Tribute to R. G. Boutilier: the effect of size on the physiological and behavioural responses of oscar, Astronotus ocellatus, to hypoxia.

Katherine A. Sloman, Chris M. Wood, Graham R. Scott, Sylvia Wood, Makiko Kajimura, Ora E. Johannsson, Vera M.F. Almeida-Val, Adalberto L. Val

Research output: Contribution to journalArticle

Abstract

The physiological and behavioural responses of two size groups of oscar (Astronotus ocellatus) to hypoxia were studied. The physiological responses were tested by measuring MO2 during decreasing environmental oxygen
tensions. Larger oscars were better able to maintain oxygen consumption during a decrease in PO2, regulating routine MO2 to a significantly lower PO2 threshold
(50·mmHg) than smaller oscars (70·mmHg).
Previous studies have also demonstrated a longer survival time of large oscars exposed to extreme hypoxia, coupled with a greater anaerobic enzymatic capability. Large oscars began aquatic surface respiration (ASR) at the oxygen tension at which the first significant decrease in MO2 was seen (50·mmHg). Interestingly, smaller oscars postponed ASR to around 22·mmHg, well beyond the PO2 at which they switched from oxyregulation to oxyconformation.
Additionally, when given the choice between an hypoxic environment containing aquatic macrophyte shelter and an open normoxic environment, small fish showed a greater preference for the hypoxic environment. Thus shelter from predators appears particularly important for juveniles, who may accept a greater physiological compromise in exchange for safety. In response to hypoxia
without available shelter, larger fish reduced their level of activity (with the exception of aggressive encounters) to aid metabolic suppression whereas smaller oscars increased their activity, with the potential benefit of
finding oxygen-rich areas.
Original languageEnglish
Pages (from-to)1197-1205
Number of pages9
JournalJournal of Experimental Biology
Volume209
DOIs
Publication statusPublished - 2006
Externally publishedYes

Fingerprint

physiological response
hypoxia
behavioral response
shelter
breathing
Respiration
Fishes
respiration
Oxygen
oxygen
group size
fish
oxygen consumption
cell respiration
macrophyte
Oxygen Consumption
aquatic environment
predator
safety
predators

Keywords

  • oxygen
  • Amazon
  • predation
  • social
  • aquatic surface respiration (ASR)
  • oscar
  • Astronotus ocellatus

Cite this

Sloman, Katherine A. ; Wood, Chris M. ; Scott, Graham R. ; Wood, Sylvia ; Kajimura, Makiko ; Johannsson, Ora E. ; Almeida-Val, Vera M.F. ; Val, Adalberto L. / Tribute to R. G. Boutilier : the effect of size on the physiological and behavioural responses of oscar, Astronotus ocellatus, to hypoxia. In: Journal of Experimental Biology. 2006 ; Vol. 209. pp. 1197-1205.
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abstract = "The physiological and behavioural responses of two size groups of oscar (Astronotus ocellatus) to hypoxia were studied. The physiological responses were tested by measuring MO2 during decreasing environmental oxygentensions. Larger oscars were better able to maintain oxygen consumption during a decrease in PO2, regulating routine MO2 to a significantly lower PO2 threshold(50·mmHg) than smaller oscars (70·mmHg). Previous studies have also demonstrated a longer survival time of large oscars exposed to extreme hypoxia, coupled with a greater anaerobic enzymatic capability. Large oscars began aquatic surface respiration (ASR) at the oxygen tension at which the first significant decrease in MO2 was seen (50·mmHg). Interestingly, smaller oscars postponed ASR to around 22·mmHg, well beyond the PO2 at which they switched from oxyregulation to oxyconformation.Additionally, when given the choice between an hypoxic environment containing aquatic macrophyte shelter and an open normoxic environment, small fish showed a greater preference for the hypoxic environment. Thus shelter from predators appears particularly important for juveniles, who may accept a greater physiological compromise in exchange for safety. In response to hypoxiawithout available shelter, larger fish reduced their level of activity (with the exception of aggressive encounters) to aid metabolic suppression whereas smaller oscars increased their activity, with the potential benefit offinding oxygen-rich areas.",
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Tribute to R. G. Boutilier : the effect of size on the physiological and behavioural responses of oscar, Astronotus ocellatus, to hypoxia. / Sloman, Katherine A.; Wood, Chris M.; Scott, Graham R.; Wood, Sylvia; Kajimura, Makiko; Johannsson, Ora E.; Almeida-Val, Vera M.F.; Val, Adalberto L.

