The taxonomic status of three closely related species of the genus Sphacelaria, S. rigidula Kützing, S. fusca (Hudson) C.F Gray and S. didichotoma Saunders was reassessed on the basis of morphological observations from herbarium specimens and phylogenetic analysis of RUBISCO spacer sequences. Sphacelaria rigidula was characterized by having only 2-armed propagules and somewhat slender filaments. Culture experiments revealed that its propagules commonly formed secondary arms, even though they were rarely produced in the field. It is concluded that S. divaricata Montagne characterized by dichotomously branched arms in propagules shoud be synonymized with S. rigidula, based on propagule morphology and measurements. Sphacelaria fusca clearly be separated from S. rigidula by having 2-4 armed propagules. These morphological differences were highly supported by the differences in the RUBISCO spacer sequences. S. didichotoma resembles S. rigidula in having propagules with two dichotomously branched arms. However, it commonly produces the secondary arms in the field. Additionally, this species has shorter primary arms than S. rigidula. Phylogenetic analyses supported the distinction of S. didichotoma from S. rigidula. The northwestern Pacific plants, previously recorded as S. divaricata, were recognized as S. didichotoma.

Polysiphonia pacifica is rhodomelaceous red algal species that includes five varieties in Pacific Ocean: P. pacifica var. delicatula, P. pacifica var. distans, P. pacifica var. determinata, P. pacifica var. disticha, and P. pacifica var. gracilis. We here report morphology and phylogeny of P. pacifica to confirm the relationships among previously described varieties as a loan of type specimens from US and to assess phylogenetic relationships of closely related species using plastid protein-coding rbcL gene. Polysiphonia pacifica is distinguished by having creeping filaments attached by unicellular rhizoids not cut off by cross walls, four pericentral cells, ecorticate, trichoblasts rare, ultimate branchlets attenuate at the tip but not pungent, and tetrasporangia in long straight series in the ultimate branchlets. The protein-coding plastid rbcL gene sequence data show that P. pacifica is distinctly different from the superficially similar species, P. morrowii and P. stricta. However, the rbcL sequences of P. pacifica var. pacifica and var. disticha are identical though they have morphological variation.

To clarify some confusions concerning identification of the Korean Peridinium species, genotypic analysis was performed with their SSU rDNA sequences. PCR was used to amplify the partial SSU rDNA of Peridinium isolates collected from three different Korean waters (Juam, Sang-sa and Togyo Reservoirs). The PCR products were allowed directly to sequence, which revealed each 942 bp of rDNA sequence. Analyses of the rDNA sequences showed that all the Korean isolates had the same genotype (100% sequence homology), and they were nearly identical to a Japanese strain of P. bipes f. occultatum (NIES 364; 99.8% sequence similarity). The sequence-based comparisons could clearly resolve P. bipes f. occultatum isolated from three different Korean waters.

Scinaia latifrons Howe occurs in rhodolith beds between 9 to 27 m depths at San Lorenzo channel, Gulf of California, Mexico. As very little was known about the morphometrics of this normally temperate species in a subtropical area, we investigated the phenological changes from December 1998 to December 1999. The gametophytic phase of the species was present from late February to late May, which represented a shorter time period to other known species in the genus. Our results suggested that two gametophytic cohorts develop over winter and early spring based on the size class structure of the frond height. Thalli became reproductively mature at a small size (1-2 cm in height) and all the plants were monoecious. Scinaia latifrons at the study location underwent allometric growth, indicated by the lack of correlation between size, width of the plants, or branching patterns.

The morhology and life history of Stylonema cornu-cervi Reinsch from Japan were investigated. The species had multiseriate erect thalli from a basal cell. The thalli usually branched dichotomously, occasionally trichotomously near the base, and non-branched thalli were sometimes observed. A dichotomous branch on the upper portion near the base occurred only one time on each erect branch. Cells contained a stellate chloroplast, which was composed of a central rounded part with an obscure pyrenoid and 5-8 cup-like lobes connected to the central part by a small thin stipe. The biseriate part was observed on the six-celled stage in culture, and the grown thalli were multiseriate except for base and apices. Monospores forming from the immediate transformation of vegetative cells were observed. Thalli grew at 15-25$^{\circ}C$ and died at 10 and 30$^{\circ}C$. The fastest growth and maturation were observed under 25$^{\circ}C$ and 14L:10D. Although S. alsidii (Zanardini) Drew usually had uniseriate thalli, irregularly branched multiseriate thalli had been reported in cultures. It is possible that in the previous report the thalli were confused with S. cornu-cervi. In this report, S. cornu-cervi were distinguished from S. alsidii in that the branches were few, the multiseriate portions were observed on the early stage (six-celled stage), and the grown thalli were multiseriate except at the base and apices.

