Response of Surf Clam Mactra veneriformis to Air Exposure during Early Growth and Development
The 1-day-old D-shaped larvae[shell length of(99.5±5.8)μm]and 15-day-old metamorphosed larvae(shell length of 246.5 μm)after hatching,30 day old juveniles[shell length of(1,065±195)μm]and 60-day-old juveniles[Large size(9.15± 0.87)mm,medium size(7.01±0.71)mm and small size(4.41±0.66)mm]in surf clam Mactra veneriformis with absorption wa-ter were set on 300 mesh silk,and suspended in a 500 mL beaker(air exposure)for 120 min,3 h,10 h,and 30 h,respectively,at room temperature of 28.8℃～29.6℃,and humidity of 50％～60％to probe the response of the surf clam to air exposure.The results showed that the survival rate of the surf clam at different developmental stages was linearly decreased with the increase in the exten-sion of air exposed time(P＜0.05).The descending order of the endurance to air exposure of the surf clam in different developmental stages,based on LT50,was expressed as large 60 d juveniles(24.7 h)＞middle 60 d juveniles(17.5 h)＞small 60 d juveniles(13.8 h)＞30 d juveniles(4 h)＞metamorphosis-stage larvae(1.61 h)＞D-stage larvae(1.05 h).There was different growth of the surf clam in different developmental stages during air exposure,with significantly lower growth rate in D-stage larvae than in the control,slow growth in metamorphosis-stage larvae at the first 4 days of air exposure,and the significantly higher growth rate in each treatment group was than that in the control group with the extension of culture time,without significant difference in the growth rate between air exposure groups and the control group in 30 d juveniles.The findings will provide basic data for artificial breeding and transporting of the surf clam.
万方数据
维普
