底栖硅藻种类和密度对仿刺参幼体和稚参生长与成活的影响

Effects of benthic diatom species and density on growth and survival in larval and juvenile sea cucumber Apostichopus japonicus

在水温为22.0~26.0℃下,研究了不同密度的圆筛藻Coscinodiscus sp.、舟形藻Navicula sp.和双肋藻Amphipteura sp.及其等比例组合对仿刺参Apostichopus japonicus体长为400~500μm的樽形幼体变态、附着及生长和成活的影响。结果表明：在单一硅藻组中,圆筛藻组幼体的附着率最高（13.3%±2.2%）,显著高于舟形藻（6.9%±1.8%）和双肋藻组（5.9%±0.7%）（P〈0.05）;混合硅藻组的附着率均高于单一硅藻组,其中圆筛藻＋舟形藻组幼体的附着率（23.2%±3.2%）显著高于对照组（18.0%±2.16%）（P〈0.05）。混合藻类密度为1~25万个/cm2时,幼体的附着率（27.2%±4.28%）均显著高于对照组（P〈0.05）。经过46 d的饲养,单一和混合藻类组幼参的最终体长（P〈0.01）和成活率（P〈0.05）均显著低于对照组。稚参变态附着后至体长为700~800μm的10 d内,以3种混合底栖硅藻为食物,之后以营养来源丰富的人工饵料为食,可明显提高仿刺参的生长速度和育苗成活率。

The species and density of benthic diatoms are important factors affecting larval settlement,and juvenile survival and growth in sea cucumber Apostichopus japonicus,which trammels the seed production of the sea cucumber.Thus,the effects of three benthic diatoms Coscinodiscus sp.,Navicula sp.,Amphipteura sp.and combinations and different biomass on larval settlement,and juvenile survival and growth in the sea cucumber were studied.Significantly more larvae were found to settle on Coscinodiscus sp.（13.3%±2.2%） plates compared to Navicula sp.（6.9%±1.8%）,and Amphipteura sp.（5.9%±0.7%） plates in the single benthic diatom species groups（P〈0.05）.In the different benthic diatom combinations,however,there were more larval settlement than those in the unialgal groups（P〈0.05）.A significantly higher number of larvae settled on different benthic diatoms compounding（27.2%±4.28%,density between 1×104 and 25×104 cells/cm2）compared to the control group（18.0%±2.16%）（P〈0.05）.The juveniles in the control group had the maximal growth and survival rate during the 46 day culture,indicating that benthic diatoms are the crucial factors for newly metamorphosed and settled juveniles within 10 days of breeding,and then the juveniles should be fed formulated nutritive diets in time.Mechanism of effects of different benthic diatoms and biomass on larval settlement and growth was discussed in detail.