Study On Physiological And Ecological Response Strategies Of Swimming Crab (Portunus Trituberculatus) To Autotomy

Portunus trituberculatus is an important marine aquaculture crab in China.It is aggressive and extremely serious mutual killing extremely serious.Although autotomy and regeneration is a self-protection mechanism,it will also bring about loss of energy and function.Therefore,This paper mainly focuses on the effects of autotomy on feeding behavior,competing ability,survival,growth,energy budget and immunity of P.trituberculatus.The results are as follows:This study was designed to explored the ability of feeding and the competition for food of P.trituberculatus with both,single and without any cheliped(C2,C1 and C0)under the condition of insufficient food in the laboratory,and the results showed that: No significant effect were detected in the time of searching food when the swimming crab lost cheliped(P>0.05).The crabs of C0 could use the first walking legs instead of chelipeds to held food,which showed the strategy of behavior compensation,but they had significantly longer feeding time than uninjured individuals.No matter the injured or uninjured crabs,some of them could took two copies of food at the same time,and the proportion was associated with the number of missing chelipeds,the more loss of cheliped,the lower the proportion of taking two copies food,such as 20% individuals of C2 took up two copies food,while only about 3% individuals in C0.The proportion and frequency of competition for food exhibited that the individual which owned more chelipeds had a stronger competition desire and were inclined to compete for food with cheliped-lost individuals.Cheliped lose has direct affected the protection of P.trituberculatus for food,the 50% individuals of C0 lost the food.On the whole,the lack of single cheliped had little effect on the feeding and feeding behavior,while the absence of 2 chelipeds will seriously affect the feeding ability of P.trituberculatus.We aimed at the effects of limb autotomy on the survival,growth and energy budget of the juvenile P.trituberculatus.The results showed that: the survival rate of the juvenile P.trituberculatus was significantly affected by autotomy.On the whole,the more the number of limbs autotomy,the lower the survival rate.Among them,the survival rate of juvenile P.trituberculatus with 4�5 limbs autotomized were only about 60%,which was significantly lower than that of control group(P<0.05).The molt cycle of the juvenile P.trituberculatus was shortened because of autotomy,and the more number of limbs autotomized,the shorter the molt cycle.The weight gain rate(WGR)of juvenile P.trituberculatus decreased with increasing number of the limbs autotomized,but specific growth rate(SGR)raising with the increase of the limbs autotomized.During the whole experiment,the feeding rate(FR)decreased slightly,but there was no significant difference with the control group(P>0.05).Nevertheless,the feed conversion rate(FCR)increased,especially in the A4 and A5 groups were most obvious,the feed conversion rate of them were significantly higher than control group(P<0.05).Limb autotomy changed them autotomy changed the energy distribution proportion of the juvenile P.trituberculatus,with an increase in the number of limb autotomized,the energy ratio used for breathing(R/C)graduallyThe effects of different degrees of appendage autotomy on the immunity of P.trituberculatus were studied by cutting the appendages of P.trituberculatus from A(0),1(A1)and 4(A4).The results showed that:(1)Autotomy replication The total number of blood cells of P.trituberculatus was affected.Within 8 hours after the incision,the total blood count(THC)of the mild self-cut group(A1)and the severe self-cut group(A4)decreased rapidly and then increased and then decreased.The A4 group showed a later change and the difference was much worse than the A1 group.(2)The proportion of large granulosa cells in the A1 group and the A4 group increased rapidly and then decreased.The small granulosa cells of the A1 group were first raised.In the trend of decline,the A4 group firstly decreased and then increased.In the A1 group,the granulosa cells of the three-spotted crabs first decreased and then increased,and the A4 group first increased and then decreased.(3)The A1 group of the three-spotted crab The activity of SOD decreased rapidly and decreased.There was no significant change in the A4 group.The activity of hemolymph PO in the A1 group decreased first and then increased.The A4 group gradually remained stable after the decline.The blood lymphocyte LZM activity in the A1 group and the A4 group was autotomy.a short decline,then gradually rise Reduce the group A1 and A4 groups hemolymph were increased ACP and AKP in the first trend.Bacterial challenge experiments showed that the 96 h mortality rate in A4 group was significantly higher than that in A1 group and control group(P<0.05).