초록

Abstract

The karyotypes of Korean endemic land snail, Koreanohadra koreana, using air-drying method wereinvestigated. Somatic cells of this species had 2n = 58. Karyotypes were also analysed with 16 metacentric, 12 submetacentric and one subtelocentric chromosome pairs. Observed chromosomes ranged from 2.6 to <TEX>$8.9{\mu}m$</TEX> and the total length was <TEX>$122.3{\mu}m$</TEX>. This is the second report on the chromosome numbers and the karyotype of K. koreana.

초록

Abstract

This study examines the morphological features of larval and postlarval shells of the paedomorphic bivalve Crenella decussata Montagu, 1808 from the Sea of Japan. During the early morphogenesis of the shell of C. decussata the following characteristics appear: prodissoconch I -the anterior and posterior provincular teeth, a broad primary ligament pit located on the chondrophore; nepioconch - the anterior and posterior juvenile teeth,primary lateral teeth, fine commarginal and radial sculpture. Larvae of C. decussata distinctly differ from other mytilid larvae by a D-shaped shell, absence of umbo, astraight hinge margin, and homogeneous fine-grained sculpture without co-marginal lines of growth. These shell characters indicate lecithotrophic development of this species. Some morphostructures are revealed which might be used in crenellin taxonomy.

초록

남해안 내만해역에서 인공부착판 투입시기와 투입기간에 따른 군집구조의 차이를 보고자 하였다. 거제도 장목만에서 2007년 3월에서 10월에 이르는 기간 동안 매월 PVC 재질의 인공부착판을 수심 50 cm에 수직방향으로 투입하였다. 2007년 11월에 저서동물이 부착된 PVC판을 회수하여 부착생물군집을 조사한 결과 지중해담치는 3월에서 7월에 투입된 부착판에서 우점종으로 출현하였고, 석회관갯지렁이와 주름멍게는 5월 이후 10월까지 투입한 부착판에서 우점종으로 남았다. 주걱따개비와 다발이끼벌레류는 6월-9월 사이에 투입한 부착판에서 우점하였다. 실험종료 시에 회수한 부착판에서의 분류군별 개체수와 습중량은 지중해담치의 우점으로 3월-7월 사이에 투입된 부착판에서 최대치를 보였다. 종간 경쟁으로 인하여 최대가입시기와 우점시기가 일치하지 않은 부착생물들이 나타났고, 투입기간과 생물량이나 개체수 간에는 가입시기의 차이로 인하여 뚜렷한 관련성을 보이지 않았다. 투입시기별 및 투입기간별로 특정 저서생물이 우점종으로 출현하였는데, 이는 유생 공급을 결정하는 가입시기와 나중에 유입되는 유생을 배제하는 종간경쟁에 의해 최종 부착생물군집의 조성에 중요한 결정 요인이 되는 것으로 나타났다.

Abstract

This study was conducted to compare the species composition of sessile organisms on the artificial substrates of PVC submerged at different time intervals and duration in Jangmok Bay, Geoje Island, southern coast of Korea. Three PVC plates were submerged at one month interval from March to October and retrieved in November, 2007. A mussel, Mytilus galloprovincialis exclusively occupied the artificial substrates submerged from March to April and occurred as a dominant species to July. An ascidian, Styela plicata occurred as a dominant sessile species from May to August. Balanus amphtrite, Bugula sp., and hydrozoans occurred as dominant species on the plates submerged from July to September. There was a mis-match between the peak time of settlement and dominance of sessile organisms due to the interspecies competitions when the PVC plates were retrieved in November. There was no clear relationship between submerged duration and the abundance of sessile organisms due to the different settlement period. M. galloprovincialis seemed to be a strong competitor which could exclude the previous recruiters of macroalgae by overgrowth and occupy the substrate surface and maintain its high population density by preventing the settlement of other species until late autumn. These results suggested that the composition of sessile organisms in vacant hard substrates could be determined by the combined effects of supply-timing of larvae and post-settlement competitions.

