• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.249-260
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• 1998

To understand the attachment of micro algae and their subsequent growths on artificial surfaces immersed in seawater, the relationship between attachment of diatoms on the immersed artificial substrates and species pool in the surrounding water was investigated. We used acryl slides for the study of diatom attachment and examined the surrounding water samples collected in Incheon Harbour from July 1995 to February 1997. Variations of species composition and abundances by exposure time in seawater were investigated during the early phase of biofilm formation on various substrates, e.g. glass, acryl, titanium, copper and antifouling paint-treated slides. Immigration rates of diatoms to acryl slides during spring and winter were significantly correlated with the abundance of benthic diatoms in surrounding water ($r^2$=0.78, p<0.01, n=42), suggesting that immigration rates were affected by variations of benthic diatom abundances in surrounding water. Immigration coefficient of monoraphid diatoms was 5 times higher than that of biraphid diatoms, but relative abundance of monoraphid diatoms was 3 times lower than that of biraphid diatoms on acryl slides in spring. In winter, immigration coefficient and relative abundance of centric diatoms were higher compared to other raphe forms. These results suggest that the attachment of diatoms seems to be caused by the abundance and immigration coefficients of benthic diatoms in surrounding water. Pennate diatoms predominantly attached to all artificial surfaces throughout all experimental periods. Interestingly, centric diatoms predominantly attached to all artificial surfaces in winter. Hantzschia virgata, Licmophora abbreviata and Melosira nummuloides appeared dominantly on antifouling paint-treated slides, probably being tolerant of the antifouling paint. During incubations, the abundance of attached diatoms increased exponentially on glass, titanium and acryl slides with exposure time. The maximum abundance was highest on glass slide, followed by acryl, titanium, copper and antifouling paint-treated slides. The growth rates of attached diatom community on all artificial surfaces were higher at temperature of $24-25^{\circ}C$ than that of $2-3^{\circ}C$. The growth rate of attached diatoms on glass slide was generally higher compared to other slides during the study period. Dominant morphotypes of observed species with exposure time in seawater were prostrate form Amphora coffeaeformis, fan shape Synedra tabulata, stalk type Licmophora paradoxa and chain type M. nummuloides. A micro-succession in the attached microalgal community was observed. The composition of dominant species seems to be the result of species-specific response to gradually limited space with development of microalgal film.

• The Korean Journal of Malacology
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• v.19 no.2
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• pp.95-106
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• 2003

The compositions of amino acid in 6 monocultured benthic diatoms used in aquaculture of Haliotis discus hannai were analyzed, and effects of 15 artificial synthetic amino acids on the settlement and metamorphosis of H. discus hannai larvae. Results showed that the content of L-aspartic acid was highest in all diatoms, and that of L-glutamic acid was second high. In experiment using settlement slat without benthic diatom attached, the highest settlement rate (33.3 ${\pm}$ 8.8%) was obtained with L-glutamic acid, and a higher value (16.7 ${\pm}$ 3.3%) was found with L-aspartic acid at 24 h after experimental commencement, compared to that of control (8.6 ${\pm}$ 5.1%). 80 h later the metamorphosis rates of L-glutamic acid (86.7 ${\pm}$ 10.7%) and L-aspartic acid (80.0 ${\pm}$ 3.3%) groups were higher than control group(0) and other amino acids significantly. The response rate of L-glutamic acid was the highest (62.0%), and those of L-aspartic acid (30.0%) and L-threonine (25.3%) groups were also significantly higher than control group. In the experiment using settlement slat with benthic diatom attached, the best effect of various amino acids on induction of larval settlement was obtained with L-glutamic (82.0 ${\pm}$ 6.9%) and L-aspartic acid (78.7 ${\pm}$ 5.1%) at 24 h after experimental commencement. The settlement rates of L-histidine, L-leucine, L-lysine, L-methionine, L-phenylalanine, and L-tyrosine groups were significantly lower than control group. The same differences in the metamorphosis rate at 56 h after experimental commencement and in the response rate were found. It should be noted that after 80 h the metamorphosis rates of L-histidine (74.0 ${\pm}$ 12.0%) and L-lysine (87.0 ${\pm}$ 8.8%) declined rapidly compared to those of 56 h (8.0 ${\pm}$ 12.0%; 7.7 ${\pm}$ 12.0%).

• Korean Journal of Ecology and Environment
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• v.56 no.3
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• pp.196-206
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• 2023

Benthic attached diatoms (BADs), a major primary producer in lotic stream and river ecosystems are micro-sized organisms and require a highly magnified microscopic technique in the observation work. Thus, it is often not easy to ensure accuracy and precision in both qualitative and quantitative analyses. This study proposed a new technique applicable to improve quality control of aquatic ecosystem monitoring and assessment using BADs. In order to meet the purpose of quality control, we developed a permanent mounting slide technique which can be used for both qualitative and quantitative analyses simultaneously. We designed specimens with the combination of grid on both cover and slide glasses and compared their efficiency. As a result of observation and counting of BADs, the slide glass designed with the color-lined grid showed the highest efficiency compared to other test conditions. We expect that the method developed in this study could be effectively used to analyze BADs and contributed to improve the quality control in aquatic ecosystem health monitoring and assessment.

