湿度对黄喉拟水龟胚胎发育与新生幼体特征的影响

Effects of different hydric environment on embryonic development and hatchling traits of yellow pond turtle(Mauremys mutica Cantor)

黄喉拟水龟(Mauremys mutica Cantor)为东亚常见的淡水水生龟类之一,主要分布于中国、日本和越南。在中国,黄喉拟水龟已成为潜在的水产养殖品种,研究了湿度对黄喉拟水龟胚胎发育和新生幼体的影响。恒温29℃时,用未受精卵做对比,在-12、-150kPa和-300kPa3种孵化湿度下,观察并记录了黄喉拟水龟胚胎发育过程中卵重的变化、孵化周期、孵化成功率、卵壳龟裂率、卵壳受精斑变化规律及新生幼体的特征。在-12kPa和-150kPa处理组,受精卵在孵化中期开始持续增重;而在-300kPa处理组,受精卵在孵化中期开始持续减轻;孵化湿度显著影响卵壳受精斑的变化,-12kPa处理组的受精斑绕卵短径合拢的时间显著长于-150kPa和-300kPa处理组;受精卵的卵壳龟裂率随着孵化湿度的增加而增加;湿度显著影响新生幼体体重和背甲宽,但对体高、背甲长、腹甲长、腹甲宽以及尾长无明显影响;孵化湿度对孵化周期及新生幼体的运动能力影响不明显。

The Asian yellow pond turtle,Mauremys mutica Cantor,is a member of the family Bataguridae,native in China,Japan and Vietnam.It has become a potential aquaculture species and its husbandry and management have been a focus of aquaculture practice recently in China.One mature female turtle lays only 2.8 eggs on average per clutch and has only 2.1 nests on average per year.Therefore,it is very important to determine how to artificially incubate those eggs under optimal incubation conditions to achieve best results for aquaculture.Yellow pond turtle does not protect its eggs and leaves the embryo development of the turtles to the mercy of environment where eggs are laid.Hydric environment is an important ecological factor,and incubation under hydric environment has been proved to have profound effects on embryonic development and husbandry outcomes.In this paper,the effects of different hydric environment on embryonic development of fertilized eggs and hatchling traits of yellow pond turtle have been studied in comparison to unfertilized eggs.The eggs were incubated in wet（-12kPa）,humid（-150kPa）and dry（-300kPa）conditions at constant temperature of 29℃,data on the egg mass change,embryonic development duration,hatching success ratio,egg shell crack ratio,egg-shell white ring change and hatchling morphological traits were collected and analyzed.Eggs mass increased from the middle to the end of incubation period under the wet（-12kPa）and humid（-150kPa）conditions,whereas eggs mass for those incubated under the dry（-300kPa）condition decreased.The hydric environment significantly affected white ring change on the eggshell.Under the wet（-12kPa）condition,white ring folding was significantly slower than that under the humid（-150kPa）and dry（-300kPa）conditions.The ratio of fertilized egg shell crack was positively correlated to the hydric environment.The effects of different hydric environment on body weight and carapace width of hatchling were significant,but were not significant on body height,carapace length,plastron length,plastron width,and trail length of hatchling.The effects of different hydric environment on duration of embryonic development and hatchling moving were not significant.The results confirm that appropriate moisture is important for the incubation management and the optimal incubation conditions for eggs of Asian yellow pond turtle are from-12kPa to-150kPa for aquaculture.