Individual and synergistic effects of warming and lower salinity on mortality, growth and regeneration following fragmentation of reef-forming corals
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1
Centro de Ciências do Mar e do Ambiente (MARE), Portugal
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2
Oceanário de Lisboa, Portugal
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3
Instituto Dom Luiz, Faculdade de Ciências, Universidade de Lisboa, Portugal
Tropical storms produce competent self-regenerating coral fragments capable of originating new coral colonies. These climatic events are predicted to increase in the future due to ocean warming, the main cause of coral bleaching. Estimated increases in precipitation will affect salinity at shallow reef areas which combined with ocean warming will aggravate the effects of coral bleaching. Thus it is imperative to understand the differential effect of these environmental variables over post-fragmentation processes among coral species. This study focused on the mortality, bleaching, growth and regeneration ability of nine Indo-Pacific reef-forming coral species. Coral fragments were exposed to temperatures of 26°C, 30°C, and 32°C and also tested for the synergistic effect of temperature and salinity: 26°C-33psu, 26°C-20psu, 30°C-33psu, and 30°C-20psu, throughout 60 days. Half of these fragments was used as control and in the other half injuries were inflicted to estimate tissue regeneration rates. In the temperature experiments, mortality rate increased with temperature, reaching 100% for most the species after 60 days, at 32°C, except for Turbinaria reniformis, Galaxea fascicularis, and Psammocora contigua. These same species also showed the lowest partial mortality and bleaching throughout the experiments. Growth rates decreased with temperature, whereas regeneration rates generally increased with temperature. In the synergy experiments, mortality rate was highest at 30°C-20psu, reaching 100% for seven species on the 20th day, 100% for Psammocora contigua on the 40th day and 75% for Galaxea fascicularis on the 60th day. These last two species presented the lowest partial mortality and bleaching. Growth rates decreased as temperature increased and salinity decreased, whereas, regeneration rates increased with temperature reaching a maximum at 30°C-33psu and a minimum at 20psu as salinity decreased. It was concluded that Turbinaria reniformis, Galaxea fascicularis, and Psammocora contigua are the most resilient to high temperatures, Galaxea fascicularis and Psammocora contigua are the most resistant to reduced salinity. Galaxea fascicularis was the only species that withstood the synergistic effects of high temperature and reduced salinity.
Acknowledgements
Authors would like to thank everyone involved in the maintenance of the experimental aquarium, in particular Patricia Napier. This study had the support of the Portuguese Fundação para a Ciência e Tecnologia (FCT) through the WarmingWebs project, PTDC/MAR-EST/2141/2012, the strategic projects Pest OE/MAR/UI0199/2011, the PhD research grant SFRH/BD/103047/2014 awarded to M. Dias, the PhD research grant PD/BD/135064/2017 awarded to R. Cereja and the FCT research position awarded to C. Vinagre.
Keywords:
ocean warming,
Synergistic effects,
high temperatures,
Reduced Salinity,
Coral Bleaching,
Coral fragments
Conference:
IMMR'18 | International Meeting on Marine Research 2018, Peniche, Portugal, 5 Jul - 6 Jul, 2018.
Presentation Type:
Poster Presentation
Topic:
Biodiversity, Conservation and Coastal Management
Citation:
Dias
M,
Ferreira
A,
Gouveia
R,
Cereja
R and
Vinagre
C
(2019). Individual and synergistic effects of warming and lower salinity on mortality, growth and regeneration following fragmentation of reef-forming corals.
Front. Mar. Sci.
Conference Abstract:
IMMR'18 | International Meeting on Marine Research 2018.
doi: 10.3389/conf.FMARS.2018.06.00114
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Received:
10 Apr 2018;
Published Online:
07 Jan 2019.
*
Correspondence:
Dr. Marta Dias, Centro de Ciências do Mar e do Ambiente (MARE), Lisbon, 1749-016 Lisbon, Portugal, maddias@fc.ul.pt