• Korean Journal of Environmental Biology
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• v.30 no.1
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• pp.71-76
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• 2012

Spills of $M/V$ Hebei Spirit on $7^{th}$ December 2007 caused a seriously damage to the ecosystem of Korean coast. Of these, microbial communities (i.e., attached benthic micro-algae) were reported to be sentive to the environmental change so it can be used for ecological risk assessment. Our experiment was designed to examine the ecological risk assessments for oil pollutant using benthic attached algal community on the artificial substrates of acrylic plates. Field monitoring in the culture system was conducted in Jangmok Bay. The abundances of attached micro-algae on artificial substrates gradually increased with increasing of sampling times. Among them, diatoms were the most important colonizer of coastal water, with the genera $Cylindrotheca$ and $Navicular$ most abundant. In particular, developed the culture system has correctly measured qualitative and quantitative abundance of attached micro-algae because same acrylic plates as artificial substrates were used. Thus, this culture system may be directly applied to the ecological risk experiments of microbial community structure from oil pollutants.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.197-205
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• 2013

Even though seedling production of Haliotis discus hannai has fully developed, the culture of benthic diatom as a live food for larvae is still a barrier to solve in commercial hatchery. The farmer depends on mixed microalgae which are non-selectively attached on the plate by flowing of natural seawater. The adequate diatom on the plate for the larvae in terms of quality and quantity is always significant bottleneck in the hatchery. In this study, two benthic diatom species, Caloneis schroederi and Rhaphoneis sp. were separately cultured in mass and inoculated to four tons' settlement tank of the larvae. And the larvae and the spats were cultured for nineteen and nine weeks, respectively. The result on seedling production of H. discus hannai with this method was compared to that of the farmer's traditional method as a control. With regard to variation of species composition of benthic diatom on the plate, C. schroederi and Rhaphoneis sp. were dominant for first three weeks after inoculation. But the diverse diatoms mainly, Navicula, Amphora, Cylindrotheca, Licmophora, Pleurosigma began to attache on the plate from the 4th week. The larvae attached 2.5 times more in C. schroederi tank than in the control tank. The final total biomass of the seeds in Rhaphoneis sp. tank was 3.2 times more than that of the control tank. The retared-spats in the seedling production also showed significantly higher growth and survival in the spat fed Rhaphoneis sp. or C. schroederi than those in the control group. We suggest that C. schroederi is proper for settlement of the larvae and Rhaphoneis sp. is appropriate for the growth of the larvae and spats in the commercial hatchery of H. discus hannai.

• Journal of Ecology and Environment
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• v.37 no.4
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• pp.245-255
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• 2014

To collect the diatom species belonging to the genus Hantzschia, bottom sediments were collected from 32 sampling sites in 23 sand-flat areas in the intertidal zone and river reaches of Nakdong River estuary, Korea. The sand sediments contained a total of 19 species of genus Hantzschia, Hantzschia amphioxys (Ehrenberg) Grunow, H. amphioxys f. capitata O. Muller, H. baltica Simonsen, H. distinctepunctata (Hustedt) Hustedt, H. elegantula (Østrup) Witkowski et al., H. longiareolata Garcia-Baptista, H. marina (Donkin) Grunow, H. pseudomarina Hustedt, H. virgata (Roper) Grunow, H. virgata var. gracilis Hustedt, H. virgata var. kariana Grunow, H. virgata var. leptocephala Østrup and H. weyprechtii Grunow, including six unconfirmed species. Eleven Hantzschia species are reported as new to Korea. Hantzschia virgata, its infraspecies, and neighboring speceis showed large morphological variations within a single species or among the closely related species. Hantzschia amphioxys, H. distinctepunctata, and H. virgata var. leptocephala prefer freshwater habitats in the upper reaches of the river, while others occurred mainly in the sand flats composed of coarse sand in the intertidal area. In the estuarine sediments, the Hantzschia taxa are classified to be typical sand-attached forms.

• Korean Journal of Ecology and Environment
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• v.50 no.2
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• pp.216-237
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• 2017

Thermal effluent of the hot spring has long been a field of interest in the relationship between temperature gradient and freshwater algae in geology, limnology and aquatic ecology throughout the world. On the other hand, many artificial hot springs have been developed in Korea, but the research on them has not been still active. This study was performed every month from December 2015 to September 2016, to elucidate the spatiotemporal effects of thermal wastewater effluent (TWE) on the ecosystem of benthic algal assemblage in four stations(BSU (upstream), HSW (hot spring wastewater outlet), BSD1~2 (downstream)) of the upstream reach of the Buso Stream, a tributary located in the Hantan River basin. During the survey, the influencing distance of temperature on TWE was <1.0 km, and it was the main source of N P nutrients at the same time. The effects of TWE were dominant at low temperature and dry season (December~March), but it was weak at high temperature and wet season (July~September), reflecting some seasonal characteristics. Under these circumstances, the attached algal communities were identified to 59 genera and 143 species. Of these, the major phylum included 21 genera 83 species of diatoms(58.0%), 9 genera 21 species of blue-green algae (14.7%) and 25 genera 32 species of green algae (22.4%), respectively. The spatiotemporal distribution of them was closely related to water temperature ($5^{\circ}C$ and $15^{\circ}C$) and current ($0.2m\;s^{-1}$ and $0.8m\;s^{-1}$). In the basic environment maintaining a high water temperature throughout the year round, the flora favoring high affinity to $PO_4$ in the water body or preferring stream habitat of abundant $NO_3-PO_4$ was dominant. As a result, when compared with the outcomes of previous algal ecology studies conducted in Korea, the Buso Stream was evaluated as a serious polluted state due to persistent excess nutrient supply and high thermal pollution throughout the year round by TWE. It can be regarded as a dynamic ecosystem in which homogeneity (Summer~Autumn) and heterogeneity (Winter~Spring) are repeated between upstream and downstream.