Cochlodinium polykrikoides Mitsunori Iwataki Asian Natural Environmental Science Center, The University of Tokyo, Japan
A harmful dinoflagellate C. polykrikoides An unarmored dinoflagellate Cochlodinium polykrikoides has formed red tides responsible for mass mortalities of caged and natural fishes in Japanese and Korean coasts. Mass mortality of cultured red sea breams, in Imari Bay, west Kyushu in 1999.
Cochlodinium polykrikoides The genus Cochlodinium has been established by Schütt (1894), circumscribing unarmored dinoflagellates possessing the cingulum encircling the cell >1.5 times (Kofoid & Swezy 1921). C. polykrikoides was described from Puerto Rico (Margalef 1961) C. catenatum In Japan, morphologically similar species, together with C. polykrikoides , were observed, including C. convolutum , C. cf. geminatum , C. fulvescens and Cochlodinium sp. type-Kasasa. C. citron . C. lebourae Cochlodinium sp. C. polykrikoides C. convolutum C. cf. geminatum C. fulvescens type-Kasasa Kofoid & Swezy 1921 (Yamatogi et al. 2010)
Cochlodinium species More than 40 Cochlodinium species have so far been described. C. achromaticum Lebour 1925 C. helikoides Lebour 1925 C. adriaticum Schiller 1933 C. helix (Pouchet) Lemmermann 1899 C. angustatum Kofoid et Swezy 1921 C. heterolobatum Silva 1967 * C. archimedes (Pouchet) Lemmermann 1899 C. lebourae Kofoid et Swezy 1921 C. atromaculatum Kofoid et Swezy 1921 C. longum Lohmann 1908 C. augustum Kofoid et Swezy 1921 C. miniatum Kofoid et Swezy 1921 C. brandtii Wulff 1916 C. moniliforme Margalef 1961 C. catenatum Okamura 1916* C. pellucidum Lohmann 1908 C. cavatum Kofoid et Swezy 1921 C. pirum (Schütt) Lemmermann 1899 C. cereum Kofoid et Swezy 1921 C. polykrikoides Margalef 1961* C. cnidophorum Biecheler 1939 C. pulchellum Lebour 1917 C. citron Kofoid et Swezy 1921 C. pupa Lebour 1925 C. clarissimum Kofoid et Swezy 1921 C. radiatum Kofoid et Swezy 1921 C. conspiratum Kofoid et Swezy 1921 C. rosaceum Kofoid et Swezy 1921 C. constriclum (Schütt) Lemmermann 1899 C. schuettii Kofoid et Swezy 1921 C. convolutum Kofoid et Swezy 1921 C. scintillans Kofoid et Swezy 1921 C. distortum Kofoid et Swezy 1921 C. strangulatum (Schütt) Schütt 1896 (Type) C. elongatum Kofoid et Swezy 1921 C. turbineum Kofoid et Swezy 1921 C. faurei Kofoid et Swezy 1921 C. vinctum Kofoid et Swezy 1921 C. flavum Kofoid et Swezy 1921 C. virescens Kofoid et Swezy 1921 C. geminatum (Schütt) Schütt 1896 C. volutum Kofoid et Swezy 1921 Blue: photosynthetic species, Red: type species
Morphological characters of Cochlodinium spp. C. cf. geminatum C. convolutum C. polykrikoides C. fulvescens ca. 60-70 µm ca. 40-60 µm ca. 30-40 µm ca. 45-50 µm Length Absent Absent Dorsal, epicone Dorsal, epicone Eye spot ca. 1.5 times ca. 1.5 times ca. twice ca. twice Cingulum Deeper Deeper Shallow, immediately Shallow, intermediate Sulcus below the cingulum of the cingulum Rectangular Spherical, median Spherical, anterior Spherical, anterior Nucleus Reticulate Reticulate Rod-like, Granulate Chloroplast aligned longitudinally Forming hyaline Cell-chains (2 cells) Cell-chains (16 cells) Cell-chains (4 cells) Others cyst
Description of Cochlodinium fulvescens Cochlodinium polykrikoides Margalef Cochlodinium fulvescens Iwataki, Kawami et Matsuoka Iwataki et al. 2007, Phycol. Res.
Apical groove of Cochlodinium polykrikoides U-shaped apical groove connected with sulcal extension. Iwataki et al. 2010, J. Eukaryot. Microbiol.
