The metabolic response of thecosome pteropods from the North Atlantic and North Pacific oceans to high CO<sub>2</sub> and low O<sub>2</sub>
As anthropogenic activities directly and indirectly increase carbon dioxide (CO<sub>2</sub>) and decrease oxygen (O<sub>2</sub>) concentrations in the ocean system, it becomes important to understand how different populations of marine animals will respond. Water that is n...
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/13/6191/2016/bg-13-6191-2016.pdf |
Summary: | As anthropogenic activities directly and indirectly increase carbon dioxide
(CO<sub>2</sub>) and decrease oxygen (O<sub>2</sub>) concentrations in the ocean system,
it becomes important to understand how different populations of marine
animals will respond. Water that is naturally low in pH, with a high
concentration of carbon dioxide (hypercapnia) and a low concentration of
oxygen, occurs at shallow depths (200–500 m) in the North Pacific Ocean,
whereas similar conditions are absent throughout the upper water column in
the North Atlantic. This contrasting hydrography provides a natural
experiment to explore whether differences in environment cause populations of
cosmopolitan pelagic calcifiers, specifically the aragonitic-shelled
pteropods, to have a different physiological response when exposed to
hypercapnia and low O<sub>2</sub>. Using closed-chamber end-point respiration
experiments, eight species of pteropods from the two ocean basins were
exposed to high CO<sub>2</sub> ( ∼ 800 µatm) while six species were
also exposed to moderately low O<sub>2</sub> (48 % saturated, or
∼ 130 µmol kg<sup>−1</sup>) and a combined treatment of low
O<sub>2</sub>/high CO<sub>2</sub>. None of the species tested
showed a change in metabolic rate in response to high CO<sub>2</sub> alone. Of
those species tested for an effect of O<sub>2</sub>, only <i>Limacina
retroversa</i> from the Atlantic showed a response to the combined treatment,
resulting in a reduction in metabolic rate. Our results suggest that
pteropods have mechanisms for coping with short-term CO<sub>2</sub> exposure and
that there can be interactive effects between stressors on the physiology of
these open ocean organisms that correlate with natural exposure to low
O<sub>2</sub> and high CO<sub>2</sub>. These are considerations that should be taken into
account in projections of organismal sensitivity to future ocean conditions. |
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ISSN: | 1726-4170 1726-4189 |