Lakes are important sites for carbon fixation and carbon dioxide (CO₂) exchange with the atmosphere. Carbon fixation rates have not previously been published for Lake Winnipeg but are important for quantifying the lake’s role in the regional greenhouse gas budget and the lake’s trophic structure and fish habitat. This study measured net ecosystem production (NEP), gross primary production (GPP), and gross respiration (GR) across the lake using a custom-built automated incubator connected to a ship’s water intake during a research cruise between July 31 and August 17, 2018 on Lake Winnipeg. The incubator estimated NEP, GR, and GPP every 60 min while moving along the ship’s track and at anchor, providing high-resolution data that are not obtainable through conventional incubations. The mean NEP for Lake Winnipeg during our survey was −8.4 ± 5.6 g C m⁻² d⁻¹, suggesting that the lake was net heterotrophic and thus a net CO₂ source to the atmosphere during the 2018 summer cruise. The high-resolution data revealed significant spatiotemporal variability, including short-lived, highly net productive events that preceded remotely sensed chlorophyll a blooms by several days. Conversely, in regions with high chlorophyll a concentrations, we observed strong net heterotrophy and low nutrients, suggesting respiration was fueled by the degradation of mature, nutrient-limited phytoplankton blooms. The incubator system used in this study demonstrated its utility for monitoring rapid changes in NEP over short spatial scales in a lake which shows heightened regional variability in its physical, biogeochemical, and biological make-up.

湖泊是固碳和二氧化碳（CO ₂) 与气氛交流。之前尚未公布温尼伯湖的碳固定率，但对于量化该湖在区域温室气体收支以及该湖的营养结构和鱼类栖息地中的作用非常重要。这项研究在 7 月 31 日至 8 月 17 日的研究巡航期间，使用连接到船舶取水口的定制自动孵化器测量了整个湖的净生态系统产量 (NEP)、总初级产量 (GPP) 和总呼吸量 (GR)， 2018 年在温尼伯湖。孵化器每 60 分钟估计一次 NEP、GR 和 GPP，同时沿着船的轨道和锚点移动，提供通过传统孵化无法获得的高分辨率数据。我们调查期间温尼伯湖的平均 NEP 为 -8.4 ± 5.6 g C m ^-2  d ^-1，表明该湖是净异养的，因此是2018 年夏季巡航期间大气中的净 CO ₂源。高分辨率数据揭示了显着的时空变异性，包括在遥感叶绿素a开花数天之前的短暂、高净生产力事件。相反，在叶绿素a高的地区浓度，我们观察到强烈的净异养和低营养，表明呼吸是由成熟的、营养有限的浮游植物繁殖的退化所推动的。本研究中使用的孵化器系统证明了其在监测湖泊中短期空间尺度内 NEP 的快速变化方面的效用，该湖泊表明其物理、生物地球化学和生物构成的区域变异性加剧。