We study on the dynamic interaction with a simulated physical-biological coupled model response to nutrient reduction scenario in Jinhae Bay. According to the low relative errors, high regression coefficients of COD and DIN, and realistic distribution in comparison to the observation, our coupled model could be applicable for assessing the marine ecosystem response to nutrient input reduction in Jinhae Bay. Due to the new construction and expansion of sewage treatment plant from our government, we reduce 50% nutrient inputs near Masan Bay and sewage treatment plant. COD achieves Level II in Korea standard of the water quality from the middle of the Masan Bay to all around Jinhae Bay except the inner Masan Bay remaining at Level III. When our experiment reduces 50% nutrient inputs near Masan Bay and Dukdong sewage treatment plant simultaneously, COD decreases to about 0.1-1.2 mg/L $(128^{\circ}30'{\sim}128^{\circ}40'\;E,\;35^{\circ}05'{\sim}35^{\circ}11'\;N)$. The COD from the middle of the Masan Bay to Jinhae Bay achieves Level II.
Excessive input of organic matters from fish cage farms to the coastal waters has been considered as one of the major factors disturbing their benthic ecosystem. Sediment samples were taken from around the two fish cage zones (A and B) in Tongyeong coast in June and August 2003, to evaluate the ecological impacts of fish cage farming activity on the macrobenthic polychaete communities. Polychaete accounted for of the total macrofauna individuals from each of the sampling stations. The number of species, abundance, diversity and dominant species of polychaete were rapidly changed with the distance from the fish cages. Within 10 m from the fish cages, Capitella capitata, which is a bio-indicator for the highly enriched sediments, was a dominant species and the lowest diversity was recorded. In particular, the maximum density () of C. capitata was found at Farm A where fish cages were more densely established within a semi-enclosed bay system. The sampling zone between 10 m and 15 m showed a rapid decrease of C. capitata with a rapid increase of the numbers of species, implying that this zone may be an ecotone point from a highly to a slightly enriched area. In the sampling zone between 15 m and 60 m, a transitional zone, which represents slightly enriched condition before normal one, was observed with additional increase and maintenance of the number of species and density of polychaete. In addition, the potential bio-indicators of organic enrichment, such as Lumbrineris longifolia and Aphelochaeta monilaris were the predominant species in the sampling zone. Multidimensional scaling (MDS) ordination plots and k-dominance curves confirmed the above results on the gradual changes in the macrobenthic polychaete communities. Our findings suggest that the magnitude of impact of fish cage farming activity on polychaete communities is probably governed by a distance from fish cage, density of fish cage and geomorphological characteristics around fish cage farm.
The efficiency of clove oil, MS-222, and 2-phenoxyethanol was evaluated as anesthetics in juvenile Scomber japonicus. Stage A5 of anesthesia was assumed to be sufficient for conducting routine aquaculture procedures in less than 3 min, with recovery (stage R5) in less than 5 min. The lowest effective doses of the three anesthetics were 50 mg $L^{-1}$ clove oil (anesthetic time of 71.3 s and recovery time of 167.0 s), 100 mg $L^{-1}$ MS-222 (anesthetic time of 70.7 s and recovery time of 115.7 s), and 400 mg $L^{-1}$ 2-phenoxyethanol (anesthetic time of 86.7 s and recovery time of 95.0 s). Anesthetic times decreased with increasing doses for all three anesthetic agents, and fish anesthetized with clove oil exhibited the longest recovery times. After 30 min, the highest plasma cortisol and lactate levels were detected with the use of clove oil, whereas the lowest values were observed with 2-phenoxyethanol. In addition, high glucose levels were maintained during recovery with clove oil, but the treatments did not significantly differ. The most effective of the three anesthetic agents was 2-phenoxyethanol, although all were considered acceptable for use in cultures of juvenile Scomber japonicus.
