• Korean Journal of Ecology and Environment
• /
• v.42 no.3
• /
• pp.404-406
• /
• 2009

This study note wished to introduce special-purpose ship for algae removal that is developed by core technology of our country. The ship is consisted of main frame and adjuvant that can attach and detach as cross (+) shape of a character. The characteristics of ship are super light weight and low draft. That is consisted of four devices as suction, collection, filtration and recovering units. Among these, filtration used screen filter (mesh size 30 ${\mu}m$). Also, can separate and remove water and algae by compression air participle notion. Percentage of moisture content of concentrated algal particle was 85%. Water parted with algae finally is exhausted to water area. Removal efficiency that compare by chlorophyll-$\alpha$ concentration was about 57% (inflow: 83.2 ${\mu}g\;L^{-1}$, outflow: 35.8 $[\mu}g\;L^{-1}$) without physical and chemical pretreatment. Forward, need to achieve effect test in various conditions (algal biomass, flow etc.) for efficiency and technological elevation of exclusion device. We wished to contribute in presuppression system construction of massive algal development that manage blue-green algae occurrence area effectively, and prevents spread as lower part of reservoir.

• Korean Journal of Ecology and Environment
• /
• v.49 no.4
• /
• pp.258-270
• /
• 2016

This study was conducted to test the green-tide mitigation technique in the lower part of the Sook Stream (Chusori) of Daecheong Reservoir from June 27 to August 24, 2014. And the effects were compared with weekly monitoring result of the watching station of the algae alert system (AAS) as well as test beds reach. The green-tide in a test bed was begun from the upstream, and it was gradually transferred and spread toward the downstream by the hydrological factors. The total amount of algae removed by algae removal device during the test period was 33,920 kg, and solids dewatered by natural gravity was 8,480 kg. Also chlorophyll-a content was 2.83 kg, the number of blue-green algae cells was equivalent to $78.6{\times}10^{14}$ cells. Compared with the results of the watching station of AAS, the pre-concentrate removal work in the outbreak waters was able to suggest the possibility of green-tide mitigation. In addition, an effective management of the green-tide was required spatial and temporal occurrence information and practical device technology. Particularly, the optimal timing of algae removal in the river-reservoir hybrid system was recommended at times before the monsoon rainy season and reached the lowest water level.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.2
• /
• pp.212-219
• /
• 2019

This study was conducted to investigate marine algal community characteristics and the status of barren ground in the summer at study sites on Jeju Island, Korea. Sampling was carried out from July to September 2017 using a qualitative and quantitative survey (including coverage of non-geniculated coralline algae and density of grazer) by scuba diving. A total of 121 species were identified, including 11 (9.1 %) green algae, 24 (19.8 %) brown algae, and 86 (71.1 %) red algae. Hyeongjeseom had the greatest diversity, with 60 species, and Harye the least, with 18 species. The mean biomass at the study sites was $1,503.0g{\cdot}m^{-2}$, while the mean for the neighboring islets ($3,268.7g{\cdot}m^{-2}$) was higher than that of the main island ($914.7g{\cdot}m^{-2}$). Also, dominant species was identified: Sargassum macrocarpum at the neighboring islets, and Ecklonia cava at the main island, with differences showing not only in biomass but also species composition. In conclusion, the marine algal community status in summer at the study sites was evaluated based on the algal community characteristics (species composition, biomass, biomass ratio of kelp species), coverage of non-geniculated coralline algae, and density of grazer. As a result, both Hyeongjeseom and Marado require preservation and management to maintain their excellent marine algal communities, and other sites on the main island require the creation and/or restoration of marine algal communities. In addition, as the generation of barren ground accelerates, it is urgent not only to grasp existing monitoring research but also to identify the status of the marine algal community where it is not known at present.

