日本沿岸の赤潮原因 Prorocentrum 属の数種

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1 日本沿岸の赤潮原因 Prorocentrum 属の数種 誌名 日本プランクトン学会報 ISSN 著者 巻 / 号 鳥海, 三郎 27 巻 2 号 掲載ページ p 発行年月 1980 年 12 月 農林水産省農林水産技術会議事務局筑波産学連携支援センター Tsukuba Business-Academia Cooperation Support Center, Agriculture, Forestry and Fisheries Research Council Secretariat

2 Bulletin of Plankton Society of Japan Vol. 27, No. 2, pp , 1980 Prorocentrum Species (Dinophyceae) Causing Red Tide in Japanese Coastal Waters 1» 2 > SABURO TORIUMI 3 > Higashi Senior High School, Tsurumi-ku, Yokohama Abstract Morphology of six Prorocentrum species (Dinophyceae), i.e., P. balticum, P. gracile, P. minimum, P. micans, P. sigmoides and P. triestinum were examined by light and scanning electron microscopy. While P. balticum and P. mimimun have similar spiny ornamentation, anterior pores and anterior spines on the valves, they are distinguishable in size and shape. P. sigmoides can be also distinguished from its closely allied species P. gracile by differences in size and shape. This is the first report of P. sigmoides from Japan. Recently, the Japanese inshore fisheries are suffering severe economic losses by red tide outbreaks. Although, until several years ago, most red tide phenomena had occurred within spring and autumn, recently the red tides also occur in other seasons frequently. On the other hand, there is some confusions in systematics of the red tide Dinophyceae owing to insufficient taxonomic studies. The present paper reports the morphology of six Prorocentrum species which cause many red tides in the coastal waters of Japan and discusses their taxonomy. Materials and Methods Six Prorocentrum species were collected by a net from the red tides occurred from 1969 to Living Prorocentrum cells were isolated and transferred into the SWII culture medium (IWASAKI 1961). rest three did not. P. minimum, P. micans, and P. balticum grew well in the medium but the For light microscopic examinations, Prorocentrum cells were fixed m Fleming's strong solution or formaldehyde-acetic acid mixture (3: 1). blue. Then the cells were stained with try pan For nuclear staining, the fixed cells were squashed on a slide and stained in acetocarmme. Feulgen reaction and methyl green-pyronine mixture were sometimes used for the nuclear staining. m Pleurax. The materials were dehydrated in an acetone series and finally mounted For the scanning electron microscopic (SEM) observations, cells were centrifuged and fixed with 2.5 % glutaraldehyde solution buffered with 0.2 M cacodylate for 1 h at room temperature. After the fixation, the cells were washed once with distilled water in the centrifuge tube and were dehydrated in an alcohol series. l) Accepted 30 September ) B :;$:t'cii*co$i~jh~u~sl Prorocentrum ~CO~li a).~~~~~. m~nr.ll*~~~tt c=r 230 m~nrtuiiz:~:!; 3-5-1) Dehydrated cells were critical

3 106 point dried with C02. For SEM examination the dried cells were mounted directly on SEM sample holders and sputter-coated with a gold-palladium mixture. Descriptions of Species Prorocentrum balticum (LOHMANN) LOEBLICH (Figs. 1, 7) LOEBLICH 1969, 906; ADACHI 1972, 52, pl. 1, :figs. d-g, pl. 14, :fig. a (sub P. baltica); DODGE 1975, 118, :fig. 4a-b, pl. 4, :fig. d. Exuviaella baltica LOHMANN 1908, 265, pl. 17, :fig. la-b; SCHILLER 1933, 17, fig. loa-d; BRAARUD et al. 1958, 43, pl. 1, :figs. a-f. Prorocentrum pomoideum BURSA 1959, 17, figs The shape of the cell is round to subspherical. at the cell's anterior. in P. minimum by LOEBLICH et al. (1979). Two pores of large and small size are situated The large anterior pore is thought to be the flagellar pore as described Small anterior spine is found adjacent to this large pore. The wide anterior spine is found adjacent to the small pore. This spine diverges at the tip as in P. minimum (Fig. 7). middle part of each pore. The two anterior spines are situated along at the The relative position of these spines and pores is unvariable like that of P. minimum. A round nucleus is situated at the posterior end of the cell. Length, 9-10 µm, Width, 7-15 µm. This species is distributed mostly at northern parts of Japan but it occurs in Tokyo Bay. This speciemen was collected from Kesennuma Bay, Miyagi Prefecture. Prorocentrum gracile SCHUTT (Figs. 2, 8) SCHUTT 1895, :figs. 3, 1-4; OKAMURA 1907, 134, pl. 4, fig. 28a-b (sub P. micans?) ; BOHM 1936, 13, fig. 3c, 1-3; ABE 1967, 371, :fig. ld-e, g (in part sub. P. micans), DODGE 1975, 114, :fig. 3b, pl. 3, fig. e; TAYLOR 1976, 22, pl. 1, :fig. 2. The shape of the cell is elongate to lanceolate form in valve view. cell is rounded and the posterior is pointed and tapering. situated at the top of the cell. as in P. micans (Fig. 8). The anterior part of the Long and short anterior spines are They stand opposite each other with the pores between them The surface of the thecal valves has many depressions and scattered trichocyst pores. The nucleus is U-shaped and situated at posterior part of the cell. Length~ µm, Width, µm. This species is rare in Japan. by P. minimum in Sagami Bay, Kanagawa Prefecture. The specimen was collected from a red tide mostly caused Prorocentrum micans EHRENBERG (Figs. 3, 9) EHRENBERG 1833, 307; DODGE 1965, 608, fig. 1, pl. 1, :figs. 1-4; 1975, 112, fig. 3a, pl. 2, figs. a-c, e-f; ABE 1967, 371, :fig. la-c (in part); ADACHI 1972, 53, pl. 2, figs. h-m, pl. 14, figs. f-g; TAYLOR 1976, 23, pl. 1, fig. 1. Prorocentrum levantinoides BURSA 1959, 19, :figs

