Microplastics in commercially important seafood species is an emerging area of food safety concern. While there have been reports of plastic particles in the gastrointestinal tract of several species, presence of microplastics in edible fish tissues has not yet been reported from India. This study examined the presence of microplastics in the edible (muscle and skin) and inedible (gill and viscera) tissues of nine commercially important pelagic fish species from Kerala, India. A total of 163 particles consisting mainly of fragments (58%) were isolated. Out of 270 fishes analysed (n = 30 per species), 41.1% of the fishes had microplastics in their inedible tissues while only 7% of fishes had microplastics in their edible tissues. The quantity of microplastics in inedible tissue was significantly larger in filter feeders than, that in visual predators (p < 0.05). The average abundance of microplastics in edible tissues was 0.07 ± 0.26 items/fish (i.e., 0.005 ± 0.02 items/g) and was 0.53 ± 0.77 items/fish (i.e., 0.054 ± 0.098 items/g) in inedible tissues. The results suggest the possibility of human intake of microplastics by the consumption of pelagic fishes from this region, albeit in small quantities.

Plastic marine debris hyper-concentrates hydrophobic contaminants such as polycyclic aromatic hydrocarbons (PAHs) and can transfer these sorbed contaminants to biota following ingestion. PAHs are known to induce cardiotoxicity and visual toxicity at sublethal doses. Juvenile White seabass (Atractoscion nobilis) fish were fed environmentally relevant concentrations of either virgin polystyrene or benzo(a)pyrene (BaP)-sorbed polystyrene for 5 days and were monitored for changes in phototactic response, swimming behavior, and hepatic cytochrome p450 1A (CYP1A) enzyme activity. No significant differences in the monitored endpoints were recorded in fish that ingested either polystyrene or BaP-sorbed polystyrene relative to control fish following the short-term exposure. However, fish exposed to 252 μg/L BaP alone as a positive control had significantly elevated CYP1A enzyme activity (p = 0.046) and impaired phototactic response (p = 0.020), though no altered swimming behavior was observed (p = 0.843) relative to control fish. These results demonstrate that pelagic fish ingesting environmentally relevant concentrations of BaP-sorbed polystyrene for a short, 5-day duration do not demonstrate measurable changes in vision, swimming activity, nor CYP1A activity. High variability within enzyme activity and behavioral responses suggest that lack of significant effects may be due to low sample size.

Pollution of coastal and marine environments by mismanaged anthropogenic debris is a global threat requiring complex, multilateral solutions and mitigation strategies. International efforts to catalogue and quantify the density, extent and nature of mismanaged waste have not yet assessed the heterogeneity of debris between nearby areas. Better understanding of how debris types and density can be used as a proxy between regions and between land and seafloor habitats at a global scale can aid in developing cost effective and representative debris monitoring systems. Using volunteer collected clean-up and survey data, we compared the proportion and density of both total debris and specific items across 19,428 coastal land and seafloor sites from International Coastal Cleanups and Dive Against Debris surveys, from 86 countries between 2011 and 2018. We show that although some items common on land are also common on the seafloor, there is an overall global mismatch between debris types and densities on land and the seafloor from nearby areas. Correlations in land/seafloor debris type/density occurred primarily for items which entangle and/or sink, including fishing line, plastic bags, glass and polyethylene terephthalate (PET) bottles. Minimal similarity between land and seafloor surveys occurs for items which float or degrade. We suggest that to accurately evaluate local debris density, land and seafloor surveys are required to gain a holistic understanding. When detailed information on debris type, relative concentration, and likely source and transport are assessed, more cost effective and efficient policy interventions can be designed and implemented from local through to global scales.