• Journal of Environmental Impact Assessment
• /
• v.24 no.3
• /
• pp.278-286
• /
• 2015

Pilot scale system was designed to identify the growth and movement of algae, depending on environmental changes(retention time, nutrient concentration, etc) in Gangjeong-Goryeong Weir of the Nakdong River. Considering the stability of algal culture and easy observation of algal growth, pilot scale system was made of transparent acrylic material(3 sets of flexible cylindrical water tanks with 1 m diameter and 4 m height). Auxiliary equipments include light intercepter, water inflow device for different water depth and storage of reclaimed water. The retention time was 2 days(before construction of weir; treatment 1), 8 days(after construction of weir, 2013; treatment 2) and 30 days(2014; treatment 3). According to the water temperature of treatment 1 were similar by depth, treatment 3 showed a difference between the surface(0 m) and bottom(4 m) more than $3^{\circ}C$. DO, pH showed relatively high in the surface than the bottom. Nutrients showed eutrophic condition in all experiments. The Chlrophyll-a concentration of the treatment 1 showed a relatively lower value than the Chlrophyll-a concentration of the treatment 2 and 3. Therefore, the retention time was considered to influence the growth of phytoplankton.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.6
• /
• pp.738-749
• /
• 2016

To understand the characteristics of the spatio-temporal distribution of phytoplankton after barrage construction in the Nakdong River Estuary, this study investigated relevant environmental parameters and phytoplankton status based on bi-monthly samples collected from the Nakdong River Estuary itself from February 2013 to December 2015. Environmental parameters did not differ significantly across these years but did vary between zones and seasons. The results suggested that the upper zone was dominated by fresh-water diatoms, green algae, and blue-green algae, whereas the lower zone was mostly dominated by dinoflagellates. The presence of Stephanodiscus spp., Asterionellopsis formosa, and Microcystis spp. in the upper zone was related to the inflow of freshwater discharge by artificial control of dyke gates. The dominant phytoplankton species in this zone were dependent on temperature, wind speed, DIP, and DIN, while those in the lower zone were mostly dependent on nutrients and wind speed. In addition, at the lower zone, there were negative correlations between Prorocentrum donghaiense, DIN, and wind speed, with its abundance being higher during the summer than other seasons. Analysis of temporal variations did not indicate any significant differences in the upper zone but did reveal variations among seasons at the lower zone. Except in 2014, the lower zone could be divided into periods dominated by diatoms (October-April) and dinoflagellates (June-August). These results suggest that the characteristics of the phytoplankton community were influenced by changes in the inflow of freshwater species and nutrients given the difference in the range affected by freshwater discharge.

• Korean Journal of Environmental Biology
• /
• v.22 no.1
• /
• pp.1-11
• /
• 2004

Ecological methods were reviewed through reports such as environmental impact assessment and damage effect of fishery in the Korean watershed. Survey items in marine ecological field were included: phytoplankton, zooplankton, benthic animal, algae, adult fish, egg and juvenile of fish. A standardization of survey method in the field of community ecology was suggested to consider the convenience, Sequency in Use of device, accuracy of data collected from that. It is necessary that spatial data should be sufficiently acquired toy statistical analysis of biodiversity and spatial comparison. Quantitative sampling method must be inevitably adopted based nature of biota and geographical type of the survey area. The same sampling method can make the data compared spatially but can't be applicable in all area. Standardizing survey method should be by no means under certain restriction of study and would become different according to survey environments. The first thing is minutely understanding about ecological character of biota inhabiting in certain area, and then determining survey method.

• Mycobiology
• /
• v.47 no.3
• /
• pp.261-272
• /
• 2019

Oomycetes are widely distributed in various environments, including desert and polar regions. Depending upon different habits and hosts, they have evolved with both saprophytic and pathogenic nutritional modes. Freshwater ecosystem is one of the most important habitats for members of oomycetes. Most studies on oomycete diversity, however, have been biased mostly towards terrestrial phytopathogenic species, rather than aquatic species, although their roles as saprophytes and parasites are essential for freshwater ecosystems. In this study, we isolated oomycete strains from soil sediment, algae, and decaying plant debris in freshwater streams of Korea. The strains were identified based on cultural and morphological characteristics, as well as molecular phylogenetic analyses of ITS rDNA, cox1, and cox2 mtDNA sequences. As a result, we discovered eight oomycete species previously unknown in Korea, namely Phytopythium chamaehyphon, Phytopythium litorale, Phytopythium vexans, Pythium diclinum, Pythium heterothallicum, Pythium inflatum, Pythium intermedium, and Pythium oopapillum. Diversity and ecology of freshwater oomycetes in Korea are poorly understood. This study could contribute to understand their distribution and ecological function in freshwater ecosystem.

