三种饲料对卵形鲳鲹幼鱼消化酶活性的影响

[目的]探讨饵料与卵形鲳鲹幼鱼消化酶活性的关系。[方法]以浮性饲料、沉性饲料、鱼浆加鳗粉喂养卵形鲳鲹幼鱼21d后,比较了3种饵料对胃、肠、肝胰脏和幽门盲囊消化酶活性的影响。[结果]胃、肠和幽门盲囊蛋白酶均以摄食鱼浆加鳗粉组增加幅度最大,肝胰脏蛋白酶以摄食浮性饲料增加幅度最大,蛋白酶活性均以摄食沉性饲料增加幅度最小。胃淀粉酶以摄食沉性饲料组增加幅度最大,肠、肝胰脏和幽门盲囊淀粉酶均以摄食浮性饲料增加幅度最大,淀粉酶活性均以摄食鱼浆加鳗粉组增加幅度最小。胃、肠、肝胰脏和幽门盲囊脂肪酶均以摄食鱼浆加鳗粉增加幅度最大,均以摄食浮性饲料增加幅度最小。[结论]该研究结果对合理配合饲料养殖有一定的指导作用。     

Summer mortality of hatchery-produced Pacific oyster spat (Crassostrea gigas). I. Estimation of genetic parameters for survival and growth

The multidisciplinary project “MOREST” aims to improve our understanding of causes of summer mortality in Crassostrea gigas juveniles in France and to reduce its impact on oyster production. As part of the MOREST project, 43 full-sib families nested within 17 half-sib families were produced, planted out and tested in 3 sites during summer 2001 to assess to what extent genetic variability exists for this trait. A strong genetic basis was found for survival as narrow-sense heritability estimates ranged from 0.47 to 1.08, with higher values in sites where summer mortality was higher. Genetic correlations across sites were positive and very high for survival, indicating no genotype by environment interaction. In contrast, lower genetic variation was observed for growth in all sites. Finally, genetic correlations between growth and survival were low, in all sites. Selective breeding in a single site should therefore be an efficient means of improving survival in oysters less than one year old along the French Atlantic and Channel coastlines with only very limited effects on growth. As yield mostly depends on survival and growth, this approach should significantly improve harvestable yield. Possible reasons why a high genetic variance for survival appears to be maintained in wild populations are discussed.     

Fouling and predation; how do they affect growth and survival of the blacklip pearl oyster, Pinctada margaritifera, during nursery culture?

This paper reports on 5 experiments conducted to assess the effect of cleaning regime and predation on growth and survival of blacklip pearl oyster (Pinctada margaritifera) juveniles in north Queensland, Australia. P. margaritifera juveniles with a mean (±SE) dorso-ventral shell height (DVH) of 4.5 ± 0.1 mm were placed into plastic mesh trays and cleaned either every 4 or 8 weeks or left uncleaned for 16 weeks. Cleaning regime had a significant effect on growth and survival (P < 0.005). Lowest DVH (16.2 ± 1.0) was shown by oysters in uncleaned trays during 16 weeks compared to oysters in cleaned trays; however, there was no significant difference in DVH between oysters held in trays cleaned every 4 (19.4 ± 1.2) or 8 weeks (21.2 ± 0.8). In contrast lowest survival was shown by oysters held in trays that were cleaned every 4 weeks (30 ± 5%), but no differences were noted between oysters cleaned every 8 weeks (63 ± 4%) and oysters that were left uncleaned for 16 weeks (75 ± 8%). Predators of P. margaritifera in northern Australia included crabs, stomatopods, flatworms, gastropods and fish. The stomatopod, Gonodactylus falcatus, was the most destructive predator with individuals consuming in excess of 20 juvenile pearl oysters per week. The leather jacket, Paramonocanthus japonicus, did not kill pearl oysters, but trimmed the margin of oysters shells significantly reducing DVH when compared to control groups cultured without fish. Removing predators monthly had a significant effect on growth of pearl oysters compared to oysters in non-inspected trays; however monthly inspection of culture trays did not significantly improve oyster survival. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of temperature regime on the respiratory activity of developmental stages of Lumbricus rubellus (Lumbricidae)

Rates of carbon dioxide production of cocoons, juveniles and matures of Lumbricus rubellus were measured at five constant (2°C, 5°C, 10°C, 15°C, 20°C) and three diurnally fluctuating temperature regimes (0–10°C, 5–15°C, 10–20°C) covering the whole range of temperature conditions experienced by this species in forests in Central Germany. Respiration rates of developmental stages significantly increased with temperature both under constant and fluctuating regimes. Overall, at constant temperature regimes Q₁₀ values for cocoons, juvenile and mature earthworms were 1.6, 2.7 and 2.0, respectively. At fluctuating temperature regimes Q₁₀ values were generally higher with 2.4, 3.6 and 3.5 for cocoons, juvenile and mature earthworms, respectively. At the same mean temperature respiration rates at fluctuating regimes exceeded those at constant regimes in all developmental stages.     

