Succession of delayed fluorescence correlated with coral bleaching in the hermatypic coral Acropora tenuis

Takeuchi, Ichirō; Takaichi, Daisuke; Katsumata, Masakazu; Ishibashi, Hiroshi

Succession of delayed fluorescence correlated with coral bleaching in the hermatypic coral Acropora tenuis

2020

Takeuchi, Ichirō | Takaichi, Daisuke | Katsumata, Masakazu | Ishibashi, Hiroshi

We investigated coral bleaching by monitoring colour changes and measuring the delayed fluorescence (DF) of symbiotic dinoflagellates in the hermatypic coral Acropora tenuis, exposed to 1.0 μg/L Irgarol 1051 (photosystem II herbicide) for 14 d. The Irgarol concentration corresponded to those from international port regions of the world. The coral colour and DFs under the control treatment were stable throughout the experiment, whereas under the Irgarol treatment the corals showed gradual bleaching. The Irgarol treatment caused a rapid decrease in the slow decay DF component (10.1–60.0 s), while the fast decay DF component (0.1–10.0 s) decreased significantly after 6 d. The significant correlation between the latter values and the coral colour indicates that if the electron accumulation function of quinones QA and QB is compromised, corals will bleach. The present study will contribute to the understanding of the mechanism involved in bleaching of coral exposed to herbicides.

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