Top-chain predators play a fundamental role in the functioning of shallow reservoirs. Studies to elucidate the cascade effects produced by fish on macroinvertebrates and periphytic algae are fundamental for understanding the functioning of aquatic ecosystems. We conducted an enclosure experiment to test the isolated and combined effects of macroinvertebrates and Prochilodus brevis (omnivorous fish) on periphytic algae and the floating macrophyte Eichhornia crassipes for 30 days in the Jazigo reservoir, Brazil. The predation of P. brevis on macroinvertebrates increased the biomass of periphytic algae during the experiment, while the effects of isolated macroinvertebrates decreased the biomass of periphytic algae and increased the biomass of E. crassipes. Macroinvertebrates (which freely colonized the enclosures) were reduced by fish; however, the biomass of the periphytic algae was not reduced. Our results showed that P. brevis has strong effects on the structure of macroinvertebrate and periphytic algae communities, with a visible cascade effect on the abundance of macroinvertebrates. This study contributes to our understanding of the ecology of tropical lakes and the regulation of periphytic algae and macrophyte growth.

顶链捕食者在浅层水库的功能中起着基本作用。阐明鱼类对大型无脊椎动物和周生藻类产生的级联效应的研究对于理解水生生态系统的功能至关重要。我们进行了围栏实验，以测试在巴西Jazigo水库中30天无脊椎动物和短食的Prochilodus brevis（杂食性鱼类）对附生藻类和漂浮的Eichhornia crassipes的分离和联合作用。在实验中，短孢子虫对大型无脊椎动物的捕食增加了附生藻类的生物量，而分离的无脊椎动物的作用降低了附生藻类的生物量，增加了藻类的生物量。E. crassipes。大型无脊椎动物（可自由定居在围栏内）被鱼捕食；但是，周生藻类的生物量并未减少。我们的研究结果表明，P.杆菌对底栖动物和藻类periphytic群落结构深刻影响，对丰大型无脊椎动物的可见级联效应。这项研究有助于我们了解热带湖泊的生态学以及调节藻类藻类和大型植物的生长。