본 조사에서는 양식업 및 수산업에 있어서 중요한 부분을 차지하고 있는 가막만을 대상으로 수질환경 변화에 대한 이매패류의 군집구조 및 연간변동을 파악하고 물리적 화학적 환경이 이매패류 군집에 미치는 영향을 분석하고자 하였다. 가막만 해역의 12개 정점을 설정하고 2001년부터 2006년까지 4월, 7월, 9월, 11월 계절별로 조사한 결과 이매패류 총 28종이 출현하였으며, 평균 서식밀도는 226.72±196.20 ind. m-2의 변동범

가막만 소호 인근해역의 용존산소 농도에 따른 등물 플랑크톤 군집 동태를 연구하기 위해 2005년 8월 22일 부터 9월 15일까지 연구를 실시하였다. 본 연구결과 저층의 용존산소 농도가 3mgL-1 이하일 때는 동물플랑크톤 출현 개체수는 현저히 낮게 나타나거나 전혀 나타나지 않았다. 수층별 분포와 출현 개체수에 대한 저층의 저산소화 영향을 연구한 결과, 용존산소 농도는 저층으로 갈수록 낮게 나타났으며, 연구해역의 동물플랑크톤 출현 개체수는 대부

The concepts of residence time and flushing time can be used to explain the exchange and transport of water or materials in a coastal sea. The application of these transport time scales are widespread in biological, hydrological, and geochemical studies. The water quality of the system crucially depends on the residence time and flushing time of a particle in the system. In this study, the residence and flushing time in Gamak Bay were calculated using the numerical model, EFDC, which includes a particle tracking module. The average residence time was 55 days in the inner bay, and the flushing time for Gamak Bay was about 44.8 days, according to the simulation. This means that it takes about 2 months for land and aquaculture generated particles to be transported out of Gamak Bay, which can lead to substances accumulating in the bay. These results show the relationships between the transport time scale and physical the properties of the embayment. The findings of this study will improves understanding of the water and material transport processes in Gamak Bay and will be important when assessing the potential impact of coastal development on water quality conditions.

The environmental changes related to hypoxic water mass were investigated at Gamak bay in summer times, June, July and August 2006. The hypoxic water mass was found, in first, at the northern area of Gamak bay on 27 June. This water mass has been sustained until the end of August and disappear on 13 September. In Gamak bay, the hypoxic water mass was closely related to geography. During the formation of oxygen deficiency, changes in dissolved nutrients was studied and found that on surface layer and lower layer, DIN were 0.80 μM~19.8 μM(6.03 μM) and 1.13 μM～60.83 μM(10.66 μM), and DIP were 0.01 μM～0.92 μM(0.24 μM), and 0.01 μM～3.57 μM(0.49 μM), respectively, far higher distribution on lower layer of the water where hypoxic water mass was occurred. The configuration of phosphorus was analyzed to figure out the possibility of release of phosphorus from sediments. It was found that the Labile-Phosphorus, which is capable of easy move to water layer by following environmental change was found more than 70%. Therefore, in Gamak bay, it was found that the possibility of large amount of release of soluble P into the water, while hypoxic water mass was occurred in deep layer was higher. It is suggested that DIP in the northern sea of Gamak bay mainly sourced from the soluble P from lower layer of the waters where hypoxic water mass was created more than that from basin. However, existence form of phosphorus in sediments during normal times, not during creation of hypoxic water mass, needs further study.

The short-term variations of the mesozooplankton community structure were investigated in Gamak Bay during summer season, 2006. The study was based on a comprehensive survey constituting from 12 stations on June 19, July 28, August 4, and August 29, respectively. Mean of temperature and chlorophyll a concentrations in the surface layer were significantly higher than those in bottom layer, and those concentrations were significantly higher in the inner bay than those in the outer bay. A total of 40 taxa including 19 copepods were observed in Gamak Bay during summer season. Mean abundance of total mesozooplankton varied from 1,859 to 26,111 indiv. m-3. The dominant species were Noctiluca scintillans, Penilia avirostris, Evadne tergestina, Paracalanus parvus s. l., Acartia omorii and Cirriped nauplii and cyprii in Gamak Bay, and they contributed 90% of mean abundance of total mesozooplankton. Noctiluca scintillans was high after the rainfall. Cluster analysis showed that the mesozooplankton community could be divided into 4 distinct groups, indicating rapid change of the community in the short-term of this survey. The relative contribution of each group of the N. scintillans, P. avirostris, E. tergestina, and P. parvus s. l. showed differences during the phytoplankton bloom period. The mesozooplankton community compositions were highly associated with water temperature, and salinity in physical conditions, and food organisms affect short-term variations in mesozooplankton composition. Interestingly, protozoa N. scintillans, and Cladocera appeared to be one of the key organisms to extinguish the phytoplankton bloom. Therefore, this study suggests that N. scintillans, and Cladocera could be a key player to control the mesozooplankton community structure during summer season, 2006.

