Abundance and characterization of microplastics in the coastal waters of Tuscany (Italy): The application of the MSFD monitoring protocol in the Mediterranean Sea

Impacts of dietary exposure to different sized polystyrene microplastics alone and with sorbed benzo[a]pyrene on biomarkers and whole organism responses in mussels Mytilus galloprovincialis

Due to their hydrophobicity and relatively large surface area, microplastics (MPs) can act as carriers of hydrophobic pollutants in the ocean and may facilitate their transfer to organisms. This study examined effects of dietary exposure to polystyrene MPs of 0.5 and 4.5 μm alone and with sorbed benzo[a]pyrene (BaP) on mussels Mytilus galloprovincialis in order to elucidate the effects of MP size and the presence of sorbed BaP on the organism. MPs were provided daily, mixed with algae, during 26 days at equivalent mass (0.058 mg/L), corresponding to 1000 particles/mL for 4.5 μm MPs and to 7.44 × 10⁵ particles/mL for 0.5 μm MPs. Effects were determined on early cellular biomarkers in hemocytes, structure and cell type composition of digestive tubules (DTs), histopathology and whole organism responses (condition index (CI), clearance rate (CR), food absorption efficiency (AE), respiration rate (RR) and scope for growth (SFG)). BaP concentrations in mussels increased with time, in particular when sorbed to smaller MPs. Large MPs were abundant in the lumen of stomach and DTs, but were also occasionally found within epithelial cells. Effects in all treatments increased with exposure time. MPs with sorbed BaP were more toxic than MPs alone according to hemocyte viability and catalase activity and to the quantitative structure of DT epithelium. Higher toxicity of small MPs compared to larger ones was recorded for DNA damage and cell composition of DTs. At tissue level a slight increase in prevalence of inflammatory responses occurred in all exposed groups. At whole organism level a compensatory effect was observed on absorption efficiency across MP treatments at day 26, resulting in increased SFG in mussels exposed to small MPs with sorbed BaP. This could be related to an increased energy need to deal with stress observed in biomarkers. Further work is required to understand the Trojan horse effect of a variety of plastic type, size, shape combinations together with a wide variety of pollutants.

Identification of marine microplastics in Eastern Harbor, Mediterranean Coast of Egypt, using differential scanning calorimetry

Microplastic pollution has gained significant attention, and there are growing concerns about its potential effects on aquatic environments. The lack of proper solid waste management in Egypt has resulted in the accumulation of plastic litter and its deposition in waterways. However, no attempts have been made to identify or assess marine plastic litter in Egypt. We provide, for the first time, a precise, simple, and cost-effective method to identify microplastics in Eastern Harbor by using differential scanning calorimetry (DSC). This screening revealed the presence of ten polymers in seawater and shoreline sediments. Most of the extracted microplastics are secondary microplastics, as they appear to be remnants of larger plastic fragments.

The chemical behaviors of microplastics in marine environment: A review

Microplastics are widely existed in marine and coastal environments, which aroused global concern in recent years. This review mainly summarized the interactions of organic pollutants and metals with microplastics based on environmental monitoring results and laboratory results reported by literatures. Firstly, the type, properties, and distribution of microplastics in the environment were briefly reviewed. Secondly, the property changes of microplastics after degradation were discussed. Thirdly, the concentrations of pollutants on microplastics in global environments were summarized. Then the effect of the factors (e.g. types and properties of microplastics, types of pollutants, and environmental conditions) on the sorption behaviors of microplastics were discussed in detail. Finally, the influences of microplastics on marine organisms were briefly evaluated.

Microplastics FTIR characterisation and distribution in the water column and digestive tracts of small pelagic fish in the Gulf of Lions

This study aims at quantifying and characterising microplastics (MP) distribution in the water column of the NW Mediterranean Sea as well as MP ingestion by the 2 main planktivorous fish of the area, sardine and anchovy. Debris of similar sizes were found in all water column samples and in all but 2 fish guts (out of 169). MP were found in 93% of water column samples with an average concentration of 0.23 ± 0.20 MP·m^-3, but in only 12% of sardines (0.20 ± 0.69 MP·ind^-1) and 11% of anchovies (0.11 ± 0.31 MP·ind^-1). Fibres were the only shape of MP encountered and polyethylene terephthalate was the main polymer identified in water columns (61%), sardines (71%) and anchovies (89%). This study confirms the ubiquity of MP in the Mediterranean Sea and imparts low occurrence in fish digestive tracts.

Spatio-temporal monitoring of coastal floating marine debris in the Balearic Islands from sea-cleaning boats

Mismanaged waste is accumulating at an alarming rate in the marine environment. Its presence has caused local authorities in the Balearic Islands to develop a coastal sea-cleaning boat service covering the region, identifying the floating marine debris, and removing it from the coastal areas. This study considered daily monitoring from May to October spanning from 2005 to 2015. Plastic marine debris composed over 54% of all floating marine debris removed daily across the Balearic Islands. The spatio-temporal patterns indicate a heterogeneous distribution of plastic in the coastal areas, with higher concentrations in the north-western and south-eastern regions of the islands and debris peaking during the month of August. Furthermore, floating marine debris was more easily collected during calm seas as well as using an integrated monitoring approach to facilitate its removal. Overall, sea-cleaning boats are highly effective in removing coastal floating marine debris.

