The estuaries of populated catchments have been documented as hotspots of plastic pollution. In this study, microplastics (0.355–5.0 mm) and large plastic debris (>5.0 mm) of surface water collected from the Inner Lingding Bay of the Pearl River Estuary (PRE) were quantified and categorized according to their size, shape, colour and composition. Both microplastics and large plastic debris were detected at all sampling sites with mean abundances of 2.376 ± 0.700 n/m³ and 0.110 ± 0.039 n/m³, respectively. Microplastics constitute 95.4% of the total abundance by number. The average microplastic concentration in the inner PRE was almost 3.5 times higher than that in the central PRE, indicating a positive correlation between plastic concentration and proximity to the river mouth. This result reveals the important role of rivers in transporting plastic debris from land to the oceans.

An intercalibration exercise on the characterisation of microplastics in marine sediment and water samples was carried out among five laboratories involved in the implementation of the Marine Strategy Framework Directive (MSFD) in their country. The samples were prepared by mixing cleaned natural sediment and sea water with microplastics sets made of particles of various polymers, shapes and colours. Overall, the errors on total counts were under 25% in absolute value. The risk of non-detection and loss of particles is greater than the risk of contamination during sample analysis. Significant differences are observed among particle types. It appears difficult to obtain reliable and comparable data on the colour of microplastics. A comparison of the errors with regards to the protocols used led to recommend NaCl [1.2 g/cm³] density separation for sediment and one filtering step (200 μm). The operators' experience appears as a key factor for the quality of the results.

Using nominal dose metrics to describe exposure conditions in laboratory-based microplastic uptake and effects studies may not adequately represent the true exposure to the organisms in the test system, making data interpretation challenging. In the current study, a novel overhead stirring method using flocculators was assessed for maintaining polystyrene (PS) microbeads (Ø10.4 μm; 1.05 g cm⁻³) in suspension in seawater during 24 h and then compared with static and rotational exposure setups. Under optimized conditions, the system was able to maintain 59% of the initial PS microbeads in suspension after 24 h, compared to 6% using a static system and 100% using a rotating plankton wheel. Our findings document for the first time that overhead stirring as well as other, commonly used exposure systems (static) are unable to maintain constant microplastic exposure conditions in laboratory setups whereas rotation is very effective. This suggests toxicological studies employing either static or overhead stirring systems may be greatly overestimating the true microplastic exposure conditions.

Microplastic fibres are a widespread pollutant in the marine environment. Their presence has been searched for in marine sponge specimens of a museum, collected over 20 years ago. The pollutant was observed in more than half of the samples analysed, allowing a reference point to be fixed in the past. Analysis has demonstrated that fibres were vagrant in the water column and were incorporated actively by sponges. Inclusion into bottom-fixed sponges has been demonstrated for the natural environment. The study of microplastic in organisms collected in the past and stored in natural history collections is the key for fixing reference points and build up temporal trends, especially considering the lack of studies on this topic before 1980. The idea of using animals preserved in natural history museums could be extended to other pollutants in order to search for reference points or past baselines.

Following the Fukushima Daiichi nuclear power plant accident in 2011, some marine radionuclide monitoring studies report a lack of evidence for contamination of Japanese coastal waters by U and Pu, or state that marine contamination by them was negligible. Nevertheless, Fukushima-derived U and Pu were reported as associated with Cs-rich microparticles (CsMPs) found in local soil, vegetation, and river/lake sediments. Over time, CsMPs can be transported to the sea via riverine runoff where actinides, as expected, will leach. We recommend establishing a long-term monitoring of U and Pu in the nearshore area of the Fukushima Prefecture using marine bivalve mollusks; shells, byssal threads and soft tissues should all be analyzed. Here, based on results from Th biosorption experiments, we propose that U and Pu could be present at concentrations several times higher in shells with a completely destroyed external shell layer (periostracum) than in shells with intact periostracum.