China is the largest plastic consumer in the world. Despite its plastic waste import ban in 2017, this populous economy inevitably generates a large amount of waste, including plastic waste, a considerable part of which has become marine litter. Data from the 2018 National Coastal Cleanup and Monitoring Project, the largest beach litter monitoring activities using the citizen science approach in China, have been retrieved and analyzed to understand spatial patterns, composition, and original usage of marine litter. Within this project, 24 beaches were surveyed every two months. As a result, the mean density was 3.85 ± 5.39 items m⁻², much higher than that reported by previous studies in China. There were great differences in the spatial distribution of litter. The highest densities appeared in the runoff-affected area of the Yangtze River, which was another difference from previous studies. Low-density, easy-to-transport foamed plastics were the major contributor to marine litter in these areas. Along China’s coast, approximately 90% of litter was from land-based sources, and over half of that originated from domestic sources. Including foamed plastic products, plastic litter with low recycling value dominated. Both natural and human factors influencing the spatiotemporal distribution and composition of litter are discussed. Socioeconomic factors, such as the lifestyle and consumption levels of citizens and local waste management systems, are possible explanations for the low-value characteristic of marine litter. The deviation between previous data and citizen science data in this study may be caused by many factors. Based on the discussion on these factors, some suggestions for citizen science research in China are also put forward.

Polystyrene nanoplastics (PS NPs), which are newly emerging as particulate pollutants, are one of the most abundant plastic types in marine debris. Although there has been extensive research on microplastics, the sorption behavior of PS NPs in surface waters remains unknown. In addition, in the previous joint toxicity studies, the concentration of organic pollutant in the joint system was based on the EC₅₀ of this pollutant, rather than the actually amount of this pollutant adsorbed on nanoplastics (NPs). In this study, the sorption behavior of PS NPs with different surface charges in the surface water of estuaries and joint toxicity of that absorbed tetracycline antibiotic in equilibrium were investigated for the first time. Because of the electrostatic repulsion, salting-out effect, and partition function, the sorption capacity of tetracycline antibiotic by differently charged PS NPs was enhanced with increasing salinity. The biological effects of exposure to tetracycline-saturated PS NPs were complicated, which can be attributed to the surface characteristics of mixtures such as hydrophobicity and charges. Thus, the role of NPs in the natural environment as a carrier of antibiotics may provide an alternative for antibiotic inputs from inland water to coastal marine water, which would not only change the environmental fate and ecotoxicology of antibiotics and NPs, but also pose challenges to the safety of coastal aquaculture and marine ecosystem.

Marine litter is currently one of the most widespread pollutants. However, monitoring the spatial-temporal changes of floating marine litter remains challenging. In this study, with data collected by citizen scientists, we investigated the distribution and density of floating marine litter in the waters around Taiwan. With 40 volunteers surveying 978 transects in 410 cruises from December 2017 to December 2018, the overall survey area was approximately 121.26 km² (5455 km in length). We found that the mean density of floating marine litter was 90.10 ± 8.60 items/km² and that the majority was plastic (63.2%). Nearly 70% of the litter was found in 30% of the surveyed area. We also identified hotspots of floating marine litter, which are at the Northwestern and Southeastern regions of Taiwan. Our study highlights the contribution of citizen science to monitor floating marine litter and provides insight into the management of marine litter.

The daily accumulation rates, composition, sizes and potential sources of marine litter collected on a remote island within the Western Indian Ocean were investigated. In total, 9119 items of marine litter were collected during 40 surveys, which equated to 0.0082 items·m⁻¹·d⁻¹. Between 2003 and 2019 there was a significant increase in the amount of litter deposited, with the highest daily accumulation rate recorded in 2019 (0.0255 items·m⁻¹·year⁻¹). All specific litter types increased over time and also differed significantly in their accumulation rates, with polystyrene fragments/pieces (0.00249 items·m⁻¹·d⁻¹), plastic items (0.00135 items·m⁻¹·d⁻¹) and plastic bottles (0.0011 items·m⁻¹·d⁻¹) being the most commonly encountered during this study. The majority of the litter found was ≤5 cm in size. Nearly all (>80%) litter collected was made of or contained some form of plastic. Recommendations for improved management of litter and the importance of establishing regular beach clean-ups within the Seychelles are briefly discussed.