To better understand zooplankton dynamics in Lake Ontario’s Toronto Harbour and adjacent coastal area (CA), we sampled zooplankton, phytoplankton, nutrients and physical parameters on six dates in 2016. Despite higher levels of nutrients, chlorophyll and primary production in the inner harbor (IH), the areas supported similar May to November zooplankton biomass (IH = 32 ± 7 and CA = 42 ± 10 mg/m³). IH values were much lower than other nutrient-enriched embayments in Lake Ontario, yet CA biomass was twice that of nearshore sites away from Toronto. Small zooplankton such as rotifers and Bosmina dominated IH; and large taxa (Daphnia, calanoids and predatory cladocerans) were more important in the CA. Daphnia, Bosmina, cyclopoids and calanoids were larger in the CA, and adult cyclopoids had higher egg ratios. This led to low annual IH production estimates for both cyclopoid and calanoid copepods. Total phosphorus and chlorophyll did not appear to regulate zooplankton biomass, but positive relationships were found with bacterial biomass in the IH and with temperature in the cool season. Atypically high fish planktivory rates likely suppressed larger IH zooplankton in 2016, allowing small, resilient Bosmina to flourish and contribute 84% of total production in the IH. Comparing 2016 data to previous zooplankton surveys revealed considerable inter-annual variation in proportions of Daphnia, Bosmina and predatory cladocerans over the 1994 to 2016 period, and the strong top-down controls observed in 2016 were not typical. Elevated microbial production may serve as an important alternate trophic pathway supporting cladoceran populations in Toronto Harbour.

为了更好地了解安大略湖多伦多港口和邻近沿海地区（CA）的浮游动物动态，我们在2016年的六个日期对浮游动物，浮游植物，养分和物理参数进行了采样。尽管内港（IH）的养分，叶绿素和初级生产水平较高），这些地区所支持的5月至11月浮游动物生物量相似（IH = 32±7和CA = 42±10 mg / m ³）。 IH 值 要低得多 比 安大略湖的其它营养丰富的embayments，但CA生物质是近岸地点从多伦多开了两次。轮虫和波斯尼亚等 小型 浮游动物主导着IH；和大类群（水蚤   ，颅骨和掠食性锁骨角类动物） 在CA中更为重要。水蚤，象鼻，cyclopoids和calanoids是在CA较大，与成人cyclopoids有较高的产蛋率。 这导致了针对摆线和and足类pe足类动物的年度IH产量估算值偏低。 总磷和叶绿素似乎没有调节浮游动物的生物量，但是在IH中发现细菌细菌的生物量与凉季的温度正相关。非正常的鱼类浮游率高可能会在2016年抑制较大的IH浮游动物，从而使 小而有 弹性的波斯尼亚蓬勃发展，并贡献了IH总产量的84％。将2016年的数据与之前的浮游动物调查进行比较，发现在1994年至2016年期间，水蚤，波斯尼亚和掠夺性枝角类鱼类的比例存在较大的年际变化，而且在 2016年观察到的自上而下的强有力控制 并不常见。 升高的微生物产量可能是支持多伦多港锁骨鱼类种群的重要替代营养途径。