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1.
SEM observations on larval shell morphology of Manila clam Ruditapes philippinarum and their utility
Nariaki Inoue Ryogen Nanbu Natsuki Hasegawa Junya Higano Hisami Kuwahara Hideo Sekiguchi 《Fisheries Science》2012,78(6):1237-1243
Manila clam Ruditapes philippinarum is common and abundant on Japanese tidal flats, forming a commercially important clam fishery. However, annual catches of Manila clam have decreased drastically since 1975?C1985. To study larval recruitment processes of Manila clam, we carried out scanning electron microscopy (SEM) observations on larval and juvenile shells of clams reared at 20 and 24?°C. There was no significant difference in final shell length of trochophores between 20 and 24?°C. However, the larval duration was much longer and the shell length of settled size of pediveligers was much larger for clams reared at 20?°C than those reared at 24?°C. These findings suggest that larval duration and growth, as well as settlement size, may vary markedly depending on temperature (and probably on season). The larval shell morphology of Manila clam can provide essential information about larval recruitment processes. 相似文献
2.
不同近交系数蛤仔橙色品系的生长和成活研究 总被引：2，自引：0，他引：2
以不同遗传背景的蛤仔（Ruditapes philippinarum）橙色品系为材料,采用建立半同胞家系子一代H1（F=0.125）、全同胞家系子一代F1（F=0.250）、全同胞家系子四代F4（F=0.594）及自然对照组C1（F=0）的方法,进行了不同近交系数蛤仔橙色品系生长和成活的研究.结果表明,在整个养殖周期中F1组的壳长生长最慢,在稚贝期和养成期均显著小于F4和C1组（P＜0.05）,H1、F4和C1组之间的壳长生长差异不显著（P＞0.05）.C1组的成活率在整个养殖周期中为最小,除幼虫期3日龄外,其他各日龄均显著小于其他试验组（P＜0.05）,而H1、F1和F4组之间的成活率则差异不显著（P＞0.05）.试验组F1壳长生长的衰退率为2.92％ ～ 18.33％,平均值为（12.05±6.54）％,试验组H1在稚贝期、养成期显现出一定的衰退现象,而试验组F4在整个养殖周期中均未表现出近交衰退现象;各试验组的成活性状在各日龄均未出现近交衰退.该研究为橙色品系的选育奠定一定的理论基础. 相似文献
3.
缢蛏选育系F5的生长优势比较及育种效应分析 总被引：1，自引：1，他引：0
以6个缢蛏(Sinonovacula constricta)自然群体(浙江象山群体、浙江乐清群体、福建霞浦群体、福建长乐群体、江苏射阳群体和上海崇明群体)为材料,构建基础群体F_0,采用群体选育方法进行多代连续选育(选择强度2.063),比较了选育系F_5与对照群体的生长差异,并估计F_5的选择反应、现实遗传力和遗传获得。结果表明,F_5的卵径及受精率与对照组无显著差异(P0.05),但F_5的变态率、存活率及后期壳长生长明显优于对照组(P0.05);7~360日龄F_5壳长的选择反应、现实遗传力与遗传获得的变化范围分别为0.30~0.78,0.14~0.37和4.83%~42.18%,平均为(0.49±0.06),(0.23±0.08)和(26.49±11.73)%。研究结果表明,对缢蛏的连续多代选育是有效的,可以明显提高其存活能力和主要经济性状。 相似文献
4.