4 TORIUMI: Prorocentrum from Red Tides 107 The shape of this species seem to be highly variable. Shape of the cell is ovate to ~ubspherical and almost circular in valve view. The anterior end of the cell is rounded and the posterior end is pointed. The middle part of the cell is the broadest. The surface of the cell is covered with regularly arranged depressions and is parforated by numerous trichocyst pores. Long and short anterior spines and anterior pores of various sizes are situated at anterior part of the cell. However, the two pores adjacent the short anterior spine are larger than the other pores (Fig. 9). These large pores seemed to be equivalent to the fl.agellar pore described in P. minimum by LOEBLICH et al. (1979). The long anterior spine sometimes decorated with a wing and the small anterior one without such appendage stand facing each other at the opposite sides of the anterior pores. The U-shaped nucleus is situated at the posterior part of the cell. Length, µm, Width, µm. This species is common in Japan. The specimen was collected from Kanagawa district of Tokyo Bay. Prorocentrum minimum (PA VILLARD) SCHILLER (Figs. 4, 10) SCHILLER 1933, 32, fig. 33a-b; DODGE 1975, 117, fig. 4e-g, pl. 3, figs. a-d; TAYLOR 1976, 24, pl. 1, fig. 17. Exuviaella minima PAVILLARD 1916, 11, pl. 1, fig. la-b. Prorocentrum triangulatum MARTIN 1929, 556, figs Exuviaella mariae-lebouriae PARKE & BALLANTINE 1957, 643, figs. 1-18; DODGE 1965, 609, fig. 3, pl. 2, figs Prorocentrum cordiformis BURSA 1959, 17, figs Prorocentrum minimum v. mariae-lebouriae (PARKE & BALLANTINE) HULBURT 1965, 95, fig. 3; ADACHI 1972, 54, pl. 2, figs. a-g, pl. 14, figs. b-c. Prorocentrum minimum v. triangulatum (MARTIN) HULBURT 1965, 95, figs. 1, 4; ADACHI 1972, 56. Prorocentrum mariae-lebouriae (PARKE & BALLANTINE) LOEBLICH 1969, 906, figs. 4-6; FAUST 1974, 315, figs The shape of the cell is ovate, triangular and sometimes heart-shaped in valve view. Posterior end of the cell is usually rounded and the anterior end is truncate with very slight depression. Trichocyst pores are mainly situated around the margin of the valves. The surface of the valve is covered with minute spines. There are two anterior spines which differ from the minute surface spines of the valves. The smaller anterior spine is found adjacent to the large pore and the larger one is found next to the small pore. The latter spine is slight curved and splits in two part at its tip (DODGE & BIBBY 1973, FAUST 1974) (Fig. 10). A nucleus is situated at posterior end of the cell and is subspherical in shape. Length, µm, Width, µm. This species is widely distributed m Japan. The specimen was collected from Sagami Bay, Kanagawa Prefecture.

