open access
메뉴인공종묘로 생산된 동죽, Mactra veneriformis의 크기, 수온, 염분 변화에 대한 여수율과 먹이섭이량의 차이를 조사하였다. 수온의 경우 소형, 대형그룹의 여수율은 <TEX>$5^{\circ}C$</TEX>에서 최소값을 보였으며 <TEX>$20^{\circ}C$</TEX>에서 가장 높은 값을 보였으나, <TEX>$25^{\circ}C$</TEX>에서 급격한 감소 경향을 보였다. 염분에 대한 소형그룹의 여수율은 26‰에서 가장 높은 값을 보였고 8‰에서 가장 낮은 값을 보였다. 대형그룹은 32‰에서 가장 높은 값을 보였고, 8‰에서 가장 낮은 값을 보였다. 본 연구를 통해 동죽의 최적 수온, 염분 환경은 <TEX>$20^{\circ}C$</TEX>, 27-32‰이며, <TEX>$10^{\circ}C$</TEX> 이하 또는 <TEX>$25^{\circ}C$</TEX> 이상의 수온과 20‰ 이하의 저염분에서 여수율이 낮아진다는 사실을 확인할 수 있었다.
Clearance rate and feeding of surf clam, Mactra veneriformis were determined for 5 different water temperature regime (5, 10, 15, 20, <TEX>$25^{\circ}C$</TEX>) and salinity regime (8, 14, 20, 26, 32 ‰) with small group (<TEX>$86.62{\pm}7.10mm$</TEX> in shell length) and large group (<TEX>$147.99{\pm}10.83mm$</TEX> in shell length). Clearance rate and feeding increased with water temperature up to <TEX>$20^{\circ}C$</TEX>, but rapidly decreased at <TEX>$25^{\circ}C$</TEX>. The minimal clearance rate and feedign was recorded at <TEX>$5^{\circ}C$</TEX>. surf clam showed low clearance rate and feeding at low salinity (below 20 ‰) and maximum values at high salinity (26-32 ‰).
북한강에 서식하고 있는 엷은재첩의 산란생태를 파악하기 위하여, 생식소 발달단계에 따른 생식주기, 군성숙도, 난경의 월별변화를 조사하였다. 각장에 대한 각고, 각폭, 전중, 육중간 의 상대성장식에서 상관계수 (<TEX>$R^2$</TEX>) 는 0.921-0.984로 높은 상관관계를 나타내었다. 엷은재첩은 기수재첩 보다는 소형종이었으며, 동시자웅동체로서 체내에서 수정되어 아가미 보육낭에서 부화되어 체외로 방출하는 난태생종이었다. 월별 비만도는 0.14-0.21 범위로 동계인 12월-2월에 낮은 값을 보이다가 2월부터 서서히 높아지기 시작하여 5월에 0.21로 정점을 보였다. 월별 육중량비는 25.9-38.7%로 비만도의 월별 변화와 같은 경향을 나타내었다. 비만도와 육중량비의 정점이 생식세포의 최성숙기와 1-2개월 차이가 있었다. 생식소의 조직상, 비만도 및 생식세포의 월별 변화를 종합하면 북한강산 엷은재첩 생식년주기는 분열증식기(12-2월), 성장기(2-5월), 성숙기(6-8월), 완숙 및 발생기(8-11월), 회복기(11-12월) 로 구분되어 하계산란종이었다. 군성숙 각장은 12.6 mm 였으며, 16 mm 이상의 개체는 모두 성숙하여 아가미에 보육낭을 형성하였다.
Gonadal development and maturation mechanism were studied on the freshwater marsh clam Corbicula papyracea (Heude), which is the endangered species in Korea. The specimens were collected in the rearing ponds and waterway of NFRDI in Gapyeong-gun, Gyeonggi-do from January to December 2004, and then investigated by condition factor, relative growth, gonadal development phases and gonad histological characters based on 30-50 individuals every month. Comparing with the freshwater marsh clam, C. papyracea is small, light olive brown shell and violet interior. The hermaphrodite individuals of C. papyracea take an internal fertilization and fertilized eggs are stored in the foster-sack in the gills, then the hatched juveniles are released outside after an ovoviviparous process. The average water temperature of inhabit area was in range of <TEX>$1.8-27.0^{\circ}C$</TEX> and usually took great effects on the gonad maturation of C. papyracea. The condition factor ranged from 0.14 to 0.21 throughout the year, which was the lowest during winter season (December-February), and gradually increased to the highest value of 0.21 in May. The ratio of meat weight to total weight was 25.9-38.7%, indicating the similar trend with condition factor. The highest values of condition factor and the ratio of meat weight appeared 1-2 months later than gonadosomatic index reached the peak value, it was probably because that the ovoviviparous eggs would spend a long period before hatching from the foster-sack in the gills. To synthesize the characters of meat weight, condition factor and gonad development by histological study, reproductive cycle of C. papyracea could be divided into five successive stages: multiplicative stage (December to February), growing stage (February to May), mature stage (June to August), spawning stage (August to November), recovery stage (November to December). The smallest shell length of matured C. papyracea was 12.6 mm, and individuals, larger than 16 mm, was formed the nursery in the gills.
