Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, U.K.
Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway.
Environ Sci Technol. 2020 May 5;54(9):5569-5579. doi: 10.1021/acs.est.0c00548. Epub 2020 Apr 23.
The acquisition of tolerance to an environmental stressor can result in organisms displaying slower growth after stress release. While well-grounded in the theory, empirical evidence of the trade-off between stress tolerance and organism fitness is scarce and blurred by the interaction with different environmental factors. Here, we report the effects of water browning on the responses, tolerance acquisition, and associated trade-offs in a population of microalgae exposed to sublethal concentrations of organic micropollutants over multiple generations. Our results show that dissolved organic matter (DOM) reduces toxic responses and modulates tolerance acquisition by the algae, possibly by complexing micropollutants. Microalgae that acquire tolerance allocate resources to fitness at the cost of reduced cell size. They yield higher productivity than nonadapted ones when grown in the presence of micropollutants but lower in their absence. The net trade-off was positive, indicating that adaptation can result in a higher productivity and fitness in tolerant species in recurrently stressed environments.
耐受环境胁迫的获得会导致生物体在胁迫解除后生长减缓。尽管这一理论有充分的依据，但在不同环境因素的相互作用下，关于胁迫耐受和生物体适应性之间权衡的经验证据仍然稀缺且模糊。在这里，我们报告了水体富营养化对微藻种群在多代时间内暴露于亚致死浓度的有机微污染物时的反应、耐受获得以及相关权衡的影响。我们的结果表明，溶解有机质（DOM）降低了藻类的毒性反应并调节了其耐受的获得，这可能是通过与微污染物络合实现的。获得耐受的微藻将资源分配给适应性，代价是细胞体积减小。与非适应种群相比，在存在微污染物的情况下，它们的生产力更高，但在不存在微污染物的情况下，它们的生产力更低。净权衡是正的，这表明在反复受到胁迫的环境中，适应性可以使耐受物种具有更高的生产力和适应性。
