Influence of river Negro on nutritional status of curimata Prochilodus nigricans (Characiformes; Prochilodontidae) juveniles in the middle river Solimoes-Amazonas, Brazil

The limnological differences between the black waters of the Negro river and the white waters of the Solimoes-Amazonas river can influence the nutritional status of detritivorous fishes by the difference in the food sources between these systems. To check the influence of the Negro river on the nutritional status of curimata juveniles Prochilodus nigricans we estimated the conductivity in the sampling points and condition factor (K, from weight/length relationship) of the juveniles in three flooding areas of the middle Solimoes-Amazon river: (1) with Negro river influence, near Manaus (2) without Negro river influence, near Manaus and (3) without Negro river influence, in a stretch of the Solimoes-Amazonas 500 km upstream from Manaus. The conductivity in the sampling points with Negro river influence was significantly lower than other areas and the K of juveniles influenced by waters of the Negro river was significantly higher than two other areas. The high selectivity of curimata may limit the assimilation of food items when they are in high abundance. In addition, the black water detritus have high potential for assimilation because of its protein quality, which demonstrates the importance of flooded forests by black waters for Amazonian detritivorous.Original Abstract: As diferencas limnologicas entre as aguas pretas do rio Negro e as aguas brancas do rio Solimoes-Amazonas podem ter influencia sobre o status nutricional de peixes detritivoros pela diferenca nas fontes dos recursos alimentares entre estes sistemas. Para verificar a influencia do rio Negro sobre o status nutricional de juvenis de curimata Prochilodus nigricans foi medida a condutividade em pontos de amostragem e estimado o fator de condicao (K, a partir da relacao peso/comprimento) dos juvenis em tres areas de inundacao do medio rio Solimoes-Amazonas: (1) com influencia do rio Negro, proxima a Manaus; (2) sem influencia do rio Negro, proxima a Manaus e (3) sem influencia do rio Negro, em um trecho do Solimoes-Amazonas 500 km a montante de Manaus. A condutividade nos pontos de amostragem com influencia do rio Negro foi significativamente menor do que as outras areas e o K dos juvenis de aguas com influencia do rio Negro foi significativamente maior. A alta seletividade do curimata pode dificultar a assimilacao de itens alimentares quando estes estao em alta abundancia. Em adicao, as aguas pretas possuem detritos com alto potencial de assimilacao devido a sua qualidade proteica, o que demon