5 108 Prorocentrum sigmoides BOHM (Figs. 5, 11) BOHM 1933, 398, fig. 1; SILVA 1956, 359, pl. 3, fig. 1 (sub P. micans?) ; DODGE 1975, 114, Fig. 3c, pl. 2, fig. d (sub P. gracile) The characters of my specimens (Figs. 5, 11), while they are not distinct S-shape in valve view, agree well with that of the original description of BOHM (1933). Cells are elongate, S-shaped in valve view. Anterior part of the cell is slightly depressed. The dorsal side of the cell is more convex than the ventral. in P. micans can be seen in this species (Fig. 11). The flagellar pores which are almost the same as Prominent and small spines also stand facing each other at the opposite sides of the anterior pores as in P. micans. The two valve surfaces are perforated by numerous trichocyst pores and are covered with regularly arranged depressions similar to P. micans. the cell. Length, µm, Width, µm. This is the :first record of this species from Japan. The large U-shaped nucleus is situated at posterior ends of The present specimens were collected from Uchinomi Bay, Kagawa Prefecture, and Maizuru Bay, Kyoto Prefecture. Prorocentrum triestinum SCHILLER (Figs. 6, 12) SCHILLER 1918, 252, fig. la-b; 1933, 40, fig. 43a-f; BOHM 1936, 15, fig. 3b, 1-2; DODGE 1965, 609, fig. 2; 1975, 112, fig. 2a-c, pl. 1, fig. e; ADACHI 1972, 58, pl. 3, figs. j-p, pl. 14, figs. d-e. Prorocentrum pyrenoideum BURSA 1959, 18, figs Prorocentrum redfieldi BURSA 1959, 19, figs Prorocentrum setouti HADA 1975, 37, figs Prorocentrum shikokuensis HADA 1975, 36, figs This species is variable and similar to P. micans in shape but is much smaller. The valves lack regularly arranged surface depressions as occur in P. micans, P. gracile and P. sigmoides. The nucleus of this species is round unlike the U-shaped nucleus of the latter three. This species have only one flagellar pore unlike other five species described in this paper (cf. LOEBLICH et al. 1979). Length, µm, Width, 7-12 µm. This species forms blooms everywhere in coastal waters all around Japan. was collected from Sagami Bay, Kanagawa Prefecture. The specimen Discussion The valve surface of P.balticum and P. minimum are covered with minute spines as described by BRAARUD et al. (1958), DODGE (1965), LOEBLICH (1969), FAUST (1974) and LOEBLICH et al. (1979), and both species have two of large and small anterior pores. Although it could not be seen flagella in P. balticum, its larger anterior pore seems to be the flagellar pore as of P. minimum (LOEBLICH et al. 1979). The structure of anterior spines and other surface ornamentation of valves are also similar to these two species but they can be distinguished by differences in cell size and shape. P. gracile is close to P. micans and P. sigmoides in the shape. On the species which is

6 TORIUMI: Prorocentrum from Red Tides 109 thought as P. gracile, OKAMURA (1907) reports as a dubtful species of P. micans. In regard to P. sigmoides, SILVA (1956) reports as a questionable species of P. micans. Generally speaking, P. gracile resembles P. micans more closely than P. sigmoides. These three species have commonly depressions on valves, U-shaped nuclei and two anterior spines. DODGE (1975) distinguished P. gracile from P. micans by having a much longer anterior spine and by being at least twice as long as broad. On the other hand, DODGE (1975), considered P. sigmoides to be synonymous with P. gracile and TAYLOR (1976), though he remains some doubts, supports DODGE's opinion. However, the characters of P. sigmoides which was collected by the present author agrees well with the original description by BOHM (1933). This species can be distinguished from P. gracile by a slight apical depression, a slight sigmoid shape and greater cell length. P. triestinum is also variable in shape and generally resembles P. micans. But P. triestinum has smooth surface or lacks the depressions on the valves (DODGE 1965) and has only one flagellar pore (LOEBLICH et al. 1979). Recently, HADA (1975) described two new species of Prorocentrum i.e., P. setouti and P. shikokuensis from the Seto Inland Sea. After comparisons of these two species with P. triestinum, the present author believes that they are conspecifi.c. In cell size they are almost equal to P. triestinum and the shape of nucleus (round) is also identical in these three species. Acknowledgements The present author wishes to express his gratitude to Prof. Dr. R. MARUMO, the Ocean Research Institute, University of Tokyo, for his kind advice. He would like to thanks Assoc. Prof. Dr. T. NEMOTO of the same institute for reading the manuscript and Dr. T. IsHIMARU and Dr. S. NISHIDA for their technical advice. He also wishes to express his thanks to Assoc. Prof. A. R. LOEBLICH, III, Directer of the Marine Science Program, University of Houston, Texas, for his critical reading the manuscript. This work was supported in part by funds from Cooperative Program (No ) provided by the Ocean Research Institute, University of Tokyo. Literature Cited ABE, T. H., The armoured Dinoflagellata: II. Prorocentridae and Dinophsidae (A). Puhl. Seto mar. biol. Lab., 14: ADACHI, R., A taxonomical study of the red tide organisms. J. Fae. Fish. pref. Univ. Mie, 9: (In Japanese with English abstract) BOHM, A., Zur Verbreitung einiger Dinoflagellaten im Siidatlantik. Bot. Arch., 35: BOHM, A., Dinoflagellates of the coastal waters of the western Pacific. Bull. Bernice P. Bishop Mus., 137: BRAARUD, T., J. MARKALI & E. NORDLI, A note on the thecal structure of Exuviaella baltica LOHM., Nytt Mag. Bot., 6: BURSA, A., The genus Prorocentrum EHRENBERG. Morphodynamics, protoplasmatic structures, and taxonomy. Canad. J. Bot., 37: DODGE, J. D., Thecal fine-structure in the dinoflagellate genera Prorocentrum and Exuviaella. J. mar. biol. Ass. U.K., 45:

