Feeding Of The Main Functional Groups Of Zooplankton In Daya Bay And Its Response To Environmental Changes

With the development of the coastal economy,various human activities such as marine aquaculture,reclamation,land-based sewage discharge and thermal pollution of nuclear power plants have an increasing impact on the Gulf environment.The eutrophication process in the Daya Bay waters has led to changes in the nutrient salt structure of Daya Bay due to the increasing human activities.The limiting factors for the growth and reproduction of zooplankton have increased year by year.As an important part of the Gulf ecosystem,zooplankton plays an important role in regulating the stability and balance of the internal environment of the system.There are many species of zooplankton,widely distributed,strong fertility and short generations,and weak activity.The biological response in a short period of time can amplify subtle environmental changes,even in local waters.The same is an important indicator of environmental change.In the past,the study of zooplankton in China mostly focused on the structure of the community,the distribution pattern,the life history of key species,the dynamic relationship between population dynamics and the physical environment.Although marine ecosystem function depends to a large extent on species diversity and community structure,it is more important to identify key contributors to ecosystem structure and function.The rich species and habitat diversity in the Daya Bay waters make it difficult to simulate the structure and function of their food webs with only key species.Based on the historical data collected from the Daya Bay zooplankton survey for nearly 20 years,this paper divides the composition of zooplankton functional groups in Daya Bay and studies the temporal and spatial changes of their functional groups.Combining field investigation and indoor molecular technology experiments to analyze the feeding diversity of different functional groups of zooplankton,study the feeding effects of the changes of the Gulf ecosystem on the dominant zooplankton in the Daya Bay and its adaptation mechanism and feeding regulation strategy for the environmental change,aiming at Daya Bay Provides basic data on key processes of nutrient delivery and food production in ecosystem functioning.Furthermore,the effects of environmental changes in the Gulf on the ecological status and ecological functions of dominant species of zooplankton are discussed,and basic data for predicting the impact of environmental changes on the structure and nutritional relationship of planktonic food networks are provided.This paper helps to accurately grasp the evolution of the Gulf's ecological environment,and provides a scientific basis for the management of the Gulf's ecological environment with the changes of zooplankton community and its energy transfer,and guarantees the healthy and sustainable development of the Gulf.The main findings are as follows:(1)Changes in environmental factors in Daya BayDaya Bay environmental factors have obvious seasonal changes,spring chlorophyll a is significantly increased;summer is high temperature and low salt environment;autumn seawater is evenly mixed;winter nuclear power plant heat effect is obvious,high salt seawater invades Daya Bay.Human activities affect the phytoplankton structure in Daya Bay,and chlorophyll a continues to increase,especially in the bay;phytoplankton dinoflagellates gain faster growth than diatoms.(2)The spatial and temporal changes of zooplankton functional groups in Daya BayThe Daya Bay zooplankton is divided into six functional groups: large floating crustacean GC,large copepod LC,small copepods,cladocerans SC,Chaetognaths,Medusae,Salps.The zooplankton functional group in Daya Bay has significant seasonal and spatial changes.In the summer,the high-yield SC functional group of the Daya Bay is the dominant species.In the autumn,the large-scale copepod LC dominant species:Oithona nana?Acartia erythraea increased the numbers.Spring species composition includes transitional features in winter and summer.Zooplankton biomass is highest in summer and relatively low in autumn and spring.Small copepod SC functional group,Pavocalanus crassirostris is an annual dominant species.The zooplankton(Jellyfish and Salps)in Daya Bay is on the rise,and the miniaturization is mainly in the warm drainage area of nuclear power plant;the gelatinization is mainly in the marine aquaculture area.In the past 20 years,the phenomenon of miniaturization and gluing of zooplankton in Daya Bay has been serious.The zooplankton biomass(dry weight)is reduced,and the dominant population structure is singular.In Daya Bay,the warm-water species of zooplankton,such as the cockroach,have a dominant position from summer to spring and autumn.The abundance of zooplankton also dominates the non-colloidal zooplankton group,but the proportion of colloidal zooplankton Raise.According to the abundance of zooplankton,Daya Bay is divided into three areas:nuclear power plant temperature drainage affected area(DNPP),cage culture area(MCCA)and less polluted or uncontaminated area(UW).(3)Spatial and temporal changes in the feeding of dominant species of zooplankton in Daya BayThe water outside the winter bay of Daya Bay brings abundant zooplankton bait,and the influence of human activities in the summer bay increases the food diversity of zooplankton.The change of natural environment makes the species of zooplankton alternately.In winter,the length of zooplankton is longer.The high nutrition and heat radiation caused by human activities cause the length of zooplankton to become shorter,which is one of the important reasons for the miniaturization of zooplankton.High-throughput test results show that zooplankton feeds a wide range of recipes,and the type of food intake far exceeds the number of native species in the environment.A large number of clear colloidal jellyfish and chlorophyll-free fungi and protozoa were identified in the test.Jellyfish occupies an important position in carnivorous and omnivorous zooplankton feeding.Omnivorous zooplankton are more likely to feed on phytoplankton in a warmer environment.Daya Bay zooplankton is preferred to feeding in high-temperature?high-salt areas and cage culture areas.In areas with runoff input,living and industrial pollution,the proportion of Ctenophora is high;in summer,the zooplankton food is mainly in low-temperature and low-salt areas.Obtained;zooplankton food in the bay is mainly in the high temperature and low salt area;inside the winter bay,zooplankton feeds food in areas with high concentration of chlorophyll a and nitrate;in the bay mouth the zooplankton mainly feeds food in high temperature areas.