Earticle

The fish fauna of Hyodon-cheon and Soesokkak in Jeju-do, Korea, was investigated for a total of 15 days underwater from 20 Oct. to 5 Nov. 2008. Fish specimens were collected with a small net by SCUBA diving and fish specimens difficult to collect were photographed underwater using a underwater camera and camcorder. The fish specimens collected from the Hyodon-cheon were identified as 6 species, belonging to 3 families and 3 orders. and the fish specimens of Soesokkak were identified as 30 species, belonging to 22 families and 7 orders. The most dominant species were observed 3 species of Gobiidae in Hyodon-cheon and 7 species of Gobiidae in Seosokkak. Further studies are need to consistently monitoring on a varieties of environmental conditions in Hyodon-cheon and Soesokkak area.

Miamiensis avidus causes scuticociliatosis in cultured olive flounders (Paralichthys olivaceus), leading to economic losses in aquaculture in Korea. Quantitative evaluation of the viability of M. avidus is important to develop an effective vaccine or chemotherapeutic agent against it. We used a colorimetric assay based on the reduction of 2- (4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1) to quantify the viability of M. avidus. Using this method, we investigated the effect of protease inhibitors on the viability of M. avidus. The assay showed a clear difference in the optical density (OD) of over 104 ciliates, and the metalloprotease inhibitors 1, 10-phenanthroline and ethylenediaminetetraacetic acid (EDTA) reduced the viability of M. avidus by more than 90% when used at concentration of 5 mM and 100 μM, respectively. However, different morphological changes in the parasite were observed when exposed to these two inhibitors. These results indicate that the WST-1 assay is a simple and reliable method to quantify the viability of M. avidus, and metalloproteases are excellent targets for the development of agents and vaccines to control M. avidus infection.

This study investigated gametogenesis, gonadal development, reproductive cycle in cultured Takifugu rubripes. Fish at SAJO CS Co., Ltd. 1-3 year old were sampled from July 2003 to June 2004. The gonadosomatic index (GSI) of male and female reached maximum values of 11.91±3.01 and 3.23±2.61 in April, respectively. The hepatosomatic index (HSI) of male reached a maximum of 13.80±1.32 in May and that of female reached a maximum of 14.60±1.08 in June. The reproductive cycle could be divided into following successive stages in the ovary: growing stage (July to June), mature stage (November to April), and degenerative stage (April to July). Likewise, in the testis, the following stages were observed: growing stage (July to March), mature stage (November to June), spent stage (February to July), and degenerative and recovery stage (May to August).

이 연구는 제주도 연안에 서식하는 큰열매모자반(Sargassum macrocarpum)의 종 동정을 위한 기초자료를 제공하기 위해 형태적 특성과 계통 유연관계를 조사하였다. 형태학적 분석 결과, 수집된 큰열매모자반은 원추상 부착기, 직립하는 줄기 그리고 주지의 치상돌기 등 형태적으로 기존에 보고된 연구결과와 유사한 양상을 보였다. 하지만 암생식기탁의 모양은 긴 주걱형과 도피침형에서 드물게 Y자형도 나타나 형태적 다양성이 관찰되었다. 부착기의 모양은 생육기간이나 부착기질에 적응하여 전형적인 원추상 에서 뭉툭한 다각형까지 여러 가지 형태적 변이를 보였다. 조천읍 조천리와 북촌리 연안에서 수집된 큰열매모자반의 mtDNA cox3 서열은 한경면 용당리에서 보고된 서열과 100% 일치하였는데, 이는 제주도 전 해역의 큰열매모자반이 유전적으로 동일한 기원 에서 유래된 것으로 판단되었다. 또한 큰열매모자반의 mtDNA cox3 서열이 Sargassum yamadae, S. siliquastrum의 서열들과 동일하여, 분류체계의 재조명이나, 교잡가능성과 생식적 격리에 대한 후속연구의 필요성을 시사하고 있다. 이번 연구결과는 해양생태계에서 해중림을 구성하는 주요 종 중 하나인 큰열매모자반의 형태적 특성과 계통 유연관계에 대한 정보를 통하여 모자반류의 종 동정 자료에 적용될 것이다.

The purpose of this study was to investigate the morphological characteristics and phylogenetic relationship to provide information for the classification of Sargassum macrocarpum inhabiting Jeju Island, Korea. The morphological characteristics of S. macrocarpum such as conical holdfast, erect stem and denticle protuberances on both edges of the main branches were similar to those of previously reported for Sargassum morphology. However, morphological variation was observed as the female receptacle is long spatulate or oblanceolate and rarely Y-shaped. The shape of holdfast showed various morphological variations from a typical cone to a blunt polygon by adapting to the age or substrate shape. The nucleotide sequences of mtDNA cox3 gene obtained from Jocheon-ri and Bukchon-ri, Jocheon-up in this study were identical to those previously reported in Yongdang-ri, Hangyeong-myeon, suggesting that the S. macrocarpum populations over whole Jeju Island seacoast might be genetically derived from the same origin. In addition, the cox3 sequences of S. macrocarpum were identical to those of S. yamadae and S. siliquastrum, suggesting that it is necessary to review their taxonomic position and to carry out future studies on inter-specific hybridization and reproductive isolation among related species. The results of the present study will be applied to Sargassum species classification through the morphological characteristics and phylogenetic relationship of S. macrocarpum, as one of main species that form forests in marine ecosystems.