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

LOPEZ VAN OOSTEROM, V.; OCON, C; BRANCOLINI, F.; MAROÑAS, M.; SENDRA, E.; RODRIGUES CAPITULO, A.

IHERINGIA. SéRIE ZOOLOGIA

Fundação Zoobotânica do Rio Grande do Sul

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

0073-4721

ABSTRACT. The diet and trophic relationships between the macroinvertebrates Phyllogomphoides joaquini Rodrigues Capítulo, 1992 andCoenagrionidae (Odonata), Chironomidae (Diptera), Diplodon delodontus (Lamarck, 1919) (Bivalvia: Hyriidae), and Pomacea canaliculata(Lamarck, 1822) (Gastropoda: Ampulariidae) and the fishes Pimelodella laticeps Eigenmann, 1917 (Heptapteridae) and Bryconamericus iheringii(Boulenger, 1887) (Characidae) in a temperate lowland lotic system in Argentina were assessed on the basis of gut contents and stable-isotopeanalyses. The feeding strategies were analyzed by the Amundsen method. Relative food items contribution for the taxa studied indicated ageneralist-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 behaviour.These feeding studies allowed us to determine the trophic relationships among taxa studied. Detritus and diatoms were a principal source of foodfor all the macroinvertebrates studied. In La Choza stream the particulate organic matter is a major no limited food resource, has a significantinfluence upon the community.