Morphological Features of Marine Dinoflagellates from Jangmok Harbour in Jinhae Bay, Korea: A Case of 30 Species in the Orders Prorocentrales, Dinophysiales, Gonyaulacales and Gymnodiniales

Korean J. Environ. Biol. 34(3) : 141~150 (2016) http://dx.doi.org/10.11626/KJEB.2016.34.3.141

IntroductIon

Marine dinoflagellates are a major component of phyto- plankton communities and play an important role as prima- ry producer in marine ecosystems. Some of these species can cause red tides and some produce neuro-toxins that can accumulate in the food chain (Hallegraeff 1993). According to Kim et al. (2013), to date, a total of 153 planktonic dino- flagellates have been described in Korean waters. However, the morphological characteristics of the dinoflagellates were not described in most studies, and few taxonomic studies on

dinoflagellates, apart from harmful species, have been con- ducted.

To observe dinoflagellates, sea water samples collect- ed along the Korean coasts have typically been fixed in formaldehyde and Lugol’s iodine solution. According to Stoecker et al. (1996), Lugol’s solution minimizes cell loss, however causes cell shrinkage and distortion. In addition, for phytoplankton in particular, the fixative stains the cells dark brown, whereas the use of formaldehyde causes only minor shrinkage and distortion, however results in the loss of cells, at a rate ranging from less than 20% (Stoecker et al. 1989) to more than 70% (Leakey et al. 1994). This indi- cates that the use of samples fixed with the commonly used Lugol’s solution and formaldehyde may cause difficulties in

* Corresponding author: Hyeon Ho Shin, Tel. 055-639-8429, Fax. 055-639-8440, E-mail. [email protected]

ⓒ 2016. Korean Society of Environmental Biology.

Morphological Features of Marine Dinoflagellates from Jangmok Harbour in Jinhae Bay, Korea:

A Case of 30 Species in the Orders Prorocentrales, Dinophysiales, Gonyaulacales and Gymnodiniales

Hyeon Ho Shin*, Eun Song Kim, Zhun Li, Joo Yeon Youn, Seul Gi Jeon and Seok Jin Oh

Library of Marine Samples, Korea Institute of Ocean Science and Technology,

Geoje 53201, Republic of Korea

1

Pukyung National University, Busan 48513, Republic of Korea

Abstract - Most previous studies on dinoflagellates in Korean coastal areas were conducted without morphological descriptions and illustrations of the observed dinoflagellates. This indicates that the species and diversity of dinoflagellates may have been respectively misidentified and underestimated in the past, probably due to cell shrinkage, distortion and loss caused by sample fixation. This study provides information on the morphological observations of four dinoflagellate orders (Prorocentrales, dinophysiales, Gonyaulacales and Gymnodiniales) from Jangmok Harbour in Jinhae Bay, Korea. The unfixed samples were collected weekly from December 2013 to February 2015. A total of 13 genera and 30 species were identified using light and scanning electron microscopy, although some samples were not clarified at the species level. Harmful dinoflagellates, Prorocentrum donghaiense, Tripos furca, Alexandrium affine, A. fundyense, Aka­

shiwo sanguinea and Cochlodinium polykrikoides, were identified based on the morphological observations. The results also reflect the occurrence and identification of dinoflagellates that had not been previously recorded in Jangmok Harbour.

Key words : dinoflagellate, morphological observation, Jangmok Harbour, Jinhae Bay

<Review paper>

optical microscopy, for quantitative and qualitative analyses of phytoplankton as well as species identification.

The taxonomic identification of dinoflagellates is gener- ally based on a unique combination of characteristics such as the size and shape of the cells, their colour, surface orna- mentation, cingulum displacement, position of the nucleus, the shape of the chloroplasts and thecal plate tabulation and variation for armored or thecate species (e.g. Balech 1995).

