Plastisphere associated communities
Plastics are abundant artificial substrates in aquatic environments that host diverse microbial communities—collectively termed the plastisphere—including potential pathogens, invasive species, and plastic-degrading organisms. Despite increasing concern about plastic pollution, little is known about plastisphere dynamics in transitional and subtropical ecosystems of the Southern Hemisphere. This study presents a comprehensive assessment of the plastisphere in the Patos Lagoon estuary (PLE) and adjacent coastal and oceanic waters in South Brazil. We combined in situ colonization experiments with floating plastic surveys to evaluate the diversity and structure of plastisphere communities. Polyethylene (PE) and polypropylene (PP) substrates were deployed for 30 and 90 days, and plastic particles were also collected using a manta net across multiple sites. Scanning Electron Microscopy (SEM) and multi-marker DNA metabarcoding (16S, 18S V4/V9, and ITS2) were applied to characterize prokaryotic and eukaryotic communities associated with the plastics. We identified 371 plastic particles of varying shapes, sizes, and polymer types, with an average concentration of 4461 items·km?² (SD ± 3914). Microplastics (0.5–5 mm) were predominant, and fragments and lines were the most common shapes. Across samples, we detected 20 bacterial phyla and 41 eukaryotic groups, including taxa with potential pathogenicity (e.g. Vibrio spp., Alexandrium tamarense) and plastic degradation capabilities (e.g. Ralstonia, Pseudomonas, Alcanivorax). Epiplastic community composition and richness were highly variable between individual plastics, but generally not determined by plastic category. These findings provide critical baseline data for understanding plastisphere dynamics in subtropical estuarine and marine systems and support the development of strategies to mitigate the ecological impacts of plastic pollution.