生长发育初期四角蛤蜊对空气暴露的响应

Response of Surf Clam Mactra veneriformis to Air Exposure during Early Growth and Development

在室温28.8℃~29.6℃、湿度50%~60%条件下,将四角蛤蜊(Mactra veneriformis)孵化后1 d的D形幼虫[壳长(99.5±5.8)μm]、孵化后15 d的变态期幼虫[壳长(246.5±23.9)μm]、30日龄稚贝[壳长(1 065±195)μm]和60日龄稚贝[大规格(9.15±0.87)mm、中规格(7.01±0.71)mm和小规格(4.41±0.66)mm]摊在300目的筛绢上,吸干水分后,悬空在500 m L烧杯中在空气中分别暴露120 min、3 h、10 h和30 h后,放回砂滤海水中继续培养,研究发育早期四角蛤蜊对空气暴露的响应。结果表明:(1)四角蛤蜊不同发育时期幼虫或稚贝的存活率随空气暴露时间的延长直线下降(P<0.05)。以半数致死时间(LT50)为依据,不同发育时期幼虫或稚贝耐空气暴露能力由大到小依次为:60日龄大规格稚贝(LT50为24.7 h)>60日龄中规格稚贝(17.5 h)>60日龄小规格稚贝(13.8 h)>30日龄稚贝(4 h)>变态期幼虫(1.61 h)>D形幼虫(1.05 h)。(2)空气暴露后,不同发育时期幼虫或稚贝的生长规律不同。空气暴露后,D形幼虫生长速度显著低于对照组(P<0.05);变态期幼虫前期(0~4 d)生长缓慢,但随着培养时间的延长(4~7 d),各处理组的生长速度显著高于对照组(P<0.05);30日龄稚贝,各处理组的生长速度与对照组无显著差异(P>0.05)。本研究为四角蛤蜊异地采苗、苗种培育以及安全运输提供了科学依据。

The 1-day-old D-shaped larvae[shell length of(99.5±5.8)μm]and 15-day-old metamorphosed larvae(shell length of 246.5μm)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 water 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 extension 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.