These features of dinoflagellates may not be observed clear- ly in fixed samples, suggesting that dinoflagellates observed using fixed samples can be misidentified. Many ecological studies on dinoflagellates in Korean coastal areas have been undertaken, which have concentrated on understanding the relationship between the dinoflagellate community and environmental factors, with an emphasis on harmful algal species (e.g. Yoo 1982; Yoo and Lee 1987; Lee et al. 1992;

Lee et al. 1998; Park et al. 2009; Baek et al. 2011; Park et al. 2012). However, the samples used in these studies were mostly fixed in formaldehyde and Lugol’s solution, and some of the identified dinoflagellates have only ever been described and illustrated in Korean coastal areas.

Jinhae Bay is a semi-enclosed embayment with minimal advection and restricted water circulation (Fig. 1). Since the early 1980s, red tides have occurred annually in this Bay, causing the mortality of fishery organisms with major eco- nomic consequences (Han et al. 1992). Jangmok Harbour is located on the northern side of Geoje Island in Jinhae Bay, where red tides caused by Akashiwo sanguinea have occasionally occurred, although these have not been report- ed in the scientific literature. Morphological descriptions and illustrations of the dinoflagellates in this bay have also rarely been reported. To determine the morphological char- acteristics of naturally occurring members of dinoflagellate community, we analysed unfixed water samples collected in Jangmok Harbour and documented dinoflagellates of the orders Prorocentrales, Dinophysiales, Gymnodiniales and Gonyaulacales.

MAterIAls And Methods

Dinoflagellates were collected weekly from December 2013 to February 2015 in Jangmok Harbour, Jinhae Bay (34°

59′39.1″N, 128°40′28.8″E), by using a plankton net with a 20-μm mesh (Fig. 1). One millilitre of the sample was placed in a Sedgwick-Rafter chamber, and the cells were isolat- ed under an inverted microscope (Primo vert, Carl Zeiss, Göttingen, Germany), and then identified and photographed using a Zeiss AxioCam MRc digital camera on an Axio Imager 2 upright microscope (Carl Zeiss, Göttingen, Ger- many). The identified cells were transferred into the indi- vidual wells of 96 well tissue plates filled with F/2 culture medium and a 30 mL culture flask by micropipetting using a capillary pipette and maintained at 20℃ and ca 100 μmol photons m

s

cool-white illumination under a 14L : 10D photo-cycle. The dinoflagellates reported in this study, ex- cluding heterotrophic species, were deposited at the Library of Marine Samples, Korea Institute of Ocean Science and Technology.

For scanning electron microscopy (SEM), the cells were collected with a micropipette and fixed with Lugol’s io- dine solution. Fixed cells were rinsed twice with deionised water, transferred onto filters and then left to dry at room temperature. These filters were mounted on stubs, coated with platinum-palladium and examined in a field emission scanning electron microscope JEOL JSM 7600F (JOEL Ltd., Tokyo, Japan).

35°12′N35°06′N35°00′N34°54′N

128°24′E

Jinhae Masan

Goseong

Geoje Sampling

site

Jinhae Bay

S

128°30′E 128°36′E 128°42′E

Fig. 1. Study area and location of the sampling site.

results And dIscussIon

A total of 13 genera and 30 species of 4 dinoflagellate orders (Prorocentrales, Dinophysiales, Gymnodiniales and Gonyaulacales) were identified, although some species were not clarified at the species level: Prorocentrum dong- haiense Lu, P. micans Ehrenberg, P. triestinum Schiller, Dinophysis acuminate Claparède & Lachmann, D. caudata Saville-Kent, D. infundibula Schiller, D. ovum Schütt, Oxy- physis oxytoxoides Kofoid, Tripos furca (Ceratium furca) (Ehrenberg) F. Gómez, T. fusus (C. fusus) (Ehrenberg) F.

