Structural parameters of biofilm and bacterioplankton are better indicators of urbanization than photosynthetic functional parameters in low-order streams

GORBARÁN, ROCÍO; VILCHES, CAROLINA; RODRÍGUEZ CASTRO, MARÍA CAROLINA; GIORGI, ADONIS; TORREMORELL, ANA

HYDROBIOLOGIA

SPRINGER

Lugar: Berlin; Año: 2022

0018-8158

The aim of this study was to assess urbanization efects on microbial communities from low-order streams. Artifcial substrata were placed upstream (control) and downstream (urban) of the cities of the selected streams. Photosynthetic parameters derived from chlorophyll-a fuorescence were measured using a Pulse of Amplitude Modulated Fluorometer, and the bacterial bioflm and bacterioplankton were counted by microscopy after staining with 4′,6-diamidino-2-phenylindole. We found higher bacterial bioflm biomass together with higher concentration of nutrients in urban reaches. The bioflm total density of bacteria was negatively correlated with the humic acid concentration, while the bacterioplankton total density was positively correlated with soluble reactive phosphorus and nitrite concentration. Autotrophic Index refected the predominance of heterotrophs in the three streams. The concentration of chlorophyll-a, the minimum fuorescence, and the other photosynthetic parameters showed variations between the streams. These would respond to environmental factors at local scale not included in this study and may be infuenced by the low development of autotrophic biomass at least in two of the streams studied. The bacterial morphotypes Small rod, Large rod, and Vibrio shaped (large) allowed the diferentiation of urban reaches and would be useful as indicators of urbanization efects in both bioflm and bacterioplankton of lowland streams