The quality of freshwater undoubtedly reflects the health of our surrounding environment,
society, and economy, as these are supported by various freshwater ecosystems. Monitoring
efforts have therefore been considered a vital means of ensuring the ecological health
of freshwater environments. Nevertheless, most aquatic environmental monitoring strategies
largely focus on bulk water sampling for analysis of physicochemical and key biological
indicators, which for the most part do not consider pollution events that occur at
any time between sampling events. Because benthic biofilms are ubiquitous in aquatic
environments, pollution released during sporadic events may be absorbed by these biofilms,
which can act as repositories of pollutants. The aim of this study was to assess whether
benthic biofilm monitoring could provide an efficient way of properly characterizing
the extent of pollution in aquatic environments. Here, bulk water and benthic biofilms
were sampled from three Hong Kong streams having various pollution profiles, and subsequently
compared via high-resolution microscopy, metagenomic analysis, and analytical chemistry.
The results indicated that biofilms were, indeed, reservoirs of environmental pollutants,
having different profiles compared with that of the corresponding bulk water samples.
Moreover, the results also suggested that biofilms sampled in polluted areas were
characterized by a higher species richness. While the analytical testing of benthic
biofilms still needs further development, the integration of chemical-pollutant profiles
and biofilm sequencing data in future studies may provide unique perspectives for
understanding and identifying pollution-related biofilm biomarkers. (C) 2019 Elsevier
Ltd. All rights reserved.