Gómez, T. muelleri (C. tripos) Bory, Alexandrium affine (In- oue & Fukuyo) Balech, A. pacificum Litaker, A. fundyense Balech, Gonyaulax spinifera (Claparède & Lachmann) Die- sing, G. polygramma Stein, Akashiwo sanguinea (Hirasaka) Hansen & Moestrup, Gyrodinium instriatum Freudenthal &

Lee, Gy. maculatum Kofoid & Swezy, Gy. spirale (Bergh) Kofoid & Swezy, Cochlodinium polykrikoides Margalef, Polykrikos kofoidii Chatton. Photographs of the identified

species are shown in Figs. 2-5. In previous studies, the harmful dinoflagellates Prorocentrum, Alexandrium species and A. sanguinea were mainly reported as the dominant species in Jinhae Bay (Yoo 1982; Yoo and Lee 1987; Lee et al. 1992; Lee et al. 1998; Park et al. 2009; Park et al. 2012), and Baek et al. (2011) reported that the dinoflagellate com- munity in Jangmok Harbour is dominated by T. furca. How- ever, most of these studies concentrated on understanding the distribution or the relationships between the occurrence of vegetative cells and environmental factors, and detailed morphological descriptions and photographs were not pro- vided, because all samples for observation of the phytoplan- kton community were probably fixed using formaldehyde or Lugol’s iodine solution. In the Prorocentrum species, the morphological characteristics of P. micans and P. triestinum found in Jinhae Bay were described by Yoo (1982). P. mi- cans is highly variable in shape and size (Dodge 1975) and has a tear-drop shape. This species is highly flattened with an apical spine. Its cells are covered by numerous trichocyst Fig. 2. Photomicrographs of the order Prorocentrales. (A, B) Prorocentrum donghaiense by light microscopy (LM) and scanning electron microscopy (SEM); (C, D) P. micans by LM; (E) left valve view of P. micans with large pores (arrow); (F) the intercalary band of P.

micans; (G, H) P. triestinum with pores (arrows) by SEM. Scale bars: 10 μm.

A B C D

E F G H

pores, which are variable in shape and size, with large pores mainly located in the apical and antapical regions (Fig. 2C- F). According to Cohen-Fernández et al. (2006), the pore patterns of this species are useful for differentiating it from the other Prorocentrum species. In comparison with P. mi- cans, P. triestinum has few trichocyst pores on its surface;

they are mainly distributed irregularly around the margin (Fig. 2G and H). These two species were found in Jinhae Bay from June to July (Lee and Lim 2006); in addition, high abundances of P. triestinum, without morphological descriptions, were also recorded in Jangmok Harbour,

(Lee and Yang 2010). According to Lee and Yang (2010), the Prorocentrum species identified at Jangmok Harbour were P. micans, P. triestinum and P. minimum. However, P.

minimum was not observed and P. donghaiense was found in our study (Fig. 2A and B). P. donghaiense can be distin- guished from P. minimum by several features, such as cell shape, valve micro-morphology and intercalary bands (Lu et al. 2005). The morphological characteristics of P. dong- haiense as recorded in our study are consistent with the results of Lu et al. (2005). In the photographs of P. dong- haiense shown by Lu et al. (2005), the species fixed with Fig. 3. Photomicrographs of the order Dinophysiales. (A, B) Dinophysis acuminata by LM; (C, D) D. caudate by LM; (E, F) D. infundibula

by LM; (G, H) D. ovum by LM; (I, J) Dinophysis sp. by LM and SEM; (K, L) Oxyphysis oxytoxoides by LM. Scale bars: 10 μm.

A B C D

E F G H

I J K L

Lugol’s solution and neutralized for maldehyde were highly variable in colour, size and shape. This indicates that the P.

minimum recorded by Lee and Yang (2010) was probably be P. donghaiense.

