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

LALLEMENT, MAILÉN ELIZABETH; RECHENCQ, MAGALÍ; FERNÁNDEZ, MARÍA VALERIA; ZATTARA, EDUARDO; SOSNOVSKY, ALEJANDRO; VIGLIANO, PABLO; GARIBOTTI, GILDA; ALONSO, MARCELO FABIÁN; LIPPOLT, GUSTAVO; MACCHI, PATRICIO JORGE

JOURNAL OF FISH BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020

0022-1112

Understanding how ecosystem processes influencing fish distribution operate across spatial scales is important to understand biological invasions. Salmonids, originally from the Northern Hemisphere, have been repeatedly introduced throughout the world, making them an ideal group to test hypotheses about factors driving invasions. We assessed the influence of environmental variables at the watershed scale on the abundance and structure of salmonid assemblages in the breeding streams of the Upper Limay river basin, Rio Negro, Argentina. We combined field captures with digital map data and geographic information systems to examine landscape-level patterns of salmonid abundance in 35 representative sub-basins of the environmental gradient. We employed a hierarchical cluster analysis and classification and regression tree models to relate the abundance of salmonids and types of species assemblages with environmental characteristics at watershed level. We found stream localization, precipitation regime, altitude and air temperature to be important predictors of abundance and assemblage structure of salmonids. Total catches showed an increasing gradient of catch-per-unit effort from West to East and from North to South, with Oncorhynchus mykiss being the most abundant species. O. mykiss relatively abundance was westward skewed, where smaller catchments with steeper and shaded valleys are drained by less productive streams with more irregular hydrological regimes, like those found in this species? North American native range. In contrast, Salmo trutta ?s abundance was eastward skewed, where larger, sunnier and more gently sloped catchments resulting in more productive streams with stable hydrological regimes, like those found in that species? European native range. Thus, differential salmonid abundance could result from the interplay between the evolutionary fingerprint left by each species? native environment (especially flow and temperature regimes) and the availability of those conditions in new environments to which they have been translocated. By furthering our understanding of how landscape conditions invasion success, these findings can help guide management of economically important introduced fish.