Status: this discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The manuscript was not accepted for further review after discussion.
Combined effects of elevated pCO2 and temperature on biomass and carbon fixation of phytoplankton assemblages in the northern South China Sea
Guang Gao,Peng Jin,Nana Liu,Futian Li,Shanying Tong,David A. Hutchins,and Kunshan Gao
Abstract. The individual influences of ocean warming and acidification on marine organisms have been investigated intensively, but studies regarding the combined effects of both global change variables on natural marine phytoplankton assemblages are still scarce. Even fewer studies have addressed possible differences in the responses of phytoplankton communities in pelagic and coastal zones to ocean warming and acidification. We conducted shipboard microcosm experiments at both off-shore (SEATS) and near-shore (D001) stations in the northern South China Sea (NSCS) under three treatments, low temperature (30.5 °C at SEATS and 28.5 °C at D001) and low pCO2 (390.0 µatm at SEATS and 420.0 µatm at D001) (LTLC), high temperature (33.5 °C at SEATS and 31.5 °C at D001) and low pCO2 (390 µatm at SEATS and 420 µatm at D001) (HTLC), and high temperature (33.5 °C at SEATS and 31.5 °C at D001) and high pCO2 (1000 µatm at SEATS and 1030 µatm at D001) (HTHC). Biomass of phytoplankton at both stations were enhanced by HT. HTHC did not affect phytoplankton biomass at station D001 but decreased it at station SEATS. At this offshore station HT alone increased daily primary productivity (DPP, µgC (µg chl a)−1 d−1) by ~ 64 %, and by ~ 117 % when higher pCO2 was added. In contrast, HT alone did not affect DPP and HTHC reduced it by ~ 15 % at station D001. HT enhanced the dark respiration rate (µg C (µg chl a)-1 d−1) by 64 % at station SEATS, but had no significant effect at station D001, and did not change the ratio of respiration to photosynthesis at either station. HTHC did not affect dark respiration rate (µg C (µg chl a)−1 d−1) at either station compared to LTLC. HTHC reduced the respiration to photosynthesis ratio by ~ 41 % at station SEATS but increased it ~ 42 % at station D001. Overall, our findings indicate that responses of coastal and offshore phytoplankton assemblages in NSCS to ocean warming and acidification are contrasting, with the pelagic phytoplankton communities being more sensitive to these two global change factors.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Guang Gao,Peng Jin,Nana Liu,Futian Li,Shanying Tong,David A. Hutchins,and Kunshan Gao
Viewed
Total article views: 1,514 (including HTML, PDF, and XML)
HTML
PDF
XML
Total
Supplement
BibTeX
EndNote
1,004
409
101
1,514
189
72
105
HTML: 1,004
PDF: 409
XML: 101
Total: 1,514
Supplement: 189
BibTeX: 72
EndNote: 105
Views and downloads (calculated since 29 Sep 2016)
Cumulative views and downloads
(calculated since 29 Sep 2016)
Viewed (geographical distribution)
Total article views: 1,464 (including HTML, PDF, and XML)
Thereof 1,460 with geography defined
and 4 with unknown origin.
Country
#
Views
%
Total:
0
HTML:
0
PDF:
0
XML:
0
1
1
Latest update: 06 Nov 2024
Guang Gao
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
Marine Resources Development Institute of Jiangsu, Huaihai Institute of Technology, Lianyungang 222005, China
Peng Jin
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
Nana Liu
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
Futian Li
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
Shanying Tong
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
David A. Hutchins
Marine Environmental Biology, Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, California 90089, USA
Our shipboard experiments showed high temperature and CO2 (HTHC) did not affect phytoplankton biomass at nearshore station but decreased it at offshore station. HT did not change dark respiration at nearshore station but enhanced it at offshore station. Our findings indicate that responses of coastal and offshore phytoplankton assemblages to ocean warming and acidification may be contrasting, with the pelagic phytoplankton communities being more sensitive to these two global change factors.
Our shipboard experiments showed high temperature and CO2 (HTHC) did not affect phytoplankton...