Apical groove of Cochlodinium fulvescens C. polykrikoides C. fulvescens C. fulvescens (Iwataki et al. 2010) (Iwataki et al. 2015)
Cochlodinium growth Where and how do cells survive at low (≤ 12.5ºC) temperature? （ Nagasaki Prefectural Institute of Fisheries 1991-2003 ）
Phylogenetic relationship in Cochlodinium spp. Gamma weighted ML tree based on partial LSU rDNA (D1-D6 region) Akashiwo sanguinea AF260396 Substitution model: TrN+G (Tamura & Nei 1993), Shape parameter: 0.5580 Karenia mikimotoi AY355460 - 71/71 Gymnodinium catenatum AF200672 Cochlodinium polykrikoides Korea (6 isolates) 72 100/99 Cochlodinium polykrikoides Japan (8 isolates) East Asian Cochlodinium polykrikoides Hong Kong Cochlodinium polykrikoides Manila Bay, Philippines 95 100/99 100 Philippines 100/ Cochlodinium polykrikoides Omura Bay, Japan 100 Cochlodinium polykrikoides Sabah, Malaysia (2 isolates) Cochlodinium polykrikoides New York, USA 96 97/83 American/Malaysian Cochlodinium polykrikoides Massachusetts, USA 100 100/100 89 Cochlodinium polykrikoides Puerto Rico 100/98 Cochlodinium polykrikoides Mexico Cochlodinium fulvescens Japan NJ 93 MP/ML 100/100 Cochlodinium fulvescens California, USA C. fulvescens 97 100/100 0.05 substitutions/site Cochlodinium fulvescens British Columbia, Canada (Iwataki et al. 2008)
Ribotypes Gamma weighted ML tree based on partial LSU rDNA (D1-D6 region) Substitution model: TrN+G (Tamura & Nei 1993), Shape parameter: 0.4298 Takahashi unpubl.
qPCR Philippines ribotype did not occur as large bloom, nor did in the same bloom of East Asian ribotype LM qPCR philippines Park et al. 2014, Harmful Algae
Cochlodinium sp. type-Kasasa kills fishes Yamatogi et al. 2010, Jpn. J. Phycol.
Cyst morphology of Cochlodinium cf. geminatum Similar resting cyst to what was identified formerly as C. polykrikoides Germinated motile cell was similar to C. polykrikoides Matsuoka & Fukuyo 2000 Fukuyo 1982
Cyst morphology of Cochlodinium polykrikoides American ribotype Tang et Gobler 2012, Harmful Algae
FISH assay of cysts in Shinnecock Bay (American ribotype) Hattenrath-Lehmann et al. 2016, Appl. Environ. Microbiol.
Cyst morphology of Cochlodinium polykrikoides East Asian ribotype Li et al. 2015, J. Phycol.
C. polykrikoides in Lampung Bay infected with Parvilucifera Parvilucifera rostrata Takahashi unpubl. Lepelletier et al. 2014
Distribution of C. polykrikoides population Cochlodinium polykrikoides Cochlodinium fulvescens
Distribution of C. polykrikoides population Japan and Korea ? Cochlodinium polykrikoides Hong Kong Manila Bay, Philippines North Sabah, America Malaysia Cochlodinium fulvescens ? Lampung Bay, C. polykrikoides Indonesia Japan, Korea Other sequences
Global distribution of Cochlodinium Cochlodinium polykrikoides Cochlodinium fulvescens not analyzed yet
Occurrence of C. polykrikoides in the Arabian Gulf
Cochlodinium bloom in Lampung Bay, 2012
Summary o C. polykrikoides and C. fulvescens . They could be distinguished by cell size, position of the sulcus, and shape of chloroplast and apical groove. o In C. polykrikoides, ribotypes (East Asian, Philippines, American and Mediterranean) can be differentiated. o Resting cysts were reported from American and East Asian ribotypes. Their morphology differ from each other in the presence/absence of ornamentation and accumulation body. FISH assay allowed to detect more than 140 cysts cm -3 in the sediment sample. o Majority of C. polykrikoides red tides occurred in Japanese, Korean and Hong Kong coasts are derived from the same population; it could be distinguished from other populations distributed in Southeast Asia. o The C. polykrikoides clade from Sabah, Malaysia and Lampung Bay, Indonesia is related to that from North and Central America.
Future study o Morphological differences among different ribotypes o Other ribotype? Cochlodinium sp. type Kasasa, also related to fish killing. o Morphology of resting cyst in each ribotype - It is unclear what factor corresponds to the morphological difference observed from East Asian and American o Harmful effects of each ribotype Fish kill was not reported by red tide of Philippines ribotype. o Environment of Cochlodinium easy to settle.
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