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Two Gonyaulax-like strains were established by isolating cells from Korean coastal waters, and their morphologies and molecular phylogenies based on SSU and LSU rRNA gene sequences were examined. The motile cells displayed neutral torsion and a plate formula typical for the genus Gonyaulax, and were characterized by a reticulated surface with many pores, and a marked antapical flange on the boundary between 1″″ and 2p or two prominent spines. The reticulate ornamentation was sometimes absent on the plate margin or on the entire plate. Pronounced rows of pores on the margins of precingular, cingular and postcingular plates were observed, and especially a distinct pore was always present on the margin of the anterior sulcal plate contacting with 1″. A spiniferate resting cyst had a red body, gonal and intergonal processes, and an antapical flange. In the phylogenetic tree, the Korean isolates had a close relationship to Gonyaulax membranacea and were clearly divergent from other Gonyaulax species. These species can be distinguished by the presence or absence of a distinct pore on the margin of the anterior sulcal plate in touch with 1″, and different process types in cyst morphology. Based on these morpho-molecular data, Gonyaulax kunsanensis sp. nov. is proposed. [ABSTRACT FROM AUTHOR]

Dense patches were observed in the tidal pools of the southern area of Korea. To clarify the causative organisms, the cells were collected and their morphological features were examined using light and scanning electron microscopy (SEM). In addition, after establishing strains for the cells the molecular phylogeny was inferred with concatenated small subunit (SSU) and large subunit (LSU) rRNA sequences. The cells were characterized by a nucleus in the hypotheca, strong reticulations in thecal plates, the separation of plates 2a and 3a, the tear-shaped apical pore complex, an elongated rectangular 1a plate and the absence of the right sulcal list. The thecal plate formula was Po, X, 4′, 3a, 7″, 6c, 4S, 5′′′, 2′′′′. Based on these morphological features, the cells were identified as Bysmatrum subsalsum. In the culture, the spherical cysts of B. subsalsum without thecal plates were observed. Molecular phylogeny revealed two ribotypes of B. subsalsum are identified; The Korean isolates were nested within the ribotype B consisting of the isolates from China, Malaysia and the French Atlantic, whereas the ribotype A includes only the isolates from the Mediterranean Sea. In the phylogeny, B. subsalsum and B. austrafrum were grouped. This can be supported by the morphological similarity between the two species, indicating that the two species may be conspecific, however B. subsalsum may distinguish from B. austrafrum, because of differences in the types of eyespots reported in previous studies. These findings support the idea that there is cryptic diversity within B. subsalsum. [ABSTRACT FROM AUTHOR]

The effects of the addition of nutrients (nitrate: N; phosphate: P; and vitamin B1) and trace metals (iron: Fe; Copper: Cu; and selenium: Se) on the growth of Gymnodinium catenatum, which was isolated from Korean coastal waters, were investigated. The Korean isolate of G. catenatum grew under a wide range of concentrations of N and P. Whilst high concentrations of N (> N: P ratio of 23.5) did not stimulate the growth rate, an enhanced growth rate and cell density were observed with the addition of P. The experimental addition of vitamin B1 revealed that G. catenatum is not dependent on vitamin B1 for growth. Moreover, the addition of Fe and Cu resulted in no significant differences in the growth patterns and rates of G. catenatum between the controls and treatments. It is thus possible that growth of the Korean isolate of G. catenatum does not require high concentrations of Fe and Cu. However, the cell densities were enhanced in the stationary phases of treatments upon addition of Se, and the maximum cell densities were higher than those in the culture experiments upon additions of other nutrient and trace metals. Our findings indicate that G. catenatum prefers P and Se for proliferation, rather than other nutritional sources. [ABSTRACT FROM AUTHOR]