Salt marshes in urban watersheds are prone to microplastics (MP) pollution due to their hydrological characteristics and exposure to urban runoff, but little is known about MP distributions in species from these habitats. In the current study, MP occurrence was determined in six benthic invertebrate species from salt marshes along the North Adriatic lagoons (Italy) and the Schelde estuary (Netherlands). The species represented different feeding modes and sediment localisation. 96% of the analysed specimens (330) did not contain any MP, which was consistent across different regions and sites.Suspension and facultative deposit-feeding bivalves exhibited a lower MP occurrence (0.5–3%) relative to omnivores (95%) but contained a much more variable distribution of MP sizes, shapes and polymers. The study provides indications that MP physicochemical properties and species' ecological traits could all influence MP exposure, uptake and retention in benthic organisms inhabiting European salt marsh ecosystems.

The uptake and discharge of bivalve larvae through ballast water operations is a highly viable mechanism for transfer of shellfish. In this paper, we investigate the effects of common water treatment processes on the planktotrophic larvae of the two invasive species of shellfish, Mytilopsis sallei and Mytella strigata. The study found that common water treatment processes used in many ballast water treatment systems were effective for the removal of bivalve larvae, although later stages of larval forms required more effort to remove.

Recently, atrazine has been increasingly used to control weeds in the corn and sugarcane farms, which affects the water resources and aquatic organisms. In this study, atrazine residual concentrations in water and fish samples of the Shadegan wetland (Iran) were investigated. Furthermore, the health and ecological risk assessment were calculated. A total of fifty water samples were collected from the wetland during three periods with a four-month time interval. Also, ten samples of ten different fish species were analyzed at the same time. The estimation of acceptable daily intake and comparison with international standards indicates danger to adjacent residential areas of wetland. Non-carcinogenic risk analysis showed that total hazard quotient (HQing + HQderm) were below the acceptable limit and there is no danger to the residents of the area. Atrazine concentration in the water and fish samples ranged between 0 and 2175.8 μg/L, and 0 to 35.58 μg/L, respectively. Results showed that 88% of the water samples were higher than EPA and WHO guidelines for drinking water in summer. The concentrations of atrazine in fish samples in summer were more than other seasons. Analysis of ecological risk assessment also showed that considering the average atrazine concentration in three seasons, the risk exposure was very high. This study will be beneficial to the both residents and government officials in management of Shadegan wetland pollution in term of toxic compounds.

We examined the concentrations of 12 trace metals in road-deposited sediments (RDS) and their contributions to the pollution of harbor/marine sediments in the port city of Busan, South Korea. The concentrations of Cr, Cu, Zn, Cd, Sn, Sb, and Pb in RDS affected by industrial and traffic activities were 6.7–25.7 times higher than those in marine sediments. The enrichment factors indicate that RDS are extremely polluted with Sb and moderately to strongly polluted with Cr, Cu, As, Sn, Pb, Zn, and Cd. The mean modified pollution index distinguished between unpolluted marine sediments, moderately to heavily polluted harbor sediments, and severely polluted RDS. Furthermore, harbor/marine sediments close to shipyards and the mouths of streams and rivers were found to be moderately polluted with Cu, Zn, Cd, Sb, and Pb. RDS containing trace metals accumulate on impervious surfaces and flow into the marine environment via untreated stormwater runoff.

Tarballs are semi-solid remnants of crude oil and they are formed in marine environment after oil-spill incidents. They are composed of diverse hydrocarbons; some of which are recalcitrant in nature. Recent studies based on amplicon sequencing of 16S rRNA gene suggested that tarballs support hundreds of bacterial genera and provided insights into their role as hydrocarbon degraders and potential human pathogens. In this study, bacterial composition of tarball-contaminated seawater from Vagator beach, Goa, India was characterized by amplicon sequencing of V₃–V₄ regions of 16S rRNA gene. The DNA data revealed an unusual surge of Vibrio in sea-water contaminated with tarballs in May 2018 (16.16% OTUs), compared to tarball-free seawater samples collected in March 2018 (no detectable OTUs) and September 2018 (0.17% OTUs). Further studies are required to investigate if Vibrio species form biofilms on tarballs which may act as good reservoirs for their survival and transmission success.

