Metabolic characteristics of the Japanese clam Ruditapes philippinarum (Adams & Reeve) during aerial exposure

Some metabolic end‐products in tissues and physiological parameters of haemolymph of the Japanese clam Ruditapes philippinarum (Adams & Reeve) were investigated under aerial exposure at 15 °C with low relative humidity (RH) (22%) or high RH (91%). Acclimated clams in water at 15 °C were used as a control and to supply the low or high RH experiment. The low RH experiment was conducted at air exposure for 50 h (LH₅₀), and the high RH experiment for 50 h (HH₅₀) and 100 h (HH₁₀₀). Accumulation of succinate and alanine in the tissues proved that the clam shifted its metabolism to anaerobiosis. Lactate accumulation did not occur. Glucose concentrations in tissues increased slightly during exposure except for HH₅₀. The total free amino acid contents (363–410 μmol g^?1) were higher than those of glucose (530–804 μmol 100 g^?1), suggesting that the free amino acids might play a more dominant role in the metabolism. Increase in the haemolymph pco ₂ did not influence the acid–base balance in the haemolymph during exposure at both humidity conditions. Increase in the haemolymph ammonia from 48.2 to 57.1 μmol 100 g^?1 and to 131.0 μmol 100 g^?1 at LH₅₀ and HH₁₀₀, respectively, suggested that ammonia might function as an important buffering factor during aerial exposure. Retention values of the haemolymph po ₂ even at the longest exposure time (16.30 mmHg at LH₅₀ and 14.69 mmHg at HH₁₀₀) indicated that the clams depend partially on some aerobic manner.     

Growth,mortality and reproduction of the transplanted Manila clam (Ruditapes philippinarum Adams & Reeve 1850) in Jiaozhou Bay

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.     

Observations on simulated depuration trials with Manila clam, Tapes philippinarum Adams and Reeve

Simulated depuration trials with Manila clams. Tapes philippinarum Adams and Reeve, were undertaken to test the effect of stocking density, seasonal temperature, water flow rate, salinity and the addition of cultured algae on oxygen levels and some other variables of water quality. Equations produced by multilinear regression analysis provided useful systems-management information for predicting the conditions required to maintain oxygen levels within known limits for satisfactory depuration of other commercial species of bivalve molluscs in temperate climates.     

Effect of dried algae diets on conditioning and fecundity of Manila clam, Tapes philippinarum (Adams and Reeve)

Abstract The effectiveness of live-algae replacement diets for the conditioning and spawning success of adult Manila clam, Tapes philippinarum (Adams and Reeve), was assessed. Two dried diets were tested: a diet of dried Tetrasetmis suecica (Kylin) Butch, and a mixed diet of dried T. suecica (70%) and dried Cyclotella cryptica Reimann et al. (30%). These diets were compared with three live diets: Skeletonema costatum (Grev.) Cleve, Dunaliella tertiolecta (Butcher) and T. suecica. An unfed group was used as a control. The same ration (dry weight) of food was supplied for all groups at 6% of the dry meat weight per day. The broodstock were conditioned for 7 weeks. After 4 weeks none of the animals was ready to spawn. After 6 weeks all the diets promoted spawning and after 7 weeks the unfed group also spawned. It seems that dried algal diets are effective for conditioning and spawning of Manila clams, as the dry meat weight, condition index and fecundity of broodstock fed these diets were significantly greater than for unfed animals. However, the fecundity and proportion of parental lipid released in the eggs of clams conditioned with dried diets was lower than for the clams conditioned with live algae.     

