• ALGAE
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• v.24 no.2
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• pp.67-77
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• 2009

The marine phytoplankton diatom Thalassiosira species are described from the Korean coastal waters, based onobservations of Fine structutre of its frustules. As a fourth series, this study deals with 5 Thlassiosira species (T. decip-iens, T. ecgentrica, T. mala, T. nodulolinmta, and T. proschinae). The most striking features of these species are also theform and position of two processes on frustules. There is a central strutted process on valve face except T. nodvlolin-eata, which has a modified one on its center. The extemal tubes of marginal strutted processes are divided twoforms: "pile" form in T. decipiens and T. proschkinae, "short straw" form in T. eccentrica and T. nodulolineata. T. maladoes not present the extemal tubes in valve margin. The labiate processes are located in valve margin except T.proschkinae, which has it on valve face. Of theae, thrce species (T. mala, T. nodulineata at a final contentration of 5%and T. proschkinae were newly recorded in the coastal waters of Korea.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.8
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• pp.1010-1020
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• 2014

Ballast water effluent treated by an electrolytic method contains reactive chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on marine environment. WET testing was carried out for three marine pelagic organisms, i.e., diatom Skeletonema costatum, rotifer Brachionus plicatilis and fish Paralichthys olivaceus. The biological toxicity test revealed that S. costatum was the only organism that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50% (EC50) values of 12.5%, 25.0% and 83.3%, respectively, at brackish water condition. In contrast, it showed insignificant toxicity at seawater condition. B. plicatilis and P. olivaceus also showed no toxicities to the effluent at the both salinity conditions. Meanwhile, chemical analysis revealed that the ballast water effluent contained total residual oxidants (TROs) below $0.03{\mu}g/L$ and a total of 20 DBPs including bromate, volatile halogenated organic compounds (VOCs), halogenated acetonitriles (HANs), halogenated acetic acids (HAAs) and chloropicrin. Based on ERA, the 20 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. Except monobromoacetic acid, the ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the other 19 DBPs did not exceed 1. Thus, our results of WET testing and ERA indicated that the ballast water effluent treated by electrolysis and subsequently neutralization was considered to have no adverse impacts on marine environment.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.6
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• pp.1336-1347
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• 2013

The marine algal flora assemblages settled on the artificial seaweed reefs in Jeju-do before and after rocky cleaning were investigated during summer and the early succession of seaweeds attached to the test panels on the structures of the artificial reef after rocky cleaning were observed by visual observations and under the dissecting microscope in order to evaluate the effects of this rocky cleaning operation. Species composition and algal biomass on the Bboolsamgak-typed seaweed artificial reefs before and after rocky cleaning were measured and compared before and after rocky cleaning. Before rocky cleaning in July 2012, only nine algal species had existed on the Bboolsamgak-typed seaweed artificial reefs, however, twenty algal species occurred on the seaweed artificial reefs after rocky cleaning in July 2013. Particularly, 15 species among them in July 2013 were not found in July 2012 and they seemed to occur newly on the artificial reefs. A large quantity of algal biomass increased in July 2013 after rocky cleaning. Based on the importance value, there was a drastic change in the dominant species between July 2012 and July 2013 after rocky cleaning. By dissecting micrographs, an epiphytic diatom, Licmophora sp. and flagellates, were observed on the 9th day. A chlorophyte, Ulothrix flacca was observed after 14 days, Ulva pertusa, Bryopsis pulmosa, crustose coralline algae, and Cladophora spp. were after one month. After two months, a significant species succession was observed from three previous chlorophyte species to crustose coralline algae existed as a dominant species on the panels. In this study, however, any brown algae were not found until three months in the early seaweed succession. All above results indicates that the rocky cleaning is a very efficient method for the establishment of macroalgal assemblages on the artificial reefs.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.236-236
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• 2017