Four Dinophysis species, D. acuminata, D. caudata, D.

infundibula, and D. ovum, were identified in Jangmok Har- bour (Fig. 3A-H). In previous studies, only D. acuminata was recorded by Lee and Yang (2010), without morpholog- ical descriptions, and high abundances of this species were also reported in Jinhae Bay (Ahn et al. 2000). Dinophysis

A B C D E F

G

H I J K L

M N O P Q

R S T U V

Fig. 4. Photomicrographs of the order Gonyaulacales. (A, B) Tripos furca by LM; (C, D) T. fusus by LM; (E) T. muelleri by LM; (F) Alexan-

drium affine by SEM; (G-I) A. pacificum by LM and SEM; (J-L) A. fundyense by LM and SEM; (M-O) Gonyaulax polygramma by LM

and SEM; (P-R) G. spinifera by LM and SEM; (S, T) Gonyaulax sp. by LM; (U, V) unidentified species by LM. Scale bars: 10 μm.

species are strongly compressed laterally and therefore usu- ally seen from a lateral view. The taxonomic identification is principally based on the size, shape and ornamentation of their large hypothecal plates, which provide the cell con- tour, and the shapes of the left sulcal lists and the three ribs (Larsen and Moestrup 1992). Although characteristics for the identification of Dinophysis species have been estab- lished, these species are difficult to identify at species level under a microscope, because the majority of the cell con-

sists of hypothecal plates and these plates are usually not visible, except for the hypotheca. However, D. caudata can be differentiated from D. acuminata, D. infundibula and D.

ovum by its presence of posterior projection.

O. oxytoxoides was reported in Jinhae Bay and Jangmok Harbour (Lee and Han 2007; Lee and Yang 2010), and the high abundances of this species have not been recorded in Korean coastal areas. O. oxytoxoides has a spindle-like shape and is laterally compressed (Fig. 3K and L). Its cell

A B C D E

F G H I J K L

M N O P Q R

Fig. 5. Photomicrographs of the order Gymnodiniales. (A) Akashiwo sanguinea showing the central nucleus (n) under LM; (B) Gyrodinium instriatum by LM; (C-E) G. maculatum by LM; (F, G) G. spirale by LM; (H) Gyrodinium sp. 1 by LM; (I, J) Gyrodinium sp. 2 by LM; (K, L) Cochlodinium polykrikoides forming chain of four cell by LM; (M, N) Polykrikos kofoidii by LM; (O) Nematopsides sp.

by LM; (P, Q) Warnowia sp. by LM; (R) Gymnodinium sp. by LM. Scale bars: 10 μm.

surface is covered with small pores, and the epitheca of the cell is narrower than the hypotheca. This species was de- scribed as the only member of the Oxyphysaceae; however, Gomez et al. (2011) concluded that this species should be transferred back to its former genus as Phalacroma oxytox- oides based on molecular data showing a close relationship to the type species of the genus Phalacroma.

The genus Ceratium contains numerous marine species and a few freshwater ones (Gómez 2012). Based on mor- phological and molecular data determined by the ecological behaviour of Ceratium, Gómez et al. (2010) proposed the splitting of Ceratium into two genera: Ceratium should be used for freshwater species, whereas a new genus name, Neoceratium should be applied to the marine species of Ceratium. However, the genus name Neoceratium is con- sidered illegitimate, and to resolve this situation, Gómez (2013) proposed that the genus Tripos should be established to replace Neoceratium. For this reason, in our study, the genus Ceratium is named as the genus Tripos. The mor- phological identification of Tripos species is based on the thecal plate pattern of the cell body, ventral area, apical and antapical horns and the number of cingular plates (Gómez et al. 2010); however under light microscopy, the thecal plate patterns are not clearly visible. Nevertheless, three Tripos species, T. furca, T. fusus and T. muelleri, were identified in Jangmok Harbour (Fig. 4A-E). In previous studies, T. furca and T. fusus were recorded without morphological descrip- tions (Lee and Yang 2010), and Baek et al. (2011) reported the high abundance and ecological behaviour of T. furca depending on the environmental conditions at Jangmok Harbour. In terms of the morphological characteristics of T.

furca, it is differentiated from T. fusus and T. muelleri by its external shape, the number and length of its horns, and by the apical horn of T. fusus being longer than those of T. fur- ca and T. muelleri. These species can probably be identified under a microscope, although the plate patterns for such an identification have not been clearly described.

