Occurrence of Karenia papilionacea (Dinophyceae) and its novel sister phylotype in Japanese coastal waters

Haruo Yamaguchi; Takeshi Hirano; Takamichi Yoshimatsu; Yuko Tanimoto; Takuya Matsumoto; Satoshi Suzuki; Yoshihiro Hayashi; Atsushi Urabe; Kazuyoshi Miyamura; Setsuko Sakamoto; Mineo Yamaguchi; Yuji Tomaru

doi:10.1016/j.hal.2016.04.007

Occurrence of Karenia papilionacea (Dinophyceae) and its novel sister phylotype in Japanese coastal waters

Harmful Algae. 2016 Jul;57(Pt A):59-68. doi: 10.1016/j.hal.2016.04.007. Epub 2016 Jun 23.

Affiliations

¹ Laboratory of Aquatic Environmental Science, Faculty of Agriculture and Marine Science, Kochi University, Nankoku, Kochi 783-8502, Japan. Electronic address: yharuo@kochi-u.ac.jp.
² Laboratory of Aquatic Environmental Science, Faculty of Agriculture and Marine Science, Kochi University, Nankoku, Kochi 783-8502, Japan.
³ Kochi Prefectural Fisheries Experiment Station, Susaki, Kochi 785-0167, Japan.
⁴ Kochi Prefectural Freshwater Fisheries Center, Kami, Kochi 782-0016, Japan.
⁵ Aquaculture and Environment Section, Fisheries Research Division, Oita Prefectural Agriculture, Forestry and Fisheries Research Center, Saiki, Oita 879-2602, Japan.
⁶ National Research Institute of Fisheries and Environment of Inland Sea, Japan Fisheries Research and Education Agency, 2-17-5 Maruishi, Hatsukaichi, Hiroshima 739-0452, Japan.
⁷ Laboratory of Environmental Microbiology, School of Marine Biosciences, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan.

PMID: 30170722
DOI: 10.1016/j.hal.2016.04.007

Abstract

Several species of the genus Karenia (Dinophyceae) form blooms and often cause the mortality of cultured and wild fish. In Japan, blooms caused by two species - namely Karenia mikimotoi and Karenia brevis - have been reported so far. On the basis of morphological and molecular-phylogenic examinations, the present investigation found Karenia papilionacea and its novel sister phylotype for the first time in the coastal waters of the various regions of Japan. Of 34 strains isolated from the coastal waters, 27 strains displayed the typical morphological characteristics of K. papilionacea and further showed consensus DNA sequences corresponding to those of the originally described K. papilionacea. The other 7 strains displayed the same morphological characteristics of K. papilionacea, but showed divergent DNA sequences, at a genetic distance of over 0.04 (Internal Transcribed Spacer regions) from those of the original phylotype of K. papilionacea. These divergent strains were characterized as a novel sister phylotype (phylotype-I) of K. papilionacea. In the coastal waters of Japan, K. papilionacea-like (K. papilionacea and/or its phylotype-I) formed blooms at 20.3-30.4°C and salinity 30.1-33.9. No K. brevis was identified in Japanese coastal waters during this study. These findings demonstrated that K. papilionacea occurs along the coasts of western Japan and possibly shares several coastal regions with K. mikimotoi and K. papilionacea phylotype-I. In order to assess the risks of Karenia blooms to aquaculture, it is essential that the growth physiology and ichthyotoxicity of K. papilionacea and its novel phylotype should be characterized.

Keywords: Bloom dynamics; Karenia papilionacea; Phylogenetic analysis; Phylotype.