Effluent treated by an NaDCC injection method in Ballast water management system (BWMS) contains reactive chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on marine environment. WET testing was carried out for four marine pelagic and freshwater organisms, i.e., diatom Skeletonema costatum, Navicula pellicuosa, chlorophyta Dunaliella tertiolecta, Pseudokirchneriella subcapitata, rotifer Brachionus plicatilis, Brachionus calyciflorus and fish Cyprinodon variegatus, Pimephales promelas. The biological toxicity test revealed that algae was the only biota that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50% (EC50) values of 25-50%, 50-100% and >100%, respectively, at three water condition, but did not show any significant toxicities on other biota. Meanwhile, chemical analysis revealed that the BWMS effluent contained total residual oxidants (TROs) below $0.03{\mu}g/L$ and a total of 25 DBPs such as bromate, volatile halogenated organic compounds (VOCs), halogenated acetonitriles (HANs), halogenated acetic acids (HAAs), chloropicrin and Isocyanuric acid. Based on ERA, the 25 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. The ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the other DBPs did not exceed 1 for General harbor environment. However, four substances (Isocyanuric acid, Tribromomethane, Chloropicrin and Monochloroacetic acid) were exceed 1 for Nearship environment. But observed toxicity in the test water on algal growth inhibition would be mitigated by normal dilution factor of 5 applied for nearship exposure. Thus, our results of WET testing and ERA showed that the BWMS effluent treated by NaDCC injection method would have no adverse impacts on marine environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.738-744
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• 2017

Effect of dietary inclusion of microalgae, diatom-dominant, oil extracts (MOE) on growth, body composition and shell color of juvenile abalone Haliotis discus was investigated. One thousand four hundred and seventy juvenile abalone were distributed into 21 plastic rectangular containers. Seven experimental diets were prepared: MOE0, MOE0.01, MOE0.05, MOE0.1, MOE0.5, MOE1 and MOE2 diets containing MOE at the concentrations of 0, 0.01, 0.05, 0.1, 0.5, 1 and 2% at the expense of mixture of squid liver and soybean oils, respectively. The experimental diets were fed to abalone in triplicate once a day with a little leftover for 16 weeks. Weight gain and specific growth rate of abalone fed the MOE1 and MOE2 diets were higher than those of abalone fed the all other diets. The shell length and soft body weight of abalone fed the MOE2 diet were longer and heavier than those of abalone fed the all other diets. Crude protein and ash content of the soft body of abalone were affected by dietary inclusion of MOE. The shell color of abalone fed the all experimental diets was different from that of wild abalone. In conclusion, dietary inclusion of MOE improved growth of abalone, but did not shell color of abalone.

• Ocean and Polar Research
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• v.29 no.2
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• pp.101-112
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• 2007

In order to examine the short-term variations of phytoplankton and heterotrophic protozoa community structures with bloom events, water samples were collected every other day at one site in the coastal water off Incheon, Korea, from August 15-September 30, 2001. $Chlorophyll-{\alpha}$ concentrations varied widely from 1.8 to $19.3\;{\mu}g\;l^{-1}$ with the appearances of two major peaks of $Chlorophyll-{\alpha}$ concentration during the study period. Size-fractionated $Chlorophyll-{\alpha}$ concentration showed that net-size fraction ($>20\;{\mu}m$) comprised over 80% of total $Chlorophyll-{\alpha}$ during the first and second bloom periods, nano-size fraction ($3{\sim}20\;{\mu}m$) comprised average 42% during the pre- (before the first bloom) and post-bloom periods (after the second bloom), and pico- size fraction ($<3\;{\mu}m$) comprised over 50% during inter-bloom periods (i.e. between the first and second bloom periods). Dominant phytoplankton community was shifted from autotrophic nanoflagellates to diatom, diatom to picophytoplankton, picophytoplankton to diatom, and then diatom to autotrophic nanoflagellates, during the pre-, the first, the inter, the second, and the post-bloom periods, respectively. During the blooms, Chaetoceros pseudocrinitus and Eucampia zodiacus were dominant diatom species composed with more than 50% of total diatom. Carbon biomass of heterotrophic protozoa ranged from 8.2 to $117.8\;{\mu}gC\;l^{-1}$ and showed the highest biomass soon after the peak of the first and second blooms. The relative contribution of each group of the heterotrophic protozoa showed differences between the bloom period and other periods. Ciliates and HDF were dominant during the first and second bloom periods, with a contribution of more than 80% of the heterotrophic protozoan carbon biomass. Especially, different species of HDF, thecate and athecate HDF, were dominant during the first and the second bloom periods, respectively. Interestingly, Noctiluca scintillans appeared to be one of the key organisms to extinguish the first bloom. Therefore, our study suggests that heterotrophic protozoa could be a key player to control the phytoplankton community structure and biomass during the study period.