초록

바지락 (Ruditapes philippinarum) 은 모래와 진흙이 많은 연안에 주로 분포하지만 드물게 울산의 태화강처럼 하천의 중류나 하류에서도 분포한다. 울산 태화강에서는 예전부터 바지락이 서식해 왔으며 인근 어민들의 전통적인 소득원으로서 주요 수산자원의 대상이 되어 왔다. 본 연구는 2009년 6월부터 2010년 6월까지 바지락의 현장조사를 통하여 자원생태학적 특성, 자원량 및 적정어획량 등의 자원평가를 실시하고 지속가능한 자원관리의 방안 제시 및 어업정책 수립을 위한 기초자료를 확보하고자 하였다. 태화강 바지락의 수명은 6세로 추정되었고 von Bertalanffy growth function에 의하여 성장계수 K 및 <TEX>$L_{\infty}$</TEX>은 0.341 및 46.64 cm로 구해졌다. Pauly 방법에 의한 순간전사망계수 (Z) 및 어획개시연령 (<TEX>$t_c$</TEX>) 은 1.171/년과 1.37년으로 구해졌고 현재의 순간어획사망계수는 0.626/년으로 계산되었다. 바지락의 자원량은 총 서식면적 <TEX>$1.46\;km^2$</TEX>과 평균 면적당 생체량 1,005.3 g/<TEX>$m^2$</TEX>으로 1,483톤으로 추정되었다. 조사해역 바지락의 순간어획사망계수 (F) 에 대한 가입당생산량 (Y/R) 과 어획개시연령 (<TEX>$t_c$</TEX>) 과의 관계는 현재의 어획개시연령인 1.37세, 현재의 순간어획사망계수 F 에서 가입당생산량이 1.38 g임을 나타내고 있으며 적정어획사망계수 (<TEX>$F_{0.1}$</TEX>)에 의한 연간 생물학적 허용어획량 (ABC) 은 512톤으로 산정되었다.

Abstract

The manila clam (Ruditapes philippinarum) is mainly distributed in the coastal area which consist of mud, sand and gravel, but they rarely live on the upper and down reaches of river. For a long time the manila clam has been inhabited in Taehwa river which has been exploited as a traditional earning resources and has become as a major object by neighborhood fishermen. This study was undertaken to evaluate stock assessment and to build management implications with the ecological parameters in Taehwa river from June 2009 to June 2010. The maximum age of manila clam was determined to 6 years old from observing ring radius of shell, the length and weight relationship was TW = <TEX>$0.0002SL^{3.063}$</TEX> (<TEX>$R^2$</TEX> = 0.925). K and <TEX>$L_{\infty}$</TEX> were respectively estimated 46.64 mm and 0.341/year by von Bertalanffy growth. The instantaneous total mortality was estimated to be 1.171/year and the age at first capture was 1.37 years by the Pauly's method using shell length composition. The current total biomass of manila clam was calculated 1,483 mt over study area <TEX>$1.46\;km^2$</TEX> by swept area method. ABC (Acceptable Biological Catch) estimates of manila clam showed 512 mt with using <TEX>$F_{0.1}$</TEX>. It's desirable to determine the optimum harvesting time as after main spawning season, as well as it's required to manage fisheries resources considering capture age and biomass through adjusting a first age at capture.

