• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.789-797
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• 2015

The concentrations of trace metals (As, Cd, Cr, Cu, Fe, Hg, Mn, Pb, and Zn) were determined in 49 surface sediment samples collected in Yeoja and Gangjin Bays on the south coast of Korea, which contain many shellfish farms, in order to assess the contamination level and to understand the spatial distribution of trace metals. The average metal concentrations in the surface sediments of both bays decreased in the order Fe > Mn > Zn > Cr > Pb > Cu > As > Cd > Hg. There were no differences in metal concentrations between shellfish farms and reference sites. The metal concentrations were significantly higher in Gangjin Bay than in Yeoja Bay. Notably, the Cu, Cd, and Hg concentrations were nearly twice as high in Gangjin Bay as in Yeoja Bay. A multivariate analysis showed a strong correlation among Fe, Mn, Zn, Pb, and Cr in the sediments of both bays, implying that the metal concentrations in the sediments in the study area were mainly dependent on natural processes, such as crustal components and diagenesis. Based on the geoaccumulation index and marine sediment quality guidelines (SQGs), the surface sediments in Yeoja and Gangjin Bays are not polluted by trace metals.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.4
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• pp.437-444
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• 2013

Eight fecal sterols were analyzed in surface sediments collected from shellfish farming areas in Yeoja Bay and Gangjin Bay, Korea, to evaluate sewage-derived fecal pollution. The concentrations of coprostanol, a good marker of sewage-derived organic contamination, in sediments were in the range of 10-530 ng/g-dry in Yeoja Bay, and 10-190 ng/g-dry in Gangjin Bay. Coprostanol levels were markedly higher in the inner bay than in the outer bay. These levels were lower than those reported in urbanized bays in Korea, however, they were comparable to levels in other shellfish farming areas including Gamak Bay. A multivariate analysis of the ratios of other sterols suggested that the sterols originated from sewage and plankton/benthos. Sewage was the dominant source at stations located close to the river mouth and wastewater treatment plant (WWTP) outfalls, and plankton/benthos was the primary source in the outer bay. These results suggest that management of point sources, e.g., WWTP as well as non-point sources, e.g., riverine inputs is important for improving the water quality in Yeoja Bay and Gangjin Bay.

• Journal of Wetlands Research
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• v.12 no.3
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• pp.107-127
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• 2010

This research is about the monitoring of people's consciousness on ecosystem change after coastal restoration project in Gangjin Bay. Tidal flat ecosystem of Ganjin Bay was major producing district of short-necked clam in Jeonnam Province. Owing to coastal restoration project (sand gathering and dredging) during 5 years, however, ecosystem was disturbed and harvesting of fish was decreased. Although a few of ark shell and oyster are harvested but drastically decreased. Even aging and depopulation is general situation like other rural regions, life pattern of villages and depopulation in Gangjin Bay was influenced by drastic decreasing of income. As the results of social monitoring, drastic decreasing of fish and shell in Gangjin Bay is significantly concerned with coastal restoration project (sand gathering and dredging) and also with difficulty of fresh-water inflow to coastal bay because of Jangheung Dam. In order to get the detail information on the cause and consequence of ecosystem change in tidal flat, it is necessary to apply the long-term socio-economic monitoring as well as biological and ecosystem monitoring.

• Korean Journal of Environmental Biology
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• v.20 no.1
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• pp.46-54
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• 2002

We observed zooplankton community to understand variations in the species composition and abundance in Gangjin Bay. Samples were collected bimonthly from February to November 1999 at 10 stations in Gangjin Bay of the southern part of Korea. Zooplankton communities consisted to nine taxa and mean biomass was 2,028 indiv. $m^{-3}$. The maximum abundance was observed to be 5,496 indiv. $m^{-3}$ in February and the minimum in November, 78 indiv. $m^{-3}$. Copepods dominated and most diverse in Gangjin Bay. Seasonal fluctuation in the copepod abundance varied between 42 and 4,159 indiv. $m^{-3}$. Dominant species are Acartia omorii, Centrophages abdominalis, Paracalanus indicus and A. steueri. Cladoceran also dominated and the maximum abundance was 765 indiv. $m^{-3}$ in April. A. omorii and Oithona davisae dominated in February, A. omorii, Eurytemora pacifica, Evadne nordmanni and Podon polyphemoides in April, Tortanus dextrilobatus and decapod nauplius in June, Paracalanus indicus, E. tergestina and Penitia avirostris in August and A. erythraea and P. indicus in October. In November, P. indicus and Sagitta crassa dominated.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.521-527
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• 1999

To investigate the variations of environmental and microbial populations in six stations at water region of Gangjin Bay, nutritive salts, water temperature, COD, DO, pH, heterotrophic bacteria, fungi and facal coliform bacteria were analysed four imes from February to November, 1998. These data were subjected to simple statistics, correlation analysis and principal factor analysis. Ecosystem of Gangiin Bay was regulated by 2∼4 factors during four seasons. We estimated that it was mainly influenced by inflow of fresh water, nutrient salts, suspended solids, salinity and variation of water temperature. These results suggested that influences of environmental factor of Gangiin Bay was relatively less than those of other bays.

