Trophic scaling of Percichthys trucha (Percichthyidae) in monospecific and multispecific lakes in western Patagonia

Abstract

a b s t r a c tPercichthys trucha is a freshwater fish, endemic to southern South America and widely distributed in both, eastern and western sides of the Andes. P. trucha has been described as top native predator in lacustrine ecosystems, experimenting diet shifting during their life history development. Salmonid invasions have impacted their natural ecology through trophic niche interference and predation over alternative high quality prey. This study focuses on populations of P. trucha in western Patagonia, where its trophic ecology have been less understood. We hypothesised a diet shift between juveniles and adults from lowertrophic position prey towards higher-trophic position prey. Fish were collected from 7 lakes belonging to Puelo and Baker river basins, covering a high diversity of environmental conditions. Stomach content and ␦ 15 N stable isotope ratio of muscle tissues of 313 individuals were analysed. Results indicate significant differences in diet between juveniles and adults, shifting from planktonic/benthic preys towards benthic/piscivory, and concomitantly enrichment in heavier nitrogen isotope suggest trophic scaling. No trophic scaling was observed in populations inhabiting lakes with any other fish species present, essentially due to lack of Galaxias sp. as available prey and absence of cannibalism. Despite the fact that P. trucha and Galaxias sp. co-occur in studied river basins, no salmonid-free lakes harbouring this two native species were found, making it difficult to elucidate exact effects of salmonids on trophic scaling of P. trucha. Consumption of aquatic Odonata nymphs, however, arises as one of potential key mechanism for resilience of native food webs to salmonid invasion.

Variation of stomach content and isotopic niche of puye Galaxias maculatus (Jenyns, 1842) in large river systems of southern Chile

“…Salmonid dominance is expected to force individuals of puye to occupy shallow zones of lakes, with or without aquatic vegetation where they consume benthic and/or terrestrial items, feeding on zooplankton in very low quantities. This change in the diet of native fish, due to the presence of introduced species, has been extensively documented (Elgueta et al., 2013; Habit et al., 2010, 2015; Ortiz‐Sandoval et al., 2015, 2017).…”

Early specialized maritime and maize economies on the north coast of Peru

“…In contrast to Huaca Prieta childhood diets, all three models (with both corrected and uncorrected δ 13 C enamal carbonate values) show that Paredones children consumed significant quantities of maize and a mix of terrestrial C 3 and C 4 proteins; the latter could include marine foods, terrestrial animals that consumed C 4 plants, top predator lake fish (67,68), and/or protein-rich amaranth (Figs. 2 and 3, Table 1, and SI Appendix, Figs.…”

High Trophic Niche Overlap between a Native and Invasive Mink Does Not Drive Trophic Displacement of the Native Mink during an Invasion Process

“…Despite multiple studies on trophic niche overlap between INNS and native species (e.g., [1,3,[9][10][11]), little is known about the specific mechanisms of the trophic displacement that can occur between the species, most commonly to the detriment of the native species. Neither it is known if/how the diet of the native species changes during the arrival and the range expansion of the INNS.…”

“…After establishment, the INNS can cause a significant reduction in the trophic position (i.e., ecological role in food web) of the native populations [11,12]. Furthermore, the response of the native species to invasion depends critically on the abundance and the trophic position of the INNS that invades relative to the abundance and the trophic position of the native species [12].…”