Mineral composition of epiphytic biofilms growing on Phalaris arundinacea and artificial substrates made of bamboo
The mineral content in water plays an important role in the growth and the structure of biofilms grown in fresh waters. Moreover, the concentration of inorganic ions within biofilms depends on their concentrations in waters. The minerals can be assimilated by algae and microorganisms within biofilms. Therefore, this study focused on the distribution and the assimilation time of the main minerals within epiphytic biofilms grown in fresh waters contaminated by human activities. Two kinds of biofilm substrates were selected such as Phalaris arundinacea, which was widespread in our study area, and artificial substrates made of bamboo planted to control the biofilm age. The main physicochemical parameters of the water were monitored at three stations TR, ZB and AV. The results revealed that several inorganic elements, such as Fe, Mn, Si, Al, Na, K, Mg, S, P and Ca, were found within the natural biofilms. Among them, Si, Fe, Mn and Al were found in a high proportion. The Si was the most common element found within all biofilms studied (40-80%), reflecting the presence of diatoms with their silica walls. Some elements such as Fe, P, Ca, K were present throughout the colonized surface. We noted that Fe, Mn, Si and Al, which can form oxides, were most often found in biofilms. Finally, the relationships between physicochemical and biological parameters in waters and biofilms were explored by Principal Component Analysis (PCA), e.g., the Fe concentrations in waters and Fe proportions within the biofilms during the summer. The research has provided new information on the dynamics operating between waters and biofilms.