초록

실험에 사용한 어미는 2010년 7월 13일 전남 영광군 백수면 하사리에서 채집된 어미를 수송하여 채란을 하였다. 실험에 사용된 초기치패는 수정란으로 부터 3일간 유생사육 한 착저치패 (각장 <TEX>$198{\pm}12{\mu}m$</TEX>) 6,000만 마리를 사용하였고, 기간은 2010년 7월 16일부터 10월 4일까지 80일간 실험하였다. 사육방법은 모래상자식, 저면여과식, 가두리식, 바닥식으로 하였고, 수온별 사육실험은 수온을 25, 28, 31, <TEX>$34^{\circ}C$</TEX>로 하였다. 먹이생물 종류에 따른 초기치패의 사육실험은 Isochrysis galbana, Chaetoceros gracilis, Phaeodactylum tricornutum, Tetraselmis tetrathele를 단독으로 공급한 시험구와 4종을 혼합하여 공급한 실험구로 각각 성장과 생존율을 조사 하였다. 초기치패의 사육방법별 시험 결과, 성장은 가두리 실험구가 각장 <TEX>$2.64{\pm}0.59{\mu}m$</TEX>로 가장 빨랐고, 모래상자 실험구가 각 장 <TEX>$2.59{\pm}0.64{\mu}m$</TEX>, 저면순환여과 실험구가 각장 <TEX>$2.56{\pm}0.52{\mu}m$</TEX>, 바닥 실험구가 각장 <TEX>$2.52{\pm}0.56{\mu}m$</TEX> 순이었다. 생존율은 모래상자 실험구가 35.9%로 가장 높았고, 바닥 실험구 34.6%, 저면순환여과 실험구 29.5%, 가두리 실험구 9.3% 순으로 나타났다. 수온별 초기치패의 성장은 <TEX>$34^{\circ}C$</TEX> 실험구가 각장 <TEX>$2.70{\pm}0.76{\mu}m$</TEX>로 가장 빨랐고 <TEX>$31^{\circ}C$</TEX> 실험구 각장 <TEX>$2.69{\pm}0.43{\mu}m$</TEX>, <TEX>$28^{\circ}C$</TEX> 실험구 각장 <TEX>$2.66{\pm}0.39{\mu}m$</TEX>, <TEX>$25^{\circ}C$</TEX> 실험구 각장 <TEX>$2.45{\pm}0.41{\mu}m$</TEX> 순으로 수온이 높을수록 빠른 성장을 나타내었다. 생존율은 수온 <TEX>$31^{\circ}C$</TEX> 실험구가 38.2%로 가장 높았고, 수온 <TEX>$28^{\circ}C$</TEX> 실험구 36.8%, 수온 <TEX>$25^{\circ}C$</TEX> 실험구 24.7%, 수온 <TEX>$34^{\circ}C$</TEX> 실험구 14.2% 순으로 나타났다. 먹이생물 공급에 따른 성장은 혼합공급 실험구가 각장 <TEX>$2.52{\pm}0.66{\mu}m$</TEX>로 가장 빨랐고 I. galbana 실험구 각장 <TEX>$2.47{\pm}0.45{\mu}m$</TEX>, C. gracilis 실험구 각장 <TEX>$2.36{\pm}0.39{\mu}m$</TEX>, T. tetrathele 실험구 각장 <TEX>$2.32{\pm}0.76{\mu}m$</TEX>, P. tricornutum 각장 <TEX>$2.29{\pm}0.43{\mu}m$</TEX>순이었다. 생존율은 혼합 실험구가 36.9%로 가장 높았고, I. galbana 실험구 32.4%, C. gracilis 실험구 28.5%, P. tricornutum 실험구 18.4%, T. tetrathele 16.2%순으로 나타났다.

Abstract

To establish technical development for artificial seed production, growth and survival for early young spats of the hard clam, Meretrix petechialis, were investigated by breeding methods. Adult clams were collected at Hasa-ri, Baeksu-eup, Yeonggwang-gun, Jeollanam-do on July 13, 2010, and then transported to the indoor aquarium at the laboratory. Eggs which were taken from mother clams, were inseminated, and after they were fertilized in the aquarium, 60 million bottom-clinging spats (<TEX>$198{\pm}12{\mu}m$</TEX> in shell length) were produced and bred. The breeding experiments were carried out from July 16 to October 4, 2010 for 80 days. The methods of sand box, sand bottom circulation filter, inclosing net, floor were used for the breeding experiments, and the experimental condition of sea water temperature for larvae were at 25, 28, 31, <TEX>$34^{\circ}C$</TEX>. Four marine cultured food organisms were used for this study as follows: Isochrysis galbana, Chaetoceros gracilis, Phaeodactylum tricornutum, Tetraselmis tetrathele. According to the experimental conditions, experimental groups of the spats in the early stage were investigated the growth rate and the survival. As the result, the method of the inclosing net section was the fastest (grew up to <TEX>$2.64{\pm}0.59{\mu}m$</TEX> in shell length), followed by sandbox (<TEX>$2.59{\pm}0.64{\mu}m$</TEX>, bottom circulating filter (<TEX>$2.56{\pm}0.52{\mu}m$</TEX>), and floor (<TEX>$2.52{\pm}0.56{\mu}m$</TEX>). The survival was the highest in the experimental condition of sandbox (35.9%), followed by floor (34.6%), bottom circulating filter (29.5%), and inclosing net (9.3%). Eexperimental condition of water temperature of <TEX>$34^{\circ}C$</TEX> showed the fastest growth rate (grew up to <TEX>$2.70{\pm}0.76{\mu}m$</TEX> in shell length), and showed the latest growth rate (grew up to <TEX>$2.45{\pm}0.41{\mu}m$</TEX> in shell length) at <TEX>$25^{\circ}C$</TEX>. The survival (%) was the highest under the water temperature conditions at <TEX>$31^{\circ}C$</TEX>, and showed the lowest (14.2%) at <TEX>$34.^{\circ}C$</TEX>. The growth rate of the experimental group fed the mixture live food was the fastest with shell length <TEX>$2.52{\pm}0.66{\mu}m$</TEX>, and that of experimental group fed P. tricornutum showed the latest (grew up to <TEX>$2.29{\pm}0.43{\mu}m$</TEX> in shell length). The survival was the highest (36.9%) under the experiment condition fed mixture live food and experimental group fed T. tetrathele showed the lowest rate (16.2%).

