Temporal And Spatial Variation Of Pleurobrachia Globosa In The Bohai Bay From 2019 To 2021

Ctenopharyngodon is a kind of plankton.P.globosa is a common jellyfish in the southeast coast of China.In recent years,various investigations have shown that it is expanding northward,causing losses to fisheries and aquaculture industries around the coast.The most important is that P.globosa outbreak will clog the nuclear power plant intake interception network and grille.It is a common disaster-causing organism in nuclear power plants.In this study,a three-year(2019-2021)survey was conducted in the Bohai Bay of the Bohai Sea to study the spatial and temporal changes of the population and predict the life history of P.globosa.The results showed that P.globosa appeared from July to October every year,and reached the peak in August.Temperature,salinity,pH,dissolved oxygen and phytoplankton abundance were the key factors affecting P.globosa.The seven developmental stages of the three groups of P.globosa were described.By analyzing and investigating the proportion of each stage of P.globosa in the early,middle and late August,it was concluded that P.globosa experienced two complete generations in August,and it was confirmed that the generation time of P.globosa was about 2 weeks,which was similar to other jellyfish.The research results can provide data support for the prevention of P.globosa disasters in nuclear power plants in the Yellow Sea and Bohai Sea.This paper will elaborate on the research of P.globosa from three aspects.The specific contents are as follows:1.Study on the spatial and temporal variation of P.globosa populationThe population abundance and spatial variation of P.globosa in three consecutive years from 2019 to 2021 were analyzed.It was found that it appeared in Bohai Bay from July to October every year,with the highest abundance in August and the lowest abundance in October.2.Study on the influencing factors of P.globosa in Bohai BayPhytoplankton and water samples were collected and analyzed in the Bohai Bay for three consecutive years.Combined with other factors such as hydrology and meteorology,10 influencing factors were obtained.The analysis showed that temperature,salinity,pH,dissolved oxygen and phytoplankton abundance were the key factors affecting the abundance of P.globosa.The abundance of P.globosa was positively correlated with temperature and phytoplankton density,and negatively correlated with salinity,pH and dissolved oxygen.3.The life history of P.globosaBy measuring the size change of P.globosa in the Bohai Bay samples,the development stages and spatial distribution of P.globosa were predicted,and the generation time of P.globosa was determined to be about 2 weeks.In this study,the temporal and spatial changes and life history of P.globosa in Bohai Bay were studied in detail for the first time,which could provide important data support for subsequent studies on its source and overwintering mechanism.