Great Lakes Institute for Environmental Research, University of Windsor , Windsor, Ontario, Canada N9B3P4.
State University of New York , College of Environmental Science & Forestry, Syracuse, New York 13035, United States.
Environ Sci Technol. 2015 Nov 3;49(21):12832-9. doi: 10.1021/acs.est.5b03978. Epub 2015 Oct 14.
Measuring in situ nutrient and energy flows in spatially and temporally complex aquatic ecosystems represents a major ecological challenge. Food web structure, energy and nutrient budgets are difficult to measure, and it is becoming more important to quantify both energy and nutrient flow to determine how food web processes and structure are being modified by multiple stressors. We propose that polychlorinated biphenyl (PCB) congeners represent an ideal tracer to quantify in situ energy and nutrient flow between trophic levels. Here, we demonstrate how an understanding of PCB congener bioaccumulation dynamics provides multiple direct measurements of energy and nutrient flow in aquatic food webs. To demonstrate this novel approach, we quantified nitrogen (N), phosphorus (P) and caloric turnover rates for Lake Huron lake trout, and reveal how these processes are regulated by both growth rate and fish life history. Although minimal nutrient recycling was observed in young growing fish, slow growing, older lake trout (>5 yr) recycled an average of 482 Tonnes·yr(-1) of N, 45 Tonnes·yr(-1) of P and assimilated 22 TJ yr(-1) of energy. Compared to total P loading rates of 590 Tonnes·yr(-1), the recycling of primarily bioavailable nutrients by fish plays an important role regulating the nutrient states of oligotrophic lakes.
原位测定时空复杂水生生态系统中的营养物质和能量流是一个主要的生态挑战。食物网结构、能量和养分预算很难测量，量化能量和养分流动以确定食物网过程和结构如何被多种胁迫所改变变得越来越重要。我们提出多氯联苯（PCB）同系物可以作为一种理想的示踪剂来定量测定营养物质和能量在不同营养级之间的原位流动。在这里，我们展示了对 PCB 同系物生物积累动态的理解如何为水生食物网中的能量和养分流动提供多种直接测量。为了证明这种新方法，我们量化了休伦湖湖鳟的氮（N）、磷（P）和热量周转率，并揭示了这些过程如何受到生长率和鱼类生活史的调节。尽管在生长迅速的幼鱼中观察到的营养物质再循环很少，但生长缓慢、年龄较大的湖鳟（>5 岁）平均再循环了 482 吨·年(-1)的 N、45 吨·年(-1)的 P，并同化了 22TJ 年(-1)的能量。与 590 吨·年(-1)的总磷负荷相比，鱼类主要对生物可利用营养物质的再循环对贫营养湖泊的营养状况调节起着重要作用。
