남극 아문젠 해의 폴리냐에서 식물플랑크톤의 분류학적 변동성과 유색 용존유기물 생산과의 상관관계

Abstract

To evaluate the relationship between the phytoplankton and the CDOM production in the Amundsen Sea, we examined the taxonomic variability of phytoplankton, nutrients and chromophoric dissolved organic matter (CDOM) from two cruises ANA02C (February, 2012) and ANA04B (January, 2014). For both cruises, the peak concentrations of chlorophyll a (Chl a) were measured in the Amundsen Sea Polynya (ASP), where the average concentration of Chl a was 1.77μg/L (± 1.14μg/L) in February 2012 and 2.25μg/L (± 2.43μg/L) in January 2014. The major phytoplankton groups were diatoms and prymnesiophytes Phaeocystis antarctica (P. antarctica), while the minor groups were cryptophytes, chlorophytes, dinophytes, chrysophytes and cyanophytes. The phytoplankton composition in the sea ice zone (SIZ), ASP and ice shelf (IS) was distinct. The predominance of P. antarctica (70–90%) was observed at all stations, except in the SIZ in January 2014. While the CDOM concentrations (a355) ranged from 0.07 to 0.98m-1, the average values of a355 of the euphotic layer in the ASP was 0.51m-1 (± 0.19m-1), which was much higher than any other region of the Southern Ocean. CDOM showed strong correlation with Chl a (r2 = 0.74) but weak correlation with salinity (r2 = 0.01), which implies that biological processes were the main source of CDOM. Among the major phytoplankton taxa, P. antarctica was confirmed as the most important contributor to the production of CDOM, according to the high correlation between marker pigment (hex-fuco) and CDOM. The unusually high CDOM in the ASP is expected to give as an impact on the environment in various aspects. As a nature of CDOM, absorption of solar radiation at the surface can result in the increase of sea surface temperature (SST), which will accelerate the ice melting. Also the photo-oxidation of CDOM can serve as a feedback to increasing atmospheric CO2 concentrations after peak bloom in austral summer.