Bacteria is an indispensable constituent of all natural and human-made ecosystems. The most attractive fractions of bacteria, known as biofilms, are where cells are attached and surrounded by sticky extracellular polymeric substances. Biofilms concentrate and integrate organic and inorganic constituents of the milieu in which they develop, making them sites of intensified biogeochemical process relative to their environment. In addition, this makes them more sensitive indicators of ambient conditions in water bodies than water column parameters, especially in the initial phase of development where allochthonous factors have a more pronounced influence on biofilm growth and activity.

Microbial biofilms are complex communities of bacteria, fungi, protozoa, microalgae, and micrometazoa that exist in a polymer matrix on submerged surfaces. Microbial biofilm communities exhibit habitat specificity as a result of the quality and quantity of resources available, and grazers controlling community structure and function. Temporal and spatial variability within biofilms reflect changes in system status, including nutrient and organic loading and the presence of contaminants. Recognition of correlations between the occurrence of microbial biofilms and various environmental conditions draws the concept of biological indicators.

Submerged microbial biofilms also adsorb toxic materials from the environment. Metals and organic toxins are sequestered within the matrix by adsorption and complexion reactions with polymers and interactions with iron and manganese oxides. Uronic acid and ketal-linked pyruvate residues facilitate these reactions. Although the concentration of toxins in the environment is enhanced, binding reactions may also limit the bioavailability of the toxic compounds.

The aim of this Special Issue is to collate original research articles with a focus on biofilm structures and their role in environmental progression. In addition, we welcome review articles discussing the development and progression on aquatic biofilms.

Potential topics include but are not limited to the following:

• History, scope, and mode of studying aquatic biofilms
• Technological advancements in biofilm formation
• Morphogenetic diversity of biofilms
• Agricultural biofilms
• Potential applications of Biofilms in bioremediation, wastewater treatment and the beverage industry
• Microbial interaction in biofilms
• Quorum sensing in biofilms
• Genetic interchanges of biofilms
• Nanotechnology and biofilms
• Impact of climate change on aquatic biofilms
• Aquatic biofilms and biogeochemical processes