Study On The Combined Effect Of Three Ecological Factors On Physiological Indexes Of Hyriopsis Cumingii

Hyriopsis cumingii is an endemic species in China,the pearls produced in freshwater pearl mussels are of excellent quality and have important economic value.Sudden changes in the water environment will have a certain impact on the physiological metabolism of shellfish.At present,most of the studies on the effects of major ecological factors on the vigour of Hyriopsis cumingii have been conducted under a single environmental factor condition,thereby ignoring the interaction effects between environmental factors.This is inconsistent with the actual living environment of Hyriopsis cumingii.At the same time,these studies only analyzed and discussed the linear effects of environmental factors on the physiological indexes of Hyriopsis cumingii,and did not establish a model and examine the quadratic effects of the factors,ignoring the cumulative effects of environmental factors on the physiological metabolism of Hyriopsis cumingii,which made the test results lack reliable predictability.Therefore,it is necessary to deeply explore the combined effects of various ecological factors on Hyriopsis cumingii.This study includes the following three parts.First,combined effect of temperature and pH on respiratory excretion of the grafted H.cummingii were studied.Second,the combined effect of temperature,pH,algae concentration of Chlorella vlgaris on filtration rate?FR?of the grafted H.cummingii were studied.Third,the combined effects of temperature,pH,algae concentration of Microcystis aeruginosa on the clearance rate?CR?of the grafted H.cummingii were studied.Results as follows:1?The central composite design?CCD?and response surface method were used to study the interactions of temperature?12±0.2??15.5±0.2??24±0.2??32.5±0.2??36±0.2??and pH?6±0.1?6.5±0.1?7.75±0.1?8.99±0.1?9.5±0.1?on the respiratory excretion of the grafted H.cummingii.The linear and quadratic effects of temperature and pH on oxygen consumption rate high significant?P<0.01?;Interaction effects of temperature and pH on oxygen consumption rate were significant?P<0.05?.The linear and quadratic effects of temperature on ammonia excretion rate high significant?P<0.01?;the linear effects of pH on ammonia excretion rate were significant?P<0.05?,the quadratic effects of pH were highly statistically significant?P<0.01?.Interaction effects of temperature and pH on ammonia excretion rate were significant?P<0.05?.The atomic ratio of O and N varied from 4.76 to 8.69 in the grafted H.cummingii.The optimization results showed that the optimal factor combination was 25.6°C/7.83,at which the maximum the oxygen consumption rate,0.725 mg·?g·h?^-1,was arrived,with the desirability of 0.992.The optimization results showed that the optimal factor combination was 25.71°C/7.86,at which the maximum the ammonia excretion rate,0.0749 mg·?g·h?^-1,was arrived,with the desirability of 0.929.The OR model was derived,with the R² being 0.9939.The Adj R² for the model reached 0.9895,the NR model was derived,with the R² being 0.9706.The Adj R² for the model reached 0.9495,indicates that the model has high accuracy.2?In consideration of the close relationship of the filtration rate to the growth and development of filter-feeding mollusks,the Box-Behnken experimental design and response surface method were used to study the interactions of temperature?12±0.2??24±0.2??36±0.2???pH?6±0.1?7.75±0.1?9.5±0.1?and algae densities?0.4×10⁶ cells/ml?0.8×10⁶ cells/ml?1.2×10⁶ cells/ml?on the filtration rate of the grafted H.cummingii.The linear and quadratic effects of temperature,pH and algae densities on the filtration rate of the grafted H.cummingii were highly significant?P<0.01?.Interaction effects of temperature and pH on filtration rate were significant?P<0.05?,but the interaction between algae densities and pH,interactive effect of temperature and algae densities were not significant?P>0.05?.The order of three ecological factors effects was temperature?A?>algae densities?C?>pH?B?.The FR model was derived,with the R² being0.9924.The Predictive R² for the model reached 0.9083,Showing that it could be employed to forecast the FR of the grafted H.cummingii.The optimization results showed that the optimal factor combination was 25.73?/7.86/0.85×10⁶cells/ml cells/ml,at which the maximum the filtration rate,0.42 mgPOM/h,was arrived,with the desirability of 0.969.The experimental verification results are close to the prediction results,and the response surface analysis method is reliable.3?The temperature?12±0.2??16.86±0.2??24±0.2??31.14±0.2??36±0.2???pH?6±0.1?6.71±0.1?7.75±0.1?8.24±0.1?9.5±0.1?and algae densities?10?g/L?28.24?g/L?55?g/L?81.76?g/L?100?g/L?for the clearance rate?CR?of the grafted H.cummingii were determined using the central composite design?CCD?and response surface method?RSM?under laboratory conditions.The linear effects of temperature on the clearance rate were significant?P<0.05?;the quadratic effects of temperature on the clearance rate were highly significant?P<0.01?;The linear effects of pH and algae densities,the quadratic effects of pH and algae densities on the clearance rate were highly significant?P<0.01?;interactions between temperature,pH and algae densities for the clearance rate have no significant?P>0.05?.The order of three ecological factors effects was algae densities?C?>pH?B?>temperature?A?.The optimization results showed that the optimal factor combination was 24.76?/7.89/59.88?g/L,at which the maximum the clearance rate,1.12 L/h,was arrived,with the desirability of 0.949.The CR model was derived,with the R² being 0.9757.The Adj R² for the model reached 0.9538,indicates that the model has high accuracy.In this paper,the effects of temperature and pH on the respiration and excretion of Hyriopsis cumingii were studied in order to understand the regularity and changes of metabolic activities of Hyriopsis cumingii,and to provide scientific basis for further energetic research.By studying the effects of temperature,pH and algae density on the filtration rate of Hyriopsis cumingii,the aim was to determine the appropriate experimental conditions for the maximum filtration rate of Hyriopsis cumingii.Provide reference materials for feeding and artificial breeding of Hyriopsis cumingii in the future.The effects of temperature,pH and algae density on the clearance rate of Hyriopsis cumingii were studied by simulating cyanobacteria blooms,and the aim was to determine suitable experimental conditions for the maximum clearance rate of Hyriopsis cumingii.It provides a certain theoretical basis for the future application of Hyriopsis cumingii in the ecological restoration of eutrophic waters.