PERSONAL DE APOYO
DONADELLI Jorge Luis
Agriculture influences ammonium and soluble reactive phosphorus retention in South American headwater streams
CUNHA, DAVI GASPARINI FERNANDES; FINKLER, NÍCOLAS REINALDO; GÓMEZ, NORA; COCHERO, JOAQUÍN; DONADELLI, JORGE LUIS; SALTARELLI, WESLEY APARECIDO; CALIJURI, MARIA DO CARMO; MIWA, ADRIANA CRISTINA POLI; TROMBONI, FLAVIA; DODDS, WALTER K.; BOËCHAT, IOLA GONÇALVES; GÜCKER, BJÖRN; THOMAS, STEVEN A.
JOHN WILEY & SONS INC
Año: 2019 vol. 13
Agricultural activities can affect the delivery of nutrients to streams, riparian canopycover, and the capacity of aquatic systems to process nutrients and sediments. Thereare few measures of nutrient uptake and metabolism from tropical or subtropicalstreams in general, and even fewer from tropical regions of South America. Weexamined ammonium (NH4+) and soluble reactive phosphorus (SRP) retention instreams in Brazil and Argentina. We selected 12 streams with relatively little orextensive agricultural activity and conducted whole-stream nutrient additions andmeasurements of gross primary production and ecosystem respiration. We used multiplelinear regression to determine potential drivers of nutrient uptake metrics acrossthe streams. Nutrient concentrations and retention differed significantly betweenland use categories. Both NH4+ and SRP concentrations were higher in the agriculturalsites (means of 161 and 495 μg l?1, respectively), whereas metabolic rates wereslower and transient storage was smaller. Our analysis indicated that agricultureincreased ambient uptake lengths and decreased uptake velocities. The regressionmodels revealed that ambient SRP had a positive effect on NH4+ uptake and viceversa, suggesting strong stoichiometric controls. Drivers for nutrient uptake instreams with low-intensity agriculture also included canopy cover, temperature, andecosystem respiration rates. Nutrient assimilation in agricultural sites was influencedby a higher number of variables (gross primary production for SRP, discharge, andtransient storage for both nutrients).