• Environmental Engineering Research
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• v.25 no.1
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• pp.43-51
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• 2020

The present study was designed to characterize the bioaccumulation of organochlorine pesticides (OCPs) in marine organisms (zooplankton, oyster, crab, and goby) on different trophic level. In the present study, sedentary bivalve (oyster) showed strong correlations in OCPs levels with surface sediment in the study area. This indicates the two compartments can be used as alternative for pollution monitoring of OCPs even in narrow scale in space. Bioaccumulation and trophic transfer of OCPs was strongly associated with their hydrophobicity (i.e., K_OW). HCHs with log K_OW < 5 did not show any enrichment through food-chain. However, log BAF values of OCPs with log K_OW > 5 positioned over the 1:1 lines of log BAF and log K_OW of the top predator, indicating the greater fugacities in the higher trophic level and thus the occurrence of biomagnification via ingestion. Based on trophic transfer factors (TTF), more hydrophobic OCPs with log K_OW > 5 were enriched by several to several ten times in the highest trophic level relative to the lowest trophic level. This finding can be used in the establishment of marine environmental water quality criteria by considering biomagnification factors (TTF in this study) of OCPs.

• Ocean and Polar Research
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• v.38 no.2
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• pp.139-148
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• 2016

The activity concentrations of $^{210}Po$ and $^{210}Pb$ within phytoplankton-zooplankton-anchovy-mackerel in the coastal water of the Jeju Island were determined to understand their distribution and bio-accumulation along the trophic level. In the surface water, the total activity concentrations of $^{210}Po$ and $^{210}Pb$ were $0.83{\pm}0.004mBq\;kg^{-1}$ and $1.27{\pm}0.03mBq\;kg^{-1}$. And the dissolved activity concentration of $^{210}Po$ and $^{210}Pb$ were $0.75{\pm}0.06mBq\;kg^{-1}$ and $1.22{\pm}0.09mBq\;kg^{-1}$ respectively. In the phytoplankton, the concentration factor (CF) of $^{210}Po$ and $^{210}Pb$ were $1.5{\times}10^5$ and $2.6{\times}10^4$ shows $^{210}Po$ is 5 times higher compared to $^{210}Pb$. The similar CF factor in the zooplankton of $^{210}Po$ was derived as $1.4{\times}10^5$. The CF of $^{210}Po$ in anchovy was increased twice compared to that in plankton. This is the evidence that there is $^{210}Po$ bio-magnification in the trophic level of plankton-anchovy. However the $^{210}Po$ activity concentration in the muscle tissue of mackerel was one-hundred times lower than that in anchovy. This reflects that in the trophic level of anchovy-mackerel, the bio-accumulation of $^{210}Po$ is decreased. The activity concentrations of $^{210}Po$ in the internal organs of anchovy and mackerel were 8 to 38 times higher than those in muscle tissues. In phytoplankton-zooplankton-anchovy, the CF of $^{210}Pb$ was decreased five times along the trophic level in order. In anchovy-mackerel it was decreased by 30-70%.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.337-346
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• 2011

We investigated nutrient loading and trophic states in a coastal estuarine system in the Asan estuary by assessing phytoplankton biomass and using the trophic index (TRIX). The monthly and yearly nutrient loading (TN, TP) from freshwater discharge from the Asan and Sapgyo reservoirs into the estuary were estimated and analyzed with related factors. Monitoring data (physio-chemical and biological variables) collected at five estuary stations were used to assess trophic states. Descriptive statistics of total phytoplankton cells, chl a concentrations and primary productivity were also used to assess seasonal trophic status. N loading from freshwater ranged $1.0{\sim}1.3{\times}10^4$ ton yearly. The yearly P loading ranged between 350 and 400 ton during 2004~2006, increasing to 570 ton in 2007. Regression results suggest that DIN and DSi were correlated with freshwater discharge at the upper region. Based on phytoplankton biomass and total cell abundance, the trophic state of the estuary was found to be eutrophic during spring due to phytoplankton bloom. Primary productivity level was remarkably high, especially in summer coinciding with high nutrient loading. Pheopigments increased during warm seasons, i.e. summer and fall. Trophic index results indicate that the trophic state varied between mesotrophic and eutrophic in the estuary water body, especially in the upper region. The results suggest that phytoplankton production was regulated by nutrient loading from freshwater whereas biomass was affected by other properties than nutrient loading in the Asan Estuary ecosystem.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2004.05a
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• pp.42-42
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• 2004

