Trophic relationships between macroinvertebrates and fish in a pampean lowland stream (Argentina)

LÓPEZ VAN OOSTEROM, M. V.; OCON, C. S.; BRANCOLINI, F.; MAROÑAS, M.; SENDRA, E.; RODRIGUES CAPÍTULO, A.

IHERINGIA. SéRIE ZOOLOGIA

FUNDACAO ZOOBOTANICA RIO GRANDE SUL

Lugar: Porto Alegre; Año: 2013 vol. 103 p. 57 - 65

0073-4721

The diet and trophic relationships between the macroinvertebrates Phyllogomphoides joaquini and Coenagrionidae (Odonata), Chironomidae (Diptera), Diplodon delodontus (Bivalvia: Hyriidae), and Pomacea canaliculata (Gastropoda: Ampulariidae) and the fish Pimelodella laticeps (Heptapteridae) and Bryconamericus iheringii (Characidae) in a temperate lowland lotic system in Argentina were assessed on the basis of gut contents and stable-isotope analyses. The feeding strategies were analyzed by the Amundsen method. Relative food items contribution for the taxa studied indicated a generalist-type trophic strategy. In macroinvertebrates, in general, the values of stable isotope confirmed the result of the analysis of gut contents. With the fish, stable-isotope analysis demonstrated that both species are predators, although B. iheringii exhibited a more omnivorous behavior. These feeding studies allowed us to determine the trophic relationships among taxa studied. Detritus and diatoms were a principal source of food for all the macroinvertebrates studied. In La Choza stream the organic matter is a major nonlimited food resource, has a significant influence upon the community.