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Updated: Jul 11, 2025
Methods for Characterizing the Co-development of Biofilm and Habitat Heterogeneity
Published on: March 11, 2015
The travelling particles: community dynamics of biofilms on microplastics transferred along a salinity gradient
Jessica Song1, Lukas Beule2, Elanor Jongmans-Hochschulz3
1Department of Microbial Ecology, Biologische Anstalt Helgoland, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, 27498, Helgoland, Germany. jessica.song@awi.de.
Abstract:
Microplastics (MP), as novel substrata for microbial colonization within aquatic ecosystems, are a matter of growing concern due to their potential to propagate foreign or invasive species across different environments. MP are known to harbour a diversity of microorganisms, yet little is understood of the dynamics of their biofilms and their capacity to successfully displace these microorganisms across different aquatic ecosystems typically marked by steep salinity gradients. To address this, we performed an in situ sequential incubation experiment to simulate MP transport from riverine to coastal seawaters using synthetic (high-density polyethylene, HDPE and tyre wear, TW) and natural (Wood) substrata. Bacterial communities on incubated particles were compared to each other as well as to those in surrounding waters, and their dynamics along the gradient investigated. All communities differed significantly from each other in their overall structure along the salinity gradient and were shaped by different ecological processes. While HDPE communities were governed by environmental selection, those on TW and Wood were dominated by stochastic events of dispersal and drift. Upon transfer into coastal seawaters, an almost complete turnover was observed among HDPE and TW communities. While synthetic particles displaced a minor proportion of communities across the salinity gradient, some of these comprised putatively pathogenic and resistant taxa. Our findings present an extensive assessment of MP biofilms and their dynamics upon displacement across different aquatic systems, presenting new insights into the role of MP as transport vectors.
Insights
Microplastics (MPs) act as rafts for microbes, potentially spreading invasive species across aquatic environments. This study reveals MPs can displace native microbes, including some pathogens, highlighting their role as vectors.
Area of Science:
- Environmental microbiology
- Ecotoxicology
- Marine biology
Background:
- Microplastics (MPs) are increasingly recognized as substrates for microbial colonization in aquatic ecosystems.
- The capacity of MP-associated microbial communities to influence species distribution across salinity gradients remains poorly understood.
- MPs may act as vectors for the dispersal of microorganisms, including potentially invasive or pathogenic taxa.
Purpose of the Study:
- To investigate the dynamics of microbial biofilms on synthetic (high-density polyethylene, HDPE; tyre wear, TW) and natural (Wood) substrata during simulated transport from riverine to coastal environments.
- To compare bacterial communities colonizing MP and natural substrata with those in surrounding waters along a salinity gradient.
- To assess the potential of MPs to displace microbial communities and introduce novel taxa into different aquatic systems.
Main Methods:
- In situ sequential incubation experiment simulating MP transport across a river-to-sea salinity gradient.
- Comparison of bacterial communities on incubated particles (HDPE, TW, Wood) and in ambient water using 16S rRNA gene sequencing.
- Analysis of ecological processes (environmental selection, dispersal, drift) shaping microbial community structure.
Main Results:
- Distinct bacterial communities were observed on HDPE, TW, and Wood, differing significantly from each other and surrounding waters along the salinity gradient.
- HDPE biofilms were primarily shaped by environmental selection, while TW and Wood communities were dominated by dispersal and drift.
- Significant community turnover occurred on HDPE and TW upon transfer to coastal waters; some displaced taxa were potentially pathogenic or resistant.
Conclusions:
- Microplastics, particularly synthetic types like HDPE and TW, facilitate microbial community shifts and can act as vectors for microbial dispersal across salinity gradients.
- The displacement of native microbial communities by MP-associated biofilms, including potentially harmful taxa, poses ecological risks.
- Understanding MP biofilm dynamics is crucial for assessing their role in aquatic ecosystem functioning and the spread of invasive species.