不同地理群体菲律宾蛤仔表型性状的相关性与通径分析 总被引：1，自引：0，他引：1
随机选取繁殖时期的南方群体北方养殖菲律宾蛤仔(SN)、北方土著品种(NN)和南方群体南方养殖蛤仔(SS),测量其壳长(SL)、壳高(SH)、壳宽(SW)、活体质量(mL)、软体质量(mM)和烘干后软体部干质量(mF),采用相关与通径分析方法分析不同地理群体的菲律宾蛤仔表型性状对软体质量的作用效果,为菲律宾蛤仔的选择育种提供理论依据和测度指标。试验结果表明,不同地理群体菲律宾蛤仔的形态学指标无显著差异(P>0.05);不同地理群体各数量性状之间的相关关系均达到极显著水平(P<0.01);决定系数分析表明,不同地理群体菲律宾蛤仔影响软体质量的主要表型性状并不相同,南方群体北方养殖蛤仔群体的壳宽直接作用最大,壳宽通过壳高的间接作用是次要因素;北方土著品种群体壳长是主要因素,壳长通过壳高的间接作用是次要因素;南方群体南方养殖蛤仔群体壳高的直接作用是主要因素,壳长通过壳高的间接作用是次要因素。对通径系数检验不显著的自变量进行删除,利用逐步回归的方法,建立不同地理群体菲律宾蛤仔软体质量的最优回归方程:SN群体,mM1=-4.276+0.211SH+0.116SW;NN群体,mM2=-2.806+0.088SL+0.087SH;SS群体,mM3=-3.101+0.290SH。回归方程分析表明回归关系均达到极显著水平(P<0.01)。 相似文献
5.
2004年5月至2005年4月对胶州湾菲律宾蛤仔（Rudimpes philippinarum）底播增殖区进行了逐月定点采样，将样品带回放于实验室内水族箱暂养，每站随机取样，共对3269个个体进行了基本生物学特性测定，研究了移植底播菲律宾蛤仔的生长、死亡等渔业生物学特性。结果表明，底播增殖菲律宾蛤仔苗种的平均个体质量0．26g、平均壳长11．1mm；底播蛤仔与野生蛤仔在生长规律上基本一致，春末至秋初（4～9月）是其主要生长期；1～3龄期间个体生长速度较快，1～2龄、2～3龄，个体质量分别增长3．88g和4．02g；1～2龄生物量增长最快，2～3龄由于死亡率增大，其生物量增长缓慢；1～3龄蛤仔软体部的生长速度快于贝壳，5～6月是菲律宾蛤仔的繁殖肥育期。根据个体生长特性，3龄为最佳采捕年龄；根据目前的养殖状况，2龄蛤仔已达到商品规格，从生物量上分析，采捕2龄蛤仔收益最高；6月是最佳的捕获时期。蛤仔生长具有明显的季节变化，水温是影响菲律宾蛤仔生长的主要环境因子。[中国水产科学，2006，13（4）：642—649] 相似文献
6.
The present work investigated the health status of the Manila clam in Ireland, with particular reference to brown ring disease
(BRD) caused by V. tapetis which has been responsible for high mortalities of this bivalve throughout Europe. BRD was diagnosed in Ireland in the 1990s,
causing heavy mortalities in Manila clam stocks in the north-west coast. In the current study, samples of clams from an Irish
hatchery were obtained and screened from two sites, Drumcliff Bay, Co. Sligo and Dungloe Bay, Co. Donegal. Turbellarians and
trematodes with some minor infections were the only parasites observed. Clams were examined for BRD, by analysis of shell
valves for brown ring signs, and for V. tapetis by microbiological methods and by polymerase chain reaction (PCR). BRD was not diagnosed in cultivated clams from either
site. It was, however, diagnosed in residual clams, which had survived the initial outbreak of BRD in the 1990s in Dungloe
Bay. V. tapetis, however was detected in clams from both sites. Additionally, BRD was diagnosed, and V. tapetis isolated, in a once-off sample of clams from Mulroy Bay, Co. Donegal, where clams had been on-grown from imported seed. Minor
heterogeneity at the 16S rDNA gene was observed between some sequenced products from Mulroy Bay and from Drumcliff Bay and
Dungloe Bay indicating that in addition to V. tapetis, a V. tapetis-like strain may have been present in Mulroy Bay. The detection of V. tapetis in asymptomatic clams in Drumcliff Bay and Dungloe Bay may indicate that disease development may only occur when a number
of factors combine to induce disease symptoms. 相似文献
7.
