Impacts of Urban Stressors on Freshwater Biofilms

Mixed light photoperiod and biocide pollution affect lipid profiles of periphyton communities in freshwater ecosystems

“…The results presented in Figure 1, Figure 2 and Figure 3 showed that the samples contained polyunsaturated fatty acids in the absence of BAC 12, indicating that the biofilms contained photoautotrophs belonging to the bacillariophyceae, chlorophyceae and cyanophyceae groups (Vestal andWhite 1989, Guschina andHarwood 2009). This was also confirmed by fluorimetry and microscopy analyses (Vrba et al 2023). Bacterial FA (BAFA index) with the sum of some SFAs and MUFAs like C15:0, C15:1, C16:0, C17:0, C17:1, C18:0 and C18:1n-7 (Napolitano 1999, Dalsgaard et al 2003 can also be used to estimate the contribution of bacteria to the biofilm community.…”

“…After five months, colonized substrates were removed from the natural environment and were randomly placed in experimental channels (on day 0 = T0) under laboratory conditions as described in Vrba et al (2023). Briefly, four experimental conditions were set up, each in pseudo-triplicates (i.e., separate 10-L channels fed by a common 10-L tank).…”

“…Quality controls were regularly injected at concentrations of 5 and 25 µg L -1 , as well as analytical blanks. Concentration values for either BAC 12 (Table A 1) or nutrients are available in Vrba et al (2023).…”

“…at the lipid class level in Vrba et al (2023). For each date and condition, we have plotted on abscissa the ratio between the average amount of glycolipids (GL), represented here by all molecular species of MGDG and DGDG, and the average amount of phospholipids (PL) such as PG, PE and PC (i.e.…”

“…The combined effects of stressors in an urban environment and the subsequent reactions of microorganisms within biofilms remain poorly understood. In this context, we carried out earlier research to determine the individual and combined effects of dodecylbenzyldimethylammonium chloride (BAC 12), as disinfecting emerging contaminant, and Artificial Light at Night (ALAN) on autotrophic organisms in the biofilm (Vrba et al 2023). This previous work revealed the predominant effects of the biocidal activity on autotrophic organisms in the environment, both at the scale of algal group (i.e., green algae, diatoms and cyanobacteria) and at the level of photosynthetic response.…”