| Zoobenthos and sedimentary environment interact and influence each other.Physical,chemical,biological and other factors in the sedimentary environment will have a certain impact on the growth,survival and reproduction of benthos.The bioturbation of zoobenthos can further change the sedimentary environment by changing the physical,chemical and biological propertie s of sediment,overlying water and sediment-water interface coupling.Therefore,the movement behavior of zoobenthos is closely relat ed to the sedimentary environment.However,the previous studies on the behavior of zoobenthos are mostly focused on the changes of sediments or nutrients caused by bioturbation,lack of description of the process of bioturbation,and even lack of quantita tive study of bioturbation.In this thesis,the choice behavior of Perinereis aibuhitensis among different sediment types,the movement behavior characteristics and ecological significance of P.aibuhitensis under different temperature conditions,and the effects of temperature and specifications on the movement behavior characteristics of P.aibuhitensis were studied.The interaction between the choice behavior of P.aibuhitensis and different sediments,and the interaction between the main behavior characteristics and cave microenvironment were quantitatively revealed.This thesis explains the selection behavior characteristic s of P.aibuhitensis and their ecological behavior mechanism of changing and adapting to the cave environment,and provides a new method for the behavior study and behavior quantification of zoobenthic polychaete.The main results of this thesis are as follows:1. Experimental study of the choice behavior of Perinereis aibuhitensis among different sediment typesUsing the behavioral experimental device,we studied the choice behavior of different sizes of P.aibuhitensis under suitable temperature and salinity for sediments 10 cm in the surface and below the depth of 60cm in low tide zone,middle tide zone and high tide zone.The results showed that the body size and sediment type had no significant effect on the choice behavior of P.aibuhitensis,but the size had a significant effect on the search time,and the search time of small size P.aibuhitensis was longer than that of large size and medium size P.aibuhitensis.The body size and sediment type also had significant influence on the moving distance of P.aibuhitensis,and the moving distance of small size P.s aibuhitensis was longer than that of large size and medium size P.aibuhitensis.This study shows that the small P.aibuhitensis is more active and sensitive,and tends to choose the sediment with lower hydrogen sulfi de content.When P.aibuhitensis drilled inside the sediment,they tended to choose sediments with low organic matter content.In general,P.aibuhitensis exhibited a slight selectivity for different natural sediment types.2. Motion behavior characteristics of Perinereis aibuhitensis under different temperature conditions and its ecological significanceBy adjusting the temperature(5,10,15,20 and 25?)in the behavioral observation device,we studied the behavior types and characteristics of P.aibuhitensis,and explored the effects of different behavior processes on cave water exchange,nutrients and dissolved oxygen threshold.The results showed that the radial undulating frequency,pumping rate,radial undulating time,axial crawling time,pumping volume and dissolution efficiency of nutrients of P.aibuhitensis all increased with the increase of temperature.The total pumping volume was the highest at 25?up to 5.13L/d,of which the pumping volume of radial undulating motion and axial crawling motion were 4.36L/d and 0.7 5L/d,respectively.The highest dissolution efficiency of phosphate,ammonia nitrogen,nitrite and sulfide were 54.94?g/cm~2/d,1.45?g/cm~2/d,19.89?g/cm~2/d and 13.52?g/cm~2/d,respectively.The axial crawling speed and pumping rate first increased and then decreased with the increase of temperature,and reached the highest value at 20?.The dissolved oxygen threshold of start-up pumping behavior of P.aibuhitensis showed an increasing trend with the increase of temperature,and the threshold range was 0.80-2.19mg/L.This study shows that P.aibuhitensis has better vitality,higher pumping volume and nutrient dissolving efficiency at 15-25?.The motion behavior in the cave accelerates the exchange of water bodies inside and outside the cave,thus releasing more nutrients and accelerating the biogeochemica l cycle of sediments,and the higher the temperature,the greater the nutrient flux.3. Effects of temperature and body size on the motion behavior characteristics of Perinereis aibuhitensisWe used the behavioral observation device to study the effects of temperature(15,20 and 25?)and body size(large size(2.2±0.20)g,medium size(1.5±0.2)g and small size(0.7±0.2)g)on the behavior characteristics of P.aibuhitensis,and explored the change rules of cave water exchange,nutrients and dissolved oxygen in different behaviors.The results showed that temperature had a significant effect on the radial undulating frequency of P.aibuhitensis(P<0.05),and the radial undulating frequency of P.aibuhitensis increased with the increase of temperature.The body size had a significant effect on the axial crawling velocity of P.aibuhitensis(P<0.05).The axial crawling velocity of large-size P.aibuhitensis slowed down with the increase of temperature,while th e axial crawling velocity of medium-size and small-size P.aibuhitensis increased with the increase of temperature.The temperature and body size had no significant effect on the radial undulating and axial crawling time(P>0.05),but the body size had significant effect on the pumping volume,pumping rate,and nutrient dissolving efficiency(P<0.05).The pumping volume and nutrient dissolvi ng efficiency increased with the increase of body size,and the maximum pumping volume of large-size P.aibuhitensis was 10.01L/d,and the maximum dissolution efficiency of phosphate,nitrite,ammonia nitrogen and sulfide in the cave were 109.80?g/cm~2/d,6.02?g/cm~2/d,60.56?g/cm~2/d and 15.40?g/cm~2/d,respectively.The dissolved oxygen threshold of start-up pumping behavior of P.aibuhitensis showed an upward trend with the increase of temperature and body size.This study shows that the large-size P.aibuhitensis moves more actively than smaller ones at low temperature and may have stronger tolerance to low temperature,the small-size P.aibuhitensis starts the pumping motion when the dissolved oxygen concentration is lower and may have a stronger tolerance to hypoxia.So when the temperature decreases,the large-size P.aibuhitensis can show better adaptability,and when the dissolved oxygen in the water decreases,it will have less effect on the small-size Perinereis aibuhitensis. |
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