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Heat tolerance, behavioural temperature selection and temperature-dependent respiration in larval Octopus huttoni

Heat tolerance, behavioural temperature selection and temperature-dependent respiration in larval Octopus huttoni
Heat tolerance, behavioural temperature selection and temperature-dependent respiration in larval Octopus huttoni
This study reports temperature effects on paralarvae from a benthic octopus species, Octopus huttoni, found throughout New Zealand and temperate Australia. We quantified the thermal tolerance, thermal preference and temperature-dependent respiration rates in 1–5 days old paralarvae. Thermal stress (1 °C increase h?1) and thermal selection (?10–24 °C vertical gradient) experiments were conducted with paralarvae reared for 4 days at 16 °C. In addition, measurement of oxygen consumption at 10, 15, 20 and 25 °C was made for paralarvae aged 1, 4 and 5 days using microrespirometry. Onset of spasms, rigour (CTmax) and mortality (upper lethal limit) occurred for 50% of experimental animals at, respectively, 26.0±0.2 °C, 27.8±0.2 °C and 31.4±0.1 °C. The upper, 23.1±0.2 °C, and lower, 15.0±1.7 °C, temperatures actively avoided by paralarvae correspond with the temperature range over which normal behaviours were observed in the thermal stress experiments. Over the temperature range of 10 °C–25 °C, respiration rates, standardized for an individual larva, increased with age, from 54.0 to 165.2 nmol larvae?1 h?1 in one-day old larvae to 40.1–99.4 nmol h?1 at five days. Older larvae showed a lesser response to increased temperature: the effect of increasing temperature from 20 to 25 °C (Q10) on 5 days old larvae (Q10=1.35) was lower when compared with the 1 day old larvae (Q10=1.68). The lower Q10 in older larvae may reflect age-related changes in metabolic processes or a greater scope of older larvae to respond to thermal stress such as by reducing activity. Collectively, our data indicate that temperatures >25 °C may be a critical temperature. Further studies on the population-level variation in thermal tolerance in this species are warranted to predict how continued increases in ocean temperature will limit O. huttoni at early larval stages across the range of this species.
Lethal thermal limit, Critical thermal maximum, Selected temperature, Octopus huttoni, Robsonbella huttoni, Paralarvae
0306-4565
83-88
Higgins, Fiona A.
ac6e61d2-181d-42b9-a14e-568292b294d6
Bates, Amanda E.
a96e267d-6d22-4232-b7ed-ce4e448a2a34
Lamare, Miles D.
ad181b20-8e12-46b1-9552-760d003d1be3
Higgins, Fiona A.
ac6e61d2-181d-42b9-a14e-568292b294d6
Bates, Amanda E.
a96e267d-6d22-4232-b7ed-ce4e448a2a34
Lamare, Miles D.
ad181b20-8e12-46b1-9552-760d003d1be3

Higgins, Fiona A., Bates, Amanda E. and Lamare, Miles D. (2012) Heat tolerance, behavioural temperature selection and temperature-dependent respiration in larval Octopus huttoni. Journal of Thermal Biology, 37 (1), 83-88. (doi:10.1016/j.jtherbio.2011.11.004).

Record type: Article

Abstract

This study reports temperature effects on paralarvae from a benthic octopus species, Octopus huttoni, found throughout New Zealand and temperate Australia. We quantified the thermal tolerance, thermal preference and temperature-dependent respiration rates in 1–5 days old paralarvae. Thermal stress (1 °C increase h?1) and thermal selection (?10–24 °C vertical gradient) experiments were conducted with paralarvae reared for 4 days at 16 °C. In addition, measurement of oxygen consumption at 10, 15, 20 and 25 °C was made for paralarvae aged 1, 4 and 5 days using microrespirometry. Onset of spasms, rigour (CTmax) and mortality (upper lethal limit) occurred for 50% of experimental animals at, respectively, 26.0±0.2 °C, 27.8±0.2 °C and 31.4±0.1 °C. The upper, 23.1±0.2 °C, and lower, 15.0±1.7 °C, temperatures actively avoided by paralarvae correspond with the temperature range over which normal behaviours were observed in the thermal stress experiments. Over the temperature range of 10 °C–25 °C, respiration rates, standardized for an individual larva, increased with age, from 54.0 to 165.2 nmol larvae?1 h?1 in one-day old larvae to 40.1–99.4 nmol h?1 at five days. Older larvae showed a lesser response to increased temperature: the effect of increasing temperature from 20 to 25 °C (Q10) on 5 days old larvae (Q10=1.35) was lower when compared with the 1 day old larvae (Q10=1.68). The lower Q10 in older larvae may reflect age-related changes in metabolic processes or a greater scope of older larvae to respond to thermal stress such as by reducing activity. Collectively, our data indicate that temperatures >25 °C may be a critical temperature. Further studies on the population-level variation in thermal tolerance in this species are warranted to predict how continued increases in ocean temperature will limit O. huttoni at early larval stages across the range of this species.

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More information

Published date: January 2012
Keywords: Lethal thermal limit, Critical thermal maximum, Selected temperature, Octopus huttoni, Robsonbella huttoni, Paralarvae
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 361228
URI: http://eprints.soton.ac.uk/id/eprint/361228
ISSN: 0306-4565
PURE UUID: c8e36ea5-6bff-47da-a7da-ec757878c02d

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Date deposited: 15 Jan 2014 14:21
Last modified: 09 Jan 2022 02:18

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Contributors

Author: Fiona A. Higgins
Author: Amanda E. Bates
Author: Miles D. Lamare

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