Microbial dynamics in coastal waters of East Antarctica: plankton production and respiration

• Published in: Marine ecology. Progress series (Halstenbek) 1999-05, Vol.180, p.23-36
• Main Authors: Robinson, Carol, Archer, Stephen D., le B. Williams, Peter J.
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Antarctica; Aquatic communities; Biological and medical sciences; Carbon; Chlorophylls; Coastal water; Cryptomonas; Fundamental and applied biological sciences. Psychology; Marine; Microbial ecology; Oxygen; Phaeocystis; Photosynthesis; Phytoplankton; Plankton; Radiocarbon; Respiration; Various environments (extraatmospheric space, air, water)
• ISSN: 0171-8630; 1616-1599
• DOI: 10.3354/meps180023

The rates of plankton community production and respiration were determined from in vitro changes in dissolved inorganic carbon and dissolved oxygen and the incorporation of NaH14CO3 at a coastal site in East Antarctica between 16 December 1993 and 12 February 1994. The breakout of seasonal fast ice was associated with a succession of dominant phytoplankton from Cryptomonas to Phaeocystis to a diatom assemblage. Gross production reached 33 mmol C m–3 d–1 and 14C incorporation peaked at 24 mmol C m–3 d–1 on 23 January 1994, at the time of the chlorophyll a maximum (22 mg chl a m–3). Dark community respiration reached its maximum (13 mmol C m–3 d–1) 4 d later. Photosynthetic rates calculated from 14C incorporation were significantly lower (17 to 59%) than rates of gross production. The derivation of plankton processes from changes in both dissolved oxygen and dissolved inorganic carbon allowed the direct measurement of photosynthetic and respiratory quotients. A linear regression of all data gave a photosynthetic quotient of 1.33 ± 0.23 and a respiratory quotient of 0.88 ± 0.14. Concurrent determinations of bacterial, heterotrophic dinoflagellate, nanoflagellate and ciliate respiration could account for 15 to 58% of measured dark community respiration. This study has improved the sparse data set of plankton respiration measurements, confirmed that heterotrophic respiration is a significant process in the carbon flux of coastal Antarctic waters and achieved a first apportionment of community respiration to the major microbial groups in this region.