Heterocapsa Mitsunori Iwataki Univ Tokyo, Japan Heterocapsa - - PowerPoint PPT Presentation

Heterocapsa

Mitsunori Iwataki Univ Tokyo, Japan

• Armored dinoflagellate.
• Forming red tides responsible to mass mortality of bivalves.
• Forming temporary cyst, but resting cyst unknown.

Temporary cyst

Heterocapsa circularisquama Heterocapsa circularisquama

• H. arctica
• H. triquetra
• H. rotundata
• H. pygmaea
• H. niei
• H. lanceolata
• H. horiguchii
• H. orientalis
• H. pseudotriquetra
• H. circularisquama

Cell shape of Heterocapsa spp. Cell shape of Heterocapsa spp.

Cell shapes are resembling each other

• H. arctica
• H. circularisquama
• H. triquetra
• H. illdefina
• H. pygmaea
• H. niei
• H. horiguchii
• H. pseudotriquetra
• H. orientalis
• H. rotundata
• H. lanceolata
• H. ovata

10µm

Cell shape of Heterocapsa spp. Cell shape of Heterocapsa spp.

Organic body scale is tiny, cell covering of Heterocapsa

Body scales of Heterocapsa spp. 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

Body scales of Heterocapsa spp. Body scales of Heterocapsa spp.

Lake Hamana 1993〜 Ago Bay 1992〜 Gokasho Bay 1994〜 Uranouchi Bay 1988〜 Hiroshima Bay 1995〜 Suo-nada 1997〜 Fukuoka Bay 1998〜 Imari Bay 1995〜 Omura Bay 1995〜 Kusuura Bay 1994〜 Buzen Sea 1997〜 Maizuru Bay 1998〜 Obama Bay 1997〜 Uchinoumi 1998〜

Motile cell Temporary cyst

Occurrences of H. circularisquama in Japan Occurrences of H. circularisquama in Japan

Occurrences of H. circularisquama in Japan Occurrences of H. circularisquama in Japan

Bivalves mass mortality responsible species H. circularisquama was suddenly occurred in western Japanese coast in 1989. 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?

114˚00’ 114˚15’ 22˚45’ 22˚30’

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

Heterocapsa blooms in Hong Kong (1986-1987) Heterocapsa blooms in Hong Kong (1986-1987)

as 7” 1” 1’ 5’ 2’ 6” 2” ps 1”’ 5”’ 1”” 2”” cp Po 2a

LM and FM of Heterocapsa in Hong Kong LM and FM of Heterocapsa in Hong Kong

• Cells are ellipsoidal
• 16-30 µm long
• Pyrenoid in the hypotheca
• Nucleus in the epitheca
• Thecal plate arrangement;

Po, cp, 5’, 3a, 7”, 6c, 5s, 5”’, 2”” (= Heterocapsa)

Body scales of Heterocapsa in HK (TEM) Body scales of Heterocapsa in HK (TEM)

Body scale ultrastructure is identical to H. circularisquama

Hong Kong 1986-1987

Uranouchi Bay 1988〜 Ago Bay 1992〜 Hiroshima Bay 1995〜

？

Heterocapsa circularisquama

LM and FM of Heterocapsa in Hong Kong LM and FM of Heterocapsa in Hong Kong

• H. circularisquama has distributed in Hong Kong (1986-1987)

before the first occurrence in Japan (1988-).

Heterocapsa circularisquama Ago Bay Heterocapsa circularisquama Obama Bay Heterocapsa circularisquama Uranouchi Bay Heterocapsa circularisquama Obama Bay Heterocapsa circularisquama Buzen Sea Heterocapsa circularisquama Obama Bay Heterocapsa lanceolata Heterocapsa rotundata Heterocapsa arctica 99 100 96 Heterocapsa pygmaea Heterocapsa pygmaea Heterocapsa pseudotriquetra Heterocapsa triquetra Heterocapsa triquetra Heterocapsa triquetra 100 100 100 100 Heterocapsa horiguchii Heterocapsa horiguchii Heterocapsa ovata 100 71 Heterocapsa illdefina 75 Prorocentrum minimum Prorocentrum triestinum Prorocentrum micans 69 100

Heterocapsa Heterocapsa circularisquama

Phylogenetic tree of Heterocapsa (ITS region) Phylogenetic tree of Heterocapsa (ITS region)

A.R. Moreira González (Harmful Algae News 41)

• H. circularisquama from Cuba?
• H. circularisquama from Cuba?

Harmful effects Harmful effects

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

Summary 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 1988. 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.

Future study Future study

• Other location in SE Asia.
• Original distribution of H. circularisquama?
• Identification of toxic substances