Several species of the genus Alexandrium are well known as producers of paralytic shellfish poisoning (PSP) toxins in Korean coastal areas (Shin et al. 2008). Outbreak of blooms and PSP in Jinhae Bay are mainly attributable to A. tama- rense (Chang et al. 1987; Han et al. 1992). In general, the most important characteristics for the identification of A.

tamarense are the ability to form chains and the presence/

absence of a ventral pore between the 1′ and 4′ plates (Fu- kuyo 1985; Yoshida et al. 2003). However, John et al. (2014) reported that these characteristics are not consistent and/or distinctive, and that species named as Group I, which in- clude A. tamarense isolates collected from Jinhae Bay, can be renamed as A. fundyense based on morphology, internal transcribed spacer (ITS)/5.8S genetic distance, ITS compen- satory base changes, mating incompatibilities and toxicity.

Consequently, the A. tamarense described in our study is consistent with A. fundyense. In Jinhae Bay and Jangmok Harbour, Alexandrium species have not been named at the species level and the identification is not well understood.

However, three Alexandrium species, A. affine, A. pacificum and A. fundyense, were identified based on the morphologi- cal characteristics suggested by Balech (1995) (Fig. 4F-L).

In Jangmok Harbour, Gonyaulax species were reported, but without descriptions of vegetative cells and without naming at the species level (Lee and Yang 2010). Actually, because Gonyaulax species shows small morphological dif- ferences, it is difficult to identify them at species level. In our study, G. polygramma was yellow-brown in colour and its nucleus was located in the hypotheca (Fig. 4M-O). The epitheca was triangular and sharply tapered to the apex, and the hypotheca was trapezoidal with a round antapex (Fig.

4M). There were two short spines in the antapex (Fig. 4N and O). The morphological characteristics were consistent with those of G. polygramma isolated from Tongyeong, Korea (Kim et al. 2006). Most of the morphological charac- teristics of the species observed under a microscope do not enable it to be differentiated from G. spinifera; however G.

spinifera has convex sides and a small epical horn (Fig. 4P- R).

Ak. sanguinea observed in Jangmok Harbour is ovoid with dorso-ventral compression (Fig. 5A). The cells have an epicone that is slightly rounded, and the hypocone pos- sesses two prominent posterior lobes. The nucleus is locat- ed above the cingulum in the epicone. The morphological characteristics of this species are consistent with previous results described by Cho et al. (2004). Outbreaks of blooms caused by Ak. sanguinea have frequently been observed in Jangmok Bay however have not been documented in the scientific literatures.

The genus Gyrodinium is one of the largest genera of the

unarmoured dinoflagellates. Its morphological identification

is usually based on the cingular displacement, the presence of an elliptical apical groove, and surface ornamentations with longitudinal striations (Daugberg et al. 2000; Saldar- riaga et al. 2001). The morphological characteristics of Gy.

instriatum are consistent with those reported in a previous study (Orlova et al. 2003) and the cells resembled those of members of Gymnodinium (Fig. 5B). A specific feature of this species is the presence of the acrobase. However, this species can be differentiated from Gy. maculatum and Gy.

spirale by its external shape; Gy. maculatum shows a much more rounded apex and antapex and Gy. spirale is common- ly elongated with a somewhat conical epicone and a pointed apex (Fig. 5F and G). In Jangmok Harbour, the presence of Gyrodinium species was reported, without naming at the species level (Lee and Yang 2010).

The unarmored chain-forming C. polykrikoides is the most notorious causative species of dense blooms that have often occurred in Korean coastal waters. However, in a pre- vious study this species was not identified in Jangmok Har- bour (Lee and Yang 2010), possibly, because unarmoured dinoflagellates may not be detectable from fixed samples.

