Among the different types of seaweed that are cultivated in Korea for food, Capsosiphon fulvescensis the filamentous green alga with the highest production value. However, its harvest yield varies significantly from year to year due to its dependence on the natural seeding method. The present study aimed to identify the conditions affecting the formation of cyst-zygotes that can be utilized as artificial seeds during the life cycle of C. fulvescens. Gametangia and zygotes of C. fulvescens were found to be highly developed at temperatures above 15°C, with a maximum gametangial development rate of about 35% observed after 7 days of culture. The formation of zygotes into cystzygotes was induced within 7 days in all temperature conditions, but after 30 days of culturing, cyst-zygotes germinated into filamentous thalli at temperatures above 20°C, while the most stable formation and stabilization were observed at 15°C. Cystzygotes formed at 15°C showed high growth when they were transferred to 25°C conditions, and zoospores matured inside the cells. The production of cyst-zygotes was mostly influenced by temperature, and a gradual increase in temperature was found to be necessary for the formation and growth of cyst-zygotes. The culture conditions facilitating the formation of cyst-zygotes reported in this study can be useful for the production of artificial seeds and breeding technology for the effective cultivation of seaweed.

This study aimed to examine the morphological characteristics and variation in main traits by comparing the growth of individuals of Ecklonia cava Kjellman (Laminariales, Phaeophyceae) under an aquaculture environment. This survey was conducted from April 2018 to November 2019 at the aquafarm in Jindo-gun, Jeollanam-do (South coast of Korea). To classify the morphology of individuals in the aquaculture farm of E. cava, we investigated fourteen morphological characteristics and calculated four ratios between the measured values. Juvenile individuals showed a simple or oblong lanceolate, and at 3-4 months, a short stipe and holdfast developed, along with a bladelet that developed into the secondary blade form. At 5-7 months, secondary blades were found to develop irregularly on the primary blade. At 8-10 months, the primary blade expanded and secondary blades elongated. At 11-12 months, the secondary blades became oblong. At 13-14 months, the thallus area expanded. At 15-16 months, tertiary blades were formed, the thallus became more complex, the stipe thickened, and the holdfast widened. At 17-18 months, secondary blades clearly developed along with lobes. At 19-20 months, tertiary blades developed and became similar to mature natural blades. In the principal component analysis (PCA), the monthly population of the first year (Q1) and that of the second year (Q2) of the cultured population were divided along PC1, which is related to secondary blade morphological characteristics and the holdfast width. Q2 and natural populations are distributed in descending order of volume in Jeju (J), East Coast (E), and South Coast (S) along PC2, which is related to primary blade and stipe morphological characteristics. The results of this study were judged to offer important criteria for the development of different varieties of E. cava.

최근 양식기법이 보급되어 어가의 양식이 활발해진 감태 (Ecklonia cava Kjellman)는 향후 다양한 품종개발이 예상되고, 이들의 구분을 위한 신품종 심사기준 (특성조사요 령) 작성과 기초자료가 되는 자연 개체군의 변이 폭과 지역적 형태 변이에 관한 연구 필요성은 더욱 커지고 있다. 본 연구는 감태 양식 개체군과 국내 연안 16개소에서 채집한 자연개체군의 형태를 비교하고, 주요 형태 형질의 특성과 변이 폭을 규명하고자 하였다. 감태의 품종 구분에 적합한 형질은 1차엽과 2차엽, 줄기에 대한 주요 형태와 특 징에 관한 14개 측정 형질과 4개 비율 형질, 총 18개 특성을 선정하였다. 군집 분석에서 전체 19개 개체군 중, 자연 개체군인 장길 (E4), 소록 (S7)은 동일 지역 개체군들과 유의한 차이를 보였고, 동해와 남해의 나머지 자연 개체군은 양식 2년생인 수유 (Q6, Q8, Q10)를 포함한 2개 집단으로 구분되었고, 제주의 3개 개체군은 별도의 집단을 이루어 지역적으로 구분되었다. 주성분 분석에서도 군집 분석에서 집단을 이룬 동해와 남해 개체군을 중심으로 양식 개체군은 중앙에 모여 나타났고, 장길 (E4), 소록 (S7)과 제주 개체군들은 주성분 1 (PC1)과 주성분 2 (PC2)에 연관된 2 차엽 지수, 줄기의 길이와 직경, 줄기 길이/1차엽 길이, 1차엽 길이와 너비, 2차엽 수, 2차엽 길이와 너비의 형질에 의해 각 축에 따라 구분되어 나타났다. 이상의 결과로 본 연구에서 조사한 18개 형질은 각 해역에서 유의한 차이를 보이는 개체군 구분을 위한 기준으로 유용성이 확인되었으 며, 감태의 각 지역 개체군은 향후 신품종 개발 후보 종으로 가능성이 클 것으로 기대되었다.

국예비 해기사 교육의 일환으로 심화교육의 일환으로 IMO 활동, 국제적인 주요협약 및 규정의 종류, 체계 및 전반적인 내용이해를 교육하기 위한 산학간 해기사 교육프로그램을 제안한다. 전체적 교육의 구성, 교육결과에 대한 만족도 분석을 통하여 바람직한 교육프로그램을 제시한다. 교육의 결과로서 미래 해기사의 IMO 활동에 대한 관심을 드높이고, 참신한 아이디어 발굴을 통한 국가 의제개발의 씨앗을 창출해내 는 역할이 기대되고, 해기사의 자긍심을 고양시키는 부수적인 잇점도 가질 수 있을 것이다.

The aim of this study is to determine harmful radioactive gas(Rn^222)-concentrations in soils and to suggest the anormalous regions of Rn^222 -concentration in Taejeon area. The range of Rn^222 -concentration in the soils (45 samples) of the survey area is 100 to 2,475 (pCi/L) and mean±δ of those values is 489±05 (pCi/L). The 2% (4 samples) of soil-gas samples (45 ones) collected in the survey area is corresponded to high risk level, 53% (24 samples) to medium one and 43% (19 samples) to low one. Especially, The Rn^222-concentration is relatively higher in schistose granite region than in other rock units (two-mica granite and biotite granite) in the survey area. The Rn^222-concentration is propotional to the uranium contents in the soils. The soil hardness among the various factors is correlative with Rn^222-concentrations. To prevent the damage from Rn^222 -concentrations, it is necessary to close the cracks of underground structure and to consider methods reducing Rn222-concentration for the anormalous regions.