Microplastics occurrence in edible fish species (Mullus barbatus and Merluccius merluccius) collected in three different geographical sub-areas of the Mediterranean Sea

The gastrointestinal tracts of 229 demersal fish belonging to two species (Mullus barbatus, Merluccius merluccius) were examined for microplastic ingestion. Samples were collected in 3 different FAO Geographical Sub-Areas (GSA-9, GSA-17, GSA-19) of the Mediterranean Sea. Ingested microplastics were characterized using a stereo-microscope: observed, photographed, measured and categorized according to size class, shape and colour. Plastic fragments (ranging from 0.10 to 6.6 mm) were detected in 23.3% of the total investigated fish; a total of 65 plastic particles (66% constituted by fibers) were recorded. The percentage of plastic ingestion shows high variability between the two species and among the different sampling area. The highest frequency (48%) was found in European hake from GSA-19. These preliminary results represent a baseline for the implementation of the Marine Strategy Framework Directive descriptor 10 in Italy as well as an important step for detecting microplastics in bioindicator species from different GSAs.

Microplastic contamination in surface waters in Guanabara Bay, Rio de Janeiro, Brazil

Microplastics (MPs) are contaminants of environmental concern that represent a threat to marine systems. Here we report data on the abundance and characteristics of MPs collected from surface waters of the urban Guanabara Bay. Samples were collected, by horizontal trawling of a plankton net on two occasions (summer of 2016). The MPs were obtained from samples by sieving and particles were manually sorted with microscope. Characterization of MPs was accomplished by gravimetry and digital image processing (for quantification and morphology categorization), and chemical composition identified by infrared spectroscopy and elemental analyses. Total MPs ranged from 1.40 to 21.3 particles/m³, which places Guanabara Bay amongst the most contaminated coastal systems worldwide by microplastics. Polyethylene and polypropylene polymers ≤1 mm were the most abundant particles. Therefore, the occurrence of MPs in Guanabara Bay is relevant to understand ecological hazards of exposition to marine biota and merits further investigation.

Interactive effects of polystyrene microplastics and roxithromycin on bioaccumulation and biochemical status in the freshwater fish red tilapia (Oreochromis niloticus)

There are hundreds of thousands metric tons of microplastics (MPs) present in aquatic environments. The MPs coexist with other pollutants in water bodies, such as pharmaceuticals, and may carry and transfer them into aquatic organisms, consequently causing unpredictable ecological risks. The purpose of the present study was to evaluate the effect of the presence of polystyrene microplastics (PS-MPs) on the distribution and bioaccumulation of roxithromycin (ROX) in freshwater fish red tilapia (Oreochromis niloticus) as well as their interactive biochemical effects in red tilapia. PS-MPs were found to enhance the bioaccumulation of ROX in fish tissues compared to ROX-alone exposure. In the treatment of PS-MPs (100 μg L^-1) combined with ROX (50 μg L^-1), the highest concentrations of ROX reached 39,672.9 ± 6311.4, 1767.9 ± 277.8, 2907.5 ± 225.0, and 4307.1 ± 186.5 μg kg^-1 in gut, gills, brain, and liver, respectively. Furthermore, compared to the ROX alone, the neurotoxicity caused by ROX was alleviated due to the presence of MPs after 14 d of exposure. The activities of cytochrome P450 (CYP) enzymes [7-ethoxyresorufin O-deethylase (EROD) and 7-benzyloxy-4-trifluoromethyl-coumarin O-dibenzyloxylase (BFCOD)] in fish livers exposed to all co-exposure treatments exhibited great variability compared to ROX alone after 14 d of exposure, suggesting that the presence of MPs may affect the metabolism of ROX in tilapia. Compared with ROX alone, the superoxide dismutase (SOD) activity increased significantly, and malondialdehyde (MDA) contents decreased in the co-exposure treatments, showing that oxidative damage in situations of co-exposure to MPs and ROX was mitigated in fish livers after 14 d of exposure. Collectively, the presence of MPs could affect the fate and toxicity of other organic pollutants in fish. The results emphasize the importance to study the interactions between MPs and other organic pollutants in aquatic environments.

Floating plastics in Adriatic waters (Mediterranean Sea): From the macro- to the micro-scale

Macro- and microplastics abundances were determined in the Adriatic Sea following the MSFD TG10 protocol. The studied areas included populated gulfs, river outlets and offshore waters in five Adriatic countries. The use of small ships enabled us to detect small sized plastics (2.5-5 cm) and record average macroplastics densities of 251 ± 601 items km^-2, one order of magnitude higher than previously considered. Results from manta net tows for microplastics revealed an average abundance of 315,009 ± 568,578 items km^-2 (217 ± 575 g km^-2). We found significantly higher microplastics abundances in nearshore (≤4 km) than in offshore waters (>4 km) and this trend seems to affect also the small sized macro plastic fragments (2.5-5 cm). The dominant polymers were polyethylene and polypropylene while the presence of some rare polymers and waxes used in food and dentistry indicated waste water treatment plants as potential sources of microplastics.