Study On Feeding Physiology And Construction Of Dynamic Energy Budget Model Of Tegillarca Granosa

Tegillarca granosa is one of the traditional farming shellfish in China.Farmers love it because of its high nutrition and low breeding cost.While long culturing time limited the development of T.granosa industry.With the continuous expansion of mariculture,farmers often engage in mariculture only by experience due to the lack of scientific breeding technology,resulting in unstable production and low benefits.Therefore,this study discussed whether T.granosa has the feeding selectivity through the physiological experiment of feeding.Two basic parameters of dynamic energy budget model were obtained.Six basic parameters of the model were obtained by laboratory physiological experiment and field measurement.Finally,the dynamic energy budget model of T.granosa was constructed by using Python software.Using this model,we simulate the growth of shell length and dry tissue weight,and quantify the energy allocation under the condition of pond culture.This model provides a scientific tool for breeding capacity evaluation and breeding management improvement.The main research contents were as followed:（1）The effects of algae species,size and density on feeding rate,water filtration rate and absorption rate of T.granosa were studied by indoor stillwater method.The results showed that there was no significant feeding selectivity of T.granosa to the three species.The algae species had no significant effects on the feeding rate,water filtration rate and absorption rate（P>0.05）.But the shellfish density and size had significant effects on the feeding rate and water filtration rate（P<0.01）.And the three factors had an interaction on the feeding rate（P<0.01）.The density and specification of shellfish had a significant effect on the water filtration rate（P<0.01）.Also,there had an interaction between algae species and specification,density and specification,and algae species,density and specification on the water filtration rate（P<0.01）.The three factors had no interaction on the absorption rate（P>0.05）.In addition,the basic parameters needed to build the model were calculated based on the feeding rate and absorption rate of T.granosa.The maximum feeding rate per unit body surface area were 346.68J/（cm².d）.The maximum surface area-specific assimilation rate were 280.81 J/（cm².d）.（2）The shape coefficient of T.granosa was calculated by regression fitting between shell length and wet tissue weight.The regression analysis of shell length（L）and wet tissue weight（MW）shows a cubic function relationship:MW=0.0556L^3.1831.The shape coefficient value was 0.405.The dry tissue weight oxygen consumption rate was measured at six temperature conditions（10℃,15℃,20℃,25℃,30℃,35℃）by circulating water temperature control method,and the T_Avalue of arrhenius temperature was calculated as（4830±586）K.The value of[E_G]、[E_M]、[P_M]and μE obtained by the hunger experiment were 5475 J/cm³,2026 J/cm³,32.2 J/（cm³.d）,23376 J/g.（3）According to DEB theory,we first obtained model parameters through laboratory physiological experiments and literature.Then,combined with the monthly growth data and environmental indicators,the dynamic energy budget model of T.granosa was constructed by using Phython software,which takes monthly water temperature and food concentration collected as the compulsory function of the model.The results showed that the dynamic energy budget model could better simulate the growth of shell length and dry tissue weight of T.granosa in pond culture.The simulated values of shell length and dry tissue weight showed a significant linear correlation with the measured values（P<0.01）,R²was 0.9893 and 0.9708.There was no significant difference between the simulated values and the measured values（P>0.05）.During the first 45 days（2020.07.25～2020.09.07）,the growth of T.granosa was relatively slow.The dry tissue weight and shell length did not increase significantly.It grew faster during 45 d～150 d（2020.09.07～2020.12.21）and 240 d～360 d（2021.03.21～2021.07.19）.The shell length and dry tissue weight increased rapidly.However,the growth of shell length stagnated,and even the dry tissue weight decreased slightly at this stage during 150 d～240 d（2020.12.21～2021.03.21）.T_Ahas the greatest influence on the growth.If T_Achanges by 10%,the dry tissue weight will increase by11.60%.Growth limiting factor analysis showed that temperature was the main limiting factor from July 25 to September 22 and from June 19 to July 19 in the following year.From January 10 to March 21 of the next year,the food restriction was stronger than the temperature restriction.The energy allocated to storage materials during January and February was not enough to maintain the growth of T.granosa.It indicated that the dry tissue weight and the survival rate in winter were decreased,and the structural materials were damaged.