Effects of copper and zinc on growth, feeding and oxygen consumption of Farfantepenaeus paulensis postlarvae (Decapoda : Penaeidae)

The effect of chronic exposure (35 days) to sub-lethal concentrations of co pper (17-212 ppb) and zinc (41-525 ppb) on growth of Farfantepenaeus paulen sis postlarvae 17 days old (PL17) was analysed. The effects of acute exposu re of PL17 to the same metal on food ingestion and oxygen consumption were also evaluated. Studies were performed using copper and zinc singly, and in a mixture of equipotent concentrations (1:2.5). Chronic exposure to copper (85 and 212 ppb and zinc (106, 212 and 525 ppb) reduced PL17 growth. Acute exposure to copper (212 ppb) and zinc (525 ppb) reduced the number of Arte mia sp. predated during 30 min and the positive feeding response induced by L-isoleucine. Despite of the lower positive feeding response when PL17 wer e exposed to zinc, a significant difference from control condition was not seen. Oxygen consumption was reduced by all copper and zinc concentrations tested. The mean reduction was approximately 32%. The copper zinc-mixture d id not modify food consumption and feeding response, or the oxygen consumpt ion of the PL17. The inhibition of food and oxygen consumption induced by c opper and zinc could explain, at least in part, the long-term reduction of growth observed in chronically exposed PL17. Our results also suggest that the inhibition of food consumption induced by copper is possibly due to an effect on chemosensory mechanisms. Finally, an antagonism between copper an d zinc was observed, when were employed to analyse feeding behaviour and ae robic metabolism after acute exposure. (C) 2000 Elsevier Science B.V. All r ights reserved.