7 110 DODGE, J. D. & B. T. BIBBY, The Prorocentrales (Dinophyceae). I. A comparative account of fine structure in the genera Prorocentrum and Exuviaella. Bot. J. Linn. Soc., 67: DODGE, J. D., The Prorocentrales (Dinophyceae). II. Revision of the taxonomy within the genus Prorocentrum. Bot. J. Linn. Soc., 71: EHRENBERG, C. G., Dritter Beitrag zur Erkenntnifs grofser Organisation in der Richtung des kleinsten Raumes. Abh. Akad. Wiss. Berlin, 1833: FAUST, M.A., Micromorphology of a small dinoflagellate Prorocentrum mariae-lebouriae (PARKE & BALLANTINE) comb. nov. J. Phycol., 10: HADA, Y., Uzubenmochu ni zokusuru genus Prorocentrum Ehrenberg no 2 shinshu ni tsuite. (On the two new species of the genus Prorocentrum EHRENBERG belonging to Dinoflagellida). Hiroshima Shudo Daigaku Ronshu 16: (In Japanese with English abstract). HULBURT, E. M., Three closely allied dinoflagellates. J. Phycol., 1: IWASAKI, H., The life-cycle of Porphyra tenera in vitro. Biol. Bull. mar. biol. Lab., Woods Hole, 121: LOEBLICH, A. R. III, The amphiesma or dinoflagellate cell covering. Proc. N. Am. Patent. Conv., Pt. G: LOEBLICH, A. R. III, J. L. SHERLY & R. J. SCHMIDT, The correct position of flagellar insertion in Prorocentrum and description of Prorocentrum rhathymum sp. nov. (Pyrrhophyta). J. Plank. Res., 1: LOHMANN, H., Untersuchungen zur Feststellung des vollstandigen Gehaltes des Meeres an Plankton. Wiss. Meeresunters., 10: MARTIN, G. W., Three new dinoflagellates from New Jersey. Bot. Caz., 87: OKAMURA, K., An annotated list of plankton microorganisms of the Japanese coast. Annot. Zool. Japan., 6: PARKE, M. & D. BALIANTINE, A new marine dinoflagellate: Exuviaella mariae-lebouriae n. sp. J. mar. biol. Ass. U.K., 36: PAVILLARD, ]., Recherches les Peridiniens du Golf du Lion. Trav. Inst. Univ. Montpellier, 4: SCHILLER, J., Uber neue Prorocentrum- und Exuviaella-Arten aus der Adria. Arch. Protistenk., 38: SCHILLER,]., 1933., Dinoflagellate (Peridineae), pp In Kryptogamenflora von Deutschland, Osterreich und der Schweiz (ed. RABENHORST, L.), 10 (Flagellatae) Sect. 3(1). (Reprint in 1971, New York, London). SCHUTT, F., Die Peridineen der Plankton-Expedition. Ergebn. Atlant. Ozean Planktonexped. Humboldt-Stift., 4, M, a: SILVA, E. S., Contribution a l'etude du microplancton de Dakar et des regions maritimes voisines. Bull. Inst. franc. Afr. noire, Ser., A, 18: TAYLOR, F. J. R., Dinoflagellates from the international Indian Ocean expedition. A report on material collected by the R. V. "Anton Bruun" Bibliotheca Bot., 132: Pl. I. The valve view of Prorocentrum species Explanation of Plates Pl. II. The flagellar pore area of Prorocentrum species Fig. 1. P. balticum ( x4,800) Fig. 7. P. balticum (x 16,000) Fig. 2. P. gracile ( x 1,200) Fig. 8. P. gracile ( x 12,000) Fig. 3. P. mi cans ( x 1,500) Fig. 9. P. micans ( x6,000) Fig. 4. P. minimum (x2,700) Fig. 10. P. minimum ( x4,000) Fig. 5. P. sigmoides ( x820) Fig. 11. P. sigmoides (x 5,000) Fig. 6. P. triestinum ( x3,500) Fig. 12. P. triestinum ( x 8,000)

8 PLATE I TORIUMI: Prorocentrum from Red Tides 111

9 112 PLATE II