In our samples, we detected C. polykrikoides in the form of chains consisting of four cell (Fig. 5K and L). Among these chain-forming cells, the anterior cell had a flattened hypo- cone, the posterior cell possessed a truncated epicone, and the cells in the middle were compressed longitudinally. The distinct features for the identification of this species, such as the positions of the sulcus, nucleus and a single pigment- ed body, are consistent with those at the single cell stage. In addition, these features are completely consistent with those of motile cells collected from Japanese coastal areas (Iwataki et al. 2008; Matsuoka et al. 2008).

The unarmoured heterotrophic dinoflagellate Polykrikos is commonly observed in many coastal areas around the world and feeds mainly on other dinoflagellates. In par- ticular, P. kofoidii can feed on various toxic harmful algal bloom species, such as Alexandrium spp. and Gymnodinium catenatum (Matsuyama et al. 1999; Matsuoka et al. 2000).

In a study by Lee and Yang (2010), this species was not observed in Jangmok Harbour, however P. schwartzii was identified there, although no morphological description was provided. P. kofoidii and P. schwartzii are very difficult to differentiate because these two species share many mor- phological features, such as the numbers of colonial and

pseudo-cells (zooids) (Matsuoka et al. 2009). In our study, the morphological features of P. kofoidii are consistent with those described by Matsuoka et al. (2009) (Fig. 5M and N).

This study does not provide descriptions of other species that were not named at the species level; however photo- graphs of the exteriors of the cells are provided in Figs. 3I and J, 4S-V, and 5O-R. It is matter of concern that many dinoflagellates are not clearly identifiable by light micro- scopy. Consequently, further studies are needed for the identification of those and other unidentified species, based on techniques such as SEM or molecular phylogenetic anal- ysis.

AcKnowledGeMent

This research was supported by a grant from KIMST (PM59610), KIOST (PE99414) and NIFS (PG49360) proj- ects.

references

Ahn DK, YS Park, JG Park, JS Lee and JA Lee. 2000. Quanti- fication of DSP toxins in the Mussels of the Jinhae Bay by fluorometric HPLC analysis and protein phosphatase inhi- bition assay. Algae 15:307-314.

Baek SH, HH Shin, HW Choi, S Shimode, OM Hwang, KS Shin and Y-O Kim. 2011. Ecological behavior of the dino- flagellate Ceratium furca in Jangmok harbor of Jinhae Bay, Korea. J. Plankton. Res. 3:1842-1846.

Balech E. 1995. The genus Alexandrium Halim (Dinoflagella- ta). Sherkin Island Marine Station, Cork, Ireland, 151 pp.

Chang DS, IS Shin, JH Pyeun and YH Park. 1987. A study on paralytic shellfish poison of sea mussel Mytilus edulis. J.

Kor. Soc. Fish. Tech. 20:293-299.

Cho SY, J-S Ki and M-S Han. 2004. Morphological character- istics and molecular phylogeny of five unarmored dinofla- gellates in Korean coastal waters. Algae 23:15-29.

Cohen-Fernández EJ, E Meave Del Castillo, IH Salgado-Ugar- te and FF Pedroche. 2006. Contribution of external mor- phology in solving a species complex: The case of Proro- centrum micans, Prorocentrum gracile and Prorocentrum sigmoides (Dinoflagellata) from the Mexican Pacific Coast.

Phycol. Res. 54:330-340.

Daubjerg N, G Hansen, J Larsen and Ø Moestrup. 2000. Phy-

logeny of some of the major genera of dinoflagellates based on ultrastructure and partial LSU rDNA sequence data, including the erection of three new genera of unarmoured dinoflagellates. Phycologia 39:302-317.

Dodge JD. 1975. The Prorocentrales (Dinophyceae). II. Revi- sion of the taxonomy within the genus Prorocentrum. Bot. J.

Linn. Soc. 71:103-125.

