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...
Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2016-11-01
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Series: | Biogeosciences |
Online Access: | https://www.biogeosciences.net/13/6247/2016/bg-13-6247-2016.pdf |
Summary: | 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. |
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ISSN: | 1726-4170 1726-4189 |