Eggs from wild-caught C. glacialis females from Svalbard, Norway (80°N), were cultured for 2 months to copepodite stage C1 in 2°C seawater under four pCO2 treatments (320, 530, 800, and 1700 μatm). Developmental rate, dry weight, and carbon and nitrogen mass were measured every other day throughout the experiment, and oxygen consumption rate was measured at stages N3, N6, and C1. All endpoints were unaffected by pCO2 levels projected for the year 2300. These results indicate that naupliar development in wild populations of C. glacialis is unlikely to be detrimentally affected in a future high CO2 ocean.

A review of naupliar development within the Harpacticidae, with naupliar description of Zaus wonchoelleei Kangtia, Dahms, Song, Myoung, Park & Khim, 2014 (Copepoda, Harpacticoida)

All six naupliar stages of the harpacticoid copepod Zaus wonchoelleei Kangtia, Dahms, Song, Myoung, Park & Khim, 2014 are described. A key for the identification of the naupliar stages is provided. Stages can be distinguished by number of segments of the exopod of antenna 2, setation of the limbs including the bud of the caudal ramus, and presence and setation of the bud of maxilla 1. In phylogenetic reconstructions there are several characters which link two taxa of different harpacticoid groups, the Harpacticidae of Exanechentera and the Thalestridae of Podogennonta. The Harpacticidae and the free-living genera of the Thalestridae develop from a 3-segmented naupliar antennular precursor in Harpacticidae and a 1-segmented antennule in Thalestridae to a 6-segmented antennule at copepodid I. Both families also share a single, stout spine terminally on the inner process of the mandibular naupliar endopodite which is unique for harpacticoid nauplii. A peculiar medial bifid seta on the antennal basis at nauplius I and II is also unique. This seta is replaced by a medial seta of the coxa at nauplius III, which has the same structure as the aforementioned set which gets reduced.