• Ocean and Polar Research
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• 제45권1호
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• pp.1-9
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• 2023

Marine microalgae have different collection methods depending on their habitat. In the case of adhesive microalgae, it is difficult to separate organisms from the substrate surface, and contamination is likely to occur during the sampling process. In this study, we analyzed the collection efficiency of adhesive microalgae using three artificial fiber materials (nylon, blend fabric, and viscose rayon). Each fiber showed different fiber diameter and pore characteristics (nylon 26.09 ㎛, blend fabric 56.6 ㎛, viscose rayon 101.3 ㎛). In addition, attached organisms were collected on the surface of artificial substrates at Bukseong Port in Incheon using each tested fiber material. After that, we investigated the population and species composition. The highest number of cells was found in nylon, which was 8 times higher than in the least collected viscose rayon material. In addition, we identified 24 microalgal species from the substrate, demonstrating that the species composition differed from that of surface water. The number of collected microalgae species varied depending on the fiber materials, with nylon containing all the adhesive microalgae. In contrast, only a few microalgae were observed in other fibers. These results suggest that, of the tested fibers, nylon material may be suitable for collecting adhesive microalgae. As a result, this study may be useful for future research on adhesive microalgae.

• 한국환경과학회지
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• 제12권7호
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• pp.715-724
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• 2003

Distributional patterns of microalgae were studied in the tidal flats of Gamami Beach(Young-Gwang, Korea) from November 1999 to 2000 July. The tidal flats of Gamami Beach was composed mainly of sandy sediment. The concentrations of nutrients were low compared with other tidal flats. In the present study, 68 species of microalgal flora were identified. These were comprised of 25 species of benthic microalgae and 59 species of planktonic microalgae. Diatoms predominated the benthic microalgae with 96.0% of total species occurred. Dominant species were Amphora sp., Cocconeis sp., Coscinodiscus asteromphalus, Coscinodiscus sp., Nitzschia sigma var. intermedia, Nitzschia distans, Navicula spp., Paralia sulcata, Pleurosigma sp. Skeletonema coastatum, and Surirella sp. Among them, Amphora sp., Paralia sulcata, and species of Pleurosigma and Nitzschia were observed throughout the studied period. Planktonic microalgae of Gamami Beach was also predominated by diatoms. They occupied 88.1% of total planktonic microalgae. The density of microalgal population was higher in silty sediment than in sandy sediment. The population density of microalgae was higher in high tide zone than that in low tide zone. The density of the benthic microalgae in the surface layer of tidal flats showed increasing tendency for 2 hours after the beginning of ebb tide. On the contrary, benthic microalgal density of subsurface layer was decreased during the period. Concentrations of chlorophyll ${\alpha}$ from sediment and water were not synchronized during the study period. Therefore, the distributional patterns of the benthic microalgae and planktonic algae seemed not to be related. Chlorophyll ${\alpha}$ of water was highly related with the concentration of NH$_4$-N, whereas, chlorophyll ${\alpha}$ of sediment uas related with NO$_3$-N concentration.

• Ocean and Polar Research
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• 제44권2호
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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.

• 한국패류학회지
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• 제25권1호
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• pp.35-40
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• 2009

The trumpet shell Charonia sauliae is an endangered and valuable species with potential for aquaculture. For artificial propagation of C. sauliae, the effects of three different food microalgae on the development, growth, and survival rate of the larvae and spat were investigated. For the larval feeding experiments, we utilized six microalgae species as food sources, namely Pavlova lutheri, Tetraselmis suecica, Nannochloris oculata, Isochrysis galbana, Chaetoceros calcitrans, and Phaeodactylum tricornutum; for the larval and spat growth and survival experiments, we utilized T. suecica, C. calcitrans, and P. tricornutum. The results showed that the temporal digestion index (TDI) for the veliger larvae was significantly different for C. sauliae fed the different microalgae species (p < 0.05), that the T. suecica, C. calcitrans, and P. tricornutum cultivars were better suited for larval consumption (p < 0.05), and that the growth and survival of the larvae and spat were significantly influenced by food type, specifically P. tricornutum (p < 0.05). Further research is needed to evaluate the effects of other microalgae species, different algal concentrations, and biochemical composition on the growth and survival of C. sauliae.

• Fisheries and Aquatic Sciences
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• 제27권1호
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• pp.23-34
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• 2024

While scientific information on the spatial variation of soda lake Microalgae is important to limnological studies, little information was reported from the Ethiopian Rift Valley Lake, Lake Chitu. This study aimed to understand the spatial distribution of the dominant Microalgae taxa in Lake Chitu, Ethiopia. The collection of samples and in situ measurements of some physico-chemical parameters were recorded at three sites for one cycle in November 2021. Fourteen species or genera of Microalgae were identified. Among those, Bacillariophyta were the most important with regard to species abundance and the rarest in species richness. Cyanophyta were the second-most important group in terms of species richness and rarity. Comparatively, all microalgae taxa were rare at both the anthropogenic areas (AA) and the flooding area (FA), which could be mainly due to intensive human and animal intervention and associated with extreme turbidity. Among Cyanophyta, Chroococcus minutus, Microcystis aeruginosa, and Spirulina platensis/fusiformis were predominant at both AA and FA, revealing their adaptation to less clear water and pollution. But S. platensis/fusiformis attained the highest abundance at the FA, indicating their preference for water in a highly nutrient-enriched area. We concluded that the spatial variation of microalgae diversity in relation to water quality parameters has implications for the importance of microalgae as a baseline indicator of water quality assessment tools in lakes.

