| It is taken for granted that predator risk may affect animal’s survival and reproduction either directly or indirectly. Preys can recognise and decide the degree of risk through the information in the enviroment, and use the corresponding countermeasures, such as behavior and physiological aspects, to improve the fitness of population. Red swamp crayfish (Procambarus clarkii) was an important aquatic product, and they encroached on themselves seriously during the breeding process. After the encroaching behavior, the conspecific alarm signal was displayed in an vital role to improve both survival and reproduction. This study was conducted to confirm the effect of the injured conspecific odors on the behaviour and the monoamine contents of red swamp crayfish, to prove the concentration effect hypothesis that the intensity of behaviour was enhanced with the increased concentration of odors, to enrich and develop the related theory about predator risk in aquatic organisms, and to provide informations for the aquaculture. development and utilization of red swamp crayfish. Testing was done in indoor conditions by using the animals caught in the breeding ponds following ethological and physiological methodologies. The following results were obtained:1) The injured conspecific odors affect the behaviour of male adult red swamp crayfish. Under the high concentration treatment, the adult male crayfish spent much more time in rest while less time and frequency in locomotion, threat and retreat in injured conspeicfic groups than control group; and the time and frequency of tussle under male conspecific odor were significantly lower than under the control group. Under the medium concentration treatment, the time and frequency of threat, tussle and retreat were significantly lower than control group. The duration and frequency of locomotion were lowest both under the medium and low concentrations. The concentration of the odors also had a significant impact on the behaviour of adult male. The rest time under high concentration was significantly higher than under the medium and low concentrations, while the time and frequency of locomotion and other acting were the lowest.2) The injured conspecific odors affect the behaviour of adult female red swamp crayfish. Under the high concentration treatment, both of the time and frequency of threat and retreat were significantly lower than control group. Under the medium concentration treatment, only the other acting time was significantly higher than that of the control group. The concentration of the odors also had a significant influence on the behaviour of adult female. Under the injured female odor, the order of the rest time was medium concentration<high concentration<low concentration, while the order of the other acting time was reversed, and both of them had significantly difference between medium and low concentration groups. Under the injured male odor, the order of the rest time was medium concentration<low concentration<high concentration, while the order of the other acting time was reversed, and there were significantly difference among three concentration groups.3) The injured conspecific odors affect the behaviour of juvenile male red swamp crayfish. Under the high concentration treatment, the time of retreat was significantly lower than control group. Under the medium concentration of injured female odor treatment, the time and frequency of tussle were significantly lower than those under the control group. Under the low concentration of injured female odor treatment,the time and frequency of locomotion, threat, retreat and other acting were all significantly lower than those under the control group, while the rest time was dramatically increased. The concentration of the odors also had a significant impact on the behaviour of juvenile male. Under the injured female odor, the order of the rest time was medium concentration<high concentration<low concentration, while the order of the locomotion time was reversed, and both of them had significantly difference between medium and low concentration groups. Under the injured male odor, the order of the locomotion time was low concentration<medium concentration <high concentration, and there was dramatically difference between high and low concentration groups. 4) The injured conspecific odors affect the behaviour of juvenile female red swamp crayfish. The time of threat was dramatically increased under all three concentrations of the injured female odor, and the tussle time under the high concentration was significantly rised. The concentration of the odors also had a significant impact on the behaviour of juvenile female. Under the injured female odor, the time and frequency of tussle were dramatically lower under the medium concentration than under the high and low concentration. Under the injured male odor, the order of the rest time among three concentrations was low concentration<medium concentration<high concentration, while the order of the other acting time was reversed, and there was dramatically difference between high and low-concentration group.5) The injured conspecific odors affect the content of monoamines of adult male red swamp crayfish. Compared with the control odor, the content of5-HT was significantly decreased under the high and medium concentration of the injured conspecific odors, and was also significantly decreased under the low concentration of the injured male odor. The content of NE was higher under all the three concentrations of the injured conspecific odors than the control group, but there were no dramatically difference. The content of DA was significantly higher under the high concentration of the injured conspecific odors than the control group. The concentration of the odors also had impact on the content of monoamines of adult male. The content of DA was significantly highest under the high concentration, the contents of5-HT and NE had no significant difference among the three concentration groups.6) The injured conspecific odors affect the content of monoamines of adult female red swamp crayfish. Compared with the control group, the content of5-HT was significantly higher at the high concentration group of injured female odor, and the content of DA was significantly lower at the high and low concentration groups of injured female odor, the content of NE were no significant difference among threee odor groups. The content of5-HT> NE and DA of adult female crayfish had no observably difference among the three concentration groups.7) The injured conspecific odors affect the content of monoamines of juvenile male red swamp crayfish. Compared with the control odor, the content of5-HT was significantly lower under the high concentration of injured male odor. The content of DA was dramatically higher under the medium concentration of injured male odor than the control group, and was observably higher under the low concentration of the injured female odor than of the other two odors. The content of NE was no significant difference among three odor groups. The concentration of the odors had no significant impact on the contents of5-HT and NE of juvenile male. While the content of DA was observably lowest under the low concentration of the injured male odor.8) The injured conspecific odors affect the content of monoamines of juvenile female red swamp crayfish. Compared with the control odor, the content of NE were observably rised at the medium and low concentration groups of the male odor, while the content of DA was observably rised at the low concentration of the male odor. The concentration of the odors had no significant impact on the contents of NE and DA of juvenile female. While the content of5-HT was observably lowest under the low concentration of the injured male odor.In sum, our results could be concluded as follows:1) Under the injured conspecific odors, the activity of procambarus clarkii was observably reduced, such as rest time increasing while locomotion time decreasing, and the aggressive behavior (threat、tussle and retreat) observably decreased.2) The injured conspecific odors have much more effect on the adult crayfish than the juvenile crayfish, and the response of the male crayfish to the injured male odor was more intense than to the injured female odor, while the response of the female crayfish was opposite to each other’s. And the intensity of the response of male individuals was higher than that of female crayfish.3) The concentration of the odors also had a significant impact on the behaviour of P. clarkii.The behavior response of P. clarkii was more intense under the high concentration, and these results mainly support the concentration effect hypothesis.4) Under the injured conspecific odors, the content of5-HT was decreased, while the content of NE and DA were increased, which suggested that the injured conspecific odors, as a kind of predation risk, had induced the crayfish to produce some physiological response. |
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