Input of allochthonous matter and structure of fauna in a Brazilian headstream

Summary

There was investigated the terrestrial plant and animal matter input, structure, and composition of the lotic fauna in two stretches of the Itaúna Stream — one inside a gallery forest and the other in an area with predominating herbaceous vegetation. In the gallery forest stretch, the litter and lateral transport attained 706 g · m^-2 · year^-1 and 421 g · m^-1 · year^-1, respectively while the animal input ranged from 78 to 588 specimen · m^-2. Twelve fish species and 43 groups of invertebrates were sampled from the water in this stretch. The herbaceous vegetation stretch showed a litter input and lateral transport of only 83 g · m^-2 · year^-1 and 124 g · m^-1 · year^-1, respectively while the animal input ranged from 143 to 876 specimen · m^-2. Fourteen fish species and 58 groups of invertebrates were recorded from this stretch. The discrepancy between the results obtained from the two stretches was attributed to an increase in light intensity towards the downstream area which supplied a larger density of marginal vegetation, shelter and food.