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.

Presence of microplastics (MPs) in a broad range of wild and cultured marine organisms is well-documented, but transfer mechanisms by which cultured organisms are contaminated with MPs is poorly understood. MP loads in three Malaysian commercial brands of fish meal were investigated. Chemical composition of extracted MP-like particles was confirmed using micro-Raman spectroscopy. Inorganic composition of MPs and pigment particles were assessed through energy-dispersive X-ray spectroscopy (EDX). Out of 336 extracted particles, 64.3% were plastic polymers, 25% pigment particles, 4.2% non-plastic items, and 6.5% were unidentified. Fragments were the dominant form of MPs (78.2%) followed by filaments (13.4%) and films (8.4%). This study demonstrates that cultured organisms could be exposed to high levels of MPs via MP contaminated fish/shellfish used in fish meal production. Fish meal replacement with other sources of protein including meat meals and plant-based meals may mitigate MP exposure to cultured or farmed organisms.

The present study is an attempt to assess the effects of contamination of several sites in the Red Sea coasts of Saudi Arabia using bivalves as a biomonitoring tool. Oxidative stress biomarkers (including reduced glutathione level (GSH), glutathione-S-transferase activity (GST), Malondialdehyde level (MDA) and Catalase activity (CAT)), neurotoxicity acetylcholinesterase activity (ACHE), and genotoxicity micronucleus rate (MN) were measured in three distinct tissues - digestive glands, gills and mantle - of specimens of the giant clam Tridacna maxima, collected from five sites in Saudi Arabian Red Sea coast (Al-Khuraybah, Al-Wajh, Yanbu, Rabigh and Thuwal). Our results demonstrated that T. maxima showed differential biomarker responses according to the nature of pollutants and human activity that affect the coast. This study can be considered as the first one using biomarkers to assess the state of the Red Sea coast in Saudi Arabia which must be followed by periodic studies for surveillance of aquatic pollution.

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.

The marine plastic pollution has drastic effect on marine species. The importance in environmental issues increases the demand to develop a significant technology which does not burden the marine environment or marine life forms. To mitigate the foreseen problems of micro and nanoplastic contamination, different biotechnological solutions has to be considered. Microbial communities exposed to plastic contaminated sites can adapt and form dense biofilms on the plastic surface and produce active catalytic enzymes. These enzymes can be able to degrade the synthetic polymers. In view of their high catalytic activity, microbial enzymes can be applicable for the degradation of synthetic polymers. This review highlights the toxicity of micro and nanoplastics on marine organisms, biodegradation of plastics and futuristic research needs to solve the issues of plastic pollution in marine environment.

In 2014–2019, a total of 31 blubber samples were collected from spotted seals (Phoca largha) in the western Sea of Japan. The samples were analyzed by gas chromatography to determine level of organochlorine pesticides (OCPs). The concentration of hexachlorocyclohexane and its isomers (∑HCH) ranged from 389 to 50,070 ng/g lipid weght; the concentration of dichlorodiphenyltrichloroethane and its metabolites (∑DDT), ranged from 62,720 to 1,110,930 ng/g lipid wt. Transfer of HCH and DDT from mother to pup during pregnancy and lactation was documented. The OCP concentration in blubber of spotted seals from the western Sea of Japan is one to two orders of magnitude higher than in spotted seals inhabiting waters off the Japan coast. Organochlorines detected in the western Sea of Japan likely come from some countries of Southeast Asia still using OCPs in the agriculture sector.

To understand the status of the radionuclides released during the Fukushima Dai-ichi Nuclear Power Plant accident, the ¹³⁴Cs, ¹³⁷Cs and ⁹⁰Sr in the seawater in the public area of the northwest Pacific Ocean were analyzed in November–December 2012. The radioactivity of ¹³⁴Cs, ¹³⁷Cs and ⁹⁰Sr decreased sharply from June 2011 to November–December 2012. The highest average values of ¹³⁴Cs and ¹³⁷Cs were found at a depth of 500 m, suggesting that ¹³⁴Cs and ¹³⁷Cs had been transported to a depth of 500 m or deeper by the end of 2012. Total inventories of 0.80 ± 0.20 pBq for ¹³⁷Cs from the surface to a depth of 500 m and 0.07 ± 0.02 pBq for ⁹⁰Sr from the surface to a depth of 100 m were obtained in the waters southeast of Fukushima. ¹³⁴Cs was detectable in the Chinese exclusive economic zone, and the seawater quality was much lower than the target level for China.

Geochemical fractionation of seven trace elements (Cr, Mn, Fe, Cu, Zn, Cd, and Pb) was investigated in the surficial coral reef sediments of three inhabited islands (Kavaratti, Kadmat, and Agatti) belonging to the Lakshadweep Archipelago. The observations indicated that the metals showed their highest contents in the residual fraction of geological origin. The extent of risk, bioavailability, and contamination of trace elements was assessed by risk assessment codes and contamination factors. Based on the results, medium potential adverse effects were observed in the sediments of Kavaratti and Agatti. The concentration of Cd in the exchangeable and carbonate-bound fractions was above its global average shale value in the sediments of Kavaratti and Agatti, suggesting its high mobility and bioavailability and thus an environmental threat to the coral reef ecosystem.

Establishing nutrient thresholds to protect coral reefs is difficult because water quality is dynamic and shifts with many environmental factors. We examined the contribution of natural and human factors in predicting water quality at the base of 34 streams on a high tropical Pacific island. Mixed regression models revealed that rainfall, sea-surface temperature, and windspeed were fixed factors predicting dissolved inorganic nitrogen (DIN) concentrations at the base of all watersheds. In contrast, human influences were captured as random components of variation associated with site-based differences. The novel modeling approach using temporal and spatial data provided daily-loading simulations that were used to evaluate exceedance criteria, defined as the percent of time each watershed exceeded a suite of DIN thresholds. Exceedance criteria were considered alongside biological data to recommend a 0.1 to 0.15 mg l⁻¹ benchmark to protect coastal water quality and coral reefs surrounding Tutuila, American Samoa.