Vibrio spp and other potential pathogenic bacteria associated to microfibers in the North-Western Mediterranean Sea

Microfibers, whether synthetic or natural, have increased dramatically in the environment, becoming the most common type of particles in the ocean, and exposing aquatic organisms to multiple negative impacts. Using an approach combining morphology (scanning electron microscopy-SEM) and molecular taxonomy (High-Throughput DNA Sequencing- HTS), we investigated the bacterial composition from floating microfibers (MFs) collected in the northwestern Mediterranean Sea. The average number of bacteria in 100 μm 2 on the surface of a fiber is 8 ± 5.9 cells; by extrapolating it to a whole fiber, this represents 2663 ± 1981 bacteria/fiber. Attached bacterial communities were dominated by Alteromonadales, Rhodobacterales, and Vibrionales, including the potentially human/animal pathogen Vibrio parahaemolyticus . This study reveals a high rate of bacterial colonization on MFs, and shows that these particles can host numerous bacterial species, including putative pathogens. Even if we cannot confirm its pathogenicity based only on the taxonomy, this is the first description of such pathogenic Vibrio living attached to MFs in the Mediterranean Sea. The identification of MFs colonizers is valuable in assessing health risks, as their presence can be a threat to bathing and seafood consumption. Considering that MFs can serve as vector for potentially pathogenic microorganisms and other pollutants throughout the ocean, this type of pollution can have both ecological and economic consequences

Spatio-temporal characterization of litter at a touristic sandy beach in South Brazil

Litter is an ecological, economic, and social problem that impacts marine environments around the world. To create prevention and mitigation measures to solve this issue, it is necessary to understand the amounts and sources of this type of pollution. Cassino Beach is an extensive sandy beach located in South Brazil (~220 km in length) that presents multiple uses, such as touristic, portuary and fishery activities. In order to evaluate the spatial and seasonal variation of litter amounts, types and sources at Cassino Beach, litter (>2.5 cm) was collected over 27 months at two urban and two non-urban sites. At each site, the litter present in three 200 m2 areas was sampled and evaluated. A total of 19,457 items were collected, mostly composed by plastic (~88%). Paper, metal, and cloth items were also present, but in low amounts. Fragments and cigarette butts were the major types of plastic litter, with abundances of 28.4% and 17.0%, respectively. Urban sites presented higher amounts of litter, with those related to beach use being more common, emphasizing the contribution of beachgoers to litter input at these sites. During the summer season, when beach use increases, the highest total litter concentration was found. Undefined and/or beach use-related sources were dominant in all sites and seasons. Mapping the predominant materials, types and potential sources of litter creates important baseline data that can contribute not only to beach monitoring, but also to the development of litter reduction strategies

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Principal coordinate analysis (PCoA) plot showing dissimilarities among the bacterial community composition attached to microfibers from summer (MF_SU) and spring (MF_SP) seasons, the free-living bacteria from the Seawater and from the Haliotis Waste Water Treatment Plant (WWTP).

Samples were grouped based on Jaccard distance matrix.</p

Number of observed OTUs per group of microfibers from spring (MFSP) and summer (MFSU) seasons, as well as from the Seawater, obtained from 16S amplicon sequence library, with significant difference between microfibers and seawater samples (Kruskal-Wallis, p < .01).

Number of observed OTUs per group of microfibers from spring (MFSP) and summer (MFSU) seasons, as well as from the Seawater, obtained from 16S amplicon sequence library, with significant difference between microfibers and seawater samples (Kruskal-Wallis, p < .01).</p

Bar chart showing taxonomic composition and dominance of a relatively small number of abundant OTUs, for seawater (SW) and floating microfibers (MF) in the Mediterranean Sea.

Similarities between microfibers collected during spring and summer seasons are detailed. For more clarity, OTUs representing less than 1% or unclassified at the class level are grouped in the Other/Unknown series.</p

Map of the northwestern Mediterranean Sea where seasonal sampling of MFs and seawater was carried out in the coastal area between Nice and Monaco, as well as in the offshore Dyfamed station, and the Haliotis waste water treatment plant.

This map was created at MATLAB software by using the M_Map package.</p

Fig 2 -

Optical microscopy of floating fibers sampled at the Mediterranean Sea (A, B), and Scanning Electron Microscopy (SEM) images of their attached bacteria, with elongated and rounded cells, as well as Extracellular Polymeric Substances (EPS) (C-F).</p

Plastics in sea surface waters around the Antarctic Peninsula

Although marine plastic pollution has been the focus of several studies, there are still many gaps in our understanding of the concentrations, characteristics and impacts of plastics in the oceans. This study aimed to quantify and characterize plastic debris in oceanic surface waters of the Antarctic Peninsula. Sampling was done through surface trawls, and mean debris concentration was estimated at 1,794 items.km−2 with an average weight of 27.8 g.km−2. No statistical difference was found between the amount of mesoplastics (46%) and microplastics (54%). We found hard and flexible fragments, spheres and lines, in nine colors, composed mostly of polyurethane, polyamide, and polyethylene. An oceanographic dispersal model showed that, for at least seven years, sampled plastics likely did not originate from latitudes lower than 58°S. Analysis of epiplastic community diversity revealed bacteria, microalgae, and invertebrate groups adhered to debris. Paint fragments were present at all sampling stations and were approximately 30 times more abundant than plastics. Although paint particles were not included in plastic concentration estimates, we highlight that they could have similar impacts as marine plastics. We call for urgent action to avoid and mitigate plastic and paint fragment inputs to the Southern Ocean