Impacts of elevated CO2 on phytoplankton community composition and organic carbon dynamics in nutrient-depleted Okhotsk Sea surface waters
Impacts of the increasing CO 2 in seawater (i.e. ocean acidification) on phytoplankton physiology may have various and potentially adverse effects on phytoplankton dynamics and the carbon cycle. We conducted a CO 2 manipulation experiment in the Sea of Okhotsk in summer 2006 to investigate the respo...
Main Authors: | , , , , , |
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Format: | Text |
Language: | English |
Published: |
2018
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Subjects: | |
Online Access: | https://doi.org/10.5194/bgd-6-4143-2009 https://www.biogeosciences-discuss.net/bg-2009-65/ |
Summary: | Impacts of the increasing CO 2 in seawater (i.e. ocean acidification) on phytoplankton physiology may have various and potentially adverse effects on phytoplankton dynamics and the carbon cycle. We conducted a CO 2 manipulation experiment in the Sea of Okhotsk in summer 2006 to investigate the response of the phytoplankton assemblage and dynamics of organic carbon. During the 14-day incubation of nutrient-depleted surface water with a natural phytoplankton assemblage under 150, 280, 480, and 590 μatm p CO 2 , the relative abundance of fucoxanthin-containing phytoplankton such as diatoms and prymnesiophytes decreased with increasing p CO 2 . The amount of DOC accumulation also decreased with increasing p CO 2 , while differences in POC accumulation between the treatments were small and did not show a clear trend with the p CO 2 . Change in the phytoplankton community composition under different CO 2 conditions will alter the organic carbon dynamics as found in the present experiment. Compared to results in the literature from nutrient-replete conditions indicating a potential enhancement of phytoplankton production with elevated CO 2 , the present results indicated a different physiological response of phytoplankton under nutrient-depleted conditions. These results indicate that the continuing increase in atmospheric CO 2 can significantly affect the structure of marine ecosystems and carbon cycle in nutrient-depleted subpolar surface waters. |
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