The role of polyethylene microplastics 4–6 μm size (MPs) in the toxicity of environmental compounds to fish early life stages (ELS) was investigated. Marine medaka Oryzias melastigma embryos and larvae were exposed to suspended MPs spiked with three model contaminants: benzo(a)pyrene (MP-BaP), perfluorooctanesulfonic acid (MP-PFOS) and benzophenone-3 (MP-BP3) for 12 days. There was no evidence of MPs ingestion but MPs agglomerated on the surface of the chorion. Fish ELS exposed to virgin MPs did not show toxic effects. Exposure to MP-PFOS decreased embryonic survival and prevented hatching. Larvae exposed to MP-BaP or MP-BP3 exhibited reduced growth, increased developmental anomalies and abnormal behavior. Compared to equivalent waterborne concentrations, BaP and PFOS appeared to be more embryotoxic when spiked on MPs than when alone in seawater. These results suggest a relevant pollutant transfer by direct contact of MPs to fish ELS that should be included in the ecotoxicological risk assessment of MPs.

Due to regulations on phthalates, non-phthalate plasticizers (NPPs) are now used as an alternative. Limited studies have been conducted on the occurrence and distribution of NPPs. In this study, sediment samples were collected from 50 locations along the Korean coast to assess the occurrence, distribution, sources, and ecological risks of phthalates and NPPs. Phthalates and NPPs were detected in all sediments, indicating ubiquitous contamination of the coastal environment. Di(2-ethylhexyl)phthalate (DEHP) and di(2-ethylhexyl)terephthalate (DEHT) were dominant, suggesting that DEHT could be an emerging contaminant of concern. The highest concentrations of phthalates and NPPs were found in sediment samples from harbors, implying they are contaminated hotspots. Sedimentary organic carbon was a major factor governing the distribution of phthalates and NPPs. Significant correlations were observed among phthalates and NPPs, suggesting similar sources and geochemical behavior. DEHP concentration exceeded threshold values, indicating potential health risks to benthic organisms in sediments.