초록

Abstract

The ultrastructural characteristics of germ cell development during spermatogenesis and mature sperm morphology of in male Scapharca subcrenata were investigated by transmission electron microscope observation. Spermatogonia are located nearest the outer wall of the acinus, while spermatocytes and spermatids are positioned near the accessory cells. The accessory cells, which is in close contact with developing germ cells, contained a large quantity of glycogen particles and lipid droplets in the cytoplasm. Therefore, it is assumed that they are involved in supplying of the nutrients for germ cell development. The morphologies of the sperm nucleus and the acrosome of this species are the oval shape and cone shape, respectively. Spermatozoa are approximately 45-<TEX>$50{\mu}m$</TEX> in length including a sperm nucleus (about <TEX>$1.30{\mu}m$</TEX> in length), an acrosome (about <TEX>$0.59{\mu}m$</TEX> in length), and tail flagellum (about 43-<TEX>$47{\mu}m$</TEX>). The axoneme of the sperm tail shows a 9 + 2 structure. As some characteristics of the acrosomal vesicle structures, the right and left basal rings show electron opaque part (region), and also the anterior apex part of the acrosomal vesicle shows electron opaque part (region). These characteristics of the acrosomal vesicle were found in Acinidae and other several families in subclass Pteriomorphia. These common characteristics of the acrosomal vesicle in subclass Pteriomorphia can be used for phylogenetic and taxonomic analysis as a taxonomic key or a significant tool. The number of mitochondria in the midpiece of the sperm of this species are five, as one of common characteristics appear in most species in Arcidae and other families in subclass Pteriomorphia. The acrosomal vesicles of Arcidae species do not contain the axial rod and several transverse bands in acrosome, unlkely as seen in Ostreidae species in subclass Pteriomorphia, These characteristics can be used for the taxonomic analysis of the family or superfamily levels as a systematic key or tools.

