Temporal And Spatial Changes And Influencing Factors Of The Health Of Coastal Ecosystems In Rudong

Rudong nearshore waters is located in the southern wings of the northern Jiangsu radial sand ridges and the north wing of Yao Sandbank(YS).The richness of the mudflats has long made them a hot spot for human exploitation activities.The nearshore waters of Rudong is a complex and variable source of material,subject to strong tidal action,with a complex hydrodynamic environment and a highly sensitive and fragile ecosystem.In order for humans to further benefit from the oceans,the health,integrity and resilience of marine ecosystems need to be ensured and further damage from human activities strategically mitigated.This paper explores new ways of protecting and managing the nearshore ecosystem of Rudong from the perspective of ecosystem health.Constructing the Rudong nearshore ecosystem health evaluation system and stress evaluation system to achieve quantitative spatial and temporal evaluation of ecosystem health.Studying the interrelationship between changes in pressures on Rudong's nearshore ecosystems and changes in ecosystem health indices to reveal the factors influencing spatial and temporal changes in the health of Rudong's nearshore ecosystems.Exploring the interface between ecosystem health change factors and integrated management of nearshore waters,proposing regulatory measures for the management of the nearshore ecosystem in Rudong,and providing decision support to relevant management departments for integrated management.The main research contents and conclusions of the paper are as follows:1.Evaluation of nearshore ecosystem health in RudongBased on the environmental and biological elements,an evaluation system for the health of the Rudong nearshore ecosystem was constructed,and the health of the ecosystem was quantitatively evaluated at three stages: Initial stage of reclamation,mid to late stage of reclamation,cessation of reclamation through a fuzzy comprehensive evaluation method.The evaluation results show that the condition of the Rudong nearshore ecosystem was basically sub-healthy and above at the beginning of the reclamation period,with only one station showing ageneral pathological state.In the middle and late stages of reclamation,the ecosystem condition was generally healthy to sub-healthy,with a significant increase in the number of generally healthy stations and a decline in ecosystem health.At the cessation of the reclamation period,the ecosystem condition is sub-healthy and above,with an improvement over the previous stage.Overall,the gradient of the ecosystem health index in the Rudong near-shore sea is less different in the three stages,and is basically in a subhealthy state.2.Spatial and temporal distribution characteristics of inshore ecosystem he alth in RudongBased on the spatial interpolation of environmental factors,biological factors and health indices,the spatial and temporal variation characteristics of ecosystem health were derived.In the initial stage of reclamation,the health of the Rudong nearshore ecosystem gradually improved from land to sea,and the health index was low in the Tiaozini and Tongzhou Bay waters,mainly due to severe eutrophication and insufficient phytoplankton diversity.In the middle and late stages of reclamation,the health index values of the outer part of the Tiaozini Reclamation Area and the outer part of the Yangkou Harbor Industrial Zone are lower,and the health index of the outer part of the sea is better than that of the shoreline sea,the input of pollutants from land-based sources is stillan important reason for the decline of ecosystem health in this stage.The health index values during the cessation of reclamation are clearly distributed in bands,with the northern part of the study area being the worst,followed by the middle and the southern part being the best.Overall,the health status is good at the beginning of the reclamation,deteriorates in the middle and late stages of the reclamation,and gradually improves during the cessation of reclamation.High eutrophication and insufficient biodiversity are the same problems faced by the Rudong inshore marine ecosystem in all three periods3.Evaluation of pressure on the nearshore ecosystem of RudongBased on the results of the identification of stressors in the Rudong nearshore ecosystem,a stress evaluation system for the Rudong near-shore ecosystem was constructed,including population pressure,economic pressure and human activity pressure.The evaluation results show that the pressure index values change in phases in a clear pattern.From 2008 to 2012,there was a clear upward trend in the coastal development environment,and from 2013 to 2017,there was a relatively high level of stress and pressure,and from 2018 to 2019,the index values decreased.The ecosystem health index values are in good agreement with the changes in stress values,while the ecosystem response to stress has a degree of lag.4.Factors influencing the health of the Rudong nearshore ecosystemFactors influencing changes in ecosystem health are derived based on changes in stress indices and changes in health indices.Population pressure is the underlying rather than the direct cause of changes in ecosystem health;economic pressure is not directly consistent with ecosystem health;and anthropogenic pressure is direct and critical to changes in ecosystem health.The main influencing factors for ecosystem health change in the three phases are beach reclamation and fish farming,waste water discharge and new marine area for transportand industrial use,and waste water and gas emissions.