• 한국물환경학회지
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• 제28권6호
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• pp.796-803
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• 2012

Potential feasibility of nutrients removal and biofuel production with microalgae was evaluated in batch culture. Distribution of microalgae in fresh water including reservoir and river was investigated to search for the species with high content of lipid that could converted into biofuel. Green algae, Chlorella and Scenedesmus sp., these are known as species containing high lipid content for biodiesel production, were observed in both summer and autumn season. However another highly lipid-containing species, botryococcus sp. was not observed in this study. In mixed culture of microalgae using synthesized wastewater medium, green algae were found to be dominant, comparing to other species of diatoms and blue-green algae. And microalgae were also capable of removing nitrogen and phosphorus in batch experiments. During the culture period of 14 days, removal efficiencies of nitrate and phosphorus were 30% and 82%, respectively. Furthermore, content of the intracellular lipid extracted from algae cell was as favorable as 12-30% in the mixed culture where Scenedesmus and Chlorella sp. were dominant. Therefore the mixed culture of microalgae could be applied to biofuel production and tertiary wastewater treatment, even though there are economic barriers to overcome.

• ALGAE
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• 제24권4호
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• pp.257-265
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• 2009

Marine microalgae are a key diet component in finfish and shellfish aquaculture. Cryopreservation of the microalgae is suggested by many other studies as the best method for long-term storage. To test cryopreservation efficacy, 19 taxas of marine microalgal species were examined. In the first experiment we compared dimethylsulfoxide ($Me_2SO$) and glycerol, which are most widely used as cryoprotectant agents (CPAs). The cryopreservation comprised two freezing procedures. Firstly, the samples containing the CPAs were kept at $4^{\circ}C$ for 10 min before being plunged into liquid nitrogen ($-196^{\circ}C$). Secondly, samples containing CPAs were pre-cooled ($-1^{\circ}C$ $min^{-1}$ to $-80^{\circ}C$ before being plunged into liquid nitrogen. Most of the species were successfully cryopreserved using $Me_2SO$, whereas the Prasinophyceae (T. striata and T. suecica) were successfully cryopreserved using glycerol. In general, the cooling method had no influence on the survival of the microalgae except in the case of the Tetraselmis species. In the second experiment, the cultured solution was divided before cryopreservation into concentrated and non-concentrated groups to identify the effect of cell density during cryopreservation. After 12 months of storage, the samples were again divided into centrifugation and non-centrifugation groups to learn the effect of $Me_2SO$ on the culture. Viability and growth of the microalgae were not influenced by cell density or the centrifugal removal of the $Me_2SO$ after thawing.

• 한국미생물·생명공학회지
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• 제46권3호
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• pp.225-233
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• 2018

In this exploratory study, eight types of microalgae from different phyla (Chlamydomonas reinhardtii, Chlorella species, Haematococcus pluvialis, Porphyridium purpureum, Porphyridium cruentum, Isochrysis species, Isochrysis galbana, and Pavlova lutheri) were tested for their antibacterial activities against eight target pathogenic bacterial strains. The agar well diffusion method and broth micro dilution assay were conducted to estimate the antibacterial activity. Microalgae cell-free supernatants, exopolysaccharides (EPS), water, and organic solvent extracts were used for inhibition analysis. EPS extracted from P. lutheri showed activity against Bacillus subtilis and Pseudomonas aeruginosa. Inhibition zone diameters of 14-20 mm were recorded on agar plates, while the minimum inhibitory concentrations in the broth micro dilution assay were $0.39-25mg\;ml^{-1}$. During this study, haptophyte microalgae, Isochrysis species, and P. lutheri extracts showed the highest activity against most of the tested pathogenic bacterial strains, while most of the extracts were active against the important foodborne pathogen P. aeruginosa. This study showed promising results regarding important microalgae phyla, which will further aid research related to extracts and exploitation of bioactive metabolic compounds in the food and pharmaceutical industries.

• 한국물환경학회지
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• 제39권2호
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• pp.181-193
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• 2023

Distribution changes in microalgae communities were studied in the Nakdonggang River at two sampling stations (St.1 Gyeongcheongyo Bridge (GB) and St.2 Daedong Wharf (DW)) at monthly intervals from January 2021 to November 2021. A total of 83 taxa included 82 species, 1 forma, belonging to 49 genera, 32 families, 21 orders, and 8 classes. The most important groups were Bacillariophyta and Chlorophyta. The number of species ranged from 5 to 24 in GB, and from 9 to 21 taxa in DW. The contribution of Bacillariophyta to the total species richness was the highest during all survey periods, and Chlorophyta yielded the next highest value in the study area. The dominant taxa were Aulacoseira ambigua, A. ambigua f. japonica, and Ulnaria acus in this study. Cluster analysis and non-metric multidimensional scaling (nMDS) analysis based on Bray- Curtis similarity identified 4 major groups, which corresponded to microalgae assemblages and their characteristic species. Correlation was analyzed through the CCA analysis. It was found that there was a correlation between the microalgae and environmental factors. It was revealed that the divided groups were distinguished because of the differences by the survey period. Therefore, seasonal change was judged as a major factor affecting the distribution of microalgae communities.

• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2000년도 춘계수산관련학회 공동학술대회발표요지집
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• pp.487-488
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• 2000

Genomic DNA was isolated from the marine microalgae representing genetic characteristics and genomic polymorphisms by polymerase chain reaction amplification of DNA as arbitrary primers. The electrophoretc analysis of PCR-RAPD products showed hig levels of variation between different genus and little variation between different species. Outer of these primers, 6 generated 248 highly reproducible RAPD markers, producing almost seven polymorphic bands per primers. The degree of similarity frequency between Chaetoceros gracilis and Chaetoceros calcitrans species showed 90％ as calculated by sharing analysis. The RAPD polymorphism generated by this primer may be used as a genetic marker for genus or species identification in important marine microalgae. (omitted)