Influence of infrastructure material composition and microtopography on marine biofilm growth and photobiology

Abstract

The impact of concrete composition and roughness on the formation of microalgal biofilms and their photobiology were studied on marine infrastructures presenting four different compositions combined with two degrees of roughness (rough and smooth). The structures were first inoculated with a natural microphytobenthic biofilm and immersed in sterilised seawater with a controlled photoperiod for six days. Photosynthetic activity was assessed with an imaging PAM-(Pulse Amplitude Modulated) fluorometer and microtopography was monitored in parallel with a 3-D camera. The results indicated that roughness had an impact on the biofilm biomass, its physiological status and its photosynthetic efficiency and capacity. The assessment of surface roughness indicated that negative reliefs were preferably colonised by MPB (microphytobenthic) cells with better photosynthetic performances. Moreover, MPB biofilms showed better photoacclimation in these microhabitats than on the positive and smooth reliefs. This study confirms the importance of microhabitat for biofilm formation and their photobiology.

Keywords:

• Biofilm
• hard substrata
• rugosity
• photosynthesis
• PAM fluorometry
• biomaterial

Acknowledgements

The results presented in this article were obtained in the collaborative project Interreg Va MARINEFF, selected under the European Cross-border Programme INTERREG FMA, and co-funded by the ERDF. The authors wish to thank the co-financiers and all project partners for their support. The authors thank the Normandy Region for funding the IMAGING-PAM (CPER Manche 2021). The authors thank Dr Richard Retoux and Mr Xavier Larose of Laboratoire CRISMAT (Normandie University, ENSICAEN, UNICAEN, CNRS, CRISMAT, 14000 Caen, France) for technical SEM support for microscopy observations. The authors thank Dr Antoine Grémare, Dr. Olivier Maire and Alicia Romero Ramirez of the University of Bordeaux for the loan of the 3-D camera and kind help in the image acquisition.

Disclosure statement

No potential conflict of interest was reported by the author(s).