The role of zooplankton in establishing carbon export regimes in the Southern Ocean - a comparison of two representative case studies in the Subantarctic region
Marine ecosystems regulate atmospheric carbon dioxide levels by transporting andstoring photosynthetically fixed carbon in the oceans interior. In particular, thesubantarctic and polar frontal zone of the Southern Ocean is a significant regionfor physically driven carbon uptake due to mode water for...
| Published in: | Frontiers in Marine Science |
|---|---|
| Main Authors: | , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Frontiers Research Foundation
2020
|
| Subjects: | |
| Online Access: | https://doi.org/10.3389/fmars.2020.567917 http://ecite.utas.edu.au/141293 |
| Summary: | Marine ecosystems regulate atmospheric carbon dioxide levels by transporting andstoring photosynthetically fixed carbon in the oceans interior. In particular, thesubantarctic and polar frontal zone of the Southern Ocean is a significant regionfor physically driven carbon uptake due to mode water formation, although it isunder-studied concerning biologically mediated uptake. Regional differences in ironconcentrations lead to variable carbon export from the base of the euphotic zone.Contrary to our understanding of export globally, where high productivity results inhigh export, naturally iron-fertilized regions exhibit low carbon export relative to theirsurface productivity, while HNLC (High Nutrient, Low Chlorophyll) waters emerge asa significant area for carbon export. Zooplankton, an integral part of the oceanicfood web, play an important role in establishing these main carbon export regimes.In this mini review, we explore this role further by focusing on the impact of grazingand the production of fecal pellets on the carbon flux. The data coverage in thesubantarctic region will be assessed by comparing two case studies - the iron-repleteKerguelen Plateau and the HNLC region south of Australia. We then discusschallenges in evaluating the contributions of zooplankton to carbon flux, namelygaps in seasonal coverage of sampling campaigns, the use of non-standardized andbiased methods and under-sampling of the mesopelagic zone, an important area ofcarbon remineralization. More integrated approaches are necessary to improve presentestimates of zooplankton-mediated carbon export in the Southern Ocean. |
|---|