• Korean Journal of Environmental Agriculture
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• v.22 no.1
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• pp.16-25
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• 2003

Manun Reservoir, located in Andong district has the capacity of 2 million tons in irrigation water supply with the drainage area of $23.8\;km^2$. Manun Reservoir is over fifty year old, and shallow in depth. The ratio of drainage area (DA) to reservoir surface area (SA) as an effective physical parameter on water quality was 56.1 and was higher than those of other agricultural reservoirs. The ratio of reservoir storage (ST) to SA in Manun Reservoir was 4.79, and the mean depth was below 8m. Both ratios of DS/SA, total area (TA)/ST and ST/SA in Manun Reservoir were relatively higher than those in other agricultural reservoir and natural lakes in Korea. These physical parameters in Manun Reservoir, however, had a eutropic potential significance. Average of COD, IN, and TP in Manun Reservoir were 11.1 mg/L 1.426 mg/L, 0.093 mg/L, respectively. In the inflow stream of Manun Reservoir, the TN ($1.426{\sim}3.809\;mg/L$) was higher than those in reservoir. Only Lyngbya spp. was dominant in phytoplankton for this study period and Gymnodinium spp., Peridinium spp., and Cryptomonas spp. were dominant in zooplankton. According to the Carlson's trophic status index, Mnnun Reservoir was eutrophic in 1996, 1997, and 1999, and hypertrophic in 1998.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.279-289
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• 2000

The objective of this study was to investigate the effect of coagulants and solid-liquid separation methods on algal removal in water treatment processes. Thus characterization of raw water quality in terms of turbidity. UV-254, $KMnO_4$ consumption, chlorophyll-a and correlation analysis of these parameters were conducted. In addition, the effect of commercial Al-based coagulants(Alum. PAC and PACS) on algal removal was studied by turbidity and organic removal, algal species removal, characteristic of pH drop and alkalinity consumption using laboratory jar tests. Organic components including UV-254, $KMnO_4$ consumption, chlorophyll-a in case of algal bloom were highly correlated with turbidity and the correlation coefficients of UV-254, $KMnO_4$ consumption, chlorophyll-a with turbidity were 0.775, 0674 and 0.623, respectively. In coagulation and sedimentation, the Al-based coagulants showed similar efficiency of organic and turbidity removal in low organic($KMnO_4$ consumption below 15mg/l) and low turbidity(below 30NTU). However, PAC and PACS showed better algal removal than alum in high organic concentration($KMnO_4$ consumption above 20mg/l) and high turbidity(above 100NTU) raw water conditions generated by high algal growth, which is considered to be due to the floc settleability. In comparison of sedimentation and flotation after chemical coagulation and flocculation, the removal efficiency of organic and turbidity were higher in case of alum dose with flotation than with sedimentation, while those were better in case or PAC and PACS with sedimentation than with flotation. Thus, Alum with flotation and PAC and PACS with sedimentation is recommended for efficient algal removal. The dominant phytoplankton in raw water were Microcystic and pediastrum simplex and the removal efficiency of algae with sedimentation using alum. PAC and PACS were 27%, 45% and 22% respectively, while those with DAF showed 100% removal of phytoplankton and zooplankton.

• Korean Journal of Environmental Biology
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• v.22
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• pp.1-10
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• 2004

We conducted three experiments to estimate the toxicity of POPs (persistent organic pollutants) on two copepod species (Acartia erythraea and A. omorii) and Artemia sp.; (1) 48 h-LC$_{50}$ of A. omorii with the five PAHs [polycyelic aromatic hydrocarbons anthracene, benzo〔a〕pyrene, fluoranthene, phenanthrene, pyrene〕 which were often detected in the Gwangyang Bay, (2) toxicity of benzo〔a〕pyrene and TBT on Artemia in different temperatures (1$0^{\circ}C$, 15$^{\circ}C$, 2$0^{\circ}C$), (3) effects of benzo〔a〕pyrene and TBT on egg Production rate, hatching rate and fecal Pellet Production of two copepod species (A. erythraea and A. omorii) fed on Heterocapsa triquetra (dinoflagellate) exposed in benzo〔a〕pyrene. Toxic chemicals which were most effective to A. omorii were flueranthene (48 h-LC$_{50}$ 19.20 $\mu\textrm{g}$ L$^{-1}$ ) and benzo〔a〕pyrene (48 h-LC$_{50}$ 29.89 $\mu\textrm{g}$ L$^{-1}$ ). The toxi- city of chemicals to Artemia increased when temperature increased. The toxicity of TBT was about 100 times higher than that of benzo〔a〕pyrene at 15$^{\circ}C$. Food materials (Heterocapsa triquetra) exposed in benzo〔a〕pyrene, affected negatively the rate of egg production, hatching rate and the fecal pellet production of the copepods at the high concentration. It is suggested that an increase in the concentration of benzo〔a〕pyrene might offset the production of copepods in marine ecosystems. This study suggests that copepods may be used as n indicator for early warning of the risk of POPs in marine ecosystems.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.2
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• pp.109-119
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• 2006

