Nutrient limitation affects biofilm enzymatic activities in a glacier-fed river

MARTYNIUK, N; M. S. SOUZA,; BASTIDAS NAVARRO, M.,; BALSEIRO, E; B. MODENUTTI,

Hydrobiologia

Springer Science and Business Media Deutschland GmbH

Año: 2022 vol. 849 p. 2877 - 2894

Inmany mountain ranges of the world,glaciersprovide water from melt to rivers. Also, glacier-fedrivers receive different tributaries that differinturbidity and canopy. In this scenario, we performedafield study to elucidate the effect of the inputoftributary streams on the elemental limitation of thebiofilmof the main glacier-fed river. We analyzedthroughgeneral additive models and standardizedmajor axis regressions the activitiesof two extracellularenzymes,β-glucosidase (GLU) and alkalinephosphatase(APA). We hypothesized that their ratiowouldreflect stoichiometric constraints to changes intherelative availability of carbon and phosphorus duetotributary streams’ influence. Along the glacier-fedriver,we observed a decrease in the glacial influenceanda spatial shift in P and dissolved organic carbonavailabilitythat affected biofilm enzymatic activity.Highenzymatic activity of GLU and APA in biofilmwasrelated to low nutrient fluxes in stream water.Inaddition, the analysis of GLU and APA showedaswitch in elemental limitation from C-limitationinheadwaters to P-limitation downstream. Finally,ourresults showed that biofilm enzymatic activityis agood ecological indicator to analyze changes inglacierretreat and their consequences in glacier-fedstreams.