Ocean Acidification does Not Limit Squid Metabolism via Blood Oxygen Supply

Matthew A. Birk; Erin L. McLean; Brad A. Seibel

doi:10.1242/jeb.187443

Ocean Acidification does Not Limit Squid Metabolism via Blood Oxygen Supply

Matthew A. Birk, Erin L. McLean, Brad A. Seibel

College of Marine Science

Research output: Contribution to journal › Article › peer-review

Abstract

Ocean acidification is hypothesized to limit the performance of squid owing to their exceptional oxygen demand and pH sensitivity of blood–oxygen binding, which may reduce oxygen supply in acidified waters. The critical oxygen partial pressure ( P crit ), the P O 2 below which oxygen supply cannot match basal demand, is a commonly reported index of hypoxia tolerance. Any CO 2 -induced reduction in oxygen supply should be apparent as an increase in P crit . In this study, we assessed the effects of CO 2 (46–143&emsp14;Pa; 455–1410&emsp14;μatm) on the metabolic rate and P crit of two squid species – Dosidicus gigas and Doryteuthis pealeii – through manipulative experiments. We also developed a model, with inputs for hemocyanin pH sensitivity, blood P CO 2 and buffering capacity, that simulates blood oxygen supply under varying seawater CO 2 partial pressures. We compare model outputs with measured P crit in squid. Using blood–O 2 parameters from the literature for model inputs, we estimated that, in the absence of blood acid–base regulation, an increase in seawater P CO 2 to 100&emsp14;Pa (≈1000&emsp14;μatm) would result in a maximum drop in arterial hemocyanin–O 2 saturation by 1.6% at normoxia and a P crit increase of ≈0.5&emsp14;kPa. Our live-animal experiments support this supposition, as CO 2 had no effect on measured metabolic rate or P crit in either squid species.

Original language	American English
Journal	Journal of Experimental Biology
Volume	221
DOIs	https://doi.org/10.1242/jeb.187443
State	Published - Oct 1 2018

Keywords

Acid–base balance
Blood–O2 binding
Hypercapnia
Cephalopod
Hypoxia tolerance
Dosidicus

Disciplines

Life Sciences

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10.1242/jeb.187443License: CC BY

https://doi.org/10.1242/jeb.187443

Cite this

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title = "Ocean Acidification does Not Limit Squid Metabolism via Blood Oxygen Supply",

abstract = " Ocean acidification is hypothesized to limit the performance of squid owing to their exceptional oxygen demand and pH sensitivity of blood\–oxygen binding, which may reduce oxygen supply in acidified waters. The critical oxygen partial pressure ( P crit ), the P O 2 below which oxygen supply cannot match basal demand, is a commonly reported index of hypoxia tolerance. Any CO 2 -induced reduction in oxygen supply should be apparent as an increase in P crit . In this study, we assessed the effects of CO 2 (46\–143\&emsp14;Pa; 455\–1410\&emsp14;\μatm) on the metabolic rate and P crit of two squid species \– Dosidicus gigas and Doryteuthis pealeii \– through manipulative experiments. We also developed a model, with inputs for hemocyanin pH sensitivity, blood P CO 2 and buffering capacity, that simulates blood oxygen supply under varying seawater CO 2 partial pressures. We compare model outputs with measured P crit in squid. Using blood\–O 2 parameters from the literature for model inputs, we estimated that, in the absence of blood acid\–base regulation, an increase in seawater P CO 2 to 100\&emsp14;Pa (\≈1000\&emsp14;\μatm) would result in a maximum drop in arterial hemocyanin\–O 2 saturation by 1.6\% at normoxia and a P crit increase of \≈0.5\&emsp14;kPa. Our live-animal experiments support this supposition, as CO 2 had no effect on measured metabolic rate or P crit in either squid species.",

keywords = "Acid–base balance, Blood–O2 binding, Hypercapnia, Cephalopod, Hypoxia tolerance, Dosidicus",

author = "Birk, \{Matthew A.\} and McLean, \{Erin L.\} and Seibel, \{Brad A.\}",

year = "2018",

month = oct,

day = "1",

doi = "10.1242/jeb.187443",

language = "American English",

volume = "221",

journal = "Journal of Experimental Biology",

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TY - JOUR

T1 - Ocean Acidification does Not Limit Squid Metabolism via Blood Oxygen Supply

AU - Birk, Matthew A.