This study investigated the effect of artificially enhanced mesozooplankton on the phytoplankton dynamics during fall blooming period using a mesocosm in Jangmok bay located in the Southern Sea of Korea in 2001. The four bags with 2,500 liter seawater containment were directly filled with the ambient water. And then, abundances of mesozooplankton in two experimental bags were treated 6 times higher than those in control bags by towing with net($300{\mu}m$) through the ambient water. Phytoplankton community between control and experimental bags were not significantly different in terms of chlorophyll-a(chl-a) concentration and standing crop (one-way ANOVA, p>0.05) during the study period. Initial high standing crop and chl-a concentration of phytoplankton drastically decreased and remained low until the end of the experiment in all bags. Diatoms, accounting for most of the phytoplankton community, consisted of Skeletonema costatum, Pseudo-nitzschia seriata, Chaetoceros curvisetus, Ch. debilis, Cerataulina pelagica, Thalassiosira pacifica, Cylindrotheca closterium, and Leptocylindrus danicus. Noctiluca scintillans dominated the temporal variation of mesozooplankton abundances, which peaked on Day 10 in the control and experimental bags, while the next dominant copepods showed their peak on Day 7. Shortly after mesozooplankton addition, copepod abundance in the experimental bags was obviously higher than that in the control bags on Day 1, however, it became similar to that in the control bags during the remnant period. It was supported by the higher abundance and length of both ctenophores and hydromedusae in experimental bags relative to the control bags. However, the cascading trophic effect, commonly leading to re-increase of phytoplankton abundance, was not found in the experimental bags, indicating that copepods were not able to control the phytoplankton in the bags based on the low grazing rate of Acartia erythraea. Besides that, rapidly sunken diatoms in the absence of natural turbulence as well as N-limited condition likely contributed the no occurrence of re-increased phytoplankton in the experimental bags.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.750-763
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• 2018

This study conducted 10 sampling sites survey 4 times to determine the trophic structure and energy flow of marine ecosystems for Uljin marine ranching area, Korean East Sea from March to October 2013. Based on the ecological characteristics of biological species, one used the non-Metric Multidimensional Scaling method based on the similarity of species. A total of 19 classified species groups formed categories including, top predators, seabirds, large pelagic fishes, small pelagic fishes, rockfishes, pleuronectiformes, benthic fishes, semi-benthic fishes, cephalopods, benthic feeders, epifauna, bivalves, abalone, Cnidaria, zooplankton, benthic algae, microalgae, phytoplankton and detritus. The biomass, production/biomass, consumption/biomass, diet composition data of each species groups to input data used in Ecopath mode estimated the trophic structure and energy flow of marine ecosystems in the Uljin marine ranching area. One estimated each species groups on the trophic level from 1 to 5.687. The sum of all consumption was estimated at $229.7t/km^2/yr$ and the sum of all exports was as estimated $3,432.4t/km^2/yr$. Total system throughput was at $6,796.2t/km^2/yr$, and the sum of all production was estimated at $3,613.1t/km^2/yr$. Net system production according to these results was estimated at $3,490.3t/km^2/yr$ and total biomass (excluding detritus) was estimated at $167.3t/km^2/yr$ in the Uljin marine ranching area.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.4
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• pp.180-195
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• 2011