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.57 no.2
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• pp.117-126
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• 2021

Diet composition and trophic level of Trachurus japonicus were studied using 417 specimens collected by trawls, set nets and purse seine fisheries from March 2019 to February 2020 in the South Sea of Korea. The size of T. Japonicus ranged from 7.0 to 49.8 cm in total length. T. japonicus were a carnivore that fed mainly on euphausiids and pisces. In eddition, T. japonicus fed on small quantities of cephalopods, crabs etc. T. japonicus showed ontogenetic changes in feeding habits. The proportion of euphausiids decreased inversely proportional to body size whereas the consumption of pisces gradually increased. As body size of T. japonicus increased the mean number of prey per stomach and the mean weight of prey per stomach tended to increase, but the mean number of prey per stomach was not significantly different. As a result of the feeding strategy analysis, T. japonicus were specialized feeders with pisces and euphausiids as their dominant prey. The trophic level ranged between 3.57 ± 0.54 and 3.91 ± 0.65, and increased asymptotically with size of specimens. The average trophic level of the T. japonicus was 3.79 ± 0.61.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.4
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• pp.389-401
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• 2003

The changes in structure and abundance of taxon or species groups in the East Sea ecosystem were compared between pre- and post-Climatic Regime Shift (CRS) occurred in the mid 1970s using an ECOPATH model. Although the East Sea ecosystem consisted of primary producers, primary consumers, secondary consumers and terminal consumers most species groups were classified as secondary consumers. The mean trophic level between pre- and post-CRS increased from 3.09 during the pre-CRS period to 3.28 during the post-CRS period. Total biomass of the species groups in the East Sea ecosystem increased by $9\%$ due to the CRS, and total catch increased by $48\%.$ The most significant differences between pre- and post-CRS models occurred at the mid/high trophic levels occupied by fishes and cephalopods. Relative contribution of the different species groups to the total energy flow was calculated for the trophic level III. As a result, the status by the dominant species in the East Sea ecosystem shifted from cephalopods to walleye pollock due to the CRS. Relative contribution of 5 species, which were commercially important, such as Pacific saury, Pacific sardine, filefish, walleye pollock and sandfish in trophic level III, were also changed due to the CRS. Finally, the CRS turned out to cause large variations in biomass and catch of fisheries resources as well as the status and role of the major species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.3
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• pp.184-195
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• 2005

A preliminary quantitative model of the trophic structure in Gwangyang bay, Korea was obtained using ECOPATH and data from relevant studies to date in the region. The model integrates and analyzes biomass, food spectrum, trophic interactions and the key trophic pathways of the system. The bay model comprises 9 groups of benthic primary producer, phytoplankton, zooplankton, benthos, bivalve, pelagic fish, demersal fish and piscivorous fish. The total system throughput was estimated at $2.4\;kgWW/m^2/yr$, including a consumption of $41\%$, exports of $9\%$, respiratory flows of $24\%$ and flows into detritus of $26\%$. All of which originate from primary producers measured at $52\%$ and detritus of $48\%$. The total biomass was seen to be high compared to the levels of Somme, Delaware, Chesapeake Bays and Seine Estuary. This seems to be possibly due to artificial bivalve aquaculture and overestimation of benthos and benthic primary producer groups. The deviation can be calibrated by neglecting aquaculture and decreasing the habitat area for the groups. The trophic network of the bay shows a low level of recycling and organization as indicated by Finn's cycling index $3.3\%$, Ascendancy $3.1\;kgC/m^2/yr$ bits, Capacity $5.1\;kgC/m^2/yr$ bits and Redundancy $2.2\;kgC/m^2/yr$ bits. A high relative ascendancy of $62\%$ and a low internal relative ascendancy of $18\%$ indicate the system is not fully organized and stable towards disturbances, depending upon external connections. Although the model should be continuously provided with field data and calibrated further in depth, this study is the first trophic model applied to the region. The model can be a useful tool to understand the ecosystem in a quantitative manner.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.155-171
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• 2011

