Landscape factors modulating patterns of salmonid distribution during summer in north Patagonian rivers

LALLEMENT, MAILÉN E.; RECHENCQ, MAGALÍ; FERNÁNDEZ, MARÍA V.; ZATTARA, EDUARDO; SOSNOVSKY, ALEJANDRO; VIGLIANO, PABLO; GARIBOTTI, GILDA; ALONSO, MARCELO F.; LIPPOLT, GUSTAVO; MACCHI, PATRICIO J.

JOURNAL OF FISH BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 97 p. 753 - 762

0022-1112

Understanding how ecosystem processes influencing fish distribution operate across spatialscales is important to understand biological invasions. Salmonids, originally from theNorthern Hemisphere, have been repeatedly introduced throughout the world, makingthem an ideal group to test hypotheses about factors driving invasions. We assessed theinfluence of environmental variables at the watershed scale on the abundance and structureof salmonid assemblages in the breeding streams of the Upper Limay river basin, RioNegro, Argentina. We combined field captures with digital map data and geographic informationsystems to examine landscape-level patterns of salmonid abundance in 35 representativesub-basins of the environmental gradient. We employed a hierarchical clusteranalysis and classification and regression tree models to relate the abundance of salmonidsand types of species assemblages with environmental characteristics at watershedlevel. We found stream localization, precipitation regime, altitude and air temperature tobe important predictors of the abundance and assemblage structure of salmonids. Totalcatches showed an increasing gradient of catch-per-unit-effort from west to east andfrom north to south, with Oncorhynchus mykiss being the most abundant species. O.mykiss relative abundance was westward skewed, where smaller catchments with steeperand shaded valleys are drained by less productive streams with more irregular hydrologicalregimes, like those found in this species´ North American native range. In contrast, theabundance of Salmo trutta abundance was eastward skewed, where larger, sunnier andmore gently sloped catchments result in more productive streams with stable hydrologicalregimes, like those found in that species´ European native range. Thus, differential salmonidabundance could result from the interplay between the evolutionary fingerprint leftby each species´ native environment (especially flow and temperature regimes) and theavailability of those conditions in new environments to which they have been translocated.By furthering our understanding of how landscape conditioned invasion success,these findings can help guide the management of economically important introduced fish.