Spatio-temporal variations in organic carbon composition driven by two different major phytoplankton communities in the Ross Sea, Antarctica

Jaehong Kim; Hyoung Sul La; Jeong-Hoon Kim; Naeun Jo; Junbeom Lee; Bo Kyung Kim; Wuju Son; Kwanwoo Kim; Hyo-Keun Jang; Sanghoon Park; Hyeju Yoo; Jaesoon Kim; Jisoo Park; So Hyun Ahn; Sang Heon Lee

doi:10.1016/j.scitotenv.2023.164666

Spatio-temporal variations in organic carbon composition driven by two different major phytoplankton communities in the Ross Sea, Antarctica

Sci Total Environ. 2023 Sep 15:891:164666. doi: 10.1016/j.scitotenv.2023.164666. Epub 2023 Jun 5.

Authors

Jaehong Kim¹, Hyoung Sul La², Jeong-Hoon Kim³, Naeun Jo¹, Junbeom Lee¹, Bo Kyung Kim², Wuju Son⁴, Kwanwoo Kim¹, Hyo-Keun Jang¹, Sanghoon Park¹, Hyeju Yoo², Jaesoon Kim¹, Jisoo Park², So Hyun Ahn⁵, Sang Heon Lee⁶

Affiliations

¹ Department of Oceanography, Pusan National University, Busan, South Korea.
² Division of Ocean Sciences, Korea Polar Research Institute, Incheon, South Korea.
³ Division of Life Sciences, Korea Polar Research Institute, Incheon, South Korea.
⁴ Division of Ocean Sciences, Korea Polar Research Institute, Incheon, South Korea; Department of Polar Science, University of Science and Technology, Daejeon, South Korea.
⁵ Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, USA.
⁶ Department of Oceanography, Pusan National University, Busan, South Korea. Electronic address: sanglee@pusan.ac.kr.

PMID: 37286011
DOI: 10.1016/j.scitotenv.2023.164666

Abstract

The compositions of organic carbon could be important in determining biological carbon pump efficiency. However, little information on them in relation to each algal assemblage is currently available in the Ross Sea. Here, we investigated the seasonal variations in organic carbon composition and the relative abundance of each organic carbon, including particulate organic carbon (POC), dissolved organic carbon (DOC), and transparent exopolymer particles (TEPs), characterized by different algal groups in the Ross Sea. The average POC and DOC contributions to the total organic carbon (TOC = POC + DOC) were 13.8 ± 3.7 % and 86.2 ± 3.7 % in mid-January 2019 and 20.9 ± 4.1 % and 79.1 ± 4.1 % in February-March 2018, respectively. The carbon content of TEP (TEP-C) contributed 19.6 ± 11.7 % and 4.6 ± 7.0 % of POC and TOC in mid-January and 36.2 ± 14.8 % and 9.0 ± 6.7 % in February-March, respectively. We found that the organic carbon compositions were affected by seasonal variations in the phytoplankton bloom phase, physical characteristics, and phytoplankton community structure. DOC concentrations and contributions to the TOC increased as phytoplankton cells became senescent in mid-January and decreased in February-March when phytoplankton were relatively active. From February-March, the deepened mixed layer depth encouraged TEP formation, subsequently increasing the TEP contributions. Regardless of the sampling season, all organic carbon concentrations per unit Chl-a were significantly higher in P. antarctica-abundant groups. The DOC contributions to the TOC were correspondingly higher at the P. antarctica-abundant stations in mid-January, which indicates that P. antarctica could be also important in the DOC contributions in the Ross Sea. The rapid alteration in environmental characteristics and phytoplankton community structures in the Ross Sea due to climate change could affect the organic carbon pool at the euphotic layer which consequently could determine the efficiency of the biological pump.

Keywords: Antarctica; Dissolved organic carbon; Particulate organic carbon; Phytoplankton; Ross Sea; Transparent exopolymer particle.

MeSH terms

Carbon*
Dissolved Organic Matter
Environmental Monitoring*
Phytoplankton*
Spatio-Temporal Analysis

Substances

Carbon
Dissolved Organic Matter