• Korean Journal of Microbiology
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• v.36 no.4
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• pp.285-291
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• 2000

To investigate the variations of physicochemical factors and microbial populations in seven stations at water region of Gangjin bay, nutritive salts, water temperature, transparency, suspended solid, salinity, COD, DO, pH, heterotrophic bacteria, fungi and fecal coliform were analysed four times from February to October, 1999. Total fecal coliform and heterotrophic bacterial population during investigation periods ranged 16.1~166.0 CFU/ml and $5.0{\times}10^3$~$13.1{\times}10^3$CFU/ml, respectively. Stational mean values of these bacterial population showed higher densities at the inlet of fresh water inflow than those of other stations. When the aspects of abiotic and biotic parameters measured were analyzed, ecosystem of Gangjin bay was regulated by factors such as inflow of fresh water, nutrient salts, salinity and variation of water temperature during four seasons.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.4
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• pp.424-436
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• 2013

Organic enrichment was investigated in surface sediments from the Yeoja and Gangjin Bays of Korea, which contain dense shellfish farms, in order to evaluate the contamination status and temporal changes in shellfish farming along these coasts. The degree of organic enrichment was determined using geochemical indicators (chemical oxygen demand, ignition loss, acid volatile sulfide, total organic carbon in sediments, and total nitrogen in sediments, ammonium and nitrate in pore water, and bioluminescence inhabitation for sediments). Temporal changes in organic enrichment conditions were detected by comparing our 2012 data to those previously reported from a survey conducted in 1999/2000. Organic enrichment was significantly higher in September than in May and July, in Gangjin Bay than in Yeoja Bay, and significantly higher in shellfish farms than in reference sites not used to culture shellfish. Ammonium concentrations in pore water were two orders of magnitude greater than nitrate concentrations, suggesting that these bays represent nitrogen-reducing environments.

• The Korean Journal of Malacology
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• v.23 no.2
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• pp.165-172
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• 2007

Gonadal development, reproductive cycle and sex ratio of the purplish Washington clam, Saxidomus purpuratus were investigated monthly by histological observations. Samples were collected from May 2006 to April 2007 in the Gangjin Bay of Namhea, Gyeongsangnam-do, Korea. The clams are dioecious. The gonads consist of a number of oogenic follicle and acinus. Monthly changes in the gonad index reached a maximum in April and a minimum in July. Monthly changes in the condition index reached a maximum in June and a minimum in November. The reproductive cycle of this species can be divided into five successive stages: the recovery and resting stage (June to December), early active stage (January to April), late active stage (February to July), ripe stage (March to October), spent stage (April to October). The main spawning of the clam occurred in July and September in Gangjin Bay. The sex ratio of female to male was not significantly different from 1:1.

• Korean Journal of Environmental Biology
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• v.20 no.2
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• pp.146-151
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• 2002

The primary productivity and physicochemical factors were surveyed seasonally in Gangjin bay from February to October in 1998. The determination of the Primary Productivity Was performed in Situ by isotope-method using NaH/sup 14/CO/sub 3/. The range of primary productivity was 2.78 mgC m/sup -3/ hr/sup -1/-4.92 mgC m/sup -3/ hr/sup -1/ according to seasons. The primary productivity showed the highest value in summer, followed by those of winter, autumn and spring. The primary productivities of station 1, 2 which are located the upper area, were lower than those of station 3, 4, 5 and 6. The correlations showed that the primary productivity correlated with chlorophyll a, underwater light intensity but reversely correlated with suspended solids. These results suggested that the primary productivity in Gangjin Bay was mainly influenced by the inflow of freshwater from Tamjin River.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.20-31
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• 2024

This study was conducted to investigate the changes in the structure of benthic communities resulting from aquaculture activities and to assess the benthic health status of surface sediment in Gangjin Bay, a region known for concentrated shellfish aquaculture on the southern coast of Korea. Survey stations were divided into longline culture, bottom culture, and non-cultivation areas. The spatiotemporal distribution of physiochemical factors such as the grain size, water temperature, salinity, and total organic carbon in Gangjin Bay showed no significant differences between sampling stations. However, the species number, density, and diversity were relatively lower at the sampling stations in the bottom culture areas than at the other stations throughout the entire survey period. Cluster analysis and principal coordinates analysis also clearly distinguished the benthic communities in the bottom culture areas from those in the other sampling areas. At the sampling stations in the longline culture and non-cultivation areas, Scolectoma longifolia and Sigambra tentaculata, which are indicator species of organically enriched areas, appeared as dominant species. However, excluding some stations influenced by physical factors such as the water depth and current speed, the occupancy rate was not high. The health assessment results, conducted using the fisheries environment assessment method, revealed good conditions with Grades 1 and 2 across the entire area. However, an examination of the spatiotemporal changes in benthic communities and the benthic health index indicated that the benthic environment in the bottom culture areas was affected by physical disturbances.