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

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

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2022

0018-8158

In many mountainous parts of the world glaciers are headwaters and provide water from melt to rivers and lakes in lowland regions. The river receives differenttributaries that differ in turbidity and canopy. In this scenario we performed a field studyto elucidate the effect of the input of tributary streams on the elemental limitation of thebiofilm of the main glacier-fed river. We analyzed through general additive models andstandardized major axis regressions the activities of two extracellular enzymes, β-glucosidase (GLU) and alkaline phosphatase (APA). We hypothesized that their ratiowould reflect stoichiometric constraints to changes in the relative availability of carbonand phosphorus due to tributary streams? influence. Along the glacier-fed river, weobserved a decrease in the glacial influence and a spatial shift in P and dissolvedorganic carbon availability, that affected biofilm enzymatic activity. High enzymaticactivity of GLU and APA in biofilm was related to low nutrient fluxes in stream water. Inaddition, the analysis of GLU and APA showed a switch in elemental limitation from Climitationin headwaters to P-limitation downstream. Finally, our results showed thatbiofilm enzymatic activity is a good ecological indicator to analyze changes in glacierretreat and their consequences in glacier-fed streams.