Due to strong regulation of phthalates, non-phthalate plasticizers (NPPs) have been introduced to the industrial market. In this study, concentrations of 16 phthalates and five NPPs in sediment were measured to investigate the occurrence, potential source, and ecotoxicological implications of these contaminants. Phthalates and NPPs were detected in all sediment samples, indicating ubiquitous contaminants. Di(2-ethylhexyl)phthalate (DEHP) and trioctyl trimellitate (TOTM) were the dominant for phthalates and NPPs, respectively, implying emerging contamination by TOTM. Spatial distribution of these contaminants showed decreasing gradients from inner to outer bays. Clear declining trends in phthalate and NPP concentrations were found in sediment near a wastewater treatment plant outfall, suggesting a potential source of contamination. Approximately 95% of sediment samples exceeded sediment quality guidelines for DEHP suggested by previous studies, implying that benthic organisms are suffering from adverse biological effects. This is the first report on the occurrence of NPPs in the coastal environment.

Most monitoring studies of marine anthropogenic debris have focused on sandy beaches, so little is known about litter on rocky shorelines. We surveyed litter trapped on a rocky intertidal shore in False Bay, South Africa, between May 2015 and March 2018. An exceptional upwelling of seabed litter occurred in November 2017 (70 items∙m⁻¹). Excluding this event, monthly clean-ups at spring low tide collected 2 (1.3–3.1) items∙m⁻¹∙month⁻¹ and 31 (19.4–49.4) g∙m⁻¹∙month⁻¹ of which 74% was plastic (31% by mass). Litter loads peaked in autumn when seasonal rains washed litter into False Bay, suggesting that most litter comes from local land-based sources. Litter composition differed from that on a nearby sandy beach, with more glass and other dense items on the rocky shore, but 60% of plastic items floated in water. Sand inundation and biotic interactions helped to trap buoyant plastics in the intertidal zone.

Several abiotic factors influence the ecological responses of aquatic invertebrates to metal toxicity. We examined the effect of salinity (10, 20, and 30 psu) and temperature (25 and 32 °C) on acute and chronic arsenic (As) toxicity to the euryhaline rotifers, Proales similis and Brachionus ibericus. In general, higher salinities and low temperature resulted in lower arsenic toxicity. The population growth studies indicated that P. similis was more sensitive than B. ibericus to As. Arsenic toxicity intensified the vulnerability of P. similis to B. ibericus competition. Life table parameters decreased with increasing As levels in the medium. Chronic toxicity bioassays were more sensitive than acute toxicity tests for determining the adverse effect of As to rotifers. Our findings provide useful insights on the effect of arsenic on rotifer populations exposed to different temperature and salinity scenarios. Proales similis could be an important complement to brachionid rotifers for marine toxicity bioassays.

We report on concentrations of polybrominated diphenylethers (PBDEs), polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB) measured in the adipose fins of returning adult Atlantic salmon (Salmo salar) and sea trout (Salmo trutta) to the river Tees in the Northeast of England. Overall, higher concentrations of these contaminants were found in sea trout samples, where detected congeners reflected the more widely used commercial formulations, in particular for the PBDEs. Our results suggest that these fish could be bioaccumulating persistent organic pollutants via diet during their migratory routes (North Sea and the Norwegian Sea) and, in addition, some level of re-mobilisation of these compounds could still be occurring in the UK eastern coastal areas. The use of adipose fin of returning salmonids could be further developed as a non-lethal approach to assess whether persistent contaminants are being accumulated during the juvenile to adult phase of salmonids originating from UK rivers.

Exposure to oil can have long-term impacts on migratory birds. Following the 2010 Deepwater Horizon blowout in the Gulf of Mexico (GOM), we investigated potential impacts of oil exposure on a population of northern gannets (Morus bassanus) that breed on Bonaventure Island (Québec, Canada) and winter in GOM and along the U.S. Atlantic coast (AC). Blood and feather samples were collected from adults previously equipped with geolocators to determine wintering locations. Parent and alkylated polycyclic aromatic hydrocarbons (PAHs); trace metals; stable isotopes of carbon, nitrogen, and hydrogen; and immune, thyroid, steroid, retinoid, and genetic endpoints were measured. PAH and trace metal concentrations did not differ between gannets using different wintering sites. Feather stable isotope values varied significantly between birds from different wintering locations. Gannets wintering in GOM showed higher feather corticosterone and plasma thyroid hormone levels, which may indicate increased energetic demands and/or greater exposure to environmental stressors.