氯霉素在菲律宾蛤仔体内生物富集和残留消除规律的研究

在半静态条件下,研究了氯霉素在菲律宾蛤仔体内富集和消除规律。试验结果表明:菲律宾蛤仔对水体中氯霉素的富集能力较低,内脏团和肌肉部分的富集系数1.8;氯霉素的蓄积量随时间的延长和给药浓度的增加而增加,在6~8 d可趋平衡;各部位的富集和消除情况存在明显差异,内脏团的富集速度快于肌肉,肌肉的生物学半衰期长于内脏团。     

Condition index and air survival time to compare three kinds of Manila clam Tapes philippinarum (Adams & Reeve) farming systems

The effects of maintaining the burrowing Manila clam in suspended culture in the sea on flesh weight changes or on condition are not yet known. This work analyses these effects using the condition index and the air survival time of clams. Samples of clams submitted to three different treatments (traditional farming on the lagoon bottom, lagoon suspended culture and open sea suspended culture) were investigated between July and November. The most sensitive of the eight condition indices for comparing the three different breeding systems was AFDW/SV. From the Tukey test (two-way ANOVA), AFDW/SV, exhibited the highest number of significantly different (P < 0.05) cases in a comparison between the month/treatment interactions. This index showed the highest values in lagoon suspension, whereas there was not much difference between bottom farming and sea suspension until after a four-month period: in November the suspended individuals recovered condition, whereas a fall was recorded in the traditional farming area. As regards air survival time, individuals in sediment were more resistant, except in November, when lagoon suspended ones were hardier. Suspended culture, which is necessary for hygiene and health reasons to market the product, is an advantageous necessity for farmers in both lagoon and sea, especially over periods of several months.     

低温对菲律宾蛤仔能量收支的影响

在实验室内采用静水法，测定了在315和8℃下，菲律宾蛤仔的耗氧率和排氨率与体重的关系及其能量收支情况。实验数据显示，在实验的温度范围内，菲律宾蛤仔的耗氧率和排氨率都与体重负相关；温度对耗氧率的影响与体重有关。摄食率、生长率（净生长率、毛生长率）与温度正相关。温度对能量分配影响较大，代谢分配率、排粪分配率随温度的升高而降低，且变化极其显著（P＜0.01)；生长分配率随温度的升高而增大。在能量收支方程中，排粪能所占比例较大，在41.131%-60.69%之间，代谢能在23.37%－32.73%之间，生长能在6.13%-34.63%之间，排泄能所占的比例最小，低于3％。     

菲律宾蛤仔土池人工育苗试验报告

于１９９５年５～８月，利用对虾养殖土池乾地菲律宾蛤仔人工育苗试验，将２００亩土 池经清淤，铺沙等改造后使用。作了蛤仔的亲贝蓄养，诱导产卵，受精孵化和浮游幼虫培养，获得附着稚贝平均为２３１０万粒／亩，面盘幼虫至附着稚贝的成活率为１１．６％，试验结果表明，在北方地区用土池培育蛤仔种苗是可行的。     

Sprinkling: a new method of distributing live algae food in marine coastal ponds used for Manila clam Tapes philippinarum (Adams & Reeve) intensive culture

Sprinkling, an agricultural irrigation technique, has been tested for the intensive culture of Manila clams up to marketable size (35-50 mm) in coastal ponds 400 m² in area. The sprinkling system is used for the distribution of seawater and live algal food Skeletonema costatum (Grev.) Clev. Sprinkling is a simple, low cost and efficient method of food distribution which resolves the major problem of decreasing bivalve growth associated with single point water entry in small-scale raceways. Uniform growth obtained with sprinkling is principally due to an even scattering of food over the whole surface area of large-scale ponds.     

Horizontal and vertical variations in survival rates of juvenile bivalves,Anadara kagoshimensis (Tokunaga, 1906), Ruditapes philippinarum (Adams & Reeve, 1850) and Atrina sp., experimentally caged in the inner area of the Sea of Ariake,Japan

International Aquatic Research - In the inner area of the Sea of Ariake, rearing experiments were conducted to examine how the survival rates of juveniles of three bivalve species (Anadara...     

