25 Apr 2022
25 Apr 2022
Status: this preprint is currently under review for the journal BG.

Upper ocean flux of biogenic calcite produced by the Arctic planktonic foraminifera Neogloboquadrina pachyderma

Franziska Tell, Lukas Jonkers, Julie Meilland, and Michal Kucera Franziska Tell et al.
  • MARUM – Center for Marine Environmental Sciences, University of Bremen, Leobener Straße 8, Bremen 28359, Germany

Abstract. With ongoing warming and sea ice loss, the Arctic Ocean and its marginal seas will likely become more hospitable to pelagic calcifiers, resulting in modifications of the regional carbonate cycle and the composition of the seafloor sediment. A substantial part of the pelagic carbonate production in the Arctic is due to the calcification of the dominant planktonic foraminifera species Neogloboquadrina pachyderma. To quantify calcite production and loss in the upper water layer by this important Arctic calcifier, we compile and analyse data from vertical profiles in the upper water column of shell concentration, shell sizes and weights of this species across the Arctic region during summer. Our data is inconclusive on whether the species performs ontogenetic vertical migration throughout its lifecycle, or whether individual specimens calcify at a fixed depth within the vertical habitat. The base of the productive zone of the species is on average located below 100 m and at maximum at 300 m and is regionally highly variable. The calcite flux immediately below the productive zone (production flux) is on average 8 mg CaCO3 m-2 d-1, and we observe that this flux is attenuated until at least 300 m below the base of the productive zone at the mean rate of 1.5 % per 100 m. Regionally, the summer production flux of N. pachyderma calcite varies by more than two orders of magnitude and the estimated mean export flux below the twilight zone is sufficient to account for about a quarter of the total pelagic carbonate flux in the region. These results indicate that estimates of the Arctic pelagic carbonate budget will have to account for large regional differences in production flux of the major pelagic calcifiers and confirm that substantial attenuation of the production flux occurs in the twilight zone.

Franziska Tell et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2022-59', Robert F. Spielhagen, 23 May 2022
  • RC2: 'Comment on bg-2022-59', Ralf Schiebel, 13 Jun 2022

Franziska Tell et al.

Franziska Tell et al.


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Short summary
This study analyses the production of calcite shells formed by one of the main Arctic pelagic calcifier, the foraminifera N. pachyderma. Using vertically resolved profiles of shell concentration, size and weight, we show that calcification occurs throughout the upper 300 m with an average production flux below the calcification zone of 8 mg CaCO3 m-2 d-1 representing 23 % of the total pelagic biogenic carbonate production. The production flux is attenuated in the twilight zone by dissolution.