Infection with Perkinsus species, primarily P. olseni, is thought to be a major cause of the decline of Manila clam populations in Japan since the 1980s. However, the pathogenicity of the infection has not been sufficiently evaluated to estimate the impact of infection on wild Manila clam populations. We experimentally challenged juvenile (3- to 6-mm shell length) and adult (18- to 22-mm shell length) Manila clams with P. olseni at 18, 23, 28, and 30 °C. Mortality was significantly higher in challenged groups than in control groups. The difference in mean mortality between the challenged and control groups (all life stages and temperatures) was only significant above a threshold of infection intensity ~106 cells/g soft wet tissue (SWT). As temperature increased, the onset of mortality occurred more rapidly. The increase in mortality occurred earlier in juveniles than adults at 28 °C and lower. Our results suggest that the pathogenicity of P. olseni is higher in juveniles than in adults and at higher water temperatures. Given the infection intensities (ca. 106 cells/g SWT) previously reported in wild Manila clams, the parasite likely has considerable impact on wild Manila clam populations, particularly juveniles during periods of high temperature. 相似文献
8.
Soft shell clams, Mya arenaria, are found from Canada to North Carolina on the U.S. Atlantic Coast and from Canada to California on the U.S. West Coast. They are also found in several other parts of the world including Europe. The primary market for these clams on the U.S. East Coast is in New England. Clams are sold whole live or in one of the several cooked forms. Commercial soft clam shucking and processing is primarily by manual methods. However, physical properties data for these clams is lacking and is a constraint on the automation of processing. Several properties of soft shell clams harvested from five different harvest locations in the Chesapeake Bay are detailed in this paper and relationships between the components of the clam are defined mathematically through regression equations. The live weight and the clam length are related to shell weight, siphon weight, meat weight, total solids and free water in the clams. Meat yields under both standard processing methods and for clams steamed and consumed with only the shell removed are detailed. The effect of harvest area on the clam parts is also defined. Soft shell clams shucked manually result in a meat yield of approximately 29% of the live weight. If steamed and eaten the meat yield may be as high as 43% of the live weight, primarily because the siphon is often consumed in steamed clams. 相似文献
9.
不同地理群体菲律宾蛤仔的选择反应及现实遗传力 总被引：5，自引：1，他引：4
对不同地理群体的3龄菲律宾蛤仔(Pp莆田群体、Dp大连群体、Tp东京群体)进行了混合选择。测量了各实验组的壳长,计算了不同地理群体菲律宾蛤仔的选择反应和现实遗传力。结果表明,3个地群体菲律宾蛤仔子代的上选组壳长显著大于对照组(P<0.05)。在不同生长发育阶段,菲律宾蛤仔的选择反应(R)和现实遗传力(hR2)随着日龄的增大而减小,即R幼虫培育期0.804±0.084>稚贝期0.705±0.039>养成期0.671±0.024;hR2幼虫期0.458±0.051>稚贝期0.402±0.025>养成期0.382±0.013。从总体水平上分析,菲律宾蛤仔R为0.726±0.1074,莆田群体、大连群体、东京群体的R分别为0.758±0.101、0.690±0.049、0.732±0.059;hR2为0.414±0.044,莆田群体、大连群体、东京群体的hR2分别为0.432±0.058、0.393±0.028、0.417±0.033。地理群体间的R和hR2次序为莆田群体>东京群体>大连群体,且彼此间无显著差异。 相似文献
10.
Samples of Manila clam (Ruditapes philippinarum Adams & Reeve 1850) were collected from May 2004 to April 2005 monthly, and plankton net trawling of planktonic larvae and bottom sediment sampling surveys were further conducted from May to October 2006 in Jiaozhou Bay. Based on the data collected, growth, mortality and reproduction of the transplanted Manila clam and the environmental effects were examined. The results showed that the enhanced clams grew well and showed a growth trend similar to the local wild ones. The main growth periods lasted from April to September, with the water temperature being the main factor affecting the growth, which was the same as that of the wild clams. There were also two reproduction cycles for the farmed Manila clams each year in Jiaozhou Bay and the main breeding period was from May to June. The phenomenon of delayed metamorphosis was quite common through larval development. The farmed clams could spawn when they reached sexual maturity, but they could not perform effective recruitment as many planktonic larvae died during metamorphosis and settlement. A preliminary study indicated that sediment perturbation and marine environment pollution were the main factors causing the death of larvae in the development process. 相似文献
11.
