Drivers of lower food web composition and productivity in Lake Ontario have undergone extensive changes in the last 40 years, including nutrient abatement, fluctuations in planktivores (Alewife), and invasion by dreissenid mussels and predatory cladocerans. Temporally intensive long-term index stations are critical for understanding these drivers and interpreting the results of periodic lake-wide spatially intensive surveys such as Cooperative Science and Monitoring Initiative (CSMI). We compare epilimnetic physical–chemical parameters and zooplankton metrics at a Kingston Basin biomonitoring site (Station 81) over three time stanzas (1981–1986, 1987–1995 and 2007–2017). In the most recent stanza, mean May-October temperature increased by 2.5 °C, and despite static total phosphorus levels, chlorophyll has significantly decreased and Secchi depth has increased. Between Stanzas 2 and 3, epilimnetic density, biomass and production of crustacean zooplankton have declined by 88%, 79% and 67%, respectively. Bosminids, Daphnia retrocurva, Diacyclops and juvenile cyclopoids are most impacted, whereas larger taxa (calanoids, Daphnia galeata, Holopedium and predatory cladocerans) have remained stable or increased. While some taxa have increased in size over time, zooplankton egg ratios have remained stable. Dreissenid veligers are now numerically dominant and have replaced some of the lost crustacean production. Redundancy Analysis showed environmental drivers (Secchi and temperature) significantly influenced zooplankton during the 1981–1995 period but not in the recent stanza. Alewife were not a significant driver despite substantial declines since the 1990s. Resource competition by Dreissena for the strongly reduced phytoplankton productivity, combined with predation by invasive cladocerans Cercopagis and Bythotrephes have also likely influenced Kingston Basin zooplankton.

在过去的 40 年里，导致安大略湖食物网组成和生产力下降的驱动因素发生了广泛的变化，包括营养减少、浮游动物 (Alewife) 的波动以及德赖森贻贝和掠食性枝角类动物的入侵。时间密集型长期指数站对于了解这些驱动因素和解释定期全湖空间密集型调查（如合作科学与监测倡议 (CSMI)）的结果至关重要。我们在三个时间段（1981-1986、1987-1995 和 2007-2017）比较了金斯敦盆地生物监测站点（81 站）的外吸物理化学参数和浮游动物指标。在最近的一节中，5 月至 10 月的平均温度上升了 2.5 °C，尽管总磷水平保持不变，叶绿素显着减少，Secchi 深度增加。在第 2 节和第 3 节之间，甲壳类浮游动物的表水密度、生物量和产量分别下降了 88%、79% 和 67%。博斯米尼德，反曲水蚤、二环水蚤和幼年类独眼龙受到的影响最大，而较大的类群（calanoids、水蚤、Holopedium和捕食性枝角类动物）保持稳定或增加。虽然随着时间的推移，一些分类群的大小有所增加，但浮游动物卵的比例保持稳定。Dreissenid veligers 现在在数量上占主导地位，并取代了一些失去的甲壳类动物产量。冗余分析表明，环境驱动因素（Secchi 和温度）在 1981-1995 年期间显着影响浮游动物，但在最近的一节中没有。尽管自 1990 年代以来大幅下降，但 Alewife 并不是一个重要的推动因素。Dreissena的资源竞赛由于浮游植物生产力的大幅降低，再加上入侵枝角类动物Cercopagis和Bythotrephes的捕食，也可能影响了金斯敦盆地的浮游动物。