Journal article
Differential impact of heat stress on reef-building corals under different light conditions
Marine Environmental Research, Vol.158, 104947
2020
PMID: 32250839
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Abstract
Heat stress is an environmental factor that regularly challenges the well-being of living organisms. This study aims to examine the physiological changes happening in two reef-building coral species exposed to thermal stress under various light conditions. The two ecologically relevant heatwave scenarios were applied under ambient lights (high irradiance) and reduced light conditions (250 and < 10 μmol photons m−2 s−1). Corals were exposed to elevated temperatures of 32 °C (plus 6°) for a period of 1 up to 5 days corresponding to heatwaves reported on the Great Barrier Reef (GBR) that were associated with coral bleaching. We monitored changes in the physiological performance of these two coral species by measuring symbionts and corals’ physiological parameters including symbiont density, levels of multiple algal pigments (chlorophyll a and peridinin), as well as the changes in the host protein concentration. During the short-term heat stress, both species were with stable physiological performance with the only exception of Stylophora pistillata under ambient lights. These results show that S. pistillata was negatively influenced by a synergistic effect of temperature and high irradiance resulting in the first signs of bleaching after only 24h of thermal stress. Exposure to prolonged thermal stress, characterised with a slower rate of temperature increase, affected both coral species investigated and resulted in bleaching mainly by day 5. Interestingly, severe light reduction (<10 μmol photons m−2 s−1) made Acropora millepora corals more thermally sensitive and resulted in earlier signs of bleaching (on day 3). These findings indicate that there was a synergistic effect of very low lights and thermal stress that caused higher levels of bleaching in A. millepora. Our results revealed differential thermal sensitivity for two branching corals exposed to different thermal stress scenarios under various light irradiance conditions, naturally found in their existing habitats. Consequently, global warming may have a differential impact on coral reef biodiversity depending on light availability. •Thermal sensitivity of coral species vary.•Heatwaves will have a different impact on corals depending on light availability.•Coral bleaching will be influenced by both, seawater heating profiles and light.•Global warming plus diverse light intensities and UV radiation will jointly affect coral bleaching modelling maps and have an impact on reef biodiversity.
Details
- Title
- Differential impact of heat stress on reef-building corals under different light conditions
- Creators
- Nedeljka Rosic (Author) - Southern Cross UniversityCamille Rémond (Author) - University Pierre and Marie CurieMatheus A Mello-Athayde (Author) - University of Queensland
- Publication Details
- Marine Environmental Research, Vol.158, 104947
- Publisher
- Elsevier
- Identifiers
- 991012832200402368
- Academic Unit
- School of Health and Human Sciences; Human Sciences; Faculty of Health
- Language
- English
- Resource Type
- Journal article