Abundance and biomass of copepods and cladocerans in Atlantic and Arctic domains of the Barents Sea ecosystem

• Published in: Journal of Plankton Research
• Main Authors: Skjoldal, Hein Rune, Aarflot, Johanna Myrseth
• Other Authors: Irigoien, Xabier, Norwegian Research Council
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2023
• Subjects: Arctic; Barents Sea; Zooplankton; Copepods
• Online Access: https://doi.org/10.1093/plankt/fbad043; https://academic.oup.com/plankt/article-pdf/45/6/870/54118501/fbad043.pdf

Abstract Zooplankton in the Barents Sea have been monitored annually with a standard procedure with determination of size-fractioned biomass since the mid-1980s. Biomass of copepods and cladocerans was estimated based on measured abundance and individual weights taken from literature. Calanus species were dominant, making up ~85% of the estimated biomass of copepods. The second most important taxon was Oithona spp. (~0.5 g dry weight (dw) m−2, ~10%), followed by Metridia spp. (~0.15 g dw m−2, 2–3%) and Pseudocalanus spp. (0.10–0.15 g dw m−2, 1–5%). Estimated biomass of cladoceran taxa (Evadne and Podon) was low (0.01 g dw m−2). Calanus spp. contributed most of the biomass of the medium size fraction (1–2 mm), whereas small copepod species (Oithona, Pseudocalanus and others) contributed to the small size fraction (<1 mm). Estimated biomass of Calanus spp. and of the sum of small copepod species were both positively correlated with measured total zooplankton biomass (R2 = 0.72 and 0.34, respectively). The biomass ratio of small copepod species to Calanus was similar in Atlantic and Arctic water masses (~0.15–0.2) but tended to increase with decreasing total biomass. This suggests a shift to relatively larger roles of small copepods as Calanus and total biomass decrease.