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The plastisphere, a unique microbial biofilm community colonizing plastic debris and microplastics (MPs) in aquatic environments, has attracted increasing attention owing to its ecological and public health implications. This review consolidates current state of knowledge on freshwater plastisphere, focussing on its biodiversity, community assembly, and interactions with environmental factors. Current biomolecular approaches revealed a variety of prokaryotic and eukaryotic taxa associated with plastic surfaces. Despite their ecological importance, the presence of potentially pathogenic bacteria and mobile genetic elements (i.e., antibiotic resistance genes) raises concerns for ecosystem and human health. However, the extent of these risks and their implications remain unclear. Advanced sequencing technologies are promising for elucidating the functions of plastisphere, particularly in plastic biodegradation processes. Overall, this review emphasizes the need for comprehensive studies to understand plastisphere dynamics in freshwater and to support effective management strategies to mitigate the impact of plastic pollution on freshwater resources. [ABSTRACT FROM AUTHOR]

It is becoming more apparent that the aquatic carnivorous plants Utricularia (Lentibulariaceae) can capture and utilise a wide range of small aquatic organisms. Although they can take up nutrients directly from the water by rootless shoots, much of their overall nutrition comes from prey caught in their traps. Most of the early literature was focused mainly on animal prey, hence the term carnivorous to describe Utricularia spp., but more recently the contribution of other microorganisms and detritus to their diet is being realised. Specifically, the importance of the phytoplankton in traps as prey is proving interesting. However, most investigations have focused on the trap communities with few comparisons to phytoplankton as potential prey, which could reveal the occurrence of feeding selectivity.The eurytopic species Utricularia australis was surveyed across 12 sites in central Italy in lentic waterbodies ranging from oligotrophic to eutrophic. Phytoplankton communities outside the traps were composed of 135 taxa from 21 orders belonging to eight phyla and the algal community in the traps comprised 124 taxa from 17 orders belonging to eight phyla, recorded from all sampling sites. Among the 12 sites phytoplankton communities were highly diverse; however, communities inside and outside the traps at each site were very similar. This similarity indicated that feeding was not selective.Algal movements are not able to elicit a trap response, yet around 70% of the traps contained phytoplankton only (no animal prey). Therefore, regular spontaneous trap firing, known to occur in U. australis, is thought to be responsible for the similarities in trap and plankton algal communities.At two sites, a Euglenophyte (Lepocinclis sp.) and a Cryptophyte (Chilomonas sp.) proliferated, which were otherwise very rare in the phytoplankton community. This is indicative of favourable growth conditions in the traps and possibly of commensal relationships. It seems that the diet requirements of U. australis are met by having a highly varied prey spectrum. [ABSTRACT FROM AUTHOR]

A microcosm designed for culturing aquatic phototrophic biofilms on artificial substrata was used to perform experiments with microphytobenthos sampled during summer toxic outbreaks of Ostreopsis cf. ovata along the Middle Tyrrhenian coast. This dynamic approach aimed at exploring the unique and complex nature of O. cf. ovata bloom development in the benthic system. Epibenthic assemblages were used as inocula for co-cultures of bloom organisms on polycarbonate slides at controlled environmental conditions. Biofilm surface adhesion, growth, and spatial structure were evaluated along with shifts in composition and matrix production in a low disturbance regime, simulating source habitat. Initial adhesion and substratum colonisation appeared as stochastic processes, then community structure and physiognomy markedly changed with time. Dominance of filamentous cyanobacteria and diatoms, and dense clusters of Amphidinium cf. carterae at the mature biofilm phases, were recorded by light and confocal microscopy, whilst O. cf. ovata growth was visibly limited in the late culture phases. Life-form strategies, competitiveness for resources, and possibly allelopathic interactions shaped biofilm structure during culture growth. HPLC (High Performance Liquid Chromatography) analysis of exopolysaccharidic matrix revealed variations in sugar total amounts and composition. No toxic compounds were detected in the final communities tested by LC-MS (Liquid Chromatography- Mass Spectrometry) and MALDI-TOF MS (Matrix Assisted Laser Desorption Ionization Time OF Flight Mass Spectroscopy) techniques. [ABSTRACT FROM AUTHOR]