FERREIRO nicolas Andres
High nutrient retention in chronically nutrient-rich lowland streams
GARCÍA VICTORIA; GANTES PATRICIA; GIMENEZ LORETA; HEGOBURU CECILIA; FERREIRO NICOLAS ANDRES; SABATER FRANCESC; FEIJOO CLAUDIA SILVINA
THE UNIVERSITY OF CHICAGO PRESS
Lugar: Chicago; Año: 2017 vol. 36 p. 26 - 40
Nutrient retention has been studied intensively in streams, but some mechanisms and processes are not yet entirely understood, especially in open-canopy streams. We evaluated PO43-, as soluble reactive P (SRP), and NH$+ uptake in 2 chronicaaly enriched Pampean streams with different macrophytic abundance. We performed short-term nutrient additions to quantify SRP and NH4+ uptake metrics throughout the year, and we investigated which hydrological and biological factors influenced nutrient uptake. The results showed that SRP and NH4+ uptakes were high in relation to pristine and impaired streams elsewhere, and they did not saturate despite elevated background nutrient levels. NH4+ areal uptake rate fit in a 1st-order uptake model, but an exponential model described the relationship between SRP areal uptake rate and SRP concentration. Consistent with this finding, SRP uptake velocity tended to increase linearly, and SRP uptake lenght decreased linearly with SRP concentration. The analysis of factors influencing uptake metrics suggested that srp uptake mainly depended on heterotrohphic demand, whereas NH4+ uptake was enhanced under more autotrophic conditions. Our results showed that nutrient uptake metrics enriched Pampean streams were similar to those observed in streams with low nutrient levels.