Effects Of Water Temperature And Predator On Survival,behaviors And Growth Of Strongylocentrotus Intermedius And Mesocentrotus Nudus:New Insights Into The Stock Enhancement

This study is based on the sea urchin Strongylocentrotus intermedius and Mesocentrotus nudus.It examines the effects of temperature and predators on their survival,behavior,and growth.As a common breeding method,bottom seeding propagation has been widely used in sea urchin farming.The changing of temperature and the presence of predators are the subjects that need to be faced during the propagation of sea urchins.Therefore,we explored the appropriate release timing and release location of the two sea urchins by placing the predator in the living environment of the sea urchin under different temperature conditions.This thesis will provide a reference for further optimizing the proliferation of sea urchins and finding suitable timings for release.1)Effects of different temperatures on the survival,behaviors and growth of S.intermedius under the suitable temperature conditionsS.intermedius was cultured in a temperature-controlled water tank at 20 ?,15 ? and 10 ? for 6 weeks,and each temperature component was cultured in 2 sizes and set.3 parallel groups.Food consumption of S.intermedius was measured during the experiment.After 6 weeks of experimentation,behavioral experiments and body size anatomy experiments were performed on Strongylocentrotus intermedius.Behavioral experiments include righting response,frequency of Aristotle's lantern reflex,foraging behavior,phototaxis behavior,and light-protection behavior;body measurements include measuring shell diameter,body weight,shell height,shell pressure,shell thickness,lantern length,lantern weight,gonad weight and gut weight.No dead individuals were seen during the experiment.This result indicates that the S.intermedius can survive normally between 10 and 20 ?.The food consumption in the 20 ? group was significantly higher than the other two temperature groups between each sizes(P < 0.001).In the foraging behavior,the foraging time in the 20 ? group was significantly higher than the other two groups(P < 0.05).In combination with food consumption,we can find that the sea urchins in the 20 ? group have a large food consumption,but the sea urchin foraging time is longer than that at 10 ? and 15 ?.In the righting response behavior and frequency of Aristotle's lantern reflex experiment,the length of the large-scale sea urchin in the 20 ? group was slightly higher than the other two groups,but there was no statistical difference(P > 0.05),but the number of frequency of Aristotle's lantern reflex was significantly lower than the other two groups.(P < 0.001),which indicates that the high temperature further affects the feeding ability of S.intermedius.In the experiment of phototaxis behavior and light-shielding behavior,the average travel distance of the small-sized S.intermedius at 20 ? was 210.89 mm,which was significantly lower than the 482.92 mm of the 15 ? group(the phototaxis behavior P<0.005,the light-shielding behavior P < 0.001),the travel time was 712.67 s,which was significantly greater than 405.5 s in the 15 ? group(phototaxis behavior P < 0.005,light-protection behavior P < 0.001).In the anatomical experiments,it can be seen that in the growth and feeding traits such as shell diameter,shell weight,shell thickness,lantern length,lantern weight and gonad and intestinal weight,20 ? group and 15 ? and 10 ? There was a significant difference in the group(P < 0.001).The results of this experiment show that the temperature does not have a fatal effect on sea urchin between 10-20 ?;S.intermedius at 15 ? is better than the other two groups in terms of behavioral ability and growth,and the intermediate ball at 10 ? Sea urchins behave better than 20 ? in behavior and growth.Therefore,between 10 and 20 ° C,10-15 ? is better than 15-20 ?for the proliferation and release of S.intermedius.2)Effects of different temperatures on the survival,behaviors and growth of M.nudus under the suitable temperature conditionsIn the experiment to explore the effect of temperature on the M.nudus,the experimental design was the same as the study on the intermediate S.intermedius.The results showed that small size group of 20 ? death(0.67 ± 0.47)sea urchins,10 ? group of death(1 ± 0.81)sea urchins,mortality is no difference between groups.In addition,the results show that when the water temperature condition is 10 ?,M.nudus in various specifications of food consumption was significantly less than 20 ? and 15 ? group,(P < 0.01).In addition to the large size of sea urchin over 10 ? group is time is(659.38 ± 375.11 s),significantly greater than 15 ? and 20 ? group of sea urchins,turn