A number of approaches have been utilized for growing bivalve hatchery seed (1 mm) to a size suitable for field planting (< 8 mm) but few have been directly compared. This study evaluated the growth and survival of northern quahog seed in three different culture systems and two different stocking densities. The three systems were: 1) a stacked-tray unit with downward water flow; 2) traditional upweller culture units with water flowing upward without seed bed expansion; and 3) upweller culture units with water flowing upward at fluidization velocities to provide seed bed expansion. The two stocking densities were 1.0 and 3.0 g whole wet weight clam/cm2 respectively. During each trial period the seed clams were fed a 1% daily ration (% dry weight algae per wet weight clam per day) of the cultured diatom Chaetoceros muelleri . After 14 d of culture at the 1.0 g whole wet weight/cm2 stocking density, seed clams (4.4 ± 0.6 mm initial shell length) under fluidized-flow condition exhibited better growth (0.54/d), and a greater final shell length (5.9 ± 1.0 mm). At the high density stocking conditions, after 28 d of culture, seed clams (4.2 ± 0.6 mm initial shell length) in the fluidized-flow culture conditions again exhibited better growth rate (0.031/d) and a greater final shell length (6.0 ± 1.0 mm). The preliminary evaluation of fluidized-flow for seed clam culture in land-based nurseries indicates its potential as a suitable alternative to raceway, downwelling, or traditional forced-flow culture methods. 相似文献
12.
The breeding potential and biochemical composition of triploid Manila clams, Tapes philippinarum Adams and Reeve 总被引：1，自引：0，他引：1
In 1989 and 1990. triploid Manila clam, Tapes philippinarum Adams and Reeve, seed were reared to 15-20 mm at the Fisheries Laboratory, Conwy, and planted out in the Menai Strait, North Wales. In each of the summers of 1992 and 1993, three of these batches, at 2, 3 or 4 years old, were returned to the laboratory to assess ploidy, size, spawning potential and biochemical composition. Percentage triploidy at this time was similar to that in the seed. After 6 and 8 weeks of warmwater conditioning. Only 45 out of l21 triploids (37%) were induced to spawn by thermal shock, with only one spawning as a male. By comparison, 75% of diploid clams spawned with a 1:1 ratio of males to females. Mean fecundity of triploids was significantly lower than that for diploids, at 0.497 compared with 1.54 million eggs per female. Compared with eggs from diploid females, eggs from triploids were larger and significantly fewer of them developed into D-larvae when fertilized by sperm from diploid males. Triploid clams were heavier and had a higher condition index and carbohydrate content than diploids of the same age, but lipid levels were similar. Potential advantages of producing and cultivating 100% triploid batches of Manila clam seed are discussed. 相似文献
13.
菲律宾蛤仔人工选育群体与野生群体的遗传多样性分析 总被引：2，自引：1，他引：1
本研究利用10对微卫星标记对菲律宾蛤仔(Ruditapes philippinarum)人工选育群体与野生群体进行遗传多样性分析。结果表明,每个位点的等位基因数为3~12个,期望杂合度范围为0.307~0.757,观测杂合度范围0.208~0.583。等位基因丰富度AR的大小范围是3.0~10.7,PCR扩增产物片段大小在178~390 bp,共得到63个等位基因,平均等位基因数范围从4.4(白蛤)到5.1(龙王塘野生群体),野生群体等位基因丰富度最大(5.278),白蛤群体的等位基因丰富度最小(4.267)。哈迪–温伯格检验发现4个群体和10对微卫星的40个组合中,有21个组合显著偏离哈迪–温伯格平衡状态。Kruskal-Wallis检验表明各个群体间的平均等位基因丰富度无显著差异。4个群体遗传分化系数F_(st)在0.086~0.180,遗传分化最大的是白斑马蛤群体与龙王塘野生群体(F_(st)=0.180),遗传分化最小的是白蛤群体和海洋橙群体(F_(st)=0.086)。人工选育群体表现为中度分化水平(F_(st):0.086~0.113);龙王塘野生群体与人工选育群体表现为较大分化水平(F_(st):0.134~0.180)。结果表明,人工选育群体的遗传多样性仍然比较高,但连续的选育对群体的遗传多样性和遗传分化有一定程度的影响。 相似文献
14.
