盐度和低温冷藏对桡足类休眠卵萌发的影响

Effects of salinity and refrigeration on the hatching of copepod resting eggs

休眠卵是桡足类渡过不良环境的重要生存策略,是水体桡足类种群的重要潜在补充来源。通过采集珠江口南沙海域表层沉积物,研究了不同盐度和低温冷藏对桡足类休眠卵萌发的影响。结果表明:南沙沉积物中休眠卵萌发量和萌发率在盐度为20和盐度为5的实验组中最高;用50μm孔径筛绢过滤后,<50μm粒径沉积物中休眠卵萌发量显著高于>50μm粒径的休眠卵(P<0.05);冷藏30 d后休眠卵萌发量显著高于冷藏前休眠卵萌发量(P<0.05);冷藏前的休眠卵主要是静止卵和已渡过不应期的滞育卵,而冷藏后的休眠卵主要是未渡过不应期的滞育卵,表明<50μm粒径沉积物中休眠卵主要以滞育卵为主。研究结果为进一步了解河口桡足类受到盐度干扰后的潜在补充机制提供了基础数据,对揭示河口桡足类种类演替规律具有重要科学意义。

The resting egg phase is an important survival strategy of copepoda in the environment,and also an important potential recruitment for copepod population in the water. Surface sediments of Nansha in the Pearl River Estuary were collected to examine the effect of salinity and refrigeration on the hatching of copepod resting eggs. Our results showed that the hatching number and hatching rate of resting eggs incubated were higher at the salinity of 5 and 20 compared to those at other salinity levels（ P〈0.05）. Two sizes of resting eggs in the sediment were separated by a 50 μm mesh size screen and the hatching number of resting eggs was significantly higher in the 〈50 μm sediment than in the 〉50 μm sediment（ P〈0.05）. The hatching number of refrigerated resting eggs was significantly higher than that of room-temperature stored resting eggs（ P〈0.05）. The resting eggs hatched before refrigeration were mainly quiescence eggs and diapause eggs,which had passed the refractory phase in the sediment,and the resting eggs hatched after refrigeration（ 30 days） were mainly diapause eggs,which did not pass the refractory phase in the sediment,indicating that the resting eggs in the sediment of 50 μm were mainly diapause eggs. The results provide a better understanding of potential recruitment of copepods from resting eggs,and have important implications for further revealing the succession mechanism of copepod species in the estuarine water.