Variability in responses to nutrients and trace elements, and transmission of stressor effects through an estuarine food web
Variability in responses to nutrients and trace elements, and transmission of stressor effects through an estuarine food web
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DOI：
10.4319/lo.1999.44.3_part_2.0837
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发表时间：
1999-05-01
影响因子：
4.5
通讯作者：
Sellner, KG
中科院分区：
文献类型：
--
作者：
Breitburg, DL;Sanders, JG;Sellner, KG
水生系统越来越多地受到来自人类活动的多重压力。这些压力源在生物群中引起的反应的一致性和程度以及额外压力源的存在如何改变其影响方面可能各不相同。了解生物环境和时间动态如何影响对压力源的反应，以及压力源如何相互作用，对于预测它们在自然环境中的影响非常重要。我们研究了时间变异的实验河口食物网的反应，以提高微量元素和营养物质，以及这两个压力的组合的非加性效应。1996年春季至秋季，在20个1-m（3）的围隔中进行了四次实验。我们测量了一系列的系统，人口，和个人水平的参数，以量化浮游植物，浮游细菌，异养nanoflagellates，桡足类，鱼类和底栖无脊椎动物的响应，微量元素和营养additions.The响应的响应是更多变的时间和浮游植物和更高的营养级类群比营养添加。大多数类群增加，无论是显着或显示出增加的趋势，在所有四个围隔运行的营养添加。与此相反，方向以及微量元素添加反应的幅度变化很大类群和实验运行之间。两种不同类型的养分x微量元素的相互作用是重要的。首先，时间动态的营养比率出现影响的时间模式的微量元素对浮游植物的毒性。第二，在6月的围隔生态系统运行时，微量元素的添加减少了生产，丰富，或许多生物的生长，这些减少往往成比例地更大的营养添加罐比没有营养添加。我们的研究结果表明，相当大的时间和分类的变化，在响应微量元素负载可能会被视为在现场设置，即使在恒定的负载系统和微量元素可能掩盖的幅度高营养负荷的富营养化系统的响应。更一般地说，多个压力源的存在可能会增加或抑制在水生系统中看到的时间和空间变异性，这取决于压力源之间的相互作用和背景环境条件和敏感物种对压力源效应表达的影响。
Aquatic systems are increasingly exposed to multiple stressors from anthropogenic sources. These stressors can vary in the consistency and magnitude of responses they elicit in biota and in how the presence of additional stressors modifies their effects. Understanding how the biological environment and temporal dynamics influence responses to stressors, and how stressors interact, is important to predicting their effects in the natural environment. We examined temporal variability in responses of an experimental estuarine food web to elevated trace elements and nutrients, as well as non-additive effects of the combination of these two stressors. Experiments were conducted four times during spring through autumn 1996 in 20 1-m(3) mesocosms. We measured a range of system-, population-, and individual-level parameters to quantify responses of phytoplankton, bacterioplankton, heterotrophic nanoflagellates, copepods, fish, and benthic invertebrates to trace element and nutrient additions.The response to trace element additions was more variable both temporally and among phytoplankton and higher trophic level taxa than was the response to nutrient additions. Most taxa increased, either significantly or showed a trend toward increasing, in response to nutrient additions in all four mesocosm runs. In contrast, the direction as well as the magnitude of responses to trace element additions varied considerably among taxa and experimental runs. Two distinct types of nutrient x trace element interactions were important. First, temporal dynamics of nutrient ratios appeared to affect the temporal pattern of toxicity of trace elements to phytoplankton. Second, in the June mesocosm run when trace element additions reduced production, abundance, or growth of many organisms, these reductions were often proportionately greater in nutrient addition tanks than where no nutrients were added. Our results suggest that considerable temporal and taxonomic variation in responses to trace element loadings are likely to be seen in field settings even under constant loadings to the system and that trace elements may mask the magnitude of the response to high nutrient loadings in eutrophic systems. More generally, the presence of multiple stressors may either increase or dampen the temporal and spatial variability seen in aquatic systems, depending on the interactions among stressors and the influence of background environmental conditions and sensitive species on the expression of stressor effects.