Norwegian Institute for Water Research, CIENS, Science Park, Oslo, Norway.
Akvaplan-niva, CIENS, Science Park, Oslo, Norway.
Environ Toxicol Chem. 2019 Oct;38(10):2197-2208. doi: 10.1002/etc.4536. Epub 2019 Sep 18.
Freshwaters are increasingly exposed to complex mixtures of pharmaceutical and personal care products (PPCPs) from municipal wastewater, which are known to alter freshwater communities' structure and functioning. However, their interaction with other disturbances and whether their combined effects can impact ecological resilience (i.e., the ability of a system to tolerate disturbances without altering the system's original structure and processes) remain unexplored. Using in situ mesocosms in 2 lakes with different nutrient levels (mesotrophic and eutrophic), we assessed whether a pulse exposure to sublethal concentrations of 12 PPCPs affects the ecological resilience of natural phytoplankton communities that experienced an abrupt environmental change involving the destabilization of the water column through mixing. Such mixing events are predicted to increase as the effects of climate change unfold, leading to more frequent storms, which disrupt stratification in lakes and force communities to restructure. We assessed their combined effects on community metrics (biomass, species richness, and composition) and their relative resilience using 4 indicators (cross-scale, within-scale, aggregation length, and gap length), inferred from phytoplankton communities by discontinuity analysis. The mixing disturbance alone had negligible effects on the community metrics, but when combined with chemical contaminants significant changes were measured: reducing total biomass, species richness, and altered community composition of phytoplankton. Once these changes occurred, they persisted until the end of the experiment (day 20), when the communities' structures from the 2 highest exposure levels diverged from the controls. The resilience indicators were not affected by PPCPs but differed significantly between lakes, with lower resilience found in the eutrophic lake. Thus, PPCPs can significantly alter community structures and reinforce mechanisms that maintain ecosystems in a "degraded state." Environ Toxicol Chem 2019;38:2197-2208. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
淡水越来越多地受到来自城市废水的复杂混合物的影响，这些混合物中包含药物和个人护理产品（PPCPs），已知会改变淡水生物群落的结构和功能。然而，它们与其他干扰因素的相互作用，以及它们的综合效应是否会影响生态弹性（即系统承受干扰而不改变系统原始结构和过程的能力）仍未得到探索。本研究使用了 2 个具有不同营养水平（中营养和富营养）的湖泊中的原位中观模型，评估了亚致死浓度的 12 种 PPCPs 脉冲暴露是否会影响自然浮游植物群落的生态弹性，这些群落经历了一个突然的环境变化，涉及到通过混合使水柱不稳定。随着气候变化的影响展开，预计这种混合事件会增加，导致更频繁的风暴，扰乱湖泊的分层，并迫使群落进行重组。我们评估了它们对群落指标（生物量、物种丰富度和组成）的综合影响，并使用不连续分析从浮游植物群落推断出的 4 个指标（跨尺度、尺度内、聚集长度和间隙长度）来评估它们的相对弹性。单独的混合干扰对群落指标几乎没有影响，但当与化学污染物结合时，会测量到显著的变化：降低总生物量、物种丰富度和改变浮游植物的群落组成。一旦这些变化发生，它们就会持续到实验结束（第 20 天），此时两个最高暴露水平的群落结构与对照明显不同。弹性指标不受 PPCPs 的影响，但在湖泊之间有显著差异，富营养湖中发现的弹性较低。因此，PPCPs 可以显著改变群落结构，并加强维持生态系统处于“退化状态”的机制。环境毒理学与化学 2019；38:2197-2208。©2019 作者。环境毒理学与化学由 Wiley 期刊出版公司代表 SETAC 出版。
