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Seasonal characteristics of nutrient and nutrient structure in the Yangtze River estuary

Li Lei, Xv Guodong, Zheng Yingjie, Jiang Mei

Archives of Environmental Protection

2023

Vol. 49, no 3

115--122

This data article aimed to evaluate the influencing mechanisms of the nutrients and the level of eutrophication in the Yangtze River estuary. The seasonal characteristics of nutrients (dissolved inorganic nitrogen (DIN), SiO3-2–Si, and PO43-P) in the seawater of the Yangtze River estuary were analyzed by conducting surveys in spring and summer of 2019. The findings revealed that the concentrations of all nutrient at the surface and bottom layers were lower in spring compared to summer. NO3–N was typically the major form of DIN. Runoff was identified as the primary source of DIN and SiO32−–Si, while PO43−–P originated from a various sources. The SiO32−–Si, while PO43−–P values in the surface and bottom layers during the spring and summer were higher than the Redfield values, indicating an imbalanced nutrient distribution. Furthermore, discrepancies were observed in the distributions of DIN/PO43−–P, SiO32−–Si/DIN, and SiO32−–Si/PO43−–P in the Yangtze River estuary. Through an examination of the ratio of DIN/PO43−–P absorbed by phytoplankton, PO43−–P was identified as a potential limiting factor for nutrition in the sea area of the Yangtze River estuary during spring and summer. The Eutrophication Index (E) values for both spring and summer were found to be higher than the eutrophication threshold, indicating severe eutrophication in the studied sea area.

Annual variability of ichthyoplankton in the Yangtze River estuary of China from August 2002 to 2009

Jiang M., Shen X. Q., Li L., Quan W. M.

Oceanological and Hydrobiological Studies

2013

Vol. 42, No. 1

59-69

The annual variability of ichthyoplankton in the Yangtze River estuary, located at the junction of the East China Sea and the Yellow Sea, on the continental shelf at the western rim of the Pacific Ocean, was studied using vertical tows at twenty stations from August 2002 to August 2009. Basic oceanographic parameters such as temperature and salinity were also measured to evaluate their relationship to the abundance of ichthyoplankton. The eggs or larvae of a total of 34 fish species were present in the samples. Only 8 species were found to occur during every year. Engraulis japonicus and Stolephorus commersonii eggs, as well as Coilia mystus and Stolephorus commersonii larvae, were highly abundant during this period. Additionally, water storage in the Three Gorges Reservoir, which began in June 2003, had significant effects on the abundance of estuarine species, as well as on the composition and diversity of ichthyoplankton; this became evident when these values were compared to the findings from 2002. The number of species (species richness) and abundance of each species varied among the stations relative to the salinity in the estuary during the study period.