Heterocapsa. Mitsunori Iwataki Univ Tokyo, Japan

Transcription

1 Heterocapsa Mitsunori Iwataki Univ Tokyo, Japan

2 Heterocapsa circularisquama - Armored dinoflagellate. - Forming red tides responsible to mass mortality of bivalves. - Forming temporary cyst, but resting cyst unknown. Temporary cyst

3 Cell shape of Heterocapsa spp. Cell shapes are resembling each other H. circularisquama H. arctica H. rotundata H. lanceolata H. triquetra H. pygmaea H. niei H. horiguchii H. pseudotriquetra H. orientalis

4 Cell shape of Heterocapsa spp. H. rotundata H. lanceolata H. arctica H. triquetra H. circularisquama H. niei H. pygmaea H. horiguchii H. illdefina H. orientalis H. pseudotriquetra H. ovata 10µm

5 Body scales of Heterocapsa spp. Organic body scale is tiny, cell covering of Heterocapsa

6 Body scales of Heterocapsa spp. H. arctica H. circularisquama H. illdefina H. niei H. pygmaea H. rotundata H. triquetra H. lanceolata H. horiguchii H. ovata H. pseudotriquetra H. orientalis

7 Occurrences of H. circularisquama in Japan Suo-nada 1997 Fukuoka Bay 1998 Imari Bay 1995 Buzen Sea 1997 Omura Bay 1995 Hiroshima Bay 1995 Maizuru Bay 1998 Uchinoumi 1998 Uranouchi Bay 1988 Obama Bay 1997 Gokasho Bay 1994 Lake Hamana 1993 Ago Bay 1992 Kusuura Bay 1994 Motile cell Temporary cyst

8 Occurrences of H. circularisquama in Japan Bivalves mass mortality responsible species H. circularisquama was suddenly occurred in western Japanese coast in Red tides killing only bivalves have not been reported in Japan. Optimum temperature for growth of H. circularisquama is relatively high (30 C). Original distribution of H. circularisquama is the tropical or subtropical?

9 Heterocapsa blooms in Hong Kong ( ) Tolo Harbour( 湾奥部 ) Dapeng Bay Tai Po Kau (1986.9) Tolo Harbour New Territories Kowloon Yung Shue Au (1987.7) Lantau Island Hong Kong Island South China Sea

10 LM and FM of Heterocapsa in Hong Kong as 2 cp Po 5 2 ps Cells are ellipsoidal µm long - Pyrenoid in the hypotheca - Nucleus in the epitheca - Thecal plate arrangement; Po, cp, 5, 3a, 7, 6c, 5s, 5, 2 (= Heterocapsa) 2a

11 Body scales of Heterocapsa in HK (TEM) Body scale ultrastructure is identical to H. circularisquama

12 LM and FM of Heterocapsa in Hong Kong LM and FM of Heterocapsa in Hong Kong H. circularisquama has distributed in Hong Kong ( ) before the first occurrence in Japan (1988-). Hiroshima Bay 1995 Ago Bay 1992 Heterocapsa circularisquama Uranouchi Bay 1988? Hong Kong

13 Phylogenetic tree of Heterocapsa (ITS region) Heterocapsa triquetra Heterocapsa triquetra Heterocapsa triquetra Heterocapsa pseudotriquetra Heterocapsa pygmaea Heterocapsa pygmaea Heterocapsa arctica Heterocapsa rotundata Heterocapsa lanceolata 100 Prorocentrum micans Prorocentrum triestinum Prorocentrum minimum Heterocapsa illdefina Heterocapsa ovata Heterocapsa horiguchii Heterocapsa horiguchii Heterocapsa circularisquama Obama Bay Heterocapsa circularisquama Buzen Sea Heterocapsa circularisquama Obama Bay Heterocapsa circularisquama Uranouchi Bay Heterocapsa circularisquama Obama Bay Heterocapsa circularisquama Ago Bay Heterocapsa Heterocapsa circularisquama

14 H. circularisquama from Cuba? A.R. Moreira González (Harmful Algae News 41)

15 Harmful effects Matsuyama 2003, Bull. Fish. Res. Agen. Kim et al. 2000, Biosci. Biotechnol. Biochem.

16 Summary - Ultrastructure of body scales is useful to distinguish Heterocapsa spp., which are superficially similar to each other under light microscopy. - In Japan, distribution of H. circularisquama is expanding since the first occurrence in Before the year, red tide of this species was confirmed in Hong Kong, suggesting recent immigration of this species to Japan. - H. circularisquama gives harmful effects not only to bivalves, but also to rotifers, gastropods, ascidians, jellyfishes, protozoans and other dinoflagellates.

17 - Other location in SE Asia. Future study - Original distribution of H. circularisquama? - Identification of toxic substances