바지락 양식장의 해수 수온은 황도가 정산포에 비하여 높은 것으로 나타났지만 염분은 황도가 낮았으며 용존산소와 pH는 비슷한 값을 나타났다. 그리고 엽록소 a 와 규산염은 황도가 높았으며 무기질소와 무기인은 비슷한 농도로 나타났다. 퇴적물의 입도는 황도가 세립질이고 분급이 양호하며, 정산포는 조립질이고 분급이 불량하였고, 유기물은 황도에서 높게 나타났다. C/N 비는 황도와 정산포에서 10 이하의 값을 나타내어 외부에 의한 오염보다는 해양기원의 유기물에 의한 것으로 조사되었으며 C/S 비는 두 지역에서 2.8 이하로 정상적인 해양환경으로 조사되었다. 중금속에 대한 농축비 (Ef) 는 두 지역에서 1 보다 크게 나타나 중금속이 유입 또는 금속황화물 형성과 관련된 축적현상으로 퇴적물에 농축되어 있음을 의미한다. 또한 농집지수 (Igeo)의 결과는 연구지역이 Igeo class가 1에 집중되어 있어 약간 오염되었거나 오염되지 않은 수준 (practically unpolluted / moderately polluted) 으로 나타났다. 조석에 따른 1차 생산력에서 황도가 정산포에 비하여 높게 나타났으며, 황도에서는 2월과 8월에 높고 5월에 낮은 반면 정산포에서는 8월만 높게 나타났다. 생산성 평가를 위하여 채집한 바지락의 비만도는 황도가 높았지만 크기와 서식밀도는 정산포가 크게 나타났다. 서식밀도의 변화에 대한 조사결과를 보면 7월까지 어획, 8월부터 종패의 가입 그리고 9월에는 폐사 때문인 것으로 사료된다.
To assess the effect of environmental factors on the sustainability of cultured production manila clam (Ruditapes philippinarum), we investigated the habitat characteristics of tidal flat (Hwangdo and Jeongsanpo in Taean). We measured the physiochemical parameters (temperature, salanity, pH, dissolved oxygen and nutrients) and the characteristics (mean size, chemical oxygen demand, ignition loss, C/N ratio and C/S ratio) of surface sediments. The C/N ratio of Hwangdo and Jeongsanpo were 9.0, 5.3 and the C/S ratio was 0.162, 0.159. The concentration of chlorophyll a at Hwangdo was higher than that of Jeongsanpo and species of micro algae were 102 and 100. The enrichment factor (Ef) and index of accumulation rate (Igeo) of the metals showed that those research areas can be classified as heavily polluted, heavily to moderately polluted, or more or less unpolluted, respectively. So two survey area of cultured clams in the tidal flat have been effected by the various environmental conditions, there are needed an improvement methods and continuous research for increasing the production of manila clam (Ruditapes philippinarum).
Gonad maturation of Manila clam, Ruditapes philippinarum was induced in this study using a recirculation system over 8 weeks in early spring. Clams used in the experiment were collected in <TEX>$15^{th}$</TEX> April 2010 from the west coast of Korea, as the surface water temperature remained <TEX>$11^{\circ}C$</TEX>. To induce gametogenesis and subsequent maturation seawater temperature was elevated <TEX>$1^{\circ}C$</TEX> per day over 10 days to reach <TEX>$20^{\circ}C$</TEX>. For the experiment, clams were raised in 120 L quadrangle tank maintained with re-circulated seawater system over 57 days. Water quality parameters including the water temperature, salinity dissolved oxygen, ammonium ion and nitrate levels in the tanks were monitored daily. Mixture of concentrated microalgae including Tetraselmis, Isochrysis, Pavlova and Thalassiosira weissflogii was supplied to clams twice a day, and quantity of the daily ration was adjusted as 3% of clam body dry weight. Histology was applied to examine gonad maturation. Daily monitoring of the water quality parameters indicated that the recirculation system supplied suitable environment to Manila clam; the nitrogenous components stayed below toxic levels (< 0.2 mg/L). At the beginning of the study, clams were mostly in early developing stage. As the seawater temperature reached <TEX>$20^{\circ}C$</TEX>, 10 days after the experiment, 20% of clams reached late development at 12 days. First ripe clams were observed at 42 days and 40% of clams were in ripe and ready for spawning at the end of study, 57 days after the experiment. In this study, gametogenesis of Manila clam was successfully induced by elevating water temperature and supplying commercially produced microalgae in a recirculation tank system.
We report two new records Korean marine bivalves. The new record species are Siliqua albida (Adams & Reeve, 1850) and Macoma (Macoma) middendorffi Dall, 1884. As a result, the family Pharidae in Korea turned out to be 8 species of 4 genera and Tellinidae are 37 species of 15 genera.
