Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrations

Diel and seasonal fluctuations in seawater carbonate chemistry are common in coastal waters, while in the open-ocean carbonate chemistry is much less variable. In both of these environments, ongoing ocean acidification is being superimposed on the natural dynamics of the carbonate buffer system t...

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Main Authors: F. Li, Y. Wu, D. A. Hutchins, F. Fu, K. Gao
Format: Article
Language:English
Published: Copernicus Publications 2016-11-01
Series:Biogeosciences
Online Access:https://www.biogeosciences.net/13/6247/2016/bg-13-6247-2016.pdf
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spelling doaj-f88ad14e25854980b9d131b9c80fe0cc2020-11-24T21:40:26ZengCopernicus PublicationsBiogeosciences1726-41701726-41892016-11-01136247625910.5194/bg-13-6247-2016Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrationsF. Li0Y. Wu1D. A. Hutchins2F. Fu3K. Gao4State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, ChinaState Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, ChinaDepartment of Biological Sciences, University of Southern California, Los Angeles, California, USADepartment of Biological Sciences, University of Southern California, Los Angeles, California, USAState Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361102, ChinaDiel and seasonal fluctuations in seawater carbonate chemistry are common in coastal waters, while in the open-ocean carbonate chemistry is much less variable. In both of these environments, ongoing ocean acidification is being superimposed on the natural dynamics of the carbonate buffer system to influence the physiology of phytoplankton. Here, we show that a coastal <i>Thalassiosira weissflogii</i> isolate and an oceanic diatom, <i>Thalassiosira oceanica</i>, respond differentially to diurnal fluctuating carbonate chemistry in current and ocean acidification (OA) scenarios. A fluctuating carbonate chemistry regime showed positive or negligible effects on physiological performance of the coastal species. In contrast, the oceanic species was significantly negatively affected. The fluctuating regime reduced photosynthetic oxygen evolution rates and enhanced dark respiration rates of <i>T. oceanica</i> under ambient CO<sub>2</sub> concentration, while in the OA scenario the fluctuating regime depressed its growth rate, chlorophyll <i>a</i> content, and elemental production rates. These contrasting physiological performances of coastal and oceanic diatoms indicate that they differ in the ability to cope with dynamic <i>p</i>CO<sub>2</sub>. We propose that, in addition to the ability to cope with light, nutrient, and predation pressure, the ability to acclimate to dynamic carbonate chemistry may act as one determinant of the spatial distribution of diatom species. Habitat-relevant diurnal changes in seawater carbonate chemistry can interact with OA to differentially affect diatoms in coastal and pelagic waters.https://www.biogeosciences.net/13/6247/2016/bg-13-6247-2016.pdf
collection DOAJ
language English
format Article
sources DOAJ
author F. Li
Y. Wu
D. A. Hutchins
F. Fu
K. Gao
spellingShingle F. Li
Y. Wu
D. A. Hutchins
F. Fu
K. Gao
Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrations
Biogeosciences
author_facet F. Li
Y. Wu
D. A. Hutchins
F. Fu
K. Gao
author_sort F. Li
title Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrations
title_short Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrations
title_full Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrations
title_fullStr Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrations
title_full_unstemmed Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO<sub>2</sub> concentrations
title_sort physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two co<sub>2</sub> concentrations
publisher Copernicus Publications
series Biogeosciences
issn 1726-4170
1726-4189
publishDate 2016-11-01
description Diel and seasonal fluctuations in seawater carbonate chemistry are common in coastal waters, while in the open-ocean carbonate chemistry is much less variable. In both of these environments, ongoing ocean acidification is being superimposed on the natural dynamics of the carbonate buffer system to influence the physiology of phytoplankton. Here, we show that a coastal <i>Thalassiosira weissflogii</i> isolate and an oceanic diatom, <i>Thalassiosira oceanica</i>, respond differentially to diurnal fluctuating carbonate chemistry in current and ocean acidification (OA) scenarios. A fluctuating carbonate chemistry regime showed positive or negligible effects on physiological performance of the coastal species. In contrast, the oceanic species was significantly negatively affected. The fluctuating regime reduced photosynthetic oxygen evolution rates and enhanced dark respiration rates of <i>T. oceanica</i> under ambient CO<sub>2</sub> concentration, while in the OA scenario the fluctuating regime depressed its growth rate, chlorophyll <i>a</i> content, and elemental production rates. These contrasting physiological performances of coastal and oceanic diatoms indicate that they differ in the ability to cope with dynamic <i>p</i>CO<sub>2</sub>. We propose that, in addition to the ability to cope with light, nutrient, and predation pressure, the ability to acclimate to dynamic carbonate chemistry may act as one determinant of the spatial distribution of diatom species. Habitat-relevant diurnal changes in seawater carbonate chemistry can interact with OA to differentially affect diatoms in coastal and pelagic waters.
url https://www.biogeosciences.net/13/6247/2016/bg-13-6247-2016.pdf
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