Rapid acclimation of microbes to changing substrate pools in epipelagic waters of an Antarctic polynya during austral summer 2003

• Published in: Polar biology Vol. 41; no. 1; pp. 1 - 10
• Main Authors: Del Negro, Paola, Celussi, Mauro, De Vittor, Cinzia, Fonda Umani, Serena
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2018; Springer; Springer Nature B.V
• Subjects: Acclimation; Acclimatization; Activity patterns; Biogeochemistry; Biomedical and Life Sciences; Chlorophyll; Chlorophyll a; Dissolved organic carbon; Dynamics; Ecology; Ecosystems; Environmental changes; Ice melting; Icebergs; Life Sciences; Microbiology; Microorganisms; Oceanography; Organic matter; Original Paper; Particulate organic carbon; Phytoplankton; Plant Sciences; Polar environments; Polls & surveys; Polynyas; Prokaryotes; Protists; Spring; Substrates; Summer; Surface water; Surveying; Surveys; Temporal variations; Variation; Zoology; DOC; Ross Sea; Prokaryotes; Exoenzymatic activity; POC
• ISSN: 0722-4060; 1432-2056
• DOI: 10.1007/s00300-017-2165-5

Antarctic polynyas are among the most productive areas in the ocean. They are subjected to strong temporal variations, having profound effects on the local ecosystems. We tested the changes occurring in several biogeochemical features [Chlorophyll a (Chl a ), phaeopigment, dissolved and particulate organic carbon (DOC and POC) concentrations] as well as in biological dynamics (prokaryotic and nanoplanktonic abundance, heterotrophic carbon production and degradative activities) at the transition between late spring and summer in surface waters (upper 125 m) in the Terra Nova Bay polynya, in the Ross Sea. Samplings were performed from January 18 to 21 and, after an interval of almost 5 days, from January 25 to 27. The first period was characterised by spring conditions still maintained by the presence in the area of two mega-icebergs (B15 and C19), which caused a delay in the ice melting that started during the second survey. Chlorophyll a concentrations were highest during the first period, whereas phaeopigments/Chl a ratio increased during the following sampling time suggesting variations in phytoplankton biomass/physiology and a change in organic matter (OM) quality. No significant differences in DOC and POC concentration were detected between the two periods together with unvaried abundances of prokaryotes and small protists. The changes in OM over time were evidenced also by changing exoenzymatic activity patterns. Notwithstanding the general variations occurring during the surveys, heterotrophic production and prokaryotic growth were not substantially modified, suggesting a rapid (timescales of days) acclimation to changing organic matter quality for the maintenance of prokaryotic metabolic requirements.