Secondary production of two species of Anacroneuria (Perlidae) in a neotropical river

Secondary production in aquatic insects is a theme of great relevance and insufficiently studied. This topic allows an understanding of the rate variability of biomass by consumers in lotic systems. Plecoptera are one of the most abundant and widely used groups of aquatic insects used in this field. Therefore, the objective of this work was to determine the secondary production of the two dominant species of stoneflies (Anacroneuria marta and A. caraca) in the middle of the Gaira River (Sierra Nevada de Santa Marta, Colombia). Sampling was carried out every 20 days during a year (14 samplings in total), in the gravel microhabitats in slow current and fast current. The identification of the nymphs was made based on morphological characters and descriptions available in the bibliography. Secondary production was estimated using the length frequency method for unrecognized cohorts. The annual biomass of A. marta was like A. caraca (B= 457.41 and B= 432.28 mg/m2, respectively). The annual production of A. caraca (4.198 g/m2/a) was greater than A marta (2.582 g/m2/a). However, the annual production per biomass ratio P/B was 9.71 a-1 for A. marta and 5.65 for a-1 A. caraca. The production of both species was high compared to other studies done in the neotropical region. These results demonstrated that the species are multivoltine and that there is no seasonal growth pattern moderated by rainfall.