莱州湾黄河口近岸幼鱼食物结构与饵料重叠

菜州湾黄河口区幼鱼可分为浮游动物食性、底栖动物食性、混合食性和游泳动物食性４个类群。主要饵料生物为浮游动物、长尾类和仔幼鱼。浮游动物食性和游泳动物食性类群饵料重叠最严重,重叠系数在０．０９以上。底栖动物食性类产有一定的偏离,重叠系数在０．４５～０．７２之间。小黄鱼、虎鱼类等幼鱼由于都以摄食长尾类和仔幼鲑为主,重叠系数在０．８以上。幼鱼的营养级在２．１～３．２之间平均比海成鱼营养级低０．４３。这是由     

A study of the pattern of digestive enzymes in Diplodus puntazzo (Cetti, 1777) (Osteichthyes, Sparidae): evidence for the definition of nutritional protocols

The digestive enzymes (proteases, carbohydrases and lipases) present along the alimentary tract of juveniles and adults of Diplodus puntazzo were studied. The data obtained showed a different distribution of the enzymatic activities in the different parts of the alimentary tract. Levels of enzymatic activity in the adults were higher than those measured in juveniles, suggesting that adults have a greater ability to digest larger pieces of food. The enzymatic pattern of D. puntazzo justifies its omnivorous habit and suggests an high potential for digesting vegetable polysaccharides. The results of this study suggest the need to adapt the diet to the digestive potential of this new farming species, thus contributing to the attainment of a product that is qualitatively more similar to the wild one.     

Morphological changes of digestive structures in starved tench Tinca tinca (L.) juveniles

The aim of the study was to evaluate the effect of short-term starvation on the morphology of the digestive system of juvenile tench Tinca tinca (L.). The morphological changes in digestive structures of juveniles, fed 70 days starter or Chironomidae larvae, were examined after 1, 12, 24 and 48 h of starvation at 28 °C. The morphological changes in the organisation of the digestive structures were as follows: (1) Intestine – proteolysis of the intestinal mucosa, especially of enterocytes in apical part of mucosal folds; (2) Liver – progressive reduction of lipid vacuoles and glycogen granules, and, in effect, volume reduction of hepatocytes cytoplasm; (3) Pancreas – progressive degeneration of exocrine pancreatic cells, parallel with decrease of zymogen activity. The fish fed natural food prior to starvation seem to be more resistant to starvation than those fed starter.     

Does overfeeding affect tench Tinca tinca (L.) juveniles?

Duplicate groups of tench (Tinca tinca) juveniles (mean weight 0.69 g) were fed at 28 °C for 70 days either a commercial formulated diet, Futura, or frozen Chironomidae larvae at four levels: below satiation, at about satiation, above satiation and well above satiation. These are represented by the feeding groups F1–F4 and C1–C4, respectively. No mortality was observed throughout the experiment. In groups F2–F4 a considerable incidence of uneaten food (>40% observations), deformities of the caudal penduncle, retarded growth, elevated condition coefficient (>1.2), reduced amounts of minerals in the tissue (<10% dry matter), high C/N ratio (>5) and high caloric value of the tissue (>28 J mg⁻¹ dry matter) (the latter two suggesting excessive fat deposits), were found. The combination of these indices was indicative of overfeeding in fish fed the Futura diet at the daily doses ≥2.7% fish biomass. First symptoms of overfeeding: a considerable incidence of uneaten food, retarded growth, and elevated C/N ratio were observed in the group fed Chironomidae larvae at the highest level, (C4, wet Chironomidae 20.7% of the fish biomass daily, that is, 3.9% of dry chironomids per fish biomass and day). Thus, restricted daily doses of formulated diet not exceeding 2.5% fish biomass are recommended for tench juveniles aged 130–200 days post hatch. Safe daily doses of frozen Chironomidae (in terms of larvae dry weight) remain below 3.5% of fish biomass.     

运输方式对企鹅珍珠贝存活、生长、消化及抗氧化性能的影响探究

为探究运输方式对企鹅珍珠贝(Pteria penguin)稚贝存活、生长、消化及抗氧化性能的影响。本研究以企鹅珍珠贝稚贝为研究对象,分别以有水运输和无水运输2种方式进行8 h实地运输。运输后暂养14 d进行观察。结果显示,在恢复期第14天,有水运输和无水运输存活率(SR)分别为(97.00±1.00)%和(82.00±0.71)%;有水运输组的壳长、壳高和体重均显著高于无水运输(P<0.05);无水运输的皮质醇(COR)含量显著下降;2种运输中淀粉酶活性均呈上升趋势,超氧化物歧化酶(SOD)活性下降。在恢复期第14天,有水运输组酶活性高于无水运输(P<0.05);有水运输后,酸性磷酸酶(ACP)、谷丙转氨酶(GPT)和谷草转氨酶(GOP)活性上升;无水运输后,ACP活性上升,GPT和GOT活性下降;在恢复阶段,有水运输组ACP活性逐渐下降,无水运输组ACP活性呈先下降后上升的趋势,GOP和GPT活性不断上升。研究表明,运输方式会对企鹅珍珠贝稚贝产生不同影响,有水运输相对无水运输可使企鹅珍珠贝稚贝在后期恢复阶段具有更好的存活效果和生长状态,稚贝运输后需一定时间进行生理恢复从而能更好地适应野外养殖环境。     

Intensification of redclaw crayfish Cherax quadricarinatus culture: I. Hatchery and nursery system

Intensification of an indoor hatchery and nursery system for the Australian redclaw crayfish Cherax quadricarinatus (von Martens) (Decapoda: Parastacidae) was obtained by increasing the surface area available for the crayfish juveniles and by synchronizing the age of the hatchlings held in each tank. The former improvement was facilitated by distributing an artificial seaweed-like material throughout almost the entire volume of small (275 l) hatching tanks. As the number of egg-bearing females was increased from 3 to 8 per hatching tank, the number of juveniles per liter also increased to as many as 6.5 juveniles/l, without reaching an apparent upper limit. The hatchlings were kept in the tanks for 75 days from the day females were found to be gravid and then harvested and graded according to size. The average juvenile weight at harvest was 0.34±0.04 g. The weight distribution of the juvenile males was not significantly different from that of the juvenile females on the day of harvest, and in both the distribution was positively skewed.