Composition, density and biomass of zooplankton in white shrimp cultivation ponds Litopenaeus vannamei in southern Brazil
Author: Alessandro Pereira Cardozo (Currículo Lattes)
Supervisor: Dr José Guilherme Bersano Filho
Abstract
The shrimp Litopenaeus vannamei is the most cultivated species in Brazil, being fed basically by commercial feed. However, some studies have shown that zooplankton in nurseries can be an integral part of the diet of this crustacean. In this work the zooplankton composition, density and biomass of shrimp cultivation farms in the extreme south of Brazil were evaluated. Collections were carried out in two nurseries over three months, using a zooplankton net with a mesh of 140 µm and a mouth with a diameter of 30 cm. The samples were fixed in a formaldehyde solution with a final concentration of 4%, and transported to the laboratory where the composition, density and also the biomass (wet weight and dry weight) were determined. The most frequent groups were Copepoda and Cladocera,and the most abundant species were those commonly found in the Lagoa dos Patos Estuary, such as Acartia tonsa, Pseudodiaptomus richardi and Moina micrura. The average density values found were higher than those commonly recorded for the Lagoa dos Patos Estuary, reaching 278 org.L-1 on 11/18/2005 in nursery 1 and 277 org.L-1 on 12/8/2005 in the nursery 2, showing that there was great availability of food in the nurseries. The wet weight and dry weight values varied between 0.15 and 13.28 gm-3 (wet weight) and between 0.01 and 2.72 gm-3 (dry weight) over the sample period, following the pattern presented density. These results indicate that zooplankton represents a food resource available to shrimp in the first months of cultivation.