Influence of Biofilms and Extracellular Polymeric Substances on High‐Frequency Acoustic Backscatter

Abstract Acoustic Backscatter Technique has been used to detect underwater targets and characterize seabed and river floor sediment properties. Microbial biofilms, consisting of microorganisms enclosed in Extracellular Polymeric Substances (EPS), have the potential to modify acoustic backscatter by altering the sediment topography, permeability, and porosity; however, these effects remain uncharacterized. Here, we performed laboratory experiments to explore the effects of microbial biofilms and EPS within sediments on acoustic backscatter. Our results show that the biofilm mat‐like structure formed by microorganisms above the sediment bed can reduce acoustic backscatter by up to 6 dB, while EPS within sediments can increase backscatter strength by up to 6 dB, with more significant changes at lower incident angles. This study highlights the critical role of biofilms in acoustic backscatter and paves the way for detecting targets and characterizing the properties of biofilm‐covered sediment beds.