The use of pesticides in aquaculture: fate and effects after applications in experimental ponds, and evaluation in fish farms and fee fishing enterprises of Mogi-Guaçu river catchments

Author(s)

Ricardo Luvizotto Santos

• Document type: Doctoral Thesis
• Press: São Carlos.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de São Carlos (EESC/SBD)
• Defense date: 2007-06-27

Examining board members

Eny Maria Vieira; Eduardo Bessa Azevedo; Daniel Rodrigues Cardoso; Evaldo Luiz Gaeta Espíndola; Odete Rocha

• Advisor: Eny Maria Vieira

Abstract

The use of pesticides has been the foremost course of action to combat the ectoparasites of farmed fee fishes, in which diflubenzuron (DFB) and the organophosphates methyl parathion (PM) and trichlorfon (TRC) (witch the main sub product is dichlorvos - DDVP) are the most widely used in the Mogi-Guaçu river catchments. The indiscriminate use of such compounds on aquaculture can cause damage to the aquatic ecosystems that receive the pond\'s effluents, hence endangering environmental quality and consumer\'s health. The knowledge of understanding the environmental fate, accumulation rate, as well as their effect upon non-target species, is particularly important for the correct aquaculture management. Samples of water, sediments and fishes (Oreochromis niloticus) from three fee fishing enterprises from Socorro, SP, Brazil (June, 2005), were analyzed to verify residues of DFB (HPLC-DAD), PM and DDVP (GC-NPD). In addition, four experimental ponds (10.000 L, 10 cm of sediment, localized on CRHEA - USP, Itirapina, SP, Brazil) were used to simulate a treatment against fish ectoparasites (June to August, 2005). In this case, before and after a single application of Dimilin (1,0 g/\'M POT.3\' DFB), Folisuper (0,25 g/\'M POT.3\' PM) and Neguvon (0,25 g/\'M POT.3\' TCF), samples of water, sediments, fishes, phytoplankton, zooplankton and benthonic macro invertebrates were collected on zero, 5 hours, 1, 2, 5 and 7 days after contamination. No pesticides residues in the samples of the three fee fishing enterprises from Socorro were detected. Pesticides residues in the compartments and effects in all of the organism groups analyzed were detected on the experimental ponds. The DFB is persistent in water and sediments, as well as the PM, which was comparatively less persistent. However, DDVP is not persistent on those compartments. There was DFB and PM accumulation on fish filets subjected to treatment with Dimilin and Folisuper, respectively, which were detected in all sampled times. These values exceed maximal level limits proposed by the Codex Alimentarius. The pesticides applications caused effects on the biological community composition and density, which varied due to the formulation applied and time exposition. Overall, the benthonic macro invertebrates were more sensitive to organophosphorates, while zooplankton were more sensitive to DFB. The cladocerans indicated high degree of sensitivity to all pesticides applied. With respect to phytoplankton, apparently, pesticides caused only indirect effects upon the composition and density of this group. (AU)