A balanced trophic model for Sinjido marine ecosystem was constructed using ECOPATH model and data obtained 1994 in the region. The model integrates available information on biomass and food spectrum, and analyses ecosystem properties, dynamics of the main species populations and the key trophic pathways of the system, and then compares these results with those of other marine environments. The model comprises 17 groups of benthic algae, phytoplankton, zooplankton, gastropoda, polychaeta, bivalvia, echinodermata, crustacean, cephalopoda, goby, flatfish, rays and skates, croaker, blenny, conger, flatheads, and detritus. The model shows trophic levels of 1.0~4.0 from primary producers and detritus to top predator as flathead group. The model estimates total biomass(B) of 0.1 $kgWW/m^2$, total net primary production(PP) of 1.6 $kgWW/m^2/yr$, total system throughput(TST) of 3.4 $kgWW/m^2/yr$ and TST's components of consumption 7%, exports 43%, respiratory flows 4% and flows into detritus 46%. The model also calculates PP/TR of 0.012, PP/B of 0.015, omnivory index(OI) of 0.12, Fin's cycling index(FCI) of 0.7%, Fin's mean path length(MPL) of2.11, ascendancy(A) of 4.1 $kgWW/m^2/yr$ bits, development capacity(C) of 8.2 $kgWW/m^2/yr$ bits and A/C of 51%. In particular this study focuses the analysis of mixed trophic impacts and describes the indirect impact of a groupb upon another through mediating one based on 4 types. A large proportion of total export in TST means higher exchange rate in the study region than in semi enclosed basins, which seems by strong tidal currents along the channels between islands, called Sinjido, Choyakdo and Saengildo. Among ecosystem theory and cycling indices, B, TST, PP/TR, FCI, MPL and OI are shown low, indicating the system is not fully mature according to Odum's theory. Additionally, high A/C reveals the maximum capacity of the region is small. To sum up, the study region has high exports of trophic flow and low capacity to develop, and reaches a development stage in the moment. This is a pilot research applied to the Sinjido in terms of trophic flow and food web system such that it may be helpful for comparison and management of the ecosystem in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.4
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• pp.527-536
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• 1996

The patterns of diel horizontal migration (DHM) of 7 copepod species are compared as part of a general investigation of the zooplankton adaptations to the surf zone habitats. In a sandy shore surf zone of Yongil Bay, 3 sites such as the bottom and surface of 1 m water depth and water's edge are sampled with a sledge net(n=108). The surf zone copepod assemblage is dominated by 7 species; Acartia hudsonica, Fseudodiaptomus marinus, Paracalanus indicus, Calanus sinicus, Oithona similis, Sinocalanus tenellus and Labidocera bipinnata. Threefold variations in copepod abundance are observed within a diel cycle. Abundances of 7 dominant species and total copepods captured in the surface exhibit significant diel differences, but those taken in the bottom are not significantly affected by diel period. It is shown that about $90\%$ of the surf zone copepods performed DHM. The nocturnal high densities of copepods occurred for a neap tide when the offshore winds prevailed, suggesting the animals' ability for horizontal orientation and an active locomotion without invoking passive transportation by currents. Photoreactive behavior of copepods triggered by relative changes in light intensity may be a primary factor inducing DHM by aggregating in the surf zone during the night and spreading out at day; then copepods may reduce encounters with visual predators. In A. hudsonica, ontogenetic variations in timings of DHM are evident. Such variations are likely to minimize intraspecific competition for diets. Data on shoreward migration of copepods indicate that A. hudsonica, P. indicus, O. similis and S. tenellus can maintain swimming velocities of about $20m\;h^{-1}$ for durations of more than an hour. Our observations of strong diel difference in abundances point out the need for both day and night samplings in surf zone habitats, if the importance of these habitats to planktonic copepods are to be fully understood.

• 한국해양학회지
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• v.14 no.1
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• pp.15-25
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• 1979

A study on field bioassay test using four species of commercially important shellfish was carried out to assess the effect of pollutants and determine the extent of marine environmental pollution of the Masan Bay from 9 to 15 August 1978. Water quality analysis and planktological examination of sea water were made during the experiment and the examination gave the following results. The water temperature was so high at 31.7$^{\circ}C$ in maximum and rather subject to change on weather condition of the land than on the effect of the water mass from outer bay. The range of DO,COD and SS at the stations were 0.3-7.08cc/l, 0.07-3.31ppm and 5.5-117ppm, respectively with the high values of COD and SS at the stations 7 and 1. The concentrations of the dissolved inorganic nitrogen in sea water, NH$\sub$4/-N, NO$\sub$2/-N, NO$\sub$3/-N, and PO$\sub$4/-P were 18.90-99.80, 2.48- 19.60, 13.00-39.00 and 1.04-14.0$\mu\textrm{g}$ at/l, respectively with decrease of their values in the outer part of the Bay. The high values mentioned above were caused by the sewage and industrial activities. The effects of organic waste are increased oxygen demand, nutrient concentration, turbidity and a higher input of pathogens, leading to structural changes in the marine ecosystems and to a considerable hazard to public health. The percentage composition of phytoplankton standing crop between diatom and dinoflagellate was characterized by making a difference between the two groups in respect of location: a decrease of diatom and a increase of dinoflagellate in numerical abundance toward inner part from outer part of the bay. Namely phytoplankton organisms were composed of 80% of diatom and 20% of dinoflagellate in outer bay, on the contrary, only 4% of diatom and 96% of dinoflagellate occupied by 94% of prorocentrum micans known as tolerant species to polluted reaas in the inner bay. On the occurrence and composition of zooplankton, there are two significant communities in the bay:one is characterized by the predominance of Oithona nana and the other by Favella sp They were composed of a range from 84% to 90% of the total organisms and monotonously constituted of themselves only at most inner station 3 even small numbers. From the results mentioned above, Oithona nana, Favella and prorocentrum micans recommed themselves as valuable indicators for judging the extent of the marine pollution.During the period of the biossays Mytilus edulis showed the highest mortality and Tapes japonica the lowest one between the four test species. The highest death rate by stations was found at most inner stations 3'and 4near Masan Free Export Zone with the most sensitive response and the lowest one occured at outer station 13 where no death specimen of oyster and arkshell was found during the whole test period.As for mussel,85 percent death rate appeared after 72 hours and 100percent rate after 120hours at station 4. It was found that the significant high mortality of the test shellfish mentioned above was caused by severe pollution with mainly organic pollutants from domestic sewage and industrial wastes from the results of too much higher concentrations of dissolved inorganic nitrogen especially ammonia-N,COD,SS and lack of dissolved oxygen,and furthermore occurrence and abundance composition of Prorcentrum,Favella and Oithona nana by stations, valuable indicator species of coastal pollution by orgnic and boilogical pollutants.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.404-417
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• 2017