We investigated fecundities in egg capsules and sizes at 50% of group sexual maturities in female Rapana venosa in three different salinity concentration regions (S-1, S-2, and S-3). In three different salinities, egg capsule heights, the number of egg capsules and the number of eggs and embryos were remarkably increased with the increase of female shell heights (or ages) and also increased with the increase of salinity concentrations. Heights of egg capsules, the number of egg capsules and fecundities (the number of eggs and embryos) were the maximum at S-1 (Gwangyang Bay (average 31.5 psu)) and the minimum at S-3 (the upper reaches of Seomjin River (average 15.5 psu)). Total numbers of fecundities of R. venosa <TEX>$individual^{-1}year^{-1}$</TEX> were about <TEX>$1{\times}10^6$</TEX> at S-1 region, about <TEX>$8{\times}10^5$</TEX> at S-2 region, and about <TEX>$2{\times}10^5$</TEX> at S-3 region. Rates (50%) of individuals reaching first sexual maturities in three different salinity regions (S-1, S-2 and S-3) were over 50% in females measuring 7.1-8.0 cm in shell height (considered to be two years old), and 100% in those > 10.1 cm (considered to be five years old). Biological minimum sizes (<TEX>$RM_{50}$</TEX>) in females in three different regions are 72.0 mm SH at S-1 region, 70.9 mm SH at S-2 region, and 74.6 mm SH at S-3 region, respectively. Exceptionally, smaller individuals (considered to be one year old) were participated in reproduction.
동양달팽이의 EST 에서 serpin 유전자는 2가지 type이 추정되었다. Ns-serpin type 1 (partial) 서열의 코딩 영역은 총 819 bp 이었으며, 272개의 아미노산으로 이루어져 있었으며, Ns-serpin type 2 (partial) 의 코딩영역은 총 555 bp, 185개의 아미노산으로 이루어져 있었다. Laminarin 처리 전에는 Ns-serpin type 1이 2개 발현되었으며 처리 후에는 Ns-serpin type 2가 1개 발현되고 있었다. BLAST 결과를 바탕으로 유사도가 높은 17개의 참고 서열과 동양달팽이의 Ns-serpin type 1, 2의 아미노산 서열을 MEGA6 프로그램의 clustalW 엔진을 이용하여 multiple sequence alignment 를 수행한 결과, 척색동물의 포유강 9종, 조류강 1종, 양서강 1종과 척색동물인 해초강, 절지동물의 거미강 1종과 곤충강 1종이 같은 군으로 묶였으며, 연체동물문의 경우 동양달팽이의 두 가지 type 을 포함한 복족강 4종이 같은 군으로 묶이는 것을 확인하였다. Psipred 프로그램을 활용하여 예측한 2D 구조도 multiple align 및 phylodendrogram 결과와 연관이 있음을 확인할 수 있었다. EST를 통해 밝힌 동양달팽이의 두 가지 type의 Ns-serpin 서열은 Aplysia californica 등의 근연종들의 서열과 유사하였다. 본 연구에서는 무척추동물에서의 선천성 면역과 연관이 있는 것으로 잘 알려진 두 종류의 serpin 유전자 서열을 동양달팽이 EST 결과에서 발굴 하였으며, 동양달팽이에서도 여러 가지 type의 serpin 이 존재 할 수 있음을 입증하였다.
Serpins are a group of proteins involved in the regulation of serine and other type of proteases, and have been identified in many kinds of organisms from invertebrates to vertebrates. Serpins are known to regulate the proteolytic cascades of the innate immune pathways in addition to their roles in blood coagulation, angiogenesis, fibrinolysis, inflammation and tumor suppression. In this study, we have isolated two partial serpin gene fragments from expressed sequence tags (ESTs) of Nesiohelix samarangae. Dotplot analysis indicates that they are of two different types, Ns-serpin type 1 and Ns-serpin type 2. Ns-serpin type 1 has 819 bp coding region (272 amino acids), whereas Ns-serpin type 2 has 555 bp coding region (185 amino acids). Molecular phylogenetic analysis shows that the identified serpins have high similarities to their counterparts in the California see slug, Aplysia californica. Yet, the precise biological and immunological roles of these Ns-serpins remain to be further investigated using RNA interference and other molecular techniques.
굴 패각은 외부 침입자들로부터 자신을 보호하는 기능 외에도 잠재적 성장범위를 의미하므로 패각모니터링은 굴 성장을 위해 중요한 의미를 지닌다. 이를 위해 우리는 서로 다른 3해역 (완도, 한산거제만, 북만) 으로부터 채집한 패각의 성분분석을 통해 양식장 환경모니터링 도구로써의 활용가능성을 살펴보았다. 완도해역에서 채집된 굴 패각은 높은 열분해온도로 비교적 안정된 나노구조체 형상을 지닌 것으로 판단되고, 이는 상대적으로 진주층이 두터울 경우의 특징이다. 또한 패각중 성분분석결과 황의 함량이 낮고 납이 검출되지 않는 등 비교적 안정적인 굴양식환경을 나타내고 있다.
Shell of oyster has a function of shelter from predator as well as growth potential. We investigated the physicochemical characteristics of oyster shells from three difference oyster farms. The shells from Wando waters characterized high stability of nanostructure, ticker nacreous layer, high thermal decomposition temperature and low content of sulphur as well. These results represent that Wando coast is pristine water for oyster farming.
