This study aims to elucidate the environmental changes signified by biogenic components, assess fluctuations in upwelling over the past century, and evaluate the potential risks associated with variations in coastal upwelling intensity on the degradation of fisheries within the Zhoushan Fishing Ground. High-resolution sediment records were established to reveal long-term variations in Zhoushan coastal upwelling. Results showed a significant reduction in nutrient components between 1900s and 1950s, suggesting a decline in upwelling strength. Since the 1960s, lightened δ15N and the incline of nutrients suggests an increase in anthropogenic nutrients influx, and increased OP and CUISST (SST-based coastal upwelling index) indicates strengthening of upwelling during the 1950s to 1980s. A positive correlation between organic phosphorus (OP) and δ13C has been observed since the 1960s, implying that P is a limiting nutrient due to increasing anthropogenic N influx, and the change in CUISST coincides well with our OP records. OP is a potential indicator of upwelling strength because upwelling contributes to over 90 % of the P on the East China Sea shelf. A prominent decline in the nutrient composition occurred from the 1980s to 2010s, despite substantially increased anthropogenic nutrients influx and eutrophication in adjoining Changjiang delta regions in the past decades. Weakening upwelling and the consequent decreasing nutrients influx has presumably hindered recovery and thus contributed to the degradation of fishery resources in recent decades.

中文翻译：

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1900 年以来舟山沿海上升流波动引起的营养物变化及其对渔业的影响


本研究旨在阐明生物成分所代表的环境变化，评估过去一个世纪上升流的波动，并评估沿海上升流强度变化对舟山渔场渔业退化的潜在风险。建立高分辨率沉积物记录以揭示舟山海岸上升流的长期变化。结果显示，在 1900 年代和 1950 年代之间，营养成分显着减少，表明上升流强度下降。自 1960 年代以来，变轻的 δ15N 和营养物质的倾斜表明人为营养物质流入的增加，而 OP 和 CUISST（基于 SST 的沿海上升流指数）的增加表明 1950 年代至 1980 年代上升流加强。自 1960 年代以来，一直观察到有机磷 （OP） 和 δ13C 之间呈正相关，这意味着由于人为氮流入增加，P 是一种限制性营养物质，并且 CUISST 的变化与我们的 OP 记录非常吻合。OP 是上升流强度的一个潜在指标，因为上升流占东海大陆架 P 的 90% 以上。尽管在过去几十年中，毗邻的长江三角洲地区的人为营养物质流入和富营养化大幅增加，但营养物质组成在 1980 年代至 2010 年代发生了显着下降。据推测，上升流的减弱和随之而来的营养物质流入减少可能阻碍了恢复，从而导致了近几十年来渔业资源的退化。