To elucidate recent changes in nutrient structure and potential phosphorus limitation in China’s coastal seas, this study analyzed the spatial distribution and interannual variability of dissolved inorganic nitrogen (DIN), phosphate (PO43-), and their molar ratio (N/P) in surface waters of the central Bohai Sea, Yellow Sea, East China Sea, and the Changjiang River Estuary, using cruise data from National Natural Science Foundation of China shared surveys, and compared these with historical observations. The results indicate that in 2015 and 2017, most areas of the central Bohai Sea and Yellow Sea exhibited elevated N/P ratios, generally exceeding the Redfield ratio (16 : 1), reflecting pronounced nutrient imbalance and a tendency toward phosphorus limitation. In most years, the East China Sea also exhibited elevated N/P ratios; however, lower values were observed in parts of the outer shelf and in regions influenced by Kuroshio intrusion, suggesting possible nitrogen limitation in these areas. The Changjiang River Estuary maintained persistently high N/P ratios (>64 : 1), indicating stronger phosphorus limitation compared with other regions. Comparison with historical data revealed that N/P ratios in the central Bohai and Yellow Seas exhibited a long-term pattern of “initial increase followed by decline”, with peak values occurring around 2008 and 2005, respectively, suggesting that both seas have remained in a persistently high N/P state. Overall, nutrient imbalance is widespread in China’s coastal seas, although pronounced interregional and intraregional differences exist, reflecting the combined influence of land-based inputs and regional oceanographic processes. These findings provide a scientific basis for understanding the evolution of nutrient structure and the associated risk of nutrient limitation in China’s coastal seas.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |