Abstract Simmatis B, Nelligan C, Rühland KM, Jeziorski A, Castro V, Paterson AM, Smol JP. 2020. Tracking ∼200 years of water quality in Muskrat Lake, a eutrophic lake trout lake in Ontario (Canada) with cyanobacterial blooms. Lake Reserv Manage. 36:260–277. Muskrat Lake is a deep (64 m), eutrophic lake in southeastern Ontario, Canada, that supports a natural lake trout population. Frequent algal blooms and low deep-water dissolved oxygen concentrations have generated management concerns. Based on anecdotal reports, algal blooms first occurred in the 1920s. Concern regarding recreational activities has escalated since the early 1980s. Monitoring records for total phosphorus (TP) and dissolved oxygen concentrations are sparse, requiring paleolimnological methods to extend our knowledge of past lake conditions. We inferred trends in past whole-lake primary production using visual-range spectroscopy-inferred chlorophyll a, nutrients using diatom assemblage changes, and end-of-summer volume-weighted hypolimnetic oxygen concentrations (VWHO) using chironomids to assess environmental conditions in Muskrat Lake over the past ∼200 years. Diatom taxa indicative of mesotrophic conditions were present throughout the sedimentary record, which suggests that Muskrat Lake was moderately productive before European settlement, with conditions worsening somewhat after ca. 1920, following land clearance and agricultural development. Chironomid-inferred VWHO trends suggest that the hypolimnion was not naturally well oxygenated, but deep-water oxygen levels declined further after ca. 1900 following European settlement. After ca. 1990, changes in diatom assemblage composition were consistent with climate-mediated increases in thermal lake properties, which might have contributed to cyanobacterial dominance. Whole-lake primary production increased after ca. 1900 and peaked ca. 1960, remaining stable until ca. 2006, after which it declined. Overall, Muskrat Lake has been productive over the past ∼200 years, but the cumulative effects of changes in nutrient loading and mixing patterns should be considered in future management decisions.

中文翻译：

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追踪麝鼠湖 200 年的水质，这是安​​大略（加拿大）富营养化湖鳟鱼湖，蓝藻大量繁殖

摘要 Simmatis B、Nelligan C、Rühland KM、Jeziorski A、Castro V、Paterson AM、Smol JP。2020. 追踪麝鼠湖 200 年的水质，这是安​​大略（加拿大）富营养化湖鳟鱼湖，蓝藻大量繁殖。湖泊保护区管理。36:260-277。麝鼠湖是加拿大安大略省东南部的一个深 (64 m) 富营养化湖泊，支持天然湖鳟种群。频繁的藻华和低深水溶解氧浓度引起了管理问题。根据轶事报道，藻华首次发生在 1920 年代。自 1980 年代初以来，人们对娱乐活动的担忧不断升级。总磷 (TP) 和溶解氧浓度的监测记录很少，需要古湖沼学方法来扩展我们对过去湖泊状况的了解。我们使用可视范围光谱推断叶绿素 a 推断过去全湖初级生产的趋势，使用硅藻组合变化推断养分，以及使用摇蚊评估麝鼠湖环境条件的夏末体积加权低湖水氧浓度 (VWHO)在过去的 200 多年里。在整个沉积记录中都存在指示中营养条件的硅藻类群，这表明麝鼠湖在欧洲人定居之前具有中等生产力，在大约 10 年后条件有所恶化。1920年，随着土地清理和农业发展。Chironomid 推断的 VWHO 趋势表明，水下层的自然氧含量不高，但深水氧含量在大约 10 分钟后进一步下降。1900 年欧洲定居后。在大约之后。1990年，硅藻组合组成的变化与气候介导的热湖特性增加相一致，这可能导致蓝藻占优势。全湖初级生产力在大约之后增加。1900 年达到峰值。1960 年，保持稳定，直到大约。2006 年，之后下降。总体而言，麝鼠湖在过去 200 年中一直富有成效，但在未来的管理决策中应考虑养分负荷和混合模式变化的累积影响。