单环刺螠幼体生长及摄食强度的研究

为探讨不同饵料(微绿拟球藻、2/3微绿拟球藻+1/3螺旋藻、1/2微绿拟球藻+1/2三角褐指藻)对单环刺螠Urechis unicinctus幼体(体质量约0.5 g)生长的影响,采用室内生态学试验方法测定了单环刺螠幼体的清滤率和滤食率。结果表明:用混合饵料投喂可显著提高单环刺螠幼体的增重率(P0.05);在一定盐度范围内,单环刺螠幼体的清滤率和滤食率均与盐度呈正相关关系;盐度为20~28时幼螠清滤率和滤食率随盐度的升高逐渐增加,盐度为28时达到最大值,幼螠的清滤率为(262.16±3.90)mL/(ind.·h),摄食率为(123.41±0.74)×10~4cells/(ind.·h);温度对幼螠的清滤率和滤食率影响显著(P0.05),温度为15~25℃时,清滤率和滤食率随温度升高逐渐增加,水温为20℃时幼螠的清滤率最高,为(251.33±10.16)mL/(ind.·h),水温为25℃时幼螠的滤食率最高,为(159.11±4.35)×10~4cells/(ind.·h)。研究表明:在较为理想的外界环境下,单环刺螠幼体的增重率与食物来源相关性较大,以混合饵料投喂效果最好;盐度和温度对单环刺螠幼体的摄食有显著的影响,幼体摄食的最适水温为20~25℃,最适盐度为28。

Growth and feeding intensity of juvenile echiuran worm Urechis unicinctus

Juvenile echiuran worm Urechis unicinctus with initial body weight of some 0.5 g were fed green alga Nannochloropsisi sp. (group Ⅰ),3/2 Nannochloropsisi sp. + 1/3 Spirulina sp. powder(groupⅡ) and 1/2 Nan-nochloropsisi sp. + 1/2 Phaeodactyum tricornutum(groupⅢ) for 2 months to evaluate the effects of different diets on growth of juvenile echiuran worm. Clearance rate(CR) and filtration rate(FR) were further investigated in ju-venile echiuran worm reared in a 6 L bucket with 10 cm sand bottom at water temperature of 15,20,25,and 30℃and a salinity of 20,24,28 and 32 to study the effects of temperature and salinity on CR and FR of juvenile echiu-ran worm.The results showed that there was higher growth rate in the juveniles fed mixed diets and positive relation-ship between the CR/FR and salinity within a certain range. The CR and FR of the juveniles were increased with the increase in salinity at a salinitiy from 20 to 28, the maximum CR(262.16 ± 3.90)mL/(ind.·h) and FR (123.41±0.74)×104cells/(ind.·h) at a salinity of 28. The CR and FR of the juveniles were found to be in-creased with the rising water temperature from 15 ℃ to 25 ℃, the maximum CR of FR(251.33 ± 10.16) mL/(ind.·h) at 20℃,and the peak FR of(159.11±4.35)×104cells/(ind·h) at 25℃. The findings revealed that the weight gain rate of juveniles was related to food sources,with the best growth of echiuran worm fed mixed algae. The water temperature and salinity had distinct effect on CR and FR of the juvenile echiuran worm,with the optimum salinity of about 28 and the optimum water temperature of 20-25 ℃ for feeding of echiuran worm.