Assessing the role of historical temperature regime and algal symbionts on the heat tolerance of coral juveniles

Quigley, K.M., Randall, C.J., van Oppen, M.J.H., and Bay, L.K. (2020) Assessing the role of historical temperature regime and algal symbionts on the heat tolerance of coral juveniles. Biology Open, 9. bio047316.

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Abstract

The rate of coral reef degradation from climate change is accelerating and, as a consequence, a number of interventions to increase coral resilience and accelerate recovery are under consideration. Acropora spathulata coral colonies that survived mass bleaching in 2016 and 2017 were sourced from a bleaching-impacted and warmer northern reef on the Great Barrier Reef (GBR). These individuals were reproductively crossed with colonies collected from a recently bleached but historically cooler central GBR reef to produce pure and crossbred offspring groups (warm–warm, warm–cool and cool–warm). We tested whether corals from the warmer reef produced more thermally tolerant hybrid and purebred offspring compared with crosses produced with colonies sourced from the cooler reef and whether different symbiont taxa affect heat tolerance. Juveniles were infected with Symbiodinium tridacnidorum, Cladocopium goreaui and Durusdinium trenchii and survival, bleaching and growth were assessed at 27.5°C and 31°C. The contribution of host genetic background and symbiont identity varied across fitness traits. Offspring with either both or one parent from the northern population exhibited a 13- to 26-fold increase in survival odds relative to all other treatments where survival probability was significantly influenced by familial cross identity at 31°C but not 27.5°C (Kaplan–Meier P=0.001 versus 0.2). If in symbiosis with D. trenchii, a warm sire and cool dam provided the best odds of juvenile survival. Bleaching was predominantly driven by Symbiodiniaceae treatment, where juveniles hosting D. trenchii bleached significantly less than the other treatments at 31°C. The greatest overall fold-benefits in growth and survival at 31°C occurred in having at least one warm dam and in symbiosis with D. trenchii. Juveniles associated with D. trenchii grew the most at 31°C, but at 27.5°C, growth was fastest in juveniles associated with C. goreaui. In conclusion, selective breeding with warmer GBR corals in combination with algal symbiont manipulation can assist in increasing thermal tolerance on cooler but warming reefs. Such interventions have the potential to improve coral fitness in warming oceans.

Item ID: 64854
Item Type: Article (Research - C1)
ISSN: 2046-6390
Keywords: Coral, Bleaching, Heat tolerance, Symbiodiniaceae,Selective breeding
Copyright Information: This is an Open Access article distributed under the terms of the Creative Commons AttributionLicense (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use,distribution and reproduction in any medium provided that the original work is properly attributed.
Date Deposited: 11 Dec 2020 03:07
FoR Codes: 06 BIOLOGICAL SCIENCES > 0608 Zoology > 060808 Invertebrate Biology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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