In: Journal of Experimental Biology, Vol. 209, 2006, p. 1197-1205.

Research output: Contribution to journalArticle

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T1 - Tribute to R. G. Boutilier

T2 - the effect of size on the physiological and behavioural responses of oscar, Astronotus ocellatus, to hypoxia.

AU - Sloman, Katherine A.

AU - Wood, Chris M.

AU - Scott, Graham R.

AU - Wood, Sylvia

AU - Kajimura, Makiko

AU - Johannsson, Ora E.

AU - Almeida-Val, Vera M.F.

AU - Val, Adalberto L.

PY - 2006

Y1 - 2006

N2 - The physiological and behavioural responses of two size groups of oscar (Astronotus ocellatus) to hypoxia were studied. The physiological responses were tested by measuring MO2 during decreasing environmental oxygentensions. Larger oscars were better able to maintain oxygen consumption during a decrease in PO2, regulating routine MO2 to a significantly lower PO2 threshold(50·mmHg) than smaller oscars (70·mmHg). Previous studies have also demonstrated a longer survival time of large oscars exposed to extreme hypoxia, coupled with a greater anaerobic enzymatic capability. Large oscars began aquatic surface respiration (ASR) at the oxygen tension at which the first significant decrease in MO2 was seen (50·mmHg). Interestingly, smaller oscars postponed ASR to around 22·mmHg, well beyond the PO2 at which they switched from oxyregulation to oxyconformation.Additionally, when given the choice between an hypoxic environment containing aquatic macrophyte shelter and an open normoxic environment, small fish showed a greater preference for the hypoxic environment. Thus shelter from predators appears particularly important for juveniles, who may accept a greater physiological compromise in exchange for safety. In response to hypoxiawithout available shelter, larger fish reduced their level of activity (with the exception of aggressive encounters) to aid metabolic suppression whereas smaller oscars increased their activity, with the potential benefit offinding oxygen-rich areas.

AB - The physiological and behavioural responses of two size groups of oscar (Astronotus ocellatus) to hypoxia were studied. The physiological responses were tested by measuring MO2 during decreasing environmental oxygentensions. Larger oscars were better able to maintain oxygen consumption during a decrease in PO2, regulating routine MO2 to a significantly lower PO2 threshold(50·mmHg) than smaller oscars (70·mmHg). Previous studies have also demonstrated a longer survival time of large oscars exposed to extreme hypoxia, coupled with a greater anaerobic enzymatic capability. Large oscars began aquatic surface respiration (ASR) at the oxygen tension at which the first significant decrease in MO2 was seen (50·mmHg). Interestingly, smaller oscars postponed ASR to around 22·mmHg, well beyond the PO2 at which they switched from oxyregulation to oxyconformation.Additionally, when given the choice between an hypoxic environment containing aquatic macrophyte shelter and an open normoxic environment, small fish showed a greater preference for the hypoxic environment. Thus shelter from predators appears particularly important for juveniles, who may accept a greater physiological compromise in exchange for safety. In response to hypoxiawithout available shelter, larger fish reduced their level of activity (with the exception of aggressive encounters) to aid metabolic suppression whereas smaller oscars increased their activity, with the potential benefit offinding oxygen-rich areas.

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KW - Amazon

KW - predation

KW - social

KW - aquatic surface respiration (ASR)

KW - oscar

KW - Astronotus ocellatus

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DO - 10.1242/jeb.02090

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