• Korean Journal of Ecology and Environment
• /
• v.38 no.2 s.112
• /
• pp.217-224
• /
• 2005

This study was aimed to analyze the long-term fluctuation of water quality and phytoplankton dynamics of Paldang reservoir in Korea and to assess the relationship between algal bloom patterns and hydrological, limnological data. Diatoms in Paldang reservoir occurred continuously through the year. Blue- green algae occurred during the summer season (from June to Sept.), and the highest count was observed in July. Occurrence pattern of green algae was similar to that of blue-green algae. The rest of algae contained a lot of Cryptomonas spp. whose concentration was high from May to Aug. Dominant algal genera (>>7,000 cells $mL^{-1}$) in Paldang reservoir were Aulacoseira, Cyclotella, Microcystis, and Cryptomonas spp. Microcystis and Anabaena occurred during the summer season. Many different green algal genera were found in Paldang reservoir but their abundances were very low. There were some significant correlations (r>0.3, p<0.05) between algal taxa and water quality; diatoms and water temperature, TP:blue-green algae and water temperature, pH, DO saturation, COD, TP; green algae and water temperature, pH, DO saturation, COD, SS, TP. Furthermore, algal genera and water quality was significantly correlated (r>0.3, p<0.05) ; Aulacoseira and TN, TP; Anabaena and water temperature, DO saturation, COD, TP : Microcystisand water temperature, pH, DO saturation, TP; Coelastrum and COD, SS; Scenedesmus and water temperature, COD, TN, TP; Cryptomonas and DO saturation, TN. In Paldang reservoir, the water temperature had relatively big effect on blue-green algal bloom that was also dependant upon its hydrologic condition.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.57 no.3
• /
• pp.278-291
• /
• 2024

This study performed three research methods (destructive, non-destructive, and panoramic image analysis) to determine the most useful for identifying seaweed habitat characteristics. Panoramic images are suitable for understanding the overall seaweed distribution. The composition of the main dominant seaweed species showed a significant difference between the destructive and non-destructive methods using Quadrat. The destructive method showed Rhodophyta dominance, whereas the non-destructive was showed Phaeophyta as dominant. Destructive methods are disadvantageous because they destroy natural communities in sea areas where bleaching is severe. Non-destructive methods are disadvantageous because of the difficulty in analyzing small species. Performing 10 surveys using a non-destructive method was found to explain up to 80% of the species identified by the destructive method. However, considering the difficulty of field investigation, repeating the investigation with non-destructive methods at least 6-7 times is necessary to ensure that more than 60% of the destructive methods can be interpreted. To understand the distribution of oceanic marine algae, performing both destructive and non-destructive surveys are necessary, as each has its own merits and demerits.

• Journal of Ecology and Environment
• /
• v.48 no.2
• /
• pp.144-151
• /
• 2024

Background: This study focused on the diet of Clithon retropictum, level II endangered species in Korea. Since the development of brackish water zones has led to a decline in the population of this species, to obtain information on the ecology of C. retropictum required for its conservation and restoration. To investigate the actual preys of C. retropictum in south coast of Korea, we conducted high-throughput sequencing and metabarcoding techniques to extract DNA from gut contents and periphyton in their habitats. Results: Total 118 taxonomic groups were detected from periphyton samples. 116 were Chromista and Cyanobacteria dominated in the most samples. In gut contents samples, 98 taxonomic groups were detected. Similar to the results of periphyton, 96 were Chromista and Cyanobacteria dominated in the most samples. In the principal component analysis based on the presence/absence of taxonomic groups, gut content composition showed more clustered patterns corresponding to their habitats. Bryophyta was the most crucial taxonomic group explaining the difference between periphyton and gut contents compositions of C. retropictum. Conclusions: Our finding suggests that C. retropictum may not randomly consume epilithic algae but instead, likely to supplement their diet with Bryophyta.