Historical changes in the ecological health of the Newark Bay Estuary, New Jersey.

A review of ecological conditions in the Newark Bay estuary over the past century was conducted to characterize chemical, physical, and biological indices of the health of the estuary and to evaluate the relationship of these trends with past and current urban-industrial influences within the watershed. The available data indicate that both the diversity and the abundance of aquatic species within the estuary have been substantially reduced since the late 1800s due to the intense industrialization and urbanization that occurred throughout the region. Water and sediment quality in major rivers and bays linked to the estuary have also been severely impacted. In addition, significant natural habitat has been destroyed as a result of industrial development, urban expansion, and shoreline modifications. Each of these parameters directly influences the status and condition of the ecological community, and their deterioration has likely been the cause of multiple adverse impacts on the overall health of the ecosystem. Review of more recent studies of sediment and water quality indicates that pollution control measures and the reduction or control of other environmental stressors have produced a gradual improvement in the ecosystem over the past 2 decades.