In this study, we analyzed response patterns of rotifer community to eutrophic state, and estimated the applicability of rotifer community as an environmental indicator for highly eutrophicated reservoirs. In order to evaluate the relationships among spatial and temporal distributions and the water quality of rotifer community, we selected the Jundae Reservoir and Chodae Reservoir in Chungcheongnam-do, Korea, which are geographically adjacent but have different water quality, particularly in their eutrophic states. For the analyses on their correlations, monthly survey of water quality and rotifer community, was conducted from April to November 2013 in both reservoirs. The rotifer community was divided into different compositions of functional groups as well as species. Functional groups were classified according to the structure and shape of trophi which can represent feeding behavior of rotifer genus. To reflect ecological characteristics of species, body size and habitat preferences were also considered. Species-based composition did not show a consistent tendency with water quality parameters related with eutrophication. On the contrary, functional group composition showed relatively clear group-specific patterns, increasing or decreasing according to the parameters. The results suggest the possible application of rotifer functional group composition as an indicatorforthe lentic systems, especially hyper-eutrophicated reservoirs. The present study can suggest the applicability based on the field observations from the limited time scale and sites, and further studies on feeding behavior of the rotifer functional group and its interactions with environmental variables are necessary for the further application.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.174-187
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• 2008

In an effort to identify structure and function of microbial loop in Paldang reservoir, we monitored environmental and biological factors at Kyungan stream (station K), Paldang dam (station P) and the confluence of North and South Han River (station M) from March to December, 2005. DOC concentration was higher in March to May and November than the others. Nutrient concentration in station K detected relatively higher than that of two stations. Both of phosphate and silicate gradually increased at all stations until September, after then decreased. The highest Chl-$\alpha$ concentration was observed at all stations in April, and November. The carbon biomass of bacteria and HNF were relatively higher in March, May and August than the others, whereas that of the ciliate showed no significant difference in monthly fluctuation. Nevertheless, the significant relationships revealed between ciliate (P<0.001) and HNF (P<0.05) and bacterial density. Tintinnopsis cratera, Didinium sp., Vorticella sp., Paramecium sp. and Strombidium sp. were dominant species in ciliate community. The dominant species of phytoplankton were Stephanodiscus hantzschii and Cyclotella meneghiniana at almost stations in Spring, Summer and Autumn. However, Aulacoseira granulata accounted for >95% of phytoplankton biomass at station P and M in Autumn. The carbon biomass of zooplankton was highest at station P and M in June, and relatively higher biomass observed at all stations in August, October and November. Diaphanosoma brachyurum and Bosmina longirostris were dominant in stations P and M of June and in all stations of October and November, respectively. The maximum growth (A. granulata: $0.17\;d^{-1}$, S. hantzschii: $0.14\;d^{-1}$) and grazing rate (A. granulata: 1.93 preys $d^{-1}$, S. hantzschii: 1.63 preys $d^{-1}$) of Bosmina longirostris revealed in algal preys as Aulacoseira granulata and Stephanodiscus hantzschii. In conclusion, these results suggest that bacteria and phytoplankton can play the most crucial source as prey within microbial food chain in Spring and Summer and grazing food chain in Autumn, respectively.