| 摘要: |
| 每天从锯缘青蟹育苗池采集幼体,在实验室内依平衡法测定从孵化至大眼幼体各天青蟹幼体的摄食率,并同时测定青蟹幼体每天的干重和比能值,比较研究了饵料密度对青蟹不同发育阶段幼体摄食的影响,以及幼体蜕皮周期内摄食的变化。结果表明,轮虫是青蟹蚤状幼体(Z)I期(Z1)和Ⅱ期(Z2)适宜的饵料,卤虫无节幼虫是青蟹幼体生长发育主要的能量来源,占整个幼体发育期摄入能量的96.48%。以干重和能量表示的青蟹幼体摄食率(CDW和CJ)随幼体蜕皮发育呈指数增长[CDW=13.463e0.8283(d+1) (r2=0.927), p<0.01; CJ=0.4018e0.7516(d+1) (r2=0.956), p<0.01];青蟹大眼幼体摄食强度显著上升,摄入能量高达整个幼体发育期摄入能量的77.25%。Z1、Z2期为被动摄食,青蟹幼体主动摄食的能力随幼体发育而逐渐提高,大眼幼体为主动摄食。锯缘青蟹各期幼体蜕皮周期内摄食率的变化是:Z1→Z4期蜕皮后上升,蜕皮前稍微下降;Z5期蜕皮后和蜕皮前较高,蜕皮间较低。Z5期日粮水平最低;青蟹大眼幼体期有2个摄食峰值,变化不规则。 |
| 关键词: 锯缘青蟹,摄食,幼体发育期,蜕皮周期,饵料密度 |
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| 基金项目:福建省重中之重项目“海洋生物优良种质和生物活性物质的应用基础研究”资助,1998—2002;国家海洋863项目“锯缘青蟹大规模人工育苗技术”资助,2002AA603013号 |
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| VARIATIONS IN FEEDING OF SCYLIA SERRATA LARVAE IN DIFFERENT DEVELOPMENTAL STAGES |
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ZHU Xiao-Ming, JIANG Xiao-Dong, LI Shao-Jing
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Department of Oceanography & Institute of Subtropical Oceanography, Xiamen University, Xiamen, 361005
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| Abstract: |
| In laboratory condition, the authors investigated the effects of prey density on consumption rate and daily ration, and the feeding variations in molting cycle of mud crab (Scylla serrata) larvae that reared in breeding ponds from hatching through megalope metamorphosis. Mud crab larvae were isolated from the culturing tank everyday during larval development. The individual dry weight and energy content of larval mud crab were determined everyday. The feeding trials were conducted 4–12h under the conditions same as in larval rearing: temperature (29±1) °C, and salinity 28. The food consumption of larvae was determined using food balance method, and the food consumption rate of larvae was in terms of mumbers, dry weight and energy content of prey per larvae per day. The results showed that rotifer, Brachionus plicatilis, was an ideal prey for mud crab zoea in Stages 1 and 2, and Artemia nauplii was best for larvae from zoea in Stage 3. Artemia nauplii supplied the majority of energy sources for crab larval development, contributed 96.48% of energy intake in whole larval stages. The food consumption rate of mud crab larvae increased exponentially with larval development. The regression equations from the first day of zoea of Stage 1 to the last day of megalope were: [CDW=13.463e0.8283(d+1) (r2=0.927), p<0.01; CJ=0.4018e0.7516(d+1) (r2=0.956), p<0.01]. The consumption was enhanced significantly in megalope stage, up to 77.25% of total energy intake in larval development. The feeding intensity of the megalope was obviously higher than that of zoea shown by the consumption rate and daily ration. The food consumption rate fluctuated during crab larval molting cycle, increased after ecdysis and decreased slightly at the end of each molting cycle from zoea of Stage 1 to Stage 4, higher in postmolt and premolt, but lower in intermolt in zoea of Stage 5. Two feeding peaks were presented in crab megalope molting cycle and they daily altered irregularly. ANOVA analysis of the effects of density and development phase on consumption rate o f the crab larvae showed that the consumption rate increased with increasing of prey density. According to the ANOVA, the development phase is significantly related to the consumption rate during molting cycle of zoea from Stage 3. The more developed, the closer the relationship. These results showed that feeding behavior of zoea in Stages 1 and 2 on rotifers was passive, and that of zoea in Stage 3 on Artemia nauplii was obviously activated and increased with larval development. The feeding behavior of megalope was active and strongly relative to mud crab zoea. Variation in the consumption rate of S. serrata larvae inmolting cycle is informative for larval rearing. Decreasing in daily ration suggested that the zoea of Stage 5 were ready for ecdysis, prolonging molting cycle could provide enough materials and energy for its metamorphism. Therefore, lengthening molting cycle by decreasing temperature in larval rearing can improve survival rate of the larvae. |
| Key words: Scylla serrata, Feeding, Larval developmental stage, Molting cycle, Prey density |
