Jin Lei, Chen Huihuang, Matsuzaki Shin-Ichiro S, Shinohara Ryuichiro, Wilkinson David M, Yang Jun
Aquatic EcoHealth Group, Fujian Key Laboratory of Watershed Ecology, Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China.
National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
Water Res. 2023 Oct 15;245:120639. doi: 10.1016/j.watres.2023.120639. Epub 2023 Sep 16.
Eutrophication and harmful algal blooms have severe effects on water quality and biodiversity in lakes and reservoirs. Ecological regime shifts of phytoplankton blooms are generally thought to be driven by the rapidly rising nutrient use efficiency of bloom-forming species over short periods, and often exhibit nonlinear dynamics. Regime shifts of trophic state, eutrophication, stratification, and clear or turbid waters are well-studied topics in aquatic ecology. However, information on the prevalence of regime shifts in relationships between trophic states and phytoplankton resource transfer efficiencies in ecosystems is still lacking. Here, we provided a first insight into regime shifts in nitrogen use efficiency of phytoplankton along the trophic state gradient. We explored the regime shifts of phytoplankton resource use efficiency and detected the tipping points by combining four temporal or spatial datasets from tropical to temperate zones in Asia and Europe. We first observed significant abrupt transitions (abruptness > 1) in phytoplankton nitrogen use efficiency along the trophic state gradient. The tipping point values were lower in subtropical/tropical waterbodies (mesotrophic states; TSIc: around 50) than those in temperate zones (eutrophic states; TSIc: 60-70). The regime shifts significantly reduced the primary production transfer efficiency via zooplankton (from 0.15 ± 0.03 to 0.03 ± 0.01; mean ± standard error) in the aquatic food web. Nitrogen-fixing filamentous cyanobacteria can drive eutrophication under mesotrophic state. Our findings imply that the time-window of opportunity for harmful algae prevention and control in lakes and reservoirs is earlier in subtropical/tropical regions.
富营养化和有害藻华对湖泊和水库的水质及生物多样性有着严重影响。浮游植物水华的生态状态转变通常被认为是由水华形成物种在短时间内迅速提高的养分利用效率所驱动的，并且常常呈现非线性动态变化。营养状态、富营养化、分层以及水体清澈或浑浊等状态的转变是水生生态学中研究较为充分的课题。然而，关于生态系统中营养状态与浮游植物资源转移效率之间关系的状态转变普遍性的信息仍然匮乏。在此，我们首次深入探究了浮游植物氮利用效率沿营养状态梯度的状态转变。我们通过整合来自亚洲和欧洲从热带到温带的四个时间或空间数据集，探索了浮游植物资源利用效率的状态转变并检测了临界点。我们首先观察到浮游植物氮利用效率沿营养状态梯度存在显著的突然转变（突变度>1）。亚热带/热带水体（中营养状态；综合营养状态指数TSIc：约50）的临界点值低于温带水体（富营养状态；TSIc：60 - 70）。这些状态转变显著降低了水生食物网中通过浮游动物的初级生产转移效率（从0.15±0.03降至0.03±0.01；均值±标准误差）。固氮丝状蓝藻在中营养状态下可推动富营养化。我们的研究结果表明，湖泊和水库中有害藻类防控的机遇时间窗口在亚热带/热带地区更早。