AU - McLean, Erin L.

AU - Seibel, Brad A.

PY - 2018/10/1

Y1 - 2018/10/1

N2 - Ocean acidification is hypothesized to limit the performance of squid owing to their exceptional oxygen demand and pH sensitivity of blood–oxygen binding, which may reduce oxygen supply in acidified waters. The critical oxygen partial pressure ( P crit ), the P O 2 below which oxygen supply cannot match basal demand, is a commonly reported index of hypoxia tolerance. Any CO 2 -induced reduction in oxygen supply should be apparent as an increase in P crit . In this study, we assessed the effects of CO 2 (46–143&emsp14;Pa; 455–1410&emsp14;μatm) on the metabolic rate and P crit of two squid species – Dosidicus gigas and Doryteuthis pealeii – through manipulative experiments. We also developed a model, with inputs for hemocyanin pH sensitivity, blood P CO 2 and buffering capacity, that simulates blood oxygen supply under varying seawater CO 2 partial pressures. We compare model outputs with measured P crit in squid. Using blood–O 2 parameters from the literature for model inputs, we estimated that, in the absence of blood acid–base regulation, an increase in seawater P CO 2 to 100&emsp14;Pa (≈1000&emsp14;μatm) would result in a maximum drop in arterial hemocyanin–O 2 saturation by 1.6% at normoxia and a P crit increase of ≈0.5&emsp14;kPa. Our live-animal experiments support this supposition, as CO 2 had no effect on measured metabolic rate or P crit in either squid species.

AB - Ocean acidification is hypothesized to limit the performance of squid owing to their exceptional oxygen demand and pH sensitivity of blood–oxygen binding, which may reduce oxygen supply in acidified waters. The critical oxygen partial pressure ( P crit ), the P O 2 below which oxygen supply cannot match basal demand, is a commonly reported index of hypoxia tolerance. Any CO 2 -induced reduction in oxygen supply should be apparent as an increase in P crit . In this study, we assessed the effects of CO 2 (46–143&emsp14;Pa; 455–1410&emsp14;μatm) on the metabolic rate and P crit of two squid species – Dosidicus gigas and Doryteuthis pealeii – through manipulative experiments. We also developed a model, with inputs for hemocyanin pH sensitivity, blood P CO 2 and buffering capacity, that simulates blood oxygen supply under varying seawater CO 2 partial pressures. We compare model outputs with measured P crit in squid. Using blood–O 2 parameters from the literature for model inputs, we estimated that, in the absence of blood acid–base regulation, an increase in seawater P CO 2 to 100&emsp14;Pa (≈1000&emsp14;μatm) would result in a maximum drop in arterial hemocyanin–O 2 saturation by 1.6% at normoxia and a P crit increase of ≈0.5&emsp14;kPa. Our live-animal experiments support this supposition, as CO 2 had no effect on measured metabolic rate or P crit in either squid species.

KW - Acid–base balance

KW - Blood–O2 binding

KW - Hypercapnia

KW - Cephalopod

KW - Hypoxia tolerance

KW - Dosidicus

UR - https://digitalcommons.usf.edu/msc_facpub/1270

UR - https://doi.org/10.1242/jeb.187443

U2 - 10.1242/jeb.187443

DO - 10.1242/jeb.187443

M3 - Article

C2 - 30111559

VL - 221

JO - Journal of Experimental Biology

JF - Journal of Experimental Biology

ER -

Ocean Acidification does Not Limit Squid Metabolism via Blood Oxygen Supply

Abstract

Keywords

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