Effects of seashore reclamation activities on the health of wetland ecosystems: A case study in the Yellow River Delta, China

Abstract

Seashore reclamation is an important way that humans utilize the oceans. In recent years, expansion of seashore reclamation activities has seriously disturbed natural coastal systems, and especially wetland ecosystems. In this paper, using China's Yellow River Delta as a case study, we evaluated the effects of seashore reclamation activities on the health of coastal wetland ecosystems. We defined a comprehensive assessment index system based on the pressure-state-response model and used the model to explore how wetland health responded to reclamation activities, including the construction of tidal embankments and ports, land reclamation, road construction, and upstream dam construction. We found that the pressure intensity index for seashore reclamation activities ranged from 0.39 to 0.77, and increased until the late 1990s. From 1950 to 2010, increasing pressure on the wetlands caused the comprehensive state and health indices to decrease from 0.87 to 0.51 and from 0.64 to 0.52, respectively; both indicate severe risks to ecosystem health. The comprehensive health index decreased continuously until about 2000, then improved. There were strong negative correlations between the comprehensive health and pressure indices and the reclamation activity pressure index (both R2 > 0.80, p < 0.05). A sensitivity analysis indicated that the assessment model was robust with respect to the effects of tidal embankment and dam construction. Our results indicate that alleviating the reclamation pressure, especially tidal embankment and dam construction, would significantly improve wetland ecosystem health. Our study will help seashore managers assess the combined effects of existing reclamation activities on coastal wetlands, and support future reclamation activity planning.