Effects of temperature and salinity on oxygen consumption and ammonia excretion in different colour strains of the Manila clam,Ruditapes philippinarum

The metabolic responses of different colour strains of Ruditapes philippinarum in terms of oxygen consumption and ammonia excretion to changes in temperature (15–35°C) and salinity (20–40) were investigated. In our range of temperatures (15–35°C), oxygen consumption rate (OCR) increases in cultivated strains (White and Zebra) in opposition to the effect in the wild strain which reach a maximum at 25°C. The highest Q₁₀ coefficients were 2.741 for zebra strain, 4.326 for white strain, and 1.944 for wild at temperatures of 25–30, 30–35 and 20–25°C respectively. In our range of salinity (20–40°C), OCRs of white strain and zebra strain firstly decreased to lowest level at 25 and 30, and then increased to highest level at 35 and 40 respectively. When the salinity is beyond 35, the OCR decreased and the turning point was found in the white strain and wild, but the zebra strain OCR still increased to a highest level (1.906 mg g^?1 h^?1) at 40 (P < 0.05). These results show that the cultivated colour strains of R. philippinarum were different from wild in terms of metabolic responses, and information on its response to different temperature and salinity have implications in the aquaculture industry.     

Larval recruitment of the manila clam Ruditapes philippinarum in Ariake Sound, southern Japan

ABSTRACT: The mechanisms by which catch yields of the manila clam Ruditapes philippinarum have decreased drastically in Kumamoto Prefecture, southern Japan, and the larval recruitment by which benthic populations of the clam are maintained were studied. Samples at different growth stages (planktonic larvae, new settlers, and small to large bivalves of the species) were collected from February 1997 to December 1998 on two tidal flats (Kawaguchi and Nameishi, 20 km distance from each other) along the eastern coast of Ariake Sound. Densities of planktonic larvae, new settlers and small bivalves were generally higher at Kawaguchi than Nameishi. The higher density of large bivalves at Kawaguchi depends on a high larval density. Larval retention mechanisms coupled with water movement at Kawaguchi, such as tidal residual currents, may be related intimately with the higher larval density at Kawaguchi. Predation by shore birds at and after recruitment may be related to the lower density of large bivalves recorded at Kawaguchi in 1998, despite larval densities being higher there.     

The breeding potential and biochemical composition of triploid Manila clams, Tapes philippinarum Adams and Reeve

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.     

不同地理群体菲律宾蛤仔的选择反应及现实遗传力

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。     

SEM observations on larval shell morphology of Manila clam Ruditapes philippinarum and their utility

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.     

胶州湾菲律宾蛤仔生态容量评估及其碳汇功能

胶州湾是我国重要的菲律宾蛤仔(Ruditapes philippinarum)养殖基地,为探究湾内菲律宾蛤仔的生态容量及其碳汇功能,本研究采用Ecopath模型法评估了胶州湾菲律宾蛤仔的生态容量,并利用Ecosim模块动态分析了菲律宾蛤仔生物量扩大对胶州湾生态系统结构与功能特征的潜在影响,同时估算了胶州湾菲律宾蛤仔个体及种群水平的碳收支情况。结果显示,胶州湾菲律宾蛤仔的生态容量为239.9 t/km2,虽然整体水平尚未达到生态容量,但局部养殖区域已远超出了菲律宾蛤仔的生态容量;当胶州湾菲律宾蛤仔生物量从当前增加至生态容量时,生态系统总流量、容量、优势度和循环指数分别提高了16.0%、3.9%、47.1%和103.0%,而熵值降低了10.4%,表明此时生态系统具有更高的成熟度与稳定性,但菲律宾蛤仔生物量扩大至生态容量10倍时会对生态系统产生不利影响甚至崩溃;菲律宾蛤仔个体在1个养殖周期内约摄取3 310.1 mg C,其中约46.2%的碳沉降至海底,约13.2%的碳通过收获移出,如按菲律宾蛤仔生物量达到生态容量时计算,胶州湾每年将有1.5万t碳以生物沉积形式沉降至海底,有0.6万t碳以收获形式移出。研究结果为指导菲律宾蛤仔增养殖产业的健康可持续发展、阐明菲律宾蛤仔的碳汇功能提供了理论依据与数据支撑     

胶州湾移植底播菲律宾蛤仔的生长和死亡特性

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]