Chlorophyll a (chl a) has been used as an indicator for phytoplankton biomass in pelagic ecosystems due to the relative ease of measurement and selectivity for autotrophs in mixed plankton assemblages. However, the use of chl a as an indicator for phytoplankton biomass is restricted due to its inability to resolve taxonomic differences of phytoplankton and the highly variable relationship of chl a with phytoplankton. Here, we describe the analysis of High-Performance Liquid Chromatography (HPLC) photosynthetic pigment data using CHEMTAX, which is a matrix factorization program that uses chemical taxonomic indices (phytoplankton carotenoids) to quantify the abundance of phytoplankton groups. Compared to direct microscopic counting that can distinguish species within broad groups, the resolution of taxonomic groups by CHEMTAX is generally coarse. It can only distinguish between diatoms, dinoflagellates, cryptophytes, cyanobacteria, chlorophytes, prasinophytes, and haptophytes. However, CHEMTAX analysis is much faster and less expensive than microscopic counting methods. HPLC pigment observations were taken in the spring, summer, fall, and winter in 2005～2006 within Gamak Bay, South Korea. CHEMTAX results revealed that diatoms were the dominant taxonomic group in Gamak Bay. In inner Gamak Bay, the ratio between diatoms and cryptophytes was 75～80%, and the ratio between dinoflagellates and cryptophytes was 10～15%. In outer Gamak Bay, the ratio between diatoms and cryptophytes was 85～90%, and the ratio between dinflagellates and cryptophytes was only 1～5%. The population structure was seasonal. Relative diatom populations were less in the summer than the winter season.

This research was performed to simulate shellfish production systems and sales in Gamak Bay, South Korea. To study the way the shellfish system generates maxima, a numerical model was developed to simulate the model under a control and a number of different scenarios. The program calculates the EMERGY flows by multiplying the flows of energy and materials by the appropriate solar transformity. In this study, an energy systems model was built to simulate the variation of sustainability for oyster aquaculture. The results of the simulation based on 2005 data that as oyster production yield slightly increases, money and assets increase to a steady state. When the program is run control simulation, the system reaches carrying capacity after 8 years. The simulation of models with price of purchased inputs increased with 3.5% inflation rate per year showed maximum benefit of shellfish production occurs after 6 years but amounts are less than control simulation, and then decreases slightly in money and yield results. The results with 3.5% inflation and increase of oyster price annually showed steady and slightly increase of money and yield.

The objective of this research is to apply more scientific, quantitative methods and procedures of environmental investigation to the development of the natural environment and the improvement of the human environment during the establishment of a sewage treatment plant and special facilities using environmental accounting. This research was performed to develop a method of strategic environmental assessment on the operation of sewage treatment plant and reuse of shellfish seeding areas through the use of environmental accounting based on EMERGY evaluation. The result was applied to marine environment policy in order to evaluate the real wealth of the regional environment and economy for both the present phase and the proposed developed phase. Using results from the comparison of EMERGY indices between the present situation and future scenarios, cost benefit analysis was performed for three different scenarios: (1) construction of a new sewage treatment plant, (2) relocation and recovery of the shellfish seeding area , and (3) relocation and re-seeding of shellfish area and construction of a new sewage treatment plant. Cost-benefit ratios of the three scenarios are 1.88, 0.94, and 1.38, respectively.

This research outlines a new method for evaluation of shellfish production in Gamak Bay based on the concept of EMERGY. Better understanding of those environmental factors influencing oyster production and the management of oyster stocks requires the ability to assess the real value of environmental sources such as solar energy, river, tide, wave, wind, and other physical mechanisms. In this research, EMERGY flows from environment sources were 76% for shellfish aquaculture in Gamak Bay. EMERGY yield ratio, Environmental Loading Ratio, and Sustainability Index were 4.26, 0.31 and 13.89, respectively. Using the Emergy evaluation data, the predicted maximum shellfish aquaculture production in Gamak Bay and the FDA (Food and Drug Administration, U.S.) designated area in Gamak Bay were 10,845 ton/y and 7,548 ton/yr, respectively. Since the predicted shellfish production was approximately 1.3 times more than produced shellfish production in 2005, the carrying capacity of Gamak Bay is estimated to be 1.3 times more than the present oyster production.

The eco-hydrodynamic model was used to estimate the environmental capacity in Gamak Bay. It is composed of the three-dimensional hydrodynamic model for the simulation of water flow and ecosystem model for the simulation of phytoplankton. As the results of three-dimensional hydrodynamic simulation, the computed tidal currents are toward the inner part of bay through Yeosu Harbor and the southern mouth of the bay during the flood tide, and being in the opposite direction during the ebb tide. The computed residual currents were dominated southward flow at Yeosu Harbor and sea flow at mouth of bay. The comparison between the simulated and observed tidal ellipses at three station showed fairly good agreement. The distributions of COD in the Gamak bay were simulated and reproduced by an ecosystem model. The simulated results of COD were fairly good coincided with the observed values within relative error of 1.93%, correlation coefficient(r) of 0.88. In order to estimate the environmental capacity in Gamak bay, the simulations were performed by controlling quantitatively the pollution loads with an ecosystem model. In case the pollution loads including streams become 10 times as high as the present loads, the results showed the concentration of COD to be 1.33～4.74㎎/ℓ(mean 2.28㎎/ℓ), which is the third class criterion of Korean standards for marine water quality. In case the pollution loads including streams become 30 times as high as the present loads, the results showed the concentration of COD to be 1.38～7.87㎎/ℓ(mean 2.97㎎/ℓ), which is the third class criterion of Korean standards for marine water quality. In case the pollution loads including streams become 50 times as high as the present loads, the results showed the concentration of COD to be 1.44～9.80㎎/ℓ(mean 3.56㎎/ℓ), which is the third class criterion of Korean standards for marine water quality.