Zoological Studies

Vol. 51 No. 2, 2012

Algal Symbionts Increase DNA Damage in Coral Planulae Exposed to Sunlight

Badrun Nesa1, Andrew H Baird2 , Saki Harii3, Irina Yakovleva4, and Michio Hidaka1,*

1Department of Chemistry, Biology and Marine Science, Univ. of the Ryukyus, Okinawa 903-0213, Japan
2ARC Centre of Excellence for Coral Reef Studies, James Cook Univ., Townsville, Queensland 4811, Australia
3Sesoko Station, Tropical Biosphere Research Center, Univ. of the Ryukyus, Okinawa 905-0227, Japan
4A.V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok 690041, Russia

Badrun Nesa, Andrew H Baird, Saki Harii, Irina Yakovleva, and Michio Hidaka (2012) To test the hypothesis that algal symbionts make coral larvae more susceptible to high photosynthetically active radiation (PAR) and ultraviolet radiation (UVR), symbiotic and non-symbiotic planulae of Acropora tenuis were exposed to natural sunlight (high PAR and UVR) at an ambient temperature of approximately 27C for 4 d. DNA damage to host cells was detected using a comet assay (single-cell gel electrophoresis). Coral cells from symbiotic planulae had longer comet tails than those from non-symbiotic planulae, indicating that cells in symbiotic larvae had more DNA damage than those in non-symbiotic larvae. This result suggests that symbiotic algae are a source of oxidative stress in larvae under conditions at the ocean surface.

Key words: Bleaching, Comet assay, Coral, Stress, Symbiosis, UVR.

*Correspondence: Tel: 81-98-895-8547. Fax: 81-98-895-8576. E-mail:hidaka@sci.u-ryukyu.ac.jp