The influence of topography and land use on hydrological and nutrient dynamics in two Andean streams from Northern Patagonia

MAILÉN ELIZABETH LALLEMENT; FERNÁNDEZ, MARÍA VALERIA; ROMINA DAGA; MAGALÍ RECHENCQ; SERGIO LEIVA; RODOLFO CANTET; ALEJANDRO SOSNOVSKY1; EDUARDO ENRIQUE ZATTARA; JOSÉ SUÁREZ

NEW ZEALAND JOURNAL OF MARINE AND FRESHWATER RESEARCH

RSNZ PUBLISHING

Lugar: Auckland; Año: 2020 p. 1 - 20

0028-8330

Fluvial dynamics are driven by multiple environmental factors and scales. Studies coupling hydrological and nutrient dynamics of mountain streams are almost non-existent in the Northern Patagonian region; which is characterized by a temperate-cold climate. We studied two adjacent streams with contrasting drainage basins: Casa de Piedra (41° 07´ 30.11? S 71° 27´ 13.16?W), originating in a small mountain lake and running through a pristine landscape, and Gutiérrez (41° 09´ 36.18´´ S 71° 24´ 37.19´´W), originating in a large piedmont lake and running through an anthropized landscape. We found that the streams presented contrasting hydrological and nutrient dynamics. Casa de Piedra had higher discharge flashiness with shorter response delays to precipitation. Interestingly, Gutiérrez?s hydrology was buffered by the upstream lake, but its nutrient exports were not. Differences observed in quality and timing of coarse particulate organic matter export and export levels of phosphorus and nitrogen could be explained by human activities affecting Gutiérrez but not Casa de Piedra. Moreover, nitrogen:phosphorus ratio indicates a possible future shift to phosphorus as the limiting nutrient in the more densely populated basin. In summary, our study shows that even under a common geology and climate, stream dynamics of adjacent basins can be starkly different due to differences in topography and land use.