Wetlands are among the most species-rich and productive ecosystems on Earth and provide many essential services for human well-being and socio-economic development.Intensifying human activities and climate change,however,are severely impacting the structural integrity and functioning of wetland ecosystems,including wetland hydrological connectivity.The present work tries to synthesize current knowledge and to investigate existing issues regarding the ecological effects of wetland hydrological connectivity.The following are emphasized:the concepts of wetland hydrological connectivity;relationship between hydrological connectivity and wetland habitats;effect of hydrological connectivity on wetland species distribution,diversity,and food webs;restoration and engineering of hydrological connectivity in degraded wetlands.A particular focus is the impact of watershed human activities and climate change on hydrological connectivity in river deltaic wetlands.Further outlined are outstanding questions and research areas that will advance fundamental theories in wetland science and underpin successful conservation and restoration of river deltaic wetlands.