The grazing effects of zooplankton communities are predicted to be strongest in mesotrophic lakes relative to eutrophic and oligotrophic lakes, an idea known as the Mesotrophic Maximum Hypothesis. We tested if the predictions of this hypothesis depend on the community of zooplankton present by evaluating whether the community of zooplankton, in addition to lake trophic state, interact to determine the magnitude of grazing effects. We conducted mesocosm experiments to evaluate the effects of Daphnia spp., Epischura nevadensis, and juvenile and adult Mysis diluviana on ecosystem function in oligotrophic Lake Tahoe and its more productive embayment, Emerald Bay. In the Lake Tahoe experiment, the Daphnia and the Adult Mysid treatments produced lower dissolved organic carbon concentrations, and the Epischura treatment yielded lower soluble reactive phosphorus concentrations compared to a Control treatment that lacked macrozooplankton. In the Emerald Bay experiment, the Daphnia treatment lowered chlorophyll a concentrations, the Daphnia and Juvenile Mysid treatments reduced small particle (diameter 0.5 – < 5 µm) concentrations, and each of the species treatments produced higher ammonium concentrations and DIN/SRP ratios compared to the Control. Analyses of similarities (ANOSIM) indicated that these taxa differed from one another in their overall effects on Emerald Bay water, but not on Lake Tahoe water. This finding supports the Mesotrophic Maximum Hypothesis, but also shows that grazing effects are dependent on the taxonomic makeup of the zooplankton community in addition to lake trophic state. As ongoing cultural eutrophication continues to elevate Lake Tahoe's productivity, the roles and importance of the lake’s zooplankton taxa may diverge.

相对于富营养化湖和贫营养化湖，浮游动物群落的放牧作用预计在中营养湖中最强，这一思想被称为中营养最大假说。我们通过评估浮游动物群落除湖泊营养状态外是否相互作用来确定放牧影响的程度，从而检验了这一假说的预测是否取决于浮游动物群落。我们进行了介观实验来评估水蚤的影响。，Epischura nevadensis，以及少年和成年糠diluviana贫营养性太浩湖及其更富生产意义的绿宝石湾的生态系统功能研究。在太浩湖实验中，与没有大型浮游动物的对照处理相比，水蚤和成年Mysid处理产生的溶解有机碳浓度较低，而Epischura处理产生的可溶性反应磷浓度较低。在Emerald Bay实验中，水蚤的处理降低了叶绿素a的浓度，水蚤和青少年Mysid处理降低了小颗粒（直径0.5 – <5 µm）的浓度，与对照相比，每种物种处理均产生了更高的铵浓度和DIN / SRP比。相似性分析（ANOSIM）表明，这些分类单元对翡翠湾水的总体影响彼此不同，但对太浩湖水的整体影响却没有差异。这一发现支持了中营养最大假说，但也表明除湖泊营养状态外，放牧效应还取决于浮游动物群落的分类组成。随着持续的文化富营养化继续提高太浩湖的生产力，该湖浮游动物类群的作用和重要性可能会发生变化。