Marine Biology of the Changjiang (Yangtze River) Estuary and Adjacent East China Sea Shelf

Abstract

This chapter focuses on the biological components of the Changjiang (Yangtze River) Estuary and adjacent East China Sea shelf, including phytoplankton, zooplankton, benthic macro-invertebrate, and fish faunas. During recent decades, the marine ecosystems in this area have experienced marked disturbances induced by human activities and changing climate. An increase in the abundance of dinoflagellates constitutes the most important change in phytoplankton populations over the last 20 years. The accelerated eutrophication related to human activity, particularly increased anthropogenic inputs into the Changjiang, and the increasingly skewed ratio of nutrient species that has accompanied global warming, might be partially responsible for these changes. The Changjiang Estuary and the adjacent East China Sea shelf are situated in the subtropical–warm temperate biogeographic boundary zone of the NW Pacific Ocean. Warming of surface waters in this area has been occurring since the middle to late 1980s. Over this same period, the abundance of temperate and warm temperate zooplankton has significantly decreased, and the abundance and frequency of occurrence of subtropical and tropical zooplankton have significantly increased. The Changjiang Estuary and the adjacent East China Sea shelf are the habitats of many resident and migratory fish species (present in various life cycle stages) that are of commercial and ecological value. However, because of human-induced disturbances (such as over-fishing) and environmental changes, many of the larger and commercially important demersal species occupying higher trophic levels have been replaced by smaller commercially marginal pelagic species occupying lower trophic levels. Thus, the recent intensification of human-induced disturbances and those of climate change necessitate and demand an integrated estuarine, coastal, and marine management strategy for this region.