Long-term ecological interactions between nutrient and phytoplankton community in the Changjiang estuary

• Published in: Chinese journal of oceanology and limnology Vol. 28; no. 4; pp. 887 - 898
• Main Author: 江涛 俞志明 宋秀贤 曹西华 袁涌铨
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science Press 01.07.2010; Springer Nature B.V
• Subjects: Bacillariophyceae; Brackish; Comparative studies; Earth and Environmental Science; Earth Sciences; Estuaries; Eutrophication; Limnology; Marine; Nitrates; Nutrient transport; Nutrients; Oceanography; Phytoplankton; Plankton; R&D; Research & development; Rivers; Salinity; Seawater; Silica; 养分投入; 历史变迁; 浮游植物群落; 海水盐度; 相互作用; 硅藻丰度; 长江河口; Changjiang River; China; INW, China, People's Rep., Changjiang Estuary; Changjiang estuary; phytoplankton community; eutrophication; nutrients
• ISSN: 0254-4059; 2096-5508; 1993-5005; 2523-3521
• DOI: 10.1007/s00343-010-9059-5

Both nitrateNO3^- and soluble reactive phosphatePO4^3- concentration in the freshwater end-member at the mouth of the Changjiang River have increased dramatically since the 1960s.Within the same period in the sea area,with surface salinity〉30,NO3^-concentration has shown an obvious increase,PO4^3- has not changed greatly and dissolved reactive silicaSiO3^2- has deceased dramatically.An examination of the elemental ratio ofNO3^-toPO4^3- at the mouth of the Changjiang River did not show a systematic trend from the 1960s to 2000s largely because both nutrients increased simultaneously.In comparison,the elemental ratio of dissolved inorganic nitrogen（DIN） toPO4^3- in surface seawater,with salinity〉22,has shown a clearly increasing trend.Furthermore,an overall historical change of theSiO3^2-：PO4^3- ratio has undergone a reverse trend in this area.Based on the changes ofSiO3^2-：PO4^3- and DIN：PO4^3- ratios,we can conclude that an overall historical change ofSiO3^2-：DIN ratio has decreased in this area from the 1950-1960s to 2000s.The argument that phytoplankton productivity in the Changjiang estuary has been enhanced by increasing nutrient input from the riverine transport was supported by these results.A comparative study analyzing the shift of phytoplankton composition from the mid-1980s to 2000s was also made.The results indicated that the average yearly percentage of diatom species in the Changjiang estuary has decreased from 84.6% during 1985-1986 to 69.8% during 2004-2005.Furthermore,the average yearly percentage of diatom abundance in the Changjiang estuary decreased from 99.5% during to 75.5% over the same time period,while the abundance of dinoflagellates has increased dramatically,from 0.7% to 25.4%.