| The Patinopecten yessoensi and Chlamys farreri are important economic shellfish in our country and even in the world,Not only play an important role in the aquaculture,but also have an extremely important economic and ecological position.In recent years,large death problems have occurred in the cultivation of Patinopecten yessoensi and Chlamys farreri,causing certain economic losses to the breeding enterprises.It is urgent to strengthen the in-depth understanding of the basic biological and ecological characteristics of scallops.Low oxygen during high summer temperatures is plaguing farmed areas around the world,killing The Patinopecten yessoensi and Chlamys farreri.Scallops can escape the predation of predators and the harsh environment through sports behavior.The stronger their exercises ability and the stronger the escape ability,the risk of predation of scallops will be reduced.According to the research about current main problems between local and overseas,this paper studies the survival and movement behavior characteristics of Chlamys farreri under high temperature stress;the survival and behavior characteristics of Patinopecten yessoensi under hypoxia stress;the predation of predator starfish and the kinetic behavior characteristics of scallops under the dual stresses of stress,predation and starvation;And discussed the physiological and biochemical responses of scallops to stress.The results are as follows:1 Immune ability of Chlamys farreri under high temperature stress.This experiment uses video recording to investigate the behavioral characteristics of Chlamys scallops(Average shell height 4-5 cm)at high temperatures,and basic experimental methodology to explore the impact of high temperature on the body’s relevant immune indicators and the body’s preventive solution.1.In this study,the video was used to record behavior characteristics of Chlamys farreri(average shell height 3-5 cm)under high temperature.And the effects of high temperature on relevant immune indexes and coping strategies of the organism were explored using basic experimental methodology.Observe and record Chlamys farreri at 27℃ Survival for 20 d found that the number of deaths reached 50%on the third day,and the number of deaths remained stable at 10%from 15 d to 20 d.(2)The SOD enzyme activity and T-AOC enzyme activity in adductor muscle tissue of Chlamys farreri at a high temperature of 27℃ increased first and then decreased with the change of days,reaching the highest value on the 3rd(P<0.05),SOD enzyme and The T-AOC enzyme stabilized after the 7th d(P<0.05),and the 7th d may be the time required for Chlamys farreri to establish an adaptation mechanism through high temperature acclimation.(3)Compared with the total 96h total frequency of the Chlamys farreri experimental group at 27℃ and 23℃ in the control group,the total number of times of exercise was significantly reduced(P<0.05),and the exercise capacity of the experimental group was significantly weakened.With the extension of time,the number of exercises in different groups was significantly reduced(P<0.05).Compared with the control group(23℃,0.2-0.4m/s),the speed of Chlamys farreri in the 96h movement range of 0.0-0.2m/s at 27℃ was decreased.As time goes by,the attached Chlamys farreri could not move away due to the secretion of foot filaments.A very small number of Chlamys farreri will choose to rotate in place.Most of the Chlamys farreri show reduced or almost no jumping movement.2 In order to study the effects of hypoxia stress on the behavior,physiology,immune,anti-epidemic functions and key respiratory enzymes of the Patinopecten yessoensi(Average shell height 4-5 cm).This experiment set up 4 dissolved oxygen gradients of 1,2,4,7mg/L(control group),and measured and analyzed the behavioral characteristics,oxygen consumption rate,ammonia excretion rate,response of antioxidant enzymes(SOD,CAT)and respiratory enzymes(LDH and PK enzyme)activities of Patinopecten yessoensi.The results showed that:(1)The survival rate of Patinopecten yessoensi decreased with the decrease of DO concentration.The survival rate was only 55%when DO was 1.0mg/L,and this dissolved oxygen concentration,the half-lethal time of Patinopecten yessoensi was 95.97h.(2)Patinopecten yessoensi exhibited behaviors that are compatible with the hypoxic environment at different times.When the Patinopecten yessoensi do not adapt to the environment,the shells will be tightly closed,and the shells will gradually open after adaptation.From the quantitative indicators of scallops’behavioral characteristics,The lower the DO concentration,the lower the score,and the greater the proportion of the worse state of Patinopecten yessoensi.