US Geological Survey, Washington Water Science Center, 934 Broadway, Suite 300, Tacoma, WA 98402, USA.
Environ Monit Assess. 2011 Apr;175(1-4):397-417. doi: 10.1007/s10661-010-1539-8. Epub 2010 Jun 25.
Many streams within the United States are impaired due to nutrient enrichment, particularly in agricultural settings. The present study examines the response of benthic algal communities in agricultural and minimally disturbed sites from across the western United States to a suite of environmental factors, including nutrients, collected at multiple scales. The first objective was to identify the relative importance of nutrients, habitat and watershed features, and macroinvertebrate trophic structure to explain algal metrics derived from deposition and erosion habitats. The second objective was to determine if thresholds in total nitrogen (TN) and total phosphorus (TP) related to algal metrics could be identified and how these thresholds varied across metrics and habitats. Nutrient concentrations within the agricultural areas were elevated and greater than published threshold values. All algal metrics examined responded to nutrients as hypothesized. Although nutrients typically were the most important variables in explaining the variation in each of the algal metrics, environmental factors operating at multiple scales also were important. Calculated thresholds for TN or TP based on the algal metrics generated from samples collected from erosion and deposition habitats were not significantly different. Little variability in threshold values for each metric for TN and TP was observed. The consistency of the threshold values measured across multiple metrics and habitats suggest that the thresholds identified in this study are ecologically relevant. Additional work to characterize the relationship between algal metrics, physical and chemical features, and nuisance algal growth would be of benefit to the development of nutrient thresholds and criteria.
由于营养物质的富集，美国许多河流的生态系统都受到了损害，尤其是在农业地区。本研究在美国西部各地的农业和受干扰较小的地点，调查了底栖藻类群落对一系列环境因素的响应，这些环境因素包括在多个尺度上收集的营养物质、生境和流域特征以及大型无脊椎动物的营养结构。第一个目标是确定营养物质、生境和流域特征以及大型无脊椎动物营养结构对解释来自沉积和侵蚀生境的藻类指标的相对重要性。第二个目标是确定是否可以确定与藻类指标相关的总氮（TN）和总磷（TP）阈值，以及这些阈值如何因指标和生境而异。农业区的营养物浓度升高且高于已公布的阈值。所有检查的藻类指标都对营养物质做出了假设的响应。尽管营养物质通常是解释每种藻类指标变化的最重要变量，但在多个尺度上运作的环境因素也很重要。根据从侵蚀和沉积生境采集的样本中计算得出的藻类指标的 TN 或 TP 阈值与没有显著差异。TN 和 TP 每个指标的阈值值的变化很小。在多个指标和生境中测量的阈值值的一致性表明，本研究中确定的阈值具有生态相关性。进一步研究藻类指标、物理和化学特征以及有害藻类生长之间的关系将有助于制定营养物阈值和标准。