Maria C Haws Puá alaikahonihò omau Pascua Robert Howerton Angela Hi'ilei Kawelo Keliiahonui Kotubetey 《Aquaculture Research》2014,45(2):312-319
Abundance, length‐frequencies and distribution of Ruditapes philippinarum (Manila Clams) and Tellina (Quidnipagus) palatum were measured at two beaches in Kāne'ohe Bay, O'ahu, Hawai'i in June, 2010. Abundances had decreased from 866.2 m?2 to 3.4 m?2 for Ruditapes and from 75.5 m?2 to 1.5 m?2 for T. palatum since 1977. Distribution of both species was patchy, but both were most commonly found >40 m from shore. Size frequencies of live clams compared with empty shells suggest that few Ruditapes survive to sexual maturity. A similar trend was not detected for T. palatum. Aquaculture trials of R. philippinarum were conducted at the He'eia and Moli'i traditional Hawaiian fishponds in the same bay. The clams failed to thrive, although triploid and diploid Crassostrea gigas performed well in concurrent trials in the same fishponds. Current lower abundances for wild R. philippinarum could be due to factors related to predation or nutrient limitations. Previously, two large sewage outfalls existed at the surveyed clam bed areas which may have temporarily increased nutrient availability for both wild and cultured clams. Current nutrient levels may inhibit Manila clam growth and recruitment in Kāne'ohe Bay. 相似文献
15.
为评估文蛤生态容量,实验根据动态能量收支理论,基于R语言构建了文蛤动态能量收支模型,采用线性与非线性回归法估算模型参数,通过对比围塘环境下文蛤壳长、湿重、软体部湿重的实测值与模拟值验证模型,并应用于模拟黄海海域滩涂区文蛤的生长过程。结果显示,文蛤模型主要参数形状系数、阿伦纽斯温度系数和单位体积结构物质所需能量分别为0.57、9 278 K和2 056 J/cm3;实测与模拟的文蛤壳长、湿重和软体部湿重相关系数R2平均为0.996,模拟值与实测值的平均误差为3.58%;如东沿海区域6月实测文蛤软体部干重为0.48 g,壳长3.12 cm,模型模拟的软体部干重、湿重和壳长分别为0.476 g,6.6 g和3.2 cm。研究表明,实验构建的文蛤动态能量收支模型的准确度较高,可真实地反映出文蛤在自然水域中的生长过程,为评估文蛤生态容纳量及构建文蛤相关的生态系统模型提供科学参考。 相似文献
16.
To determine whether genetic improvement can be attained through a selective breeding programme, divergent selection for shell length was applied to two stocks of Haliotis diversicolor. Stock A was descended from the cross between males from a Japanese wild population and females from a Taiwan aquacultured population and Stock B was from the Taiwan cultured population, which had been successively cultured in mainland China for about 10 generations. The 10% largest and 10% smallest abalones for each of these two stocks were selected as parents for the large‐selected and small‐selected lines respectively. Equal numbers of abalone were randomly chosen from the two stocks to serve as parents for the control lines before the selection. The selected and control lines were reared under the same conditions at early juvenile, later juvenile and grow‐out stages. Stock A showed a significantly higher response to selection and realized heritability than Stock B (P<0.01). The large‐selected line of Stock A and Stock B grew 12.79% and 4.58% faster than their control lines on shell length respectively. The average realized heritability for shell length was 0.441±0.064 for Stock A and 0.113±0.013 for Stock B. Responses to selection were different at different ages in each stock and the body weights of the selected lines were significantly different from the control lines in both stocks at the grow‐out stage. Asymmetric responses to selection in the two directions were also observed in both stocks. Differences in response to selection and realized heritability between the two stocks are presumably due to genetic variability. 相似文献
17.
