Abstract

WALTHER-MENDOZA, Mariana; REYES-BONILLA, Héctor; LAJEUNESSE, Todd C.  and  LOPEZ-PEREZ, Andrés. Distribution and diversity of symbiotic dinoflagellates in stony corals off the coast of Oaxaca, Mexican Pacific. Rev. Mex. Biodiv. [online]. 2016, vol.87, n.2, pp.417-426. ISSN 2007-8706.  https://doi.org/10.1016/j.rmb.2016.03.007.

Reef corals are associated with symbiont dinoflagellates —zooxanthellae— which provide food to its host. There is limited information about this kind of mutualism in the western coast of Mexico, and thus the objective of this paper was to characterize the zooxanthellae populations maintained by corals at the coast of the state of Oaxaca. Samples of 3 coral genera were taken: Pocillopora, Pavona and Porites, at 6 locations and at different depths. Microalgal DNA was extracted, and the ITS2 region was amplified to identify clades using denaturing gradient gel electrophoresis. Seven zooxanthellae types were identified from clade C, and a single one from clade D, evidencing that in Oaxaca the diversity of zooxanthellae is high compared with other regions of the Mexican Pacific. The highest variety of Symbiodinium was found in the genus Porites (gonochoric) followed by Pavona (hermaphroditic), and finally in Pocillopora (of frequent asexual reproduction, and in which all species and colonies hosted type D1), which suggests a relationship between genetic diversity in the microalgae and the reproductive mode of the coral. Genetic isolation for distance was observed, as well as a variable composition of symbiont type at each sampling location, and the presence of private clades; these findings point towards a relatively limited gene flow of Symbiodinium in the region.

Keywords : Symbiodinium; Clades; ITS2; Holobiont; Coral reproduction; Pocillopora; Pavona; Porites.

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