Acid–base regulatory ability of the cephalopod (Sepia officinalis) in response to environmental hypercapnia

Gutowska, Magdalena, Melzner, Frank, Langenbuch, Martina, Bock, C., Claireaux, G. and Pörtner, H. O. (2010) Acid–base regulatory ability of the cephalopod (Sepia officinalis) in response to environmental hypercapnia Journal of Comparative Physiology B - Biochemical Systemic and Environmental Physiology, 180 (3). pp. 323-335. DOI 10.1007/s00360-009-0412-y.

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Abstract

Acidification of ocean surface waters by anthropogenic carbon dioxide (CO2) emissions is a currently developing scenario that warrants a broadening of research foci in the study of acid–base physiology. Recent studies working with environmentally relevant CO2 levels, indicate that some echinoderms and molluscs reduce metabolic rates, soft tissue growth and calcification during hypercapnic exposure. In contrast to all prior invertebrate species studied so far, growth trials with the cuttlefish Sepia officinalis found no indication of reduced growth or calcification performance during long-term exposure to 0.6 kPa CO2. It is hypothesized that the differing sensitivities to elevated seawater pCO2 could be explained by taxa specific differences in acid–base regulatory capacity. In this study, we examined the acid–base regulatory ability of S. officinalis in vivo, using a specially modified cannulation technique as well as 31P NMR spectroscopy. During acute exposure to 0.6 kPa CO2, S. officinalis rapidly increased its blood [HCO3 −] to 10.4 mM through active ion-transport processes, and partially compensated the hypercapnia induced respiratory acidosis. A minor decrease in intracellular pH (pHi) and stable intracellular phosphagen levels indicated efficient pHi regulation. We conclude that S. officinalis is not only an efficient acid–base regulator, but is also able to do so without disturbing metabolic equilibria in characteristic tissues or compromising aerobic capacities. The cuttlefish did not exhibit acute intolerance to hypercapnia that has been hypothesized for more active cephalopod species (squid). Even though blood pH (pHe) remained 0.18 pH units below control values, arterial O2 saturation was not compromised in S. officinalis because of the comparatively lower pH sensitivity of oxygen binding to its blood pigment. This raises questions concerning the potentially broad range of sensitivity to changes in acid–base status amongst invertebrates, as well as to the underlying mechanistic origins. Further studies are needed to better characterize the connection between acid–base status and animal fitness in various marine species.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/211384
Additional Information: WOS:000274457300002
Keywords: Zoology; Marine Biology; Biogeochemistry; Acid–base regulation; Sepia officinalis; Ocean acidification; Extracellular pH; CARBON-DIOXIDE; SIPUNCULUS-NUDUS; INTRACELLULAR PH; DISSOCIATION-CONSTANTS; METABOLIC DEPRESSION; OCEAN ACIDIFICATION; CARCINUS-MAENAS; OXYGEN-BINDING; ION REGULATION; SHORE CRAB
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EOE-B Experimental Ecology - Benthic Ecology
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s00360-009-0412-y
ISSN: 0174-1578
Projects: BIOACID
Date Deposited: 16 Dec 2010 08:32
Last Modified: 04 Jul 2017 08:52
URI: http://oceanrep.geomar.de/id/eprint/10540

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