Fukuyo Y. 1985. Morphology of Protogonyaulax tamarensis (Lebour) Taylor and Protogonyaulax catenella (Whedon and Kofoid) Taylor from Japanese coastal waters. Bull.

Mar. Sci. 37:529-537.

Gómez F. 2012. A checklist and classification of living dinofla- gellates (Dinoflagellata, Alveolata). CICIMAR Oceánides 27:65-140.

Gómez F. 2013. Reinstatement of the dinoflagellate genus Tri- pos to replace Neoceratium, marine species of Ceratium (Dinophyceae, Aveolata). CICIMAR Oceánides 28:1-22.

Gámez F, P López-García and D Moreira. 2011. Molecular phylogeny of dinophysoid dinoflagellates: The systemat- ic position of Oxyphisis oxytoxoides and the Dinophysis hastata group (Dinophysales, Dinophyceae). J. Phycol. 47:

393-406.

Gómez F, D Moreira, P López-García. 2010. Neoceratium gen.

nov., a new genus for all marine species currently assigned to Ceratium (Dinophyceae). Protist 161:35-54.

Hallegraeff GM. 1993. A review of harmful algal blooms and their apparent global increase. Phycologia 32:79-99.

Han M-S, JK Jeon and Y-O Kim. 1992. Occurrence of dino- flagellate Alexandrium tamarense, a causative organism of paralytic shellfish poisoning in Chinhae Bay, Korea. J.

Plankton Res. 14:1581-1592.

Iwataki M, H Kawami and K Matsuoka. 2008. Cochlodinium fulvescens sp. nov. (Gymnodiniales, Dinophyceae), a new chain-forming unarmored dinoflagellate from Asian coasts.

Phycol. Res. 55:231-239.

John U, RW Litaker, M Montresor, S Murray, ML Brosnahan and DM Anderson. 2014. Formal Revision of the Alexan- drium tamarense Species Complex (Dinophyceae) Taxon- omy: The Introduction of Five Species with Emphasis on Molecular-based (rDNA) Classification. Protist 165:779- 804.

Kim HS, SH Kim, MM Jung and JB Lee. 2013. New record of dinoflagellates around Jeju Island. J. Ecol. Environ. 36:

273-291.

Kim K-Y, Y-S Kim, C-H Hwang, C-K Lee, W-A Lim and C-H Kim. 2006. Phylogenetic analysis of dinoflagellate Gon- yaulax polygramma Stein responsible for harmful algal blooms based on the partial LSU rDNA sequence data. Al- gae 21:283-286.

Larsen J and Ø Moestrup. 1992. Potentially toxic phytoplank- ton 2. Genus Dinophysis (Dinophyceae). pp. 1-12. In ICES Identification Leaflets for Plankton 180. (Lindley JA ed.).

ICES, Copenhagen,

Leakey RJG, PH Burkhill and MA Sleigh. 1994. A comparison of fixatives for the estimation of abundance and biovolume of marine planktonic ciliate populations. J. Plankton Res.

16:375-389.

Lee CK and W-A Lim. 2006. Variation of harmful algal blooms in Masan-Chinhae Bay. ScienceAsia 32:51-56.

Lee J-S, JK Jeon, M-S Han, Y Oshima and T Yasumoto. 1992.

Paralytic shellfish toxins in the mussel Mytilus edulis and dinoflagellate Alexandrium tamarense from Jinhae Bay, Korea. J. Korean Fish Soc. 25:144-150.

Lee JB, DY Kim and JA Lee. 1998. Community dynamics and distribution of dinoflagellates and their cysts and Ma- san-Chinhae Bay, Korea. J. Korean Fish Soc. 1:283-292.

Lee JY and M-S Han. 2007. Change of blooming pattern and population dynamics of phytoplankton in Masan Bay. J.

Kor. Soc. of Oceanogr. 12:147-158.