초록

패류양식장과 실내 사육수조에서 큰구슬우렁이(Glossaulax didyma didyma) 에 의해 말백합 종패와 성패를 대상으로 패각에 형성된 천공들의 형태적 특징, 천공율 및 포식률 등 여러 가지 형태수치 조사 결과자료를 비교 분석하였다. 천공 조사는 2007년 6월부터 9월까지 패류양식장과 실내 사육수조에서 수행하였다. 패류양식장에서 조사된 말백합 종패와 성패의 패각에 형성된 천공형태는 분화구형으로, 자연생태 집단을 대상으로 이미 조사된 바지락 치패와 백합 치패에서 흔히 나타나는 분화구형들과 동일한 경향을 나타내었다. 패류양식장 조사와 실내 사육수조 조사에서, 말백합 성패와 종패의 패각 위에 나타나는 천공들의 크기를 보면, 천공 외부의 외경들의 크기가 내부의 내경들의 크기 보다 더 큰 것으로 나타났다. 전반적으로 말백합 종패의 패각 위에 출현하는 천공들의 외경과 내경의 크기는 성패 패각 위에 출현하는 천공들의 크기보다 좀 더 작았다. 말백합 종패 패각 위의 천공들의 위치는 말백합 각장의 크기에 따라 넓게 다르게 나타났다. 그러나 패류양식장과 실내 사육수조 조사에서, 말백합 성패 패각 위에 출현하는 대부분 천공들의 위치 분포상은 말백합 패각의 각정 부위 가까이에 위치하였다. 전반적으로 볼 때, 패류양식장과 실내 사육수조 조사에서 천공의 외경과 내경은 말백합의 각장이 증가함에 따라 비례하여 증가하는 경향을 보였다. 실내 사육수조에서 15일간 3회에 걸쳐 천공폐사 실험을 하는 동안 저자들은 큰구슬우렁이가 말백합 종패와 성패에 천공하는 것을 확인할 수 있었으며, 다음과 같은 결과를 얻었다: 패각 위에 출현하는 천공형태도 역시 분화구형을 나타내었다. 실험에 사용된 총 개체들 중 폐사된 총 개체들의 비율은 평균 41.5%이었고, 시료 총 폐사개체들 중 총 천공폐사된 개체들의 비율은 평균 47.1%이었으며, 총 개체들 중 천공되어 폐사한 개체들의 천공폐사율 (천공률) 은 평균 19.3%를 나타내었다. 큰구슬우렁이의 포식율을 조사한 결과, 포식 행동은 주간보다 야간에 좀 더 활발하게 나타났다. 특히, 말백합 종패와 성패의 경우, 큰구슬우렁이 한 개체가 말백합을 천공하여 포식하는 일간 평균 포식량을 실험결과를 토대로 산출한 결과 평균 0.5 개체로 밝혀졌다. 전반적으로 포식은 말백합의 각장과 천공복족류 (큰구슬우렁이) 의 각폭 (shell width) 에 따라 다르게 나타나는 특징을 보였다.

Abstract

Boring caracteristics, boring rate, and predation, rates on the valves of the seed and adult clams of Meretrix petechialis by Glossaulax didyma didyma in the shellfish aquafarm and the indoor rearing aquarium were investigated by various morphometric data. The investigations were carried out from June to September, 2007. The morphology of drilled holes on the valves of M. petechialis showed the crater type as seen in the spats of Ruditapes philippinarum and M. lusoria. The sizes of the outer diameters of holes were greater than the inner diameters of the holes on the valves of M. petechialis in the shellfish aquafarm and the indoor aquarium at the laboratory. On the whole, the sizes of the holes on the valves of the seeds of M. petechialis was smaller than those bored holes on the adult valves. The location of the bored holes on the valves of the seeds varied widely with the the sizes of the individuals of M. petichialis, while most of holes on the valves of adult clams were located near the umbo position of the valves of the clams in the shellfish aquafarm and the indoor aquarium at the laboratory. On the whole, the outer and inner diameters of the bored holes increased with increase of shell lengths of the clams in the shellfish aquafarm and the indoor rearing aquarium at the laboratory. The authors could confirm experimentally the boring snail, G. didyma didyma, drilled the seeds and adult clams of M. petechialis. In the experiments for 15 days (three times repeated) in the indoor rearing aquarium at the laboratory, the mortality of dead shells to total shells of M. petechialis by boring snail Glossaulax didyma didyma was totally average 41.5%, and percent of drilled shells to total dead shells of clams by the boring snail was average 47.1%. Of total shells, percent of drilled shells to total shells of clams by the boring snail was totally average 19.3%. Predation of G. didyma didyma were greater at night than the day time. Average 0.5 seed and adult individuals of M. petewchialis were consumed per G. didyma didyma, per day. Predation varied with shell lengths of M. petechialis and shell widths of G. didyma didyma.

