The Pre-spawning Breeding Behavior And Optimization Of The Filtering Pool For Ecological Breeding Of Chinese Giant Salamander (Andrias Davidianus) In Zhangjiajie City

The imitation ecological breeding is the main technique for the breeding of Chinese giant salamander(CGS,Andrias davidianus).For enhancing the breeding efficiency of CGS in Zhangjiajie City,the structure of ecological breeding farm especially the filtering pool is urgent to be improved.In order to investigate the ecological mechanism of the reproductive behavior of CGS,which would provide a scientific basis for its optimizing ecological breeding management,we carried out this study.We employed the digital monitoring system to observe the whole period of breeding behavior of CGS,and uncovered the relationship of pre-spawning behavior and ecological factors in the water habitat of CGS.This study we recorded the occurrence time of some pre-spawning reproductive behaviors,the activity peak,the single duration time,total duration time and ratio,meanwhile,we analyzed the relationship of pre-spawning behavior and ecological factors in the water habitat of CGS.In addition,we studied the correlation of the structure of filtering pool and the index of water quality in the imitational field breeding farm,and analyzed the filtration efficiency of the filtering pool and proposed the key points of optimizing the filter pool.The main results and conclusions are as follows:(1)The sand pushing behavior of male CGS was mainly from limbs and tail,but less from head and body.The sand-pushing activity from limbs concentrated in the period of 20:00?3:00.Before and during the middle stage,the activity time of limbs sand pushing behavior concentrated in 20:00?23:00,while the activity time of limbs sand pushing behavior in the later stage concentrated in 0:00?3:00.The peak time of tail sand pushing activity was from 21:00 to 23:00.The total time of sand pushing behavior of CGS was significantly correlated with water temperature(WT)and dissolved oxygen(DO).It indicates that WT and DO are important factors in controlling the sand-pushing behavior of CGS.At the early stage of reproduction,the duration time of sand-pushing behavior of CGS changed significantly.When the temperature outside the den was higher than inside,the behavior and activity time was shorter.On the contrary,their behavioral activity time was significantly longer.(2)The showering behavior of CGS included head showering,trunk showering,tail showering,bending showering and heading up showering,and its frequency decreased in the above sequence.The head showering behavior of CGS mainly occurred at 19:00?23:00,and the activity time of trunk and tail showering behaviors concentrated in the period of 21:00?3:00.There was no significant correlation of the behaviors of head and trunk showering,with the factors of WT and DO,whichh indicated that the head and trunk showering behaviors of CGS might be more affected by their own physiological factors.The correlation of the tail showering behaviors,with WT was extremely significant,and with DO was significant,which indicated that the WT and DO were important ecological factors that affecting the tail showering behavior of CGS.In addition,the duration of the tail showering behavior and the WT might have seasonal changes.(3)The courtship behaviors observed in CGS including side-by-side,colliding belly,climbing,kissing,chasing,invitation,cohabitation and turning over,and correspondingly,its frequency decreased in the above sequence.Among the above mentioned eight behaviors,the time of cohabitation was the longest,followed by the side-by-side behavior.In general,there was no significant correlation between the courtship behavior and the water factors such as WT and DO.However,the courtship behavior seemed to be relevant to the spawning time,when the closer the courtship time to spawning was,the more obvious the courtship behavior showed.It can be seen that courtship behavior of CGS might be an inborn behavior like other animals with gender difference,which was not easy to be influenced by outside environmental changes such as WT and DO..(4)The average water depth and the height difference of the studied filtering pool increased gradually from the inlet to the fifth stage.The fifth stage of filtering pool had the largest area,followed by the sixth stage pool.The main water quality indexes measured from the water inlet to the water outlet showed that the WT and DO increased;water turbidity,electric conductivity,total nitrogen(TN),total phosphorus(TP),chemical oxygen demand(COD)decreased;and the number of coliform bacteria increased;however,all these factors fell into the water quality requirements of CGS.In order to ensure the optimal water temperature in the breeding season of CGS,from the knowledge that the area size and the water temperature rise rate of each pool,we suggested to increase the fifth stage pool appropriately when left the water depth unchanged.Additionally,it's necessary to clean regularly and set up switch to export the sediment discharge.In summary,as the spawning time getting close,the water temperature in the inside of the den increased gradually and become higher than that outside of the den,therefore,the activity time of sand pushing behavior from the limbs and the tail,as well as the tail showering behavior increased apparently.It would be beneficial for the spawn and reproduction of CGS.When the content of DO in the water increased,the activity time of sand pushing behavior from the limbs and the tail,as well as the tail showering behavior also increased,which indicated that the DO could also play important role to the spawn and reproduction of CGS.Theoretically,increasing the WT and DO appropriately could promote the pre-spawning reproduction behavior of CGS,which could be realized by increasing the WT and DO in the filtering pool system.Therefore,it was important to increase the reproduction efficiencies in the imitation ecological breeding system through enlarging the surface area and strengthening the management of the filtering pool system.