CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China.
South China Sea Ecological Center, Ministry of Natural Resources, Guangzhou 510300, China.
Water Res. 2024 Oct 1;263:122147. doi: 10.1016/j.watres.2024.122147. Epub 2024 Jul 25.
Human-induced nutrient inputs to global coastal waters are leading to increasing nutrients and escalating eutrophication. However, how aquatic ecosystem functioning responds to these changes remains insufficiently studied. Here we report the long-term changes in the nutrient regime and planktonic ecosystem functioning in the Daya Bay, a typical subtropical semi-enclosed bay experiencing rapid economic and social development for several decades. Time-series (from 1991 to 2018) data with a mostly quarterly resolution were collected to depict long-term changes in dissolved inorganic nutrients and plankton abundances, based on which we constructed simplified abundance size spectra (SASS) and plankton abundance ratios to describe the functioning of the planktonic ecosystem. The results revealed a long-term increase in system productivity but a decrease in integrated energy transfer efficiency of the planktonic ecosystem, with rising concentrations of dissolved inorganic nitrogen (DIN). Shifts in the nutrient regime and planktonic ecosystem functioning were detected at a tipping point or threshold around 2006-2007. The shifts were characterized by abrupt changes in the trends of nutrient (phosphate, ammonia, nitrite) concentrations, nutrient ratios (DIN/phosphate, silicate/phosphate), plankton abundance, and total plankton biomass. Compared to the nutrient regime, the planktonic ecosystem functioning shifted several years later. Overall, this study indicates that the pelagic ecosystem regime can shift significantly in response to long-term increasing input of human-induced nutrients in coastal waters such as the Daya Bay. The regime shifts may have profound implications for fishery production, and ecosystem management in the bay.
人类向全球沿海水域输入的营养物质导致营养物质增加和富营养化加剧。然而，水生生态系统对这些变化的反应仍研究不足。本研究报告了经历了几十年快速经济和社会发展的典型亚热带半封闭海湾——大亚湾的营养状况和浮游生物生态系统功能的长期变化。收集了 1991 年至 2018 年的时间序列（大多为季度分辨率）数据，以描述溶解无机养分和浮游生物丰度的长期变化，并据此构建简化丰度大小谱（SASS）和浮游生物丰度比来描述浮游生物生态系统的功能。结果表明，系统生产力长期增加，但浮游生物生态系统的综合能量传递效率下降，溶解无机氮（DIN）浓度升高。在 2006-2007 年左右，营养状况和浮游生物生态系统功能发生了转变。转折点或阈值的变化特征是营养物（磷酸盐、氨、亚硝酸盐）浓度、营养物比（DIN/磷酸盐、硅酸盐/磷酸盐）、浮游生物丰度和总浮游生物生物量的趋势发生了突然变化。与营养状况相比，浮游生物生态系统功能转变滞后几年。总体而言，本研究表明，在像大亚湾这样的沿海水域，长期增加人类引起的营养物质输入会导致浮游生态系统状况发生重大变化。这种生态系统的转变可能对海湾的渔业生产和生态系统管理产生深远影响。
