First study of food webs in a large glacial river: the trophic role of invasive trout

TAGLIAFERRO, M.; KELLY, S.P.; PASCUAL, M.A.

NEOTROPICAL ICHTHYOLOGY

SOC BRASILEIRA ICTIOLOGIA

Lugar: Porto Alegre; Año: 2020 vol. 18 p. 1 - 25

1679-6225

The aim of this study was to determine the food webs structure of a largePatagonian river in two river sections (Upstream and Midstream) and to evaluateisotopic overlap between native and introduced species. We used stable isotopeanalyses of δ15N and δ13C and stomach content. The Upstream section had amore complex food webs structure with a greater richness of macroinvertebratesand fish species than Midstream. Upstream basal resources were dominated byfilamentous algae. Lake Trout were found to have a higher trophic position thanall other fish species in that area although, the most abundant fish species, wereRainbow Trout. Depending on the life stage, Rainbow Trout shifted from preyto competitor/predator. In the Midstream section, the base of the food webs wasdominated by coarse particulate organic matter, and adult Rainbow Trout hadthe highest trophic level. Isotopic values changed among macroinvertebrates andfish for both areas. The two most abundant native and invasive species ? Puyenand Rainbow Trout ? showed an isotopic separation in Midstream but did notin Upstream areas. The presence of invasive fish that occupy top trophic levelscan have a significant impact on native fish populations that have great ecologicalimportance in the region.