초록

연구는 양질의 피조개 수정란 확보와 안정적 종묘생산을 위하여 피조개 모패의 먹이생물로 미세조류 3종 (Isochrysis galbana, Tetraselmis tetrathele, Phaeodactylum tricornutum) 을 단독 또는 혼합 공급하여 먹이생물에 따른 피조개 모패의 비만도, 생식소발달, 성숙유도율 및 생존율을 조사하였다. 사육 45일 경과 후 피조개 모패의 완숙기 출현율, 성숙유도율 및 생존율은 3종의 미세조류를 혼합 공급하거나 T. tetrathele를 단독공급한 실험구에서 가장 높았다.

Abstract

Even though ark shell, Scapharca broughtonii is commercially important species, its artificial seed production is not yet fully developed. This study was carried out to understand the effect of three microalgal species on gonadal development and sex maturation of S. broughtonii in terms of broodstock management and food organism. Isochrysis galbana, Phaeodactylum tricornutum and Tetraselmis tetrathele were supplied to S. broughtonii broodstock in single or mixed. And condition index, gonadal development, sexual maturation and survival of the broodstock were analysed. After 45 rearing days, frequency of ripe stage of gonadal phases, rate of induced sexual maturation and survival of S. broughtonii broodstock fed mixed diet with 3 microalgal species or single diet of T. tetrathele were the highest.

초록

Abstract

Some characteristics of the formations of acrosomal vesicles during the late stage of spermatids during spermiogenesis and taxonomical charateristics of sperm morphology in male two species (Saxidomus purpurata and Meretrix petechialis) in the family Veneridae were investigated by electron microscope observations. In two species, the morphologies of the spermatozoa have the primitive type and are similar to those of other bivalves in that it contains a short midpiece with five mitochondria surrounding the centrioles. The morphologies of the sperm nuclear types of S. purpurata and M. petechialis in Veneridae have the curved cylindrical and cylinderical type, respectively. And the acrosome shapes of two species are the same cap-shape type. In particular, the axial filament is not found in the lumen of the acrosome of two species, however, subacrosomal material are observed in the subacrosomal spaces between the anterior nuclear fossa and the acrosomal vesicle of two species. The spermatozoon of S. purpurata is approximately 46-<TEX>$52{\mu}m$</TEX> in length, including a curved sperm nucleus (about <TEX>$3.75{\mu}m$</TEX> in length), a long acrosome (about <TEX>$0.40{\mu}m$</TEX> in length),and a tail flagellum (about 45-<TEX>$47{\mu}m$</TEX> long). And the spermatozoon of M. petechialis is approximately 47-<TEX>$50{\mu}m$</TEX> in length including a slightly curved sperm nucleus (about <TEX>$1.50{\mu}m$</TEX> in length), an acrosome (about <TEX>$0.56{\mu}m$</TEX> in length) and tail flagellum (44-<TEX>$48{\mu}m$</TEX> in length). In two species, the axoneme of the sperm tail flagellum of each species consists of nine pairs of microtubules at the periphery and a pair of cental doublets at the center. Therefore, the axoneme of the sperm tail flagellum shows a 9 + 2 structure. In particular, taxonomically important some charateristics of sperm morphologies of two species in the family Veneridae are acrosomal morphology of the sperm, The axial filament is not found in the acrosome as seen in a few species of the family Veneridae in the subclass Heterodonta. The acrosomal vesicle is composed of right, left basal rings and the apex part of the acrosomal vesicle. In particular, right and left basal rings show electron opaque part (region), while the apex part of the acrosomal vesicle shows electron lucent part (region). These charateristics belong to the subclass Heterodonta, unlikely a characteristic of the subclass Pteriomorphia showing all part of the acrosome being composed of electron opaque part (region). Therefore, it is easy to distinguish the families or the subclasses by the acrosomal structures. The number of mitochondria in the midpiece of the sperm of S. purpurata and M. petechialis in Veneridae are five. However, the number of mitochondria in the midpiece of the sperm in most species of Veneridae in the subclass Heterodonta are four. Therefore, the number of mitochondria of the sperm midpiece of two species are exceptionally 5, and it is only exceptional case in the species in Veneridae in the subclass Heterodonta. Except these cases, the number of mitochondria in the sperm midpiece in all families in the subclass Heterodontaare are 4, and now widely used in taxonomic analyses.