Dynamic Energy Budget Of Mytilus Galloprovincialis And The Nutrient Characteristics In Different Aquaculture Area In Haizhou Bay

Located along the border of Shandong and Jiangsu,Haizhou Bay is an open bay and a typical Mytilus galloprovincialis aquaculture area in China,with an annual aquaculture output of more than 150,000 tons and a value of 300 million yuan.With the expansion of the scale of aquaculture,the density of coastal aquaculture has increased.Nevertheless,due to the input of land-based pollutants,diseases have increased and aquaculture benefits have decreased.To pursue higher benefits,mariculture has gradually developed in offshore areas.In this context,it is of great theoretical and practical significance to carry out an environmental investigation and analysis of the growth and nutritional characteristics of mussels in different aquaculture areas of Haizhou Bay to inform management strategies for this mussel.In this study,the physical and chemical factors and the temporal and spatial characteristics of the benthic habitats in the main rearing areas of Haizhou Bay were investigated,and the dynamic energy budget(DEB)model of the mussel was constructed under different environmental conditions.Additionally,the nutritional characteristics and main influencing factors of mussels in different rearing areas were analyzed.The main research results were as follows:1.From November 2020 to April 2021,three large-scale surveys were conducted in the main aquaculture areas of Haizhou Bay.Based on the data of the water temperature,salinity,chlorophyll a(Chl-a)concentration,dissolved oxygen(DO),p H,and macrobenthos,we analyzed the spatial and temporal distribution characteristics of the physical and chemical factors and the benthic habitat status in the main aquaculture areas.The results showed there were significant seasonal differences in the water temperature,Chl-a concentration,and DO but not in the p H.In terms of spatial distribution,the water temperature showed a decreasing trend from the nearshore to the far shore in spring and autumn,and the temperature was high in the far shore in winter.The p H distribution was relatively uniform in all seasons.Also,the Chl-a concentration increased from nearshore to far shore.Survey areas with large biomass of benthic animals belonged to the high-value areas in the aquaculture zones and M.galloprovincialis section.While the low-value areas had offshore oysters and laver.Furthermore,there were benthic habitat status differences between the seasons,and the diversity index of the aquaculture zones was higher in spring(April)and autumn(November)but it was lower in winter(January).Also,in spring(April)and autumn(January),the water environment of the M.galloprovincialis area was severely polluted,there are obvious differences in the evaluation results between different evaluation methods.The ABC curve shows that there is no interference in Haizhou Bay in November and April,which is similar to the evaluation results of ambi,while the composite index m-ambi shows that the ecological environment of Haizhou Bay is in an excellent or good state in the three voyage surveys.2.To better understand the dynamic growth in the mussels that were cultured offshore in Haizhou Bay,an individual growth model was constructed using Python software according to DEB theory.The Chl-a concentrations and water temperatures that were observed from August 30,2020 to April 16,2021 at Cheniushan Island,Haizhou Bay were used as forcing functions,the shape parameters were obtained from experiments,and the other parameters in the model were obtained from the existing literature.The growth conditions of the mussel length and soft tissue quality were simulated.Then,the model was validated based on measured data of mussel growth at Cheuniushan Island.The results showed that the model could simulate the growth of shell length and wet weight of the mollusks well,and the simulated values of the wet weight of the soft tissue and shell length were linearly correlated with the actual values(P<0.01),with an R~2 of 0.9594 and 0.9999,respectively.However,the predictions of the wet weight of the shell were different under different environmental conditions,and the simulated values of shell length were more stable.3.Based on the different aquaculture zones,the M.galloprovincialiss offshore distance index(under the conditions of 1–3 months,nutrients,amino acids,and the change in the physical and chemical factors of the water environment)and the electronic nose smell analysis found that the smell of the different aquaculture zones varied but the difference was not significant.The offshore aquaculture zones for the M.galloprovincialiss were rich in nutrients and amino acid content in February;however,the accumulation of nutrients in the nearshore culture zone was slow,and the difference in the nutrient reserves was mainly related to the water temperature and feed density.In contrast,the offshore culture zone was more conducive to the accumulation and growth of nutrients for the M.galloprovincialis.