The Effects Of Environmental Stress On Behavior And Physiological Activity Of Litopenaeus Vannamei

Two experiments were conducted to study the effects of temperature, salinity, hypoxia, starvation and stocking densities on behaviors and energy budget of Litopenaeus vannamei. In experiment I the body weights of the shrimps were 1.338 ± 0.143g, and in experiment II those were 4.340 ± 0.271g. The behaviors of the shrimps were videoed by a video track record system. The effects of stocking densities on growth of the shrimps were examined by the parameters of behavior and bioenergetics.1. The effects of temperature change on L. vannamei showed that the frequency of movement (FOM) and the swimming-walking speed (SWS) in all temperature treatments had no significant differences in experiment I , but in experiment II FOM and SWS increased with the temperature changing to 36℃ and decreased significantly with the temperature changing to 18 ℃, respectively. The time for seeking feed got longer with the lower temperatures. And the temperature change had a significant effect on the scaphognathite beat rate.2. The effects of salinity change on L. vannamei showed that FOM and SWS of all salinity treatments were insignificantly different in experiment Ⅰ , but increased significantly with the decrease of salinity in experiment Ⅱ. When the salinity were down to 10 and 5, the time for seeking feed prolonged significantly, and the scaphognathite beat rate increased significantly, with the reverse beat of the scaphognathite intermittently occurring.3. The effects of hypoxia on L. vannamei performed that FOM and SWS decreased significantly when dissolved oxygen (DO) below 3.00mg · L-1. The scaphognathite beat rate increased with decreasing DO. But when DO was below 1.43mg · L-1, some shrimps asphyxiated with the significant decrease of the scaphognathite beat rate, and shrimps died then the scaphognathite beat stopped.4. The effects of starvation on L. vannamei showed that FOM did not change significantly, but SWS and the time for seeking feed decreased significantly. The scaphognathite beat rate was lower with more days of starvation.5. The effects of stocking densities on L. vannamei performed that the specific growth rate and food conversion efficiencie of the shrimps in the density of 40 ind ·m-2 were significantly higher as compared to those in other treatments. FOM, distances between individuals, oxygenconsumption rate and ammonia excretion rate were increased with the increase of stocking densities. It was showed that with the increase of stocking densities, the percentage of energy consumption invested in growth decreased, but the percentage of energy consumption invested in respiration and excretion increased.