The research assessed water quality using physico-chemical factors, trophic status index and attached diatom index in 10 reservoirs located in Chungcheongnam-do from October 2007 to June 2008. The physico-chemical water quality assessments revealed that Dangjin-gun (St. 1~5), which displayed a high chemical oxygen demand (V and VI) and chlorophyll-${\alpha}$ (Eutrophic-Hypereutrophic), was more polluted than Yesan and Cheongyang-gun. The sample were also hypereutrophic [trophic status index (TSI) 74.6] and ${\beta}$-mesosaprobic [diatom assemblage index to the organic water pollution (DAIpo) 44.47]. Yesan and Cheongyang-gun. Which were mid-level in their pollution status, were eutrophic (TSI 56.9) and ${\alpha}$-oligosaprobic (DAIpo 60.11). TSI correlated strongly with the attached diatom index (of DAIpo 0.60~0.62, and trophic diatom index of 0.72~0.74). Hence, the attached diatom index can be used with the trophic status assessment of lakes using TSI, and lake trophic status index (LTSI).

• Korean Journal of Ecology and Environment
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• v.49 no.3
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• pp.228-235
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• 2016

Aquatic ecosystems are receiving various harmful effects due to anthropogenic chemical pollutions. To protect wildlife, risk assessments of the chemicals are conducted using reference indexes of toxicity estimated by species-level laboratory tests and/or micro-/mesocosm community-level studies. However, the existing micro-/mesocosm communities are structurally too complicated, and it is also difficult to compare the experimental results directly with those from species-level tests. Here, we developed a procedure of a simple bi-trophic microcosm experiment which contains the common species (a green algae, Pseudokirchneriella subcapitata and a cladoceran, Daphnia magna) for testing chemical toxicities. For the proper operation of bitrophic microcosm experiment, the minimum required concentration of primary producer (P. subcapitata) is $5{\times}10^5cells\;mL^{-1}$. The microcosm system showed higher stability when the initially introduced D. magna population was composed of neonates (<24-h old) than adults and those mixture. This simple microcosm system would be an applicable tool to estimate the disturbing impacts of pollutants on plant-herbivore interactions, and linking the species- and population-/community level risk assessments in the future studies.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.3
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• pp.3-15
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• 2001

The in situ observations and the seawater analyses were conducted for 3 years from August 1996 to August 1999 in order to elucidate and evaluate seasonal variations of marine water quality and trophic state in Mokpo harbour of Korea. Compared the seasonal seawater qualities of Mokpo harbour with the OECD standards of trophic classification in parameters such as Secchi depth, dissolved inorganic nitrogen, phosphate phosphorus and chlorophyll-a, the trophic level of seawater in Mokpo harbour was evaluated to be in mesotrophic or eutrophic state through all 4 seasons and to be in eutrophic state, particularly In summer. The estimation of pollution index by eutrophication showed the seawater quality of Mokpo harbour to deteriorate and fall under the regular grades through all 4 seasons, although the seawater quality of Mokpo harbour was evaluated to be equivalent to the second or third class of the Korean seawater quality standards in view of COD values. The results of eutrophication index estimation showed the high potentiality of red tide occurrence In Mokpo harbour, particularly in summer or fall. In the light of the average atomic ratio of N/P in seawater, the limiting nutrient factor against the growth of phytoplankton was concluded to be phosphorus rather than nitrogen in Mokpo Harbour.