(3)Hypoxia stress has a significant effect on the oxygen consumption rate of the Patinopecten yessoensi(P<0.05).At the same time,under 96 h hypoxia(1 mg/L)stress,the ammonia excretion rate was significantly affected(P<0.05);Under DO<2mg/L stress,if the molar ratio of oxygen to nitrogen is less than 7,the Patinopecten yessoensi is mainly powered by protein;DO>4mg/L,the Patinopecten yessoensi is mainly powered by the oxidation of protein and fat.(4)Hypoxia stress has a significant effect on SOD,CAT and respiratory enzymes of the Patinopecten yessoensis(P<0.05).24h of hypoxic stress increased the active oxygen concentration of hepatopancreas and adductor muscle;48-96 h of hypoxic stress,enzyme activity began to decrease;(5)The metabolic pathways under different dissolved oxygen concentrations were different,and the study found that DO=2 mg/L,the metabolic pathway of aerobic metabolism is converted to the glucose-pyruvate-lactate respiratory pathway,when DO=lmg/L,the glucose-succinate pathway is preferred for the respiratory pathway.(6)Observed the structural changes of adductor muscle,hepatopancreas,gills and mantle tissue cells of the Patinopecten yessoensi under hypoxic pressure by transmission electron microscopy(TEM).The DO=lmg/L experimental group was at the cellular level and there was a certain degree of vacuolation at the mitochondrial level.3 In order to study the behavioral and physiological responses of the Patinopecten yessoensi and Chlamys farreri in the presence of starfish,The video of this experiment recorded the behavior of two kinds of scallops(two groups of size:small size average shell height 2-4 cm,large size average shell height 4-6 cm)under different densities and starvation conditions in the presence of starfish,and measured their glycogen content.And behavior.(1)The changes of movement speed and glycogen of the two scallops under different conditions(j umping movement in the natural state(group A)and jumping movement due to the proximity or touch of starfish(group B))were analyzed.The movement speed and glycogen content of the two scallops under predator stress were both greater than that under the natural condition.The average speed of Chlamys farreri is higher than that of Patinopecten yessoensi.As for movement speed,large size scallops of average speed are greater than small scallops.And the glycogen content of large size scallops is less than that of small size scallops.Under the stress of predators,the movement speed of Patinopecten yessoensi increased by 40%-200%,and that of scallop Chlamys farreri increased by 20%-30%.(2)In the two-predator system,when the experimental scallop densities were 4,8,12,16/1.56 m2,the total observed values and predicted values were calculated respectively.There was no significant difference in each density(P>0.05),indicating that the starfish were independent predators,and there was a significant independent multi-predator effect,and there was no cooperative relationship.(3)Under the stress of the predator starfish,the speed and glycogen changes of the two types of scallops under 0,15,30,and 45 days of starvation were compared.With the increase in the number of days of starvation,the glycogen content of Patinopecten yessoensi was increased first and then decreased(P<0.05),and the glycogen content of Chlamys farreri gradually decreased with the increase of the number of days of starvation(P<0.05).Both scallops had the lowest glycogen content under 45 days of starvation stress.As the number of days of starvation increased,the total number of movements of Patinopecten yessoensi decreased first and then decreased again in 45 days after 30 days of recovery.The number of movements of small-sized scallops was greater than that of large-sized scallops;the total number of movements of scallops was significantly less than that of large-sized scallops.The total number of exercises of Chlamys farreri was significantly lower than the exercises of Patinopecten yessoensi,and the number of exercises of Chlamys farreri increased first and then decreased with the increase of time,and the number of exercises increased when the Chlamys farreri was starved for 15 days.The 30th day of starvation had a significant effect on SOD enzyme in the obturator muscle of both scallops(P<0.05). |
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