Population dynamics and biogeochemical significance of Limacina helicina antarctica in the Scotia Sea (Southern Ocean)

Bednaršek, N., Tarling, G. A., Fielding, S. and Bakker, D. C. E. ORCID: https://orcid.org/0000-0001-9234-5337 (2012) Population dynamics and biogeochemical significance of Limacina helicina antarctica in the Scotia Sea (Southern Ocean). Deep-Sea Research Part II: Topical Studies in Oceanography, 59-60. pp. 105-116. ISSN 0967-0645

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Abstract

Limacina helicina antarctica is a common part of the Southern Ocean zooplankton community but little is known about its life cycle. Here we determine the population structure and standing stock biomass of this species in the Scotia Sea region and use this information to derive estimates for rates of growth, mortality and secondary productivity. Three non-overlapping cohorts were present in the size–frequency distribution, a G2 generation (0-year) with a modal peak at 0.3 mm shell diameter, a G1 generation (1-year) with a modal peak at 2.7 mm and a G generation (2-year) cohort with sizes between 4 and 10 mm. We surmise that at least some L. helicina ant. are capable of living 3 years or more, growing at an average rate of 0.01 mm d-1. Mortality rates were 0.01 d-1 or 3.83 year-1, with 2% of individuals surviving beyond 1 year of age and 0.05% beyond 2 years of age. Standing stock biomass was 178 mg DW m-2 or 32 mg C m-2, divided between 23 mg Corg m-2 and 9 mg Cinorg m-2. The inorganic fraction had a calcium carbonate composition equivalent to 72 mg CaCO3 m-2. Maximum daily productivity during the summer was 1.8 mg C m-2 d-1, made up of 1.3 Corg mg m-2 d-1 and 0.5 mg Cinorg m-2 d-1, and equivalent to 4.2 mg CaCO3 m-2 d-1. The mass specific growth rate (P:B d-1) was 0.06 within the summer period. Growth and production appeared to continue over the autumn and winter months at rates almost equivalent to those in summer. We propose that autumn peaks in sedimenting L. helicina ant., reported by other studies, do not appear to be the consequence of the termination of the life-cycle but are more likely to result from a combination of environmental and behavioural factors.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups: Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Marine and Atmospheric Sciences (former - to 2017)
Faculty of Science > Research Groups > Climate, Ocean and Atmospheric Sciences (former - to 2017)
Depositing User: Users 2731 not found.
Date Deposited: 24 Oct 2011 13:06
Last Modified: 04 Mar 2024 16:36
URI: https://ueaeprints.uea.ac.uk/id/eprint/35147
DOI: 10.1016/j.dsr2.2011.08.003

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