A study on the seasonal changes in the phytoplankton community was carried out in four aquaculture ponds of Bangladesh over a period of 16 months from August 2000 to November 2001. Out of 45 phytoplankton species identified, 30 belong to Cyanophyceae, 7 to Chlorophyceae, 5 to Bacillariophyceae and 3 to Euglenophyceae. The highest phytoplankton abundance was observed in spring followed by early autumn, summer, and the lowest was in winter. The annual succession of Cyanophyceae was characterized by spring and early autumn period dominated by Microcystis sp. Anabaena sp. and Planktolymbya sp. with Microcystis sp. as the main blue-green algae represented. Chlorophyceae was characterized by rainy season domination of Chlorella vulgaris, Pediastrum sp. and Scenedesmus denticulatus with maximum abundance of Chlorella vulgaris. Whereas Bacillariophyceae was dominant during the winter period. Navicula angusta and Cyclotella meneghiniana were the most frequently occurring species of Bacillariophyceae throughout the study period. Euglenophyceae was dominant in late autumn and Euglena sp. was the dominant species. The effect of various physicochemical water quality parameters on the seasonal distribution and succession of the above mentioned phytoplankton population as well as the interaction and eutrophication are discussed.

The objective of this study was to clarify marine algal flora and community structure of 16 uninhabited islands in Sinangun area, south western coast of Korea. As a result, a total of 63 species - 11 greens, 16 browns and 36 reds - was identified. The functional groups of marine algal species were filamentous 14.3%, foliose 20.5%, corticated 45.3%, leathery 13.7%, and articulated calcareous algae 6.2%. The (R+C)/P value was calculated as 2.9 showed temperate flora. The result of DCA showed that 16 uninhabitated islands tend to be distributed eastern and western parts. The dominant species was Ulva pertusa, while the subdominats were Gelidium divaricatum, Myelophycus simplex. The vertical distribution pattern of intertidal marine algae represented three distinct zones; Gloiopeltis furcata, Myelophycus simplex, Gelidium divaricatum - Ulva pertusa, Enteromorpha spp., Ishige okamurae - Ulva pertusa, Sargassum thunbergii, Symphyocladia latiuscula.

Agar was extracted from Gelidium amansii, which was harvested at the shores of Jeju Island in South Korea. As a unique solvent, the ability of dimethyl sulfoxide (DMSO) was used to separate agarose from agar by removing agaropectine and quality of the resultant agarose was characterized for chromatography purposes. Agar sample was agitated by motor-driven stirrer with DMSO in a water bath (at 70$^{\circ}C$ for 2 h) and centrifuged (3,000 rpm for 20 min). Resultant upper agarose layer was gelled, washed, dried and milled. The quality of agarose was evaluated by the analysis of proximate chemical composition, sulfate content, gelling strength and DNA migration. In this study, the separated agarose showed low sulfate amount (0.28%) and showed high gel strength (1190 g ${\cdot}\;cm^{-2}$). The resolution power and the ligase activities gave clear picture about the suitability of the present agarose for practical purposes.

Hizikia fusiformis is well known edible brown seaweed both in Korea and Japan. It has been intensively studied due to its pronounced health benefits. In this study, the radical scavenging (antioxidative) activities of its hydrophilic phlorotannin constituents were studied. An aqueous extract/original extract (OE) of H. fusiformis was initially prepared with heat, enzymes and pH control treatments. Then the original extract was further fractionated (with methylene chloride and methanol) and crude hydrophilic phlorotannin extract (CHPE) was prepared. The radical scavenging activities of both OE and CHPE were determined by using electron spin resonance (ESR) spectrophotometric assays such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl and alkyl radical assays. The CHPE reported significantly (p < 0.05) higher total phenolic (phlorotannins) content (1.23 mg ${\cdot}ml^{-1}$) than that of the OE (0.21 mg ${\cdot}ml^{-1}$). Both OE and CHPE have reported good radical scavenging activities and those activities were dose-dependent. The CHPE have demonstrated significantly higher radical scavenging activities than that of the OE. In comparison, the DPPH radical (6 $\times$ 10$^{-5}$ M) scavenging activities of all the CHPE concentrations (0.25, 0.5 and 1 mg ${\cdot}ml^{-1}$) tested were significantly higher (37.3, 78.2 and 91.6%, respectively) than that of the OE counterparts (11.4, 34.6 and 61.7%, respectively). Alkyl radical scavenging percentages of CHPE at 0.0625, 0.125, 0.25 and 0.5 mg${\cdot}ml^{-1}$ were significantly higher (34.3, 69.2, 80.4 and 88.7%, respectively) than that of the OE (16.6, 41.4, 62.3 and 77.4%, respectively). The percentages of hydroxyl radical scavenging activities of CHPE at the concentrations of 0.25, 0.5 and 1 mg ${\cdot}ml^{-1}$ were 32.5, 59.4 and 84.2 % respectively. Moreover, the hydroxyl radical scavenging activity of OE was quite lower than that of the CHPE. Therefore, these results suggest that the hydrophilic phlorotannins of H. fusiformis are potential radical scavengers thus, a great source of antioxidative nutraceuticles.