Sequential extraction was used to determine the geochemical distribution of trace metals in coastal sediments from Trinidad and Tobago. The results showed that there was considerable variation in the bioavailability, mobility and ecological risk of the metals determined. Cadmium had very high ecological risk: 57–88% of cadmium was associated with the exchangeable and carbonate bound metal fraction (F1). Ecological risk decreased in the order manganese> nickel> lead> zinc. Copper had the lowest ecological risk: lowest percentages of copper were associated with F1 (1–15%) and F2 (3–15%), while considerable percentages (48–55%) were associated with the residual fraction. Management of the risks posed by these metals in the marine environment requires a holistic approach including reduction in trace metal inputs from point and non-point sources of pollution, particularly off the west coast of Trinidad, and public education on the impacts of trace metals in the environment and on human health.

The spatiotemporal variation, seasonal variation, and potential ecological risk of eight heavy metals (HMs) in the Meishan Bay (MSB) a new artificial lagoon –from 2014 to 2019 were investigated. The levels of As, Cu, Pb, Cr, Ni, and Zn in winter were higher than in other seasons, Hg in winter and summer were higher than in other seasons, while Cd in summer and spring (wet season) were the highest. The seasonal distribution of HMs was mainly affected by particle size, anthropogenic sources, rainfall, and water characteristics. The concentrations of these HMs showed a general downward trend, while Hg showed an upward trend from2014 to 2019. Higher levels of HMs were found outside the North dyke and some sluice gates. The sources of Cd, Zn, and Pb could be attributed to ship discharges and traffic exhaust, while pesticides and fertilizers were the main sources of Hg. Among all these HMs, Cd and Hg caused moderate pollution in the MSB.

The goal of this study was to evaluate biomarkers (glutathione S-transferase and catalase) and microorganisms in soft tissues of Crassostrea rhizophorae to assess possible contamination of seafood in Brazil. The oysters were sampled from a reference area (Ports 1 and 2) and an impacted area (Ports 3 and 4) in Brazil (São Luís Island, Maranhão). Six attributes were examined in sampled oysters: glutathione S-transferase activity, catalase activity, concentrations of total coliforms and thermotolerant coliforms, and levels of Escherichia coli and Aeromonas hydrophila. Water samples were analysed for aluminium, cadmium, iron, manganese, lead, mercury, phenolics, and polychlorinated biphenyls. We found that Ports 3 and 4 are impacted by several contaminants (mercury, phenolics, and polychlorinated biphenyls), while Ports 1 and 2 are still relatively free of these contaminants. Changes in enzymes activity as well as the highest tissue bacterial concentrations were recorded in oysters from Ports 3 and 4 during the rainy season.

Industrial activities and urbanization are the main sources of pollutants in estuarine environments. Diesel, which is widely used in urban and port activities, is an important source of hydrocarbons in the aquatic environment, and its water-accommodated fraction (WAF) is toxic to the local biota. This study was performed to analyze the effects of diesel oil WAF on fish. Specifically, we characterized the gill morphology of the seahorse Hippocampus reidi and analyzed the histopathological changes in the gills after exposure to 50% diesel oil WAF. Acute (12, 24, 48, and 96 h) and subchronic (168 and 336 h) toxicity tests were performed. Furthermore, a recovery protocol was conducted: after exposure to 50% WAF for 168 h, the fish were transferred and kept in seawater without contaminants for 336 h, for a total experimental period of 504 h. The seahorse branchial apparatus was found to be tufted with short filaments; the apical surfaces of the pavement cells in the filament and lamellar epithelia formed “crests” and had microridges. Mitochondria-rich cells were distributed exclusively in the lamellar epithelium, while mucous cells were distributed in the filament epithelium. All pathologies observed after acute and subchronic exposure featured progressive time-dependent alterations of lamellar structure that might disrupt gill physiological and metabolic functions. During the recovery period, the gill alterations were gradually repaired.

Heavy metals in the sediments of urban roads (RDS), storm drains (SDS), and marine areas (MS) were investigated to assess road pollution in a beach town adjacent to the coast in Busan and identify their relationships with the marine environment. RDS were considerably polluted with Zn, Cu, Cr, and Pb, with mean concentrations of 1090, 178, 171, and 199 mg/kg, respectively. MS were severely contaminated with Zn and Cu, exceeding the effects range median (ERM; Cu = 270, Zn = 410 mg/kg). PCA and HCA identified tire and brake wear in RDS as the major sources of Zn, Pb, Cu, and Cd, and that high levels of Zn, Cu, and Pb in RDS originating from traffic activities contaminated MS through the urban storm drain system. The results suggested that traffic-originated metals in RDS are potential pollutants in coastal environments, and further studies on their fate and management should be conducted.