Study On The Stability Of Food Web In Mountainous Rivers Based On Bioenergetic Model

Food web is the main carrier of material circulation and energy flow in ecosystem,and its complexity and stability have always been one of the hot issues studied by ecologists.Different species in the food web interact through competition and predation,and the outbreak or extinction of one species often affects other species through interspecies interactions.Aquatic ecosystem is a kind of fragile ecosystem.The main biological groups of phytoplankton and zooplankton have the characteristics of large fluctuation and sensitivity to environmental changes.Studying the stability of aquatic ecological food web is of great significance to solve eutrophication,inhibit algae outbreak and reduce species extinction.In this paper,phytoplankton,zooplankton,benthic organisms and other biological communities were sampled and investigated in the Taizicheng River Basin,the core area of the Winter Olympics from August 2018 to June 2019 to determine the species composition,density and biomass characteristics.The structure of aquatic eco-food network was determined based on species competition and predation.According to the food network structure and the energy flow process between species,the bioenergy model was constructed,and the model parameters were calibrated using the ecological metabolism theory and the individual size of species.The effects of eutrophication,food web connectivity and species diversity on community biomass,stability and species coexistence were studied by numerical simulation.The main results and conclusions are as follows.(1)When the connectance was 0.1,0.2 and 0.3,the growth of environmental capacity had a significant positive impact on the growth of phytoplankton,zooplankton and benthic biomass,and there was a linear correlation between environmental capacity and phytoplankton,zooplankton and benthic biomass.For benthic biomass and environmental capacity,the greater the connectance,the stronger the linear correlation.When the connectance is 0.2 to 0.3,the increase of environmental capacity has a significant negative effect on the time series stability(TSI)of phytoplankton and zooplankton,and a significant positive effect on the TSI of benthic animals.When the connectance is 0.1,0.2 and 0.3,the increase of environmental capacity has a significant negative impact on the number of coexisting species of phytoplankton,zooplankton and benthic animals.In other words,eutrophication increases the biomass of food web,but inhibits the species diversity of food web.When the connectance is large,the stability of phytoplankton and zooplankton is reduced,but the stability of benthic animals is improved.(2)The increase of connectance C had significant negative effects on phytoplankton community biomass,temporal stability index and the number of coexisting species.There were significant positive effects on biomass and temporal stability index of zooplankton.When the environmental capacity is 10,the increase of connectance has a positive impact on the number of zooplankton coexistence species.When the environmental capacity is 110,the increase of connectance has a negative impact on the number of zooplankton coexistence species.When the environmental capacity is 60 and 110,connectance has a significant positive effect on the biomass and stability of benthic animals,and has a significant negative effect on the number of species coexistence of benthic animals.The increase of connectance inhibited the growth of phytoplankton biomass and reduced the stability and diversity of phytoplankton time series.However,the biomass and temporal stability of zooplankton increased.When the environmental capacity was small(10),the diversity of zooplankton increased,and when the environmental capacity was large(110),the diversity of zooplankton decreased.When the environmental capacity is large(60,110),the increase of connectance increases the biomass and temporal stability of benthic animals,but reduces the diversity of benthic animals.(3)The increase of species extinction,that is,the decrease of species diversity,has a significant positive effect on phytoplankton biomass and a significant negative effect on zooplankton and benthic biomass.The increase in species extinction has a positive impact on the time stability index of phytoplankton when the environmental capacity and connectance are small(environmental capacity is 10,connectance is 0.1),and has a significant negative impact on the time series stability of zooplankton.When the environmental capacity is high(60,110),the extinction number has a significant negative effect on the temporal stability index of benthic animals.These results and conclusions are of great significance for us to understand the effects of eutrophication,connectance and species diversity on the coexistence and stability of food web species.At the same time,this paper constructs the food network dynamics model of the real mountain river Taizicheng River based on the biomechanics model.The method of model construction and research has certain reference significance for the study of food network characteristics in the aquatic ecosystem.