The University of Southampton
University of Southampton Institutional Repository
Warning ePrints Soton is experiencing an issue with some file downloads not being available. We are working hard to fix this. Please bear with us.

Night-time temperature reprieves enhance the thermal tolerance of a symbiotic cnidarian

Night-time temperature reprieves enhance the thermal tolerance of a symbiotic cnidarian
Night-time temperature reprieves enhance the thermal tolerance of a symbiotic cnidarian
Responses of cnidarian-Symbiodiniaceae associations to warming are determined, in part, by high-frequency temperature variability. Yet, the role of such variability in determining specific maximum temperature thresholds of cnidarian holobionts (the ecological units comprised of cnidarian hosts and associated microorganisms, including Symbiodiniaceae) remains untested. Here we contrasted the thermal resilience (that is the ability to resist stress) of a model symbiotic cnidarian from the Red Sea (jellyfish of the genus Cassiopea) under stable and diel oscillating temperature conditions that provide night-time reprieves from daily maximum temperatures. Holobionts were subjected to two thermal trajectories; one that increased but plateaued at 2 °C below identified bleaching thresholds and another that increased incrementally until holobionts bleached. We used behavior, growth, photochemical efficiency, Symbiodiniaceae (symbiont) cell density, and total chlorophyll cell content to characterize thermal resilience and examined Symbiodiniaceae community composition responses at 1 and 13 days of exposure, and post-bleaching. Lower night-time temperatures, resulting in lower daily mean temperatures, allowed holobionts to withstand daily maximum temperatures close to their bleaching thresholds for two extra days than those under stable maximum temperature conditions. Lower night-time temperatures increased the bleaching threshold of the holobionts, whereby holobionts exposed to night-time thermal reprieves tolerated a more extreme daily mean temperature of 40.6 ºC and reached a daily thermal maxima 4 ºC higher than those under stable temperature conditions. However, post-bleaching observations indicate that night-time temperature reprieves did not prevent symbiont cell or pigment loss. Symbiodiniaceae communities were unaffected by lower night-time temperatures and no directional changes indicative of symbiont shuffling/ selection of thermally tolerant lineages were observed. We show that stable experimental treatments may fail to accurately identify maximum thermal thresholds of non-calcifying cnidarians and limit their relevance to in situ environments that are often characterized by high levels of temperature fluctuations.
Cassiopea sp., Bleaching, warming, Temperature oscillations, diel variations, climate change, Holobiont
2296-7745
Klein, Shannon
fd1ed337-5b36-4e77-88d5-f09ed5cfa703
Pitt, Kylie
770b5546-f4b6-47a2-91d5-e5d6264301f3
Lucas, Cathy H.
521743e3-b250-4c6b-b084-780af697d6bf
Hung, Shiou-Han
3cb1ecfe-d989-4da1-8801-c525e5c9e038
Schmidt-Roach, Sebastian
b24f5e1e-70fa-4dce-91e6-91e6b7c7efca
Aranda, Manuel
c53c6c9f-5c25-49cd-8b66-5adf97c0e214
Duarte, Carlos
861fbe39-21e4-4ede-8cef-5ec104829c52
Klein, Shannon
fd1ed337-5b36-4e77-88d5-f09ed5cfa703
Pitt, Kylie
770b5546-f4b6-47a2-91d5-e5d6264301f3
Lucas, Cathy H.
521743e3-b250-4c6b-b084-780af697d6bf
Hung, Shiou-Han
3cb1ecfe-d989-4da1-8801-c525e5c9e038
Schmidt-Roach, Sebastian
b24f5e1e-70fa-4dce-91e6-91e6b7c7efca
Aranda, Manuel
c53c6c9f-5c25-49cd-8b66-5adf97c0e214
Duarte, Carlos
861fbe39-21e4-4ede-8cef-5ec104829c52

Klein, Shannon, Pitt, Kylie, Lucas, Cathy H., Hung, Shiou-Han, Schmidt-Roach, Sebastian, Aranda, Manuel and Duarte, Carlos (2019) Night-time temperature reprieves enhance the thermal tolerance of a symbiotic cnidarian. Frontiers in Marine Science. (doi:10.3389/fmars.2019.00453).

Record type: Article

Abstract

Responses of cnidarian-Symbiodiniaceae associations to warming are determined, in part, by high-frequency temperature variability. Yet, the role of such variability in determining specific maximum temperature thresholds of cnidarian holobionts (the ecological units comprised of cnidarian hosts and associated microorganisms, including Symbiodiniaceae) remains untested. Here we contrasted the thermal resilience (that is the ability to resist stress) of a model symbiotic cnidarian from the Red Sea (jellyfish of the genus Cassiopea) under stable and diel oscillating temperature conditions that provide night-time reprieves from daily maximum temperatures. Holobionts were subjected to two thermal trajectories; one that increased but plateaued at 2 °C below identified bleaching thresholds and another that increased incrementally until holobionts bleached. We used behavior, growth, photochemical efficiency, Symbiodiniaceae (symbiont) cell density, and total chlorophyll cell content to characterize thermal resilience and examined Symbiodiniaceae community composition responses at 1 and 13 days of exposure, and post-bleaching. Lower night-time temperatures, resulting in lower daily mean temperatures, allowed holobionts to withstand daily maximum temperatures close to their bleaching thresholds for two extra days than those under stable maximum temperature conditions. Lower night-time temperatures increased the bleaching threshold of the holobionts, whereby holobionts exposed to night-time thermal reprieves tolerated a more extreme daily mean temperature of 40.6 ºC and reached a daily thermal maxima 4 ºC higher than those under stable temperature conditions. However, post-bleaching observations indicate that night-time temperature reprieves did not prevent symbiont cell or pigment loss. Symbiodiniaceae communities were unaffected by lower night-time temperatures and no directional changes indicative of symbiont shuffling/ selection of thermally tolerant lineages were observed. We show that stable experimental treatments may fail to accurately identify maximum thermal thresholds of non-calcifying cnidarians and limit their relevance to in situ environments that are often characterized by high levels of temperature fluctuations.

Text
fmars-06-00453 - Version of Record
Available under License Creative Commons Attribution.
Download (8MB)

More information

Accepted/In Press date: 8 July 2019
e-pub ahead of print date: 25 July 2019
Keywords: Cassiopea sp., Bleaching, warming, Temperature oscillations, diel variations, climate change, Holobiont

Identifiers

Local EPrints ID: 433648
URI: http://eprints.soton.ac.uk/id/eprint/433648
ISSN: 2296-7745
PURE UUID: 0d3ab42e-3da9-4745-902f-12688eec9009
ORCID for Cathy H. Lucas: ORCID iD orcid.org/0000-0002-5929-7481

Catalogue record

Date deposited: 28 Aug 2019 16:31
Last modified: 26 Nov 2021 02:37

Export record

Altmetrics

Contributors

Author: Shannon Klein
Author: Kylie Pitt
Author: Cathy H. Lucas ORCID iD
Author: Shiou-Han Hung
Author: Sebastian Schmidt-Roach
Author: Manuel Aranda
Author: Carlos Duarte

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×