Department of Environmental Sciences and Lake Erie Center, The University of Toledo, 6200 Bay Shore Rd., Oregon, OH, USA.
Department of Environmental Sciences and Lake Erie Center, The University of Toledo, 6200 Bay Shore Rd., Oregon, OH, USA.
Sci Total Environ. 2024 Nov 1;949:174998. doi: 10.1016/j.scitotenv.2024.174998. Epub 2024 Jul 23.
Substantial increases in the salinity of freshwater ecosystems has occurred around the globe from causes such as climate change, industrial operations, and the application of road deicing salts. We know very little about how plastic responses in life history traits or rapid evolution of new traits among freshwater organisms could promote stability in ecological communities affected by salinization. We performed a cohort life history analysis from birth to death with 180 individuals of a ubiquitous freshwater zooplankter to understand how life history traits are affected by exposure to two common salt types causing salinization-sodium chloride (NaCl) and calcium chloride (CaCl)-across two environmentally relevant concentrations. We also tested if a multi-generational exposure history to high salinity altered life-history responses. We tracked and measured lifespan, time to maturation, brood size, brood interval, and body size. We found smaller brood sizes but slightly longer lifespans occurred at a low concentration of NaCl (230 mg Cl/L). The longer lifespans led to more, albeit smaller broods, which generated a similar lifetime reproductive output compared to the no-salt control populations. At higher concentrations of NaCl and CaCl, we found lifetime reproductive output was reduced by 23 % to 83 % relative to control populations because no tradeoff among life history traits occurred. In CaCl, we observed shorter life spans, longer time intervals between smaller broods, and smaller body sizes leading to reduced lifetime reproductive output. We also found that a multi-generational exposure to the salt types did not convey any advantages for lifetime reproductive output. In some cases, the exposure history worsened the life history trait responses suggesting maladaptation. Our findings suggest that life history tradeoffs for freshwater species can occur in response to salinization, but these tradeoffs will largely depend on salt type and concentration, which will have implications for biodiversity and ecological stability.
淡水生态系统的盐度大幅增加是由气候变化、工业作业和道路融雪盐的应用等原因造成的，这一现象在全球范围内都有发生。我们对于生物如何通过生活史特征的可塑性反应或新特征的快速进化来促进受盐化影响的生态群落的稳定性知之甚少。我们对一种普遍存在的淡水浮游动物进行了从出生到死亡的队列生活史分析，以了解生活史特征如何受到两种常见盐类（氯化钠 (NaCl) 和氯化钙 (CaCl)）在两个与环境相关的浓度下导致盐化的影响。我们还测试了多代高盐暴露是否改变了生活史的反应。我们跟踪和测量了寿命、成熟时间、窝卵数、窝卵间隔和体型。我们发现，在低浓度 NaCl（230mg Cl/L）下，窝卵数较小，但寿命略长。较长的寿命导致了更多的（尽管较小的）窝卵数，这与无盐对照种群产生了相似的终生繁殖输出。在 NaCl 和 CaCl 的较高浓度下，我们发现终生繁殖输出相对于对照种群减少了 23%至 83%，因为生活史特征之间没有权衡。在 CaCl 中，我们观察到寿命较短，较小窝卵之间的间隔时间较长，体型较小，导致终生繁殖输出减少。我们还发现，多代暴露于盐类并没有为终生繁殖输出带来任何优势。在某些情况下，暴露史会使生活史特征的反应恶化，表明适应不良。我们的研究结果表明，淡水物种的生活史权衡可能会对盐化做出反应，但这些权衡在很大程度上取决于盐的类型和浓度，这将对生物多样性和生态稳定性产生影响。
