Okun N, Brasil J, Attayde JL, Costa IAS
Enclosures, Omnivory, phytoplankton, Trophic cascades, water, transparency, Zooplankton, european mesocosm experiment, oreochromis-niloticus, top-down, nile, tilapia, shallow lakes, whole-lake, ecological interactions, intraguild, predation, herbivorous fish, long-term, mesocosm, Brasil, Rio Grande, 7m3, freshwater
1. Strong trophic cascades have been well documented in pelagic food webs of temperate lakes. In contrast, the limited available evidence suggests that strong cascades are less typical in tropical lakes. 2. To measure the effects of omnivorous tilapia on planktonic communities and water transparency of a small man-made tropical lake, we performed a 5-week in situ enclosure experiment with five densities of fish randomly allocated to 20 enclosures. Zooplankton and Phytoplankton biomasses as well as water transparency were measured weekly. 3. Results show that omnivorous tilapia significantly decreased the abundance of large Cladocerans, increased the abundance of small algae (greatest axial linear dimension