RESUMEN
The pejerrey Odontesthes bonariensis is the most important freshwater fish of Argentina central region. The present study was conducted to describe the seasonal variation of parasitism in O. bonariensis from La Viña reservoir (31 degrees 17'S, 65 degrees 01'W), located in the province of Córdoba, Argentina. Between years 1999 and 2002, 573 fishes were caught, and their parasite infection and relative weight (Wr) were assesed. Three parasites were found, Lernaea cyprinacea (Crustacea), Contracaecum spp. larvae (Nematoda) and Cangatiella macdonaghi (Cestoda). Overall, Contracaecum spp. prevalence and intensity were very low. Lernaea cyprinacea and Cangatiella macdonaghi prevalences increased during summer and spring (P < 0.01), respectively. Lernaea cyprinacea infection showed also seasonal differences in intensity (P < 0.05), as well as C. macdonaghi regarding parasites density (P < 0.01). Cangatiella macdonaghi average parasites density was 32.0 (+/-22.5) cestodes per cm(3)of digestive content. No association between parasitism and fish relative weight was found. Besides the seasonality variations observed, the parasite burden found did not compromise fish body condition.
Asunto(s)
Peces/parasitología , Animales , Argentina , Agua Dulce , Estaciones del AñoRESUMEN
The pejerrey Odontesthes bonariensis is the most important freshwater fish of Argentina central region. The present study was conducted to describe the seasonal variation of parasitism in O. bonariensis from La Viña reservoir (31º 17'S, 65º 01'W), located in the province of Córdoba, Argentina. Between years 1999 and 2002, 573 fishes were caught, and their parasite infection and relative weight (Wr) were assesed. Three parasites were found, Lernaea cyprinacea (Crustacea), Contracaecum spp. larvae (Nematoda) and Cangatiella macdonaghi (Cestoda). Overall, Contracaecum spp. prevalence and intensity were very low. Lernaea cyprinacea and Cangatiella macdonaghi prevalences increased during summer and spring (P < 0.01), respectively. Lernaea cyprinacea infection showed also seasonal differences in intensity (P < 0.05), as well as C. macdonaghi regarding parasites density (P < 0.01). Cangatiella macdonaghi average parasites density was 32.0 (±22.5) cestodes per cm³ of digestive content. No association between parasitism and fish relative weight was found. Besides the seasonality variations observed, the parasite burden found did not compromise fish body condition.
O peixe rei Odontesthes bonariensis é um peixe de água doce de grande importância na região central da Argentina. O objetivo deste trabalho foi descrever a sazonalidade do parasitismo de O. bonariensis no reservatrio La Viña (31º 17'S, 65º 01'W), província de Córdoba, Argentina. Durante os anos 1999 e 2002 foram capturados 573 peixes. Nestes se fez à avaliação da condição corporal usando como parâmetro o peso relativo e identificaram-se os seguintes parasitos: Lernaea cyprinacea (Crustacea), Contracaecum spp. (Nematoda) e Cangatiella macdonaghi (Cestoda). As prevalências e intensidades de Contracaecum spp. foram muito baixas. Houve diferenças nas prevalências de L. cyprinacea e C. macdonaghi na época do ano (P < 0,01), sendo maiores no verão e na primavera, respectivamente. Houve diferenças estacionais na intensidade de L. cyprinacea (P < 0,05) e na densidade de C. macdonaghi (P < 0,01), neste ultimo alcançou-se um valor máximo nas amostras de 32,0 (±22,5) parasitos por cm³ de conteúdo digestivo. Não houve associação entre o parasitismo e o peso relativo dos peixes. Embora haja certa sazonalidade, as diferentes cargas parasitárias encontradas nâo prejudicam a saúde de O. bonariensis enquanto sua condição corporal.