speed is significantly smaller than the rest of the two groups of sea urchin;In diameter shell,shell height and weight,in addition to the large size was not significantly less than 20 ? group of sea urchins,all the rest of the 10 ? group M.nudus was significantly less than 20 ? and 15 ? temperature group(P < 0.05),and the small specification and specifications in 10 ? group is significantly smaller than the other two groups(P < 0.001).Same situation is found in the length and weight of the lanterns' measurement data,in addition to the large size,small size and specifications of the 10 ? M.nudus are extremely significant temperature is less than the other two groups of sea urchin(P < 0.001),while 15 ? sea urchin in group data significantly greater than 20 ?.This shows that under the condition of three temperature,sea urchins have 15 ? group feeding speed and the righting behavior is faster,and grow better;the 20 ? group's action is faster than the 10 ? group's action,and they have better growth.If you have to meke a chioce between two temperature interval,M.nudus are more suitable for breeding discharge within the range of 15 to 20 ?,no matter live,behavior and growth relative to 10 to 15 ? range.3)Effects of predator on the survival,behaviors and growth of M.nudusThe experiment was divided into 72-hour short-term experiment and 6-week long-term experiment.The short-term experiment was carried out to observe the mortality and position distribution of sea urchin in the presence or absence of reef conditions.Long-term experiments were carried out to determine the mortality,behavioral traits and body size traits of sea urchin.In the short-term experiment,the mortality of large-size sea urchins in the absence/reef condition was 33.33% ± 47.14% and 8.89% ± 12.57%,respectively,and the mortality under small-scale no/reef conditions was 42.22% ± 38.62% and 17.78% ± 25.14%.Although the data did not show significantness,the mortality of two sizes of M.nudus was significantly lower than that of the non-bunker group in the presence of shelter.In the results of the distribution,the distribution of large-size sea urchin pools in the reef group is significantly larger than that in the bottom of the pool(P = 0.020),and there are significant differences in the number of sea urchins distributed between different positions of small-sized sea urchins in the reef group.P < 0.05).It was found that in the case of predator exposure and the presence of reefs,sea urchins distributed significantly on the pool wall,while distribution at the bottom of the pool was significantly less.This shows that sea urchins can perceive predators that inhabit the bottom of the pool,and then they escape.In the 6-week long-term experiment,all the small-sized sea urchins died regardless of the presence or absence of bunkers,and all the large-sized sea urchins had no body bunkers.All the small-sized sea urchins had all the bunker groups,and the large-sized sea urchins had the bunker group mortality rate 53.33% ± 35.69%.The results showed that Charybdis japonica had a significant feeding effect on the sea urchin,and it was a hostile creature in the process of sea urchin farming.During the 6-week experiment,most of the sea urchins in the predator group died except for the predator-free group.Therefore,we only statistically analyzed the sea urchins in the non-predator group for 6 weeks with or without reef conditions.Behavior and body size.The correction time of small sea urchins in the reef-free group was significantly less than that in the reef group(P < 0.001).There was no significant difference in the number of bite occlusions between the two respirators(P > 0.05).In the foraging behavior experiment,the travel path of small-sized sea urchins in the reef group was significantly smaller than that in the non-reef-like conditions(P < 0.001),and the small-sized sea urchins traveled significantly less than the large-size sea urchins in the case of reefs(P < 0.001).This indicates that sea urchins with shelter habitats have good foraging and feeding ability.In the bunker environment for 6 weeks,the sea urchin correction reaction time increased significantly.The results of body size data show that the shell diameter,shell thickness,body weight,lantern length and weight of the sea urchin in the reef group are significantly lower than those in the reef-free group.The above related traits of the sea urchin in the case of no reef are greater than those with reef.This may be related to the plasticity of the shell during the growth of the sea urchin.It may also be related to the limitations of this study as a laboratory simulation experiment.In the future,field experiments will be carried out in the sea area for in-depth research.