Lee WJ and U-J Yang. 2010. Temporal variations of Heterotro- phic- and Photosynthetic dinoflagellates at a single station in Jangmok Bay in summer 2003. J. Env. Sci. Intern. 19:

607-615.

Lu D, J Goebel, Y Qi, J Zou, X Han, Y Gao and Y Li. 2005.

Morphological and genetic study of Prorocentrum dong- haiense Lu from the East China Sea, and comparison with some related Prorocentrum species. Harmful Algae 4:494- 505.

Matsuoka K, HJ Cho and DM Jacobson. 2000. Observation of the feeding behavior and growth rates of the heterotrophic dinoflagellate Polykrikoides kofoidii (Polykrikaceae, Dino- phyceae). Phycologia 39:82-86.

Matsuoka K, M Iwataki and H Kawami. 2008. Morphology and taxonomy of chain-forming species of the genus Co- chlodinium (Dinophyceae). Harmful Algae 7:261-270.

Matsuoka K, H Kawami, S Nagai, M Iwataki and H Takaya- ma. 2009. Re-examination of cyst-motile relationships of Polykrikos kofoidii Chatton and Polykrikos schwartzii Bütschli (Gymnodiniales, Dinophyceae). Rev. Palaeobot.

Palynol. 154:79-90.

Matsuyama Y, M Miyamoto and Y Kotani. 1999. Grazing im- pact of the heterotrophic dinoflagellate Polykrikos kofoidii on a bloom of Gymnodinium catenatum. Aqua. Microb.

Ecol. 17:91-98.

Orlova TY, MS Selina and OG Shevchenko. 2003. The mor- phology of cysts and motile cells of Gyrodinium instriatum (Dinophyta), a species new to the Sea of Russia. Russ. J.

Mar. Biol. 29:120-122.

Park K-W, YS Suh and W-A Lim. 2012. Seasonal changes in phytoplankton composition in Jinhae Bay, 2011. J. Korean Soc. Mar. Environ. Saf. 18:520-529.

Park T-G, YS Kang and Y-T Park. 2009. Abundance of the tox- ic dinoflagellate Alexandrium catenella in Jinhae Bay, Ko- rea as measured by specific real-time PCR probe. J. Korean Fish Soc. 12:227-235.

Saldarriaga JF, FJR Taylor, PJ Keeling and T Cavalier-Smith.

2001. Dinoflagellate nuclear SSU rRNA phylogeny sug- gests multiple plastid losses and replacements. J. Mol.

Evol. 53:204-213.

Shin HH, YH Yoon, H Kawami, M Iwataki and K Matsuoka.

2008. The first appearance of toxic dinoflagellate Alexan- drium tamarense (Gonyaulacales, Dinophyceae) responsi- ble for the PSP contamination in Gamak Bay, Korea. Algae 23:251-255.

Stoecker DK, DE Gustafson and PG Verity. 1996. Micro- and mesoprotozooplankton at 140°W in the equatorial Pacific:

heterotrophs and mixotrophs. Aquat. Microb. Ecol. 10:

273-282.

Stoecker DK, A Taniguchi and AE Michaels. 1989. Abundance of autotrophic, mixotrophic and heterotrophic ciliates in shelf and slope waters. Mar. Ecol. Prog. Ser. 50:241-254.

Yoo K-I and J-B Lee. 1987. On the trophic correlation between Tintinnids and dinoflagellates in Masan Bay, Korea. Bull.

Korean Fish. Soc. 20:230-236.

Yoo KW. 1982. Taxonomic study on the causative organisms of red tide: Genus Prorocentrum. Bull. Environ. Sci. Ha- nyang Univ. 3:25-31.

Yoshida M, K Mizushima and K Matsuoka. 2003. Alexandrium acatenella (Gonyaulacales: Dinophyceae): Morphological characteristics of vegetative cell and resting cyst. Plankton Biol. Ecol. 50:61-64.

Received: 13 June 2016

Revised: 28 August 2016

Revision accepted: 29 August 2016