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 fishdistribution operate across spatial scales is important to understand biologicalinvasions. Salmonids, originally from the Northern Hemisphere, have been repeatedlyintroduced throughout the world, making them an ideal group to test hypothesesabout factors driving invasions. We assessed the influence of environmentalvariables at the watershed scale on the abundance and structure of salmonidassemblages in the breeding streams of the Upper Limay river basin, Rio Negro,Argentina. We combined field captures with digital map data and geographicinformation systems to examine landscape-level patterns of salmonid abundancein 35 representative sub-basins of the environmental gradient. We employed ahierarchical cluster analysis and classification and regression tree models torelate the abundance of salmonids and types of species assemblages with environmentalcharacteristics at watershed level. We found stream localization, precipitation regime,altitude and air temperature to be important predictors of abundance and assemblagestructure of salmonids. Total catches showedan increasing gradient of catch-per-unit-effort from West to East and fromNorth to South, with Oncorhynchus mykiss being the most abundantspecies. O. mykiss relatively abundance was westward skewed, wheresmaller catchments with steeper and shaded valleys are drained by lessproductive streams with more irregular hydrological regimes, like those foundin this species? North American native range. In contrast, Salmo salar?sabundance was eastward skewed, where larger, sunnier and more gently slopedcatchments resulting in more productive streams with stable hydrologicalregimes, like those found in that species? European native range. Thus, differential salmonid abundancecould result from the interplay between the evolutionary fingerprint left byeach species? native environment (especially flow and temperature regimes) and theavailability of those conditions in new environments to which they have beentranslocated. By furthering our understanding of how landscape conditions invasionsuccess, these findings can help guide management of economically importantintroduced fish.