Evaluation Of The Ecological Health Of Hongze Lake Based On The Structural Characteristics Of The Benthic Macroinvertebrate Community

It is important to investigate the impact of regional landscape change on ecosystem biodiversity and to scientifically recognize the interaction between the two,in order to promote the use,protection,optimization and improvement of regional resources,as well as to maintain the stability and health of the landscape ecosystem.Research on the impact of changes in land use types in the basin on the water ecosystem has received much scholarly attention,but changes in the landscape types of the water ecosystem itself have not received widespread attention.Hongze Lake is the fourth largest freshwater lake in China,Fishery aquaculture changes the landscape type of the littoral zone and increases the difference in landscape structure between the sublittoral zone and the littoral zone.Because of the continuous economic development in the watershed,the large nutrient loads from rapid urbanisation and industrialisation.The eutrophication problem of Hongze Lake has been delayed and the water ecosystem has been damaged,and the landscape structure and its functions have been changed accordingly.This paper investigates the species composition and abundance of benthic macroinvertebrate in sublittoral zone and the littoral zone respectively,and uses multivariate statistical analysis methods such as ANOVA and structural equation model to investigate the response of benthic macroinvertebrate community structure to differences in landscape structure of the sublittoral and thelittoral zone,and to explore the sensitivity of benthic macroinvertebrate to different disturbances under differences in landscape structure.and constructed a Benthic-index of biotic intergrity for the evaluation of the aquatic ecological health of Hongze Lake,we also gives recommendations for ecological restoration.The specific findings of the study are as follows:Seasonally driven changes in landscape have impacted on the sublittoral zone.Analysis of similarity showed that the benthic macroinvertebrate community in autumn differed significantly from the other three seasons.However,the characteristic species in each season are mostly pollution resistant species.Species diversity was generally low,with non-significant differences between seasons and little spatial variation.Functional feeding groups were dominated by gather-collectors and shredders,with the least occurrence of predators.The benthic macroinvertebrate communities of the estuarine and levee littoral types are significantly different from those of other types of littoral zones.The species diversity index of all types of lakeside zones is generally low,The BPI and BMWP are more suitable for the biological assessment of water quality in the littoral zone of Hongze Lake during the period of High Water Period.The sublittoral subject to higher wind and wave disturbance and the littoral zone subject to higher nutrient loads.Species diversity being the least responsive to nutrient,while functional diversity,phylogenetic diversity and functional feeding groups can be used as good indicators of ecosystem health.The assessment of the B-IBI show that the sublittotal zone of Hongze Lake is in a ’poor’state,and the health of the Chengzihu zone is in a ’very poor’ state,which is severely affected by the inflowing rivers.The assessment of the B-IBI show that the littoral zone as a whole is in fair state and the estuarine type is in a ’poor’ state,some of the spots in the light beach type are seriously polluted.Changes in the landscape type affect the ecological health of the littoral zone by influencing Chl.a,the number of aquatic plant taxa and transparency.Based on the results of the current situation and ecological health assessment of Hongze Lake,we suggest that improvement and restoration measures such as bioregulation,littoral zone aquatic plant zone reconstruction,buffer zone establishment and polder-returning project should be started simultaneously;and it is also suggested that the monitoring programme of large shallow lakes should be deployed for both the littoral zone and the sublittoral zone to obtain a more comprehensive monitoring section.This paper discusses the study based on benthic macroinvertebrate by regions,seasons and landscape types,which can provide some feasible references for the development of the monitoring scheme in Hongze Lake.