The effect of thermal history on the susceptibility of reef-building corals to thermal stress

Middlebrook, Rachael, Hoegh-Guldberg, Ove, and Leggat, William (2008) The effect of thermal history on the susceptibility of reef-building corals to thermal stress. Journal of Experimental Biology, 211 (7). pp. 1050-1056.

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Abstract

The mutualistic relationship between corals and their unicellular dinoflagellate symbionts (Symbiodinium sp.) is a fundamental component within the ecology of coral reefs. Thermal stress causes the breakdown of the relationship between corals and their symbionts (bleaching). As with other organisms, this symbiosis may acclimate to changes in the environment, thereby potentially modifying the environmental threshold at which they bleach. While a few studies have examined the acclimation capacity of reef-building corals, our understanding of the underlying mechanism is still in its infancy. The present study focused on the role of recent thermal history in influencing the response of both corals and symbionts to thermal stress, using the reef-building coral Acropora aspera. The symbionts of corals that were exposed to 31°C for 48 h (pre-stress treatment) 1 or 2 weeks prior to a 6-day simulated bleaching event (when corals were exposed to 34°C) were found to have more effective photoprotective mechanisms. These mechanisms included changes in non-photochemical quenching and xanthophyll cycling. These differences in photoprotection were correlated with decreased loss of symbionts, with those corals that were not prestressed performing significantly worse, losing over 40% of their symbionts and having a greater reduction in photosynthetic efficiency. These results are important in that they show that thermal history, in addition to light history, can influence the response of reef-building corals to thermal stress and therefore have implications for the modeling of bleaching events. However, whether acclimation is capable of modifying the thermal threshold of corals sufficiently to cope as sea temperatures increase in response to global warming has not been fully explored. Clearly increases in sea temperatures that extend beyond 1–2°C will exhaust the extent to which acclimation can modify the thermal threshold of corals.

Item ID: 6573
Item Type: Article (Refereed Research - C1)
Keywords: acclimation; thermal stress; Symbiodinium sp.; coral bleaching; photoprotectiuve mechanisms
ISSN: 1477-9145
Date Deposited: 24 Feb 2010 23:25
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060203 Ecological Physiology @ 100%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960506 Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments @ 100%
Citation Count from Scopus Scopus 48
Downloads: Total: 1
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