Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada.
Limnology Laboratory, Department of Biology, University of Regina, Regina, SK, S4S 0A2, Canada.
Glob Chang Biol. 2016 Jan;22(1):271-83. doi: 10.1111/gcb.13076. Epub 2015 Nov 18.
Coherent timing of agricultural expansion, fertilizer application, atmospheric nutrient deposition, and accelerated global warming is expected to promote synchronous fertilization of regional surface waters and coherent development of algal blooms and lake eutrophication. While broad-scale cyanobacterial expansion is evident in global meta-analyses, little is known of whether lakes in discrete catchments within a common lake district also exhibit coherent water quality degradation through anthropogenic forcing. Consequently, the primary goal of this study was to determine whether agricultural development since ca. 1900, accelerated use of fertilizer since 1960, atmospheric deposition of reactive N, or regional climate warming has resulted in coherent patterns of eutrophication of surface waters in southern Alberta, Canada. Unexpectedly, analysis of sedimentary pigments as an index of changes in total algal abundance since ca. 1850 revealed that while total algal abundance (as β-carotene, pheophytin a) increased in nine of 10 lakes over 150 years, the onset of eutrophication varied by a century and was asynchronous across basins. Similarly, analysis of temporal sequences with least-squares regression revealed that the relative abundance of cyanobacteria (echinenone) either decreased or did not change significantly in eight of the lakes since ca. 1850, whereas purple sulfur bacteria (as okenone) increased significantly in seven study sites. These patterns are consistent with the catchment filter hypothesis, which posits that lakes exhibit unique responses to common forcing associated with the influx of mass as water, nutrients, or particles.
农业扩张、化肥施用、大气养分沉积和全球加速变暖的协调时间预计将促进区域地表水的同步施肥以及藻类水华和湖泊富营养化的协调发展。虽然在全球荟萃分析中明显出现了广泛的蓝藻扩张，但对于在共同湖区内的离散集水区中的湖泊是否也通过人为胁迫表现出协同的水质退化，知之甚少。因此，本研究的主要目标是确定自 1900 年以来的农业发展、自 1960 年以来加速使用化肥、大气中活性氮的沉积或区域气候变暖是否导致加拿大艾伯塔省南部地表水富营养化的协同模式。出乎意料的是，分析自 1850 年以来总藻类丰度变化的沉积色素作为指标，揭示了尽管在 150 年间，10 个湖泊中有 9 个湖泊的总藻类丰度（以β-胡萝卜素、脱镁叶绿素 a 计）增加，但富营养化的发生时间却相差一个世纪，并且在不同流域之间不同步。同样，使用最小二乘法回归分析时间序列的结果表明，自 1850 年以来，8 个湖泊中蓝藻（echinenone）的相对丰度要么减少，要么没有显著变化，而在 7 个研究点中紫色硫细菌（okenone）的丰度显著增加。这些模式与集水区过滤器假说一致，该假说认为，湖泊对与水、养分或颗粒的流入相关的共同胁迫表现出独特的反应。