• Journal of the korean society of oceanography
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• v.32 no.1
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• pp.46-55
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• 1997

The quantitative determination of carotenoids, chlorophylls and their degradation products from marine phytoplankton was performed by reverse-phase high performance liquid chromatography (HPLC). Separated and quantified chlorophylls and their degraded products are chlorophyll a, b, c, chlorophyllide a, phaeophytin a, b and phaeophorbide a. Concentrations of six carotenoids including fucoxanthin, 19'-butanoyloxyfucoxanthin, 19'-hexanoyloxyfucoxan-thin, prasinoxanthin, alloxanthin, zoaxanthin/lutein were also determined from natural field samples by absorbance. Results of pigment analysis of field samples collected from the southern waters of the East Sea on October 8th, 1996 were reported. Concentration of chi a ranged from 7.2 to 180.4 ng/1. Concentration of chi b and chi c ranged from 22.7 to 53.7 ng/1 and from 3.3 to 58.5 ng/1, respectively. Significant concentrations of phaeophytin a, and chlorophyllide a were also detected at different depths. Fucoxanthin, 19'-hexanoyloxyfucoxanthin and zoaxanthin/lutein were the most abundant carotenoids and 19'-butanoyloxyfucoxanthin, prasinoxanthin and alloxanthin were also detected relatively at low concentrations. These results of pigment analyses suggest predominance of diatom, prymnesiophytes and cyanobacteria and presence of crysophyte, green algae (prasinophyte and prochlorophyte), and cryptophyte in the study area on October 8th, 1996, We report prymnesiophyte for the first time as an important biomass component of marine phytoplankton in the study area. Vertical profiles for the concentration changes of the major pigments were also given.

• Korean Journal of Ecology and Environment
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• v.35 no.2 s.98
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• pp.141-144
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• 2002

The construction of river mouth dam has prevented seawater from backwarding to upstream in Kum river estuary since 1990. Field observation on environmental factors, and zooplankton and phytoplankton dynamics have been carried out three times with two month interval in the summer and autumn in 2000 at three selected stations in Kum river estuary. Blockade of seawater flowing backward to upstream caused sharp contrast of zooplankton fauna and phytoplankton flora between upstream and downstream of the river mouth dam. Freshwater cladocerans i.e., Bosmina longisrostris and Daphnia galeata dominated in the upstream, and marine copepods of Acartia omorii and Paracalanus crassirostris occurred abundantly in downstream of the dam. Freshwater diatoms did not distributed in the downstream of the dam except Melosira varians, while marine diatom of Cylidrotheca closterium occurred in benthic waters bath in upstream and downstream of the dam. The construction of the river mouth dam seems to play an ecological role to blockade the input of marine organism into the upstream in Kum river estuary.

• The Korean Journal of Malacology
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• v.20 no.1
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• pp.27-34
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• 2004

Based on both field and laboratory experiments, seasonal changes in the species composition and abundance of phytoplankton in the gut contents of the jedo venus clam, Protothaca jedoensis, and its feeding selectivity were investigated. The phytoplankton in the gut contents comprised Bacillariophyceae (diatom), Chlorophyceae, Chrysophyceae, and Dinophyceae, of which the diatoms being the most predominant throughout the year. Although the number of species and the abundance of phytoplankton in the sea water were always more diverse and more abundant than in the gut contents, the relative number and abundance were generally similar in the seawater and in the gut contents. In the laboratory experiments, the relative abundances of Coscinodiscus marginatus and Thalassirosira eccentrica were much more higher in the gut contents than any other algal species, while Paralia sulcata, Skeletonema costatum, and Eucampia zodiacus were abundant in order of cell density in the ambient water. These results suggest that P. jedoensis may feed preferably on single algal cell or smaller chains of algal cells.

• Ocean and Polar Research
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• v.44 no.2
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• pp.161-177
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• 2022

Microalgae can attach to the surface of ships and then spread to various areas by means of ship transport. The introduction of invasive species through ships is recognized as a marine problem worldwide. Identification of attached microalgae is necessary to investigate such movement between countries through ships. In the present study, through analytical methods we reviewed research data to identify the taxa of domestic attached microalgae and assess the ecological impacts of such microalgae. A total of 87 genera and 153 species (143 species of diatoms, 10 species of cyanobacteria, and 4 genera of dinoflagellates) were identified as native attached microalgae in Korea, and diatoms accounted for 93% of the total. Most of these attached microalgae were identified through research on natural substrates such as seaweeds and bedrock, and some were also identified through experiments using artificial adherent plates. To date, there is no information on microalgae attached to international ships and introduced into Korea. Molecular genetic analysis and systematic management through on-site sampling of international ships, microscopic analysis, and meta-barcoding are necessary to assess the inflow and spread path of hull-attached marine alien species and evaluate the risk they pose to the domestic ecosystem.