TY - JOUR
T1 - Loss of zooxanthellae in a coral under high seawater temperature and nutrient enrichment
AU - Tanaka, Yasuaki
AU - Inoue, Mayuri
AU - Nakamura, Takashi
AU - Suzuki, Atsushi
AU - Sakai, Kazuhiko
N1 - Funding Information:
We are grateful to H. Kinjyo (University of the Ryukyus) for the experimental setup and technical assistance and to I. Mimura (University of the Ryukyus) for supporting the analysis of nutrients. This study was financially supported by Research Fellowship of the Japan Society for the Promotion of Science (JSPS) for Young Scientists ( 24-3911 ), Global Environmental Research Fund of the Ministry of the Environment of Japan ( RF-1009 ), and KAKENHI ( 24244090 ) funded by JSPS. [SS]
PY - 2014/8
Y1 - 2014/8
N2 - To investigate the effect of nutrient concentrations on coral-algal symbiosis under thermal stress, the abundance and release of zooxanthellae in the coral Acropora tenuis were quantified under laboratory conditions. The coral fragments were first cultured in either low-nutrient (LN) or high-nutrient (HN) seawater condition at 27°C for 25days and the seawater temperature was then elevated and kept at 31°C for 1week for both nutrient conditions. Nutrient enrichment at 27°C increased the densities of symbiotic algae and chlorophyll a and the algal release rates (AR) from the host coral to the ambient seawater. The percentage of algal release rate to the standing stock (AR%) was approximately 0.015%h-1 for both nutrient conditions at 27°C. After the seawater temperature was elevated to 31°C, the densities of zooxanthellae in the corals decreased by 21-61%, and AR and AR% increased. The corals in HN lost more zooxanthellae per unit surface area than those in LN, but the lost percentages were not significantly different between LN and HN. AR% was also not significantly different between LN and HN at 31°C. These results indicated that the percentage rate of symbiotic algal loss was not affected by the nutrient condition, implying that nutrient incorporation itself would not accelerate coral bleaching susceptibility.
AB - To investigate the effect of nutrient concentrations on coral-algal symbiosis under thermal stress, the abundance and release of zooxanthellae in the coral Acropora tenuis were quantified under laboratory conditions. The coral fragments were first cultured in either low-nutrient (LN) or high-nutrient (HN) seawater condition at 27°C for 25days and the seawater temperature was then elevated and kept at 31°C for 1week for both nutrient conditions. Nutrient enrichment at 27°C increased the densities of symbiotic algae and chlorophyll a and the algal release rates (AR) from the host coral to the ambient seawater. The percentage of algal release rate to the standing stock (AR%) was approximately 0.015%h-1 for both nutrient conditions at 27°C. After the seawater temperature was elevated to 31°C, the densities of zooxanthellae in the corals decreased by 21-61%, and AR and AR% increased. The corals in HN lost more zooxanthellae per unit surface area than those in LN, but the lost percentages were not significantly different between LN and HN. AR% was also not significantly different between LN and HN at 31°C. These results indicated that the percentage rate of symbiotic algal loss was not affected by the nutrient condition, implying that nutrient incorporation itself would not accelerate coral bleaching susceptibility.
KW - Algal density
KW - Algal release
KW - Coral
KW - Nutrients
KW - Seawater temperature
KW - Zooxanthellae
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U2 - 10.1016/j.jembe.2014.04.019
DO - 10.1016/j.jembe.2014.04.019
M3 - Article
AN - SCOPUS:84900503364
VL - 457
SP - 220
EP - 225
JO - Journal of Experimental Marine Biology and Ecology
JF - Journal of Experimental Marine Biology and Ecology
SN - 0022-0981
ER -