| Sea cucumber(Apostichopus japonicus) is our important economic aquatic farming products,which still with single breeding primarily.Yet the system is not stable, difficult to deal with complex environment effectively.This study choiced Gracilaria lemaneiformis and Gracilaria lichenoides as polyculture varieties with A. japonicus.The growth situation of A. japonicus was compared at different treatments, the changes of pond water quality changes and ecophysiology changes of A.Japonicus during aestivation were also detected. The main conclusions are as follows: Polyculture of sea cucumber (Apostichopus japonicus) and Gracilaria lemaneiformis was conducted from October to November in 2009. Water temperature changed from 4.6℃to 19℃.A. japonicus was cultured at densities of 40ind·2.25m-2 with feed, G.lemaneiformis was cultured at densities of 0,1,2.5,4kg·2.25m-2. The growth of A. japonicus was compared at different treatments and the changes of environmental nutrient were also detected. The results showed that the highest daily weight gain (Mdwg) and Specific Growth Rate (SGR) of A. Japonicus were acquired when the density of A. Japonicus and G. lemaneiformis were 40ind·2.25m-2 and 4kg·2.25m-2 respectively. Dissolved oxygen of all treatments were all over 6mg/L.The dissolved nutrients(NH4-N,NO2-N)in the three polyculture tanks were lower than the tank without Gracilaria lemaneiformis.The dissolved nutrients(NO3-N)in the three polyculture tanks were lower than the tank without Gracilaria lemaneiformis except November 11.Polyculture of sea cucumber (Apostichopus japonicus) and Gracilaria lemaneiformis was conducted with land-based enclosure and orthogonal design from May to July in 2010. A. japonicus was cultured at densities of 15,20,25 ind·m-2 without feed, G.lemaneiformis was cultured at densities of 0,180,360 g·m-2. The growth and survival situation of A. japonicus and G.lemaneiformis were compared at different treatments and the changes of environmental nutrient were also detected. The results showed that the final average weight (Wf) , daily weight gain (Mdwg) and Specific Growth Rate (SGR) of A. Japonicus were affected by the density of A. Japonicus significantly. Wf, Mdwg and SGR of A. japonicus were not significantly affected by the density of G. lemaneiformis. The highest Wf, Mdwg and SGR of A. Japonicus were acquired when the density of A. Japonicus and G. lemaneiformis were 15ind·m-2 and 360g·m-2 respectively. The highest yield of G. Lemaneiformis was acquired when the density of A. japonicus and G. lemaneiformis were 25ind·m-2 and 360g·m-2 respectively. The highest SGR of G. lemaneiformis was acquired when the density of A. Japonicus and G. lemaneiformis were 25ind·m-2 and 180g·m-2 respectively. The analysis of water quality showed that the content of total nitrogen and total phosphorus in mud had the largest decline when the density of A. Japonicus was 15ind·m-2. In sum, polyculture of A. japonicus and G. Lemaneiformis could improve water quality and increase the SGR of A. japonicus.Polyculture of sea cucumber (Apostichopus japonicus) and Gracilaria lichenoides was conducted from June 23 to October 13 in 2010. The trial is over 112, water temperature changed from 18℃to 32℃.During the experiment, A. Japonicus's wet weight the digestive tract wet weight,the digestive tract length and Zihler's index (ZI) were significantly reduced. The changing trends were basically the same as water temperature changes.The pond water temperature began to rise slowly from the beginning of experiment to late August and maintained with high temperature, suddenly reduced and then rose slowly, yet temperature was below than before.The wet weight of the control group and the treatment group significantly degenerated during aestivation with 57.57% and 58.54% respectively of the corresponding maximum values at the start of the experiment, and the wet weight of treatment group was higher than control group.The relative gut mass (RGM) in A. Japonicus of treatment group was higher than control group. Zihler's index in A. Japonicus of treatment group was higher than control group at later period.The results showed that the were lowest amylase activity in A. Japonicus between treatment and control were acquired in August and September respectively.treatment,and treatment group was higher than control group all the time. The cellulase activity in A. Japonicus of treatment group was higher than control group except September 10. The pepsin activity in A. Japonicus of treatment group was higher than control group except August 27. The trypsin activity in A. Japonicus of treatment group was slightly higher than control group. |
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