Densidade planctônica do policultivo de Litopenaeus vannamei e Oreochromis niloticus

An experiment was conducted during 95 days to evaluate plankton densities in polyculture of Pacific white shrimp  Litopenaeus vannamei  and Nile tilapia  Oreochromis niloticus . The experiment design was randomized with three treatments and four replicates each. The treatments were as follows: monoculture with 10 shrimps m² (10S:0F); polyculture with 10 shrimps and 0.5 fish m² (10S:0.5F); polyculture with 10 shrimps and 1 fish m² (10S:1F); monoculture with 2 fishes m² (2F:0S); polyculture with 2 fishes and 2.5 shrimps m² (2F:2.5S); and polyculture with 2 fishes and 5 shrimps m² (2F:5S). Neither water exchange nor aeration was provided during the experimental period, only water was used to complete the volume lost by evaporation. The phytoplankton ranged from 78,981 to 303,260 cells.mL-1 and the zooplankton ranged from 470 to 1,421 org.L-1. The most frequent groups were Bacillariophyta (phytoplankton) and Rotifera (zooplankton). In conclusion, in the polyculture system of Pacific white shrimp  Litopenaeus vannamei  and Nile tilapia  Oreochromis niloticus  there are no significant changes in the densities of phytoplankton and zooplankton due to the alteration in the culture stocking density. Keywords:  phytoplankton; shrimp; tilapia; zooplankton.