Stoco Lake (Tweed, Ontario, Canada) has a history of industrial contamination and is heavily influenced by inflow from the Moira River. Stoco Lake is frequently affected by nuisance algal blooms (including cyanobacteria), which have largely been attributed to cultural eutrophication. To further our understanding of the environmental dynamics of Stoco Lake, we applied paleolimnological techniques to examine long-term trends in subfossil invertebrate assemblages, geochemistry, and inferred trends in whole-lake primary production from a sediment core representing ~ 70 years of environmental history. We examined past trends in Simuliidae abundance, geochemical variables, and historical river flow records to examine past hydrological conditions in Stoco Lake. Inferred whole-lake primary production and sediment core organic content increased between the late 1950s and early 1970s, likely reflecting increased eutrophication (e.g. from agricultural intensification and increased catchment activities), with some stabilization in the post-1970s sediments coinciding with the installation of a sewage treatment plant. The geochemical composition of the core highlighted the decrease in catchment-derived sediment inputs and an increase in percentage of organic content towards the top of the core. In addition, declines in the proportion of As and Ni coincided with the closure of the upstream Deloro Mine Site in the 1960s. Chironomidae and Chaoboridae (Diptera) assemblages indicate expansion of littoral habitat after the 1960s and a general stability of low-oxygen conditions in the hypolimnion over the past ~ 70 years. Several Simuliidae (Diptera: Nematocera) remains, indicators of fluvial conditions rarely discussed in paleolimnological studies, were present at their highest abundances in the pre- ~ 1975 sediments of the core, but disappeared after the early 1990s. Our findings suggest that changes in river flow (discharge, velocity, or seasonality) may have contributed to recent algal blooms. Overall, this study highlights the potential of Simuliidae in paleohydrological studies to help understand the role of river flow on lake conditions.

中文翻译：

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Subfossil Simuliidae 追踪河流流入一个被工业污染的湖泊

斯托科湖（加拿大安大略省特威德）有工业污染的历史，深受莫伊拉河流入的影响。斯托科湖经常受到有害藻华（包括蓝藻）的影响，这在很大程度上归因于文化富营养化。为了进一步了解 Stoco 湖的环境动态，我们应用古湖泊学技术来检查亚化石无脊椎动物组合、地球化学的长期趋势，以及从代表约 70 年环境历史的沉积物核心推断出的全湖初级生产趋势。我们检查了 Simuliidae 丰度、地球化学变量和历史河流流量记录的过去趋势，以检查 Stoco 湖过去的水文条件。推断的全湖初级生产和沉积物核心有机物含量在 1950 年代末和 1970 年代初之间增加，可能反映了富营养化（例如农业集约化和集水活动增加）的增加，1970 年代后沉积物中的一些稳定与安装污水处理厂。岩心的地球化学组成突出了集水区沉积物输入的减少和岩心顶部有机物含量百分比的增加。此外，As 和 Ni 比例的下降恰逢 1960 年代上游 Deloro 矿场关闭。Chironomidae 和 Chaoboridae（双翅目）组合表明 1960 年代之后沿海栖息地的扩张以及过去 70 年中水下层低氧条件的总体稳定性。一些 Simuliidae（双翅目：Nematocera）残骸是古湖泊学研究中很少讨论的河流状况的指标，它们在 1975 年之前的岩心沉积物中以最高丰度存在，但在 1990 年代初期之后消失了。我们的研究结果表明，河流流量（流量、流速或季节性）的变化可能导致了最近的藻类大量繁殖。总体而言，这项研究强调了 Simuliidae 在古水文研究中的潜力，以帮助了解河流流量对湖泊状况的作用。古湖泊学研究中很少讨论的河流条件指标在 1975 年之前的岩心沉积物中以最高丰度存在，但在 1990 年代初期之后消失。我们的研究结果表明，河流流量（流量、流速或季节性）的变化可能导致了最近的藻类大量繁殖。总体而言，这项研究强调了 Simuliidae 在古水文研究中的潜力，以帮助了解河流流量对湖泊状况的作用。古湖泊学研究中很少讨论的河流条件指标在 1975 年之前的岩心沉积物中以最高丰度存在，但在 1990 年代初期之后消失。我们的研究结果表明，河流流量（流量、流速或季节性）的变化可能导致了最近的藻类大量繁殖。总体而言，这项研究强调了 Simuliidae 在古水文研究中的潜力，以帮助了解河流流量对湖泊状况的作用。