ABSTRACT Samples of Turbo ( Batillus ) cornutus Lightfoot, 1786 in Jeju Island were collected from September 2009 to May 2010. Population ecological parameters and stock assessment of the turban shell were determined, based on the length and age composition data from 2000 to 2009 and ecological parameters. Instantaneous coefficient of total mortality (Z) of turban shell was estimated to be 2.2062/year. The estimated instantaneous coefficient of natural mortality (M) was 0.874/year. The age of turban shell at its first capture (t c ) was 2.636 year. Yield-per-recruit were estimated under harvest strategies that based on F max , F 0.1 , F 35% , and F 40% was 10.44 g, 1.87 g, 6.53 g and 7.46 g. Key words: Turban shell, Natural mortality, Fishing mortality, Yield-per-recruit 서 론 소라, Turbo ( Batillus ) cornutus Lightfoot, 1786 는 연체동물 문 복족 강 소라 과에 속하는 종으로서, 대마난류의 영향을 받는 우리나라, 일본, 중국, 대만 등의 연안해역에 분포한다. 조간대로부터 수심 20 m 내외의 암초지역에 서식하고, 우리나라의 경우는 남해안과 울릉도 등에서도 부분적으로 분포하지만 제주도에 주로 분포한다. (NFRDI, 1999).본 종은 자웅이체이고, 육안으로 보아 생식선이 백색이면 수컷이고, 녹색이면 암컷이다. 식용으로 가치고 높으며 내해에 사는 것은 가시가 짧거나 없는 개체도 있지만 제주도산 소라는 전반적으로 외해에 접하여 남해안산보다 가시가 크다 (Yoo, 1995).제주도산 소라는 1970년대 초반부터 대일수출이 이루어지면서 지역 특산 전략상품으로 중요한 위치를 차지하여 왔다 . 과도한 어획 영향으로 연간 어획량이 급감함에 따라 1991년 10월부터 수산관련 연구·행정·지도기관과 수협이 공동으로 자원량 회복을 위한 자율적 TAC (Total Allowable Catch) 제도를 실시하여 우리나라 최초 자원관리의 성공적 사례를 보여준 종이다 (Chang, 2002).우리나라에서 소라에 대한 연구로는 서식장의 해양환경 (Lee and Lee, 1984) 연구가 있으며, 자원생물학적 연구로는 생식소 및 연체부의 칼로리 함량비교 (Lee and Lee, 1979), 생식소 주기에 관한 조직학적 연구 (Lee and Lee, 1984), 정자의 미세구조 (Lee, 1984) 등의 연구가 있다. 생태특성에 있어서는 상대성장 (Hwang and Chung, 1979), 표지방류를 통한 성장 (Chung, 1983) 과 각고조성을 이용한 성장 (Chang and Chung, 2001) 의 연구가 있다.자원평가 및 관리에 관한 연구로는 Chung (1983)이 소라 종묘구의 효과와 자원분석에 관하여 연구한 결과가 있으며 , 가입특성과 자원관리 (Chang
The giant honeycomb oyster Hyotissa hyotis occurs at a high density in the shallow subtidal rocky bottom of Jeju Island off the south coast of Korea, where the sea surface temperature ranges from 14°C to 25°C seasonally. Unlike other oysters, H. hyotis has an extraordinarily large adductor muscle (AM) that accounts for more than 40% of the total tissue weight. This study analyzed the proximate composition, amino acids, and fatty acids of the AM of H. hyotis in Jeju Island to evaluate the nutritional potential. For the analyses, oysters were grouped based on their reproductive condition as prespawning (May–August), spawning (September–November), and postspawning (December–April). The AM contained a high level of protein (54.7%–69.4%) followed by carbohydrate (16.0%–25.3%) and lipid (4.5%–9.9%) throughout the year, indicating that the AM is enriched with protein. The total amino acids (TAA) in the AM ranged from 9.4 to 12.9 g/100 g dry weight annually, and essential amino acids accounted for up to 36.7% of the TAA. Like other marine bivalves, the AM contained a high level of taurine, which accounted for 26.5%–28.5% of the total free amino acids. The AM also included high levels of essential fatty acids, such as palmitic acid, docosahexaenoic acid, and eicosapentaenoic acid, as these fatty acids accounted for 35.9%–37.0% of the total fatty acids. The AM of prespawning oysters collected during May and August contained comparatively higher total proteins and carbohydrates. Results suggested that, like scallops and pen shells, the AM of the giant honeycomb oyster is highly suitable as seafood, and H. hyotis should be considered as a species of high potential for future aquaculture efforts.
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