干露及淡水浸泡对菲律宾蛤仔稚贝生长和存活的影响 总被引：4，自引：0，他引：4
于2004年3—5月研究了干露及淡水浸泡对菲律宾蛤仔稚贝生长及存活的影响。试验结果表明,(1)同种规格稚贝耐干露和淡水浸泡能力随着温度升高而下降;相同温度下,不同规格稚贝耐干露能力随规格的增加而增大,耐淡水浸泡能力在稚贝壳长9.5mm时,随规格增大而增大,当稚贝规格9.5mm时,耐淡水浸泡能力随规格的增大而减小。(2)经干露和淡水浸泡的稚贝在开始7d内生长缓慢,生长速度远不及未经处理的稚贝,7d后各种规格的稚贝生长明显加快,达到、甚至超过未经处理稚贝的生长速度,存在补偿生长现象。 相似文献
18.
ABSTRACT: The effect of various tooth spacing on the contact selection and the net-mouth available selection of a dredge for the equilateral Venus clam Gomphina melanaegis is evaluated by applying a contact-probability model based on the SELECT method to the data of paired-gear tests with a control dredge of 12-mm tooth spacing and four test dredges of tooth spacing 16, 20, 24 and 35 mm. A master selection curve was estimated to be s ( R ) = exp(−11.23 R + 4.799)/(1 + exp[−11.23 R + 4.799]) where, R is l / d , the ratio of the shell length, l , to the tooth spacing, d . The shell width of 50% retention was slightly smaller than the tooth spacing, which means that size selectivity of teeth was a type of contact selection which was dependent on the tooth spacing. Contact probability, δ, of the clams coming into contact with the teeth were 0.625, 0.467, 0.563, 0.670 and 0.976 for tooth spacing 12, 16, 20, 24 and 35 mm, respectively. This indicates that some clams entered the dredge bagnet without contacting the teeth as the sand clogging the tooth spacing carried them into the bagnet. Available selection curve of the dredge net-mouth with teeth was obtained as δ s ( R ) + 1 − δ , and examined in terms of the legal landing size of the Venus clam. 相似文献
19.
This work reports on the effects of intertidal planting heights upon the growth and survival of the northern quahog, Mereenaria mercenaria (L.) and the Atlantic sod clam, Spisula solidissima (Dillwyn), in the castal waters of Georgia. Quahogs (N = 100 per cage) at 19.5 mm in shell length were planted in replicate cages (N = 3) placed at the spring (SLW), mean (MLW), one (+1), two (+2), and three (+3) hours above mean low water mark. Surf clams (N = 200 per cage) at 41.5 mm in shell length were placed in replicate cages (N = 3) deployed, as above, in all sites except +3. Quahogs grown at the SLW mark after 15 months were significantly larger than clams planted at other tidal heights. Quahogs planted at the MLW mark were significantly greater in shell length than those planted at the +3, +2, and +1 marks. Clams at the upper three sites were not significantly different in size. An inverse relationship between clam growth and intertidal planting height was evident among surf clams. Surf clams grown at the SLW mark for six months were signplificmtly larger than those at the MLW mark which were larger than those grown at the +1 above MLW mark. No significant differences in quahog survival were detected between intertidal planting sites. There was no significant difference in surf clam survival between SLW (77.5%) and MLW (61%) marks, but there was significantly lower survival at the +1 mark (15%) and no survival at the +2 mark. 相似文献
20.
为比较文蛤红壳色选育系与江苏野生群体在不同条件下滤水率的差异并找出文蛤最佳滤水率条件,采用了试验生态学方法和响应面法对文蛤红壳色选育系幼贝进行滤水率的研究。试验结果显示,在一定范围内,文蛤幼贝滤水率随盐度、温度和藻类密度的增加而增大,超过一定范围,幼贝滤水率随盐度、温度和藻类密度的增加而减小;在同等条件下,文蛤红壳色选育系幼贝与野生群体滤水率无显著差异,但文蛤红壳色选育系生长速率显著高于野生群体;通过响应面法优化,文蛤红壳色选育系幼贝的最佳滤水率条件为:盐度21.82、温度27.40℃、藻类密度9.96×10^4个/mL,此条件下滤水率的预测值为1.62 mL/(个·min)。 相似文献