Department of Biological Sciences, Great Lakes Research Centre, Michigan Technological University, Houghton, Michigan, USA.
Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada.
Environ Toxicol Chem. 2020 Sep;39(9):1712-1723. doi: 10.1002/etc.4794. Epub 2020 Jul 13.
The Lake Huron ecosystem is unique among the Laurentian Great Lakes (USA/Canada) in that its surface area encompasses 3 distinct basins. This ecosystem recently experienced significant ecological restructuring characterized by changes in primary production, species dominance and abundances, and top predator energy dynamics. However, much of the evidence for this restructuring has been largely derived from biomonitoring data obtained from long-term sampling of the lake's Main Basin. We examined polychlorinated biphenyl (PCB) concentrations and the stable isotopes of carbon (δ C) and nitrogen (δ N) in rainbow smelt (Osmerus mordax), bloater (Coregonus hoyi), and round goby (Neogobius melanostomus) to determine spatial variability in these environmental markers as indicators of the ubiquity of trophic restructuring throughout Lake Huron. Stable isotopes indicated that North Channel fish occupied trophic positions between 0.5 and 1.0 lower relative to Main Basin and Georgian Bay conspecifics, respectively. Sum PCB concentrations for 41 congeners were highest for fish from the Main Basin (27.5 ± 3.0 ng g wet wt) and Georgian Bay (26.3 ± 3.4 ng g wet wt) relative to North Channel (13.6 ± 1.2 ng g wet wt) fish. Discriminant functions analysis demonstrated basin-specific PCB congener profiles with individual species also having distinct profiles dependent on their basin of collection. These bioaccumulation patterns among Lake Huron forage fish mirror those reported for lake trout in this lake and indicate that the degree of food-web ecological restructuring in Lake Huron is not equivalent across the basins. Specifically, basin-specific PCB congener profiles demonstrated that differences among Lake Huron secondary and top predator consumer species are likely dictated by cross-basin differences in zooplankton community ecology and trophodynamics that can regulate the efficiencies of prey energy transfer and PCB congener bioaccumulation patterns in aquatic food webs. Environ Toxicol Chem 2020;39:1712-1723. © 2020 SETAC.
休伦湖生态系统在劳伦森大湖（美国/加拿大）中是独一无二的，因为其表面积涵盖了 3 个不同的盆地。该生态系统最近经历了重大的生态结构重组，表现为初级生产力、物种优势和丰度以及顶级捕食者能量动态的变化。然而，这种结构重组的大部分证据主要来自于对该湖主盆地进行的长期采样获得的生物监测数据。我们检查了多氯联苯（PCB）浓度以及彩虹鲦（Osmerus mordax）、白鲑（Coregonus hoyi）和圆鳍鱼（Neogobius melanostomus）的碳（δ C）和氮（δ N）稳定同位素，以确定这些环境标记物的空间变异性，作为整个休伦湖普遍存在营养结构重组的指标。稳定同位素表明，与主盆地和乔治亚湾的同种鱼相比，北海峡的鱼分别占据低 0.5-1.0 个营养位。41 种同系物的总 PCB 浓度以主盆地（27.5 ± 3.0 ng g 湿重）和乔治亚湾（26.3 ± 3.4 ng g 湿重）的鱼最高，而北海峡（13.6 ± 1.2 ng g 湿重）的鱼最低。判别函数分析表明，各盆地之间存在特定的 PCB 同系物特征，个别物种也具有独特的特征，取决于其采集的盆地。这些休伦湖觅食鱼的生物累积模式与该湖湖鳟的报道模式相似，表明休伦湖食物网生态结构重组的程度在各盆地之间并不相同。具体而言，各盆地之间 PCB 同系物特征的差异表明，休伦湖次要和顶级捕食者消费者物种之间的差异可能是由浮游动物群落生态学和营养动态的跨盆地差异决定的，这些差异可以调节猎物能量传递的效率和水生食物网中 PCB 同系物的生物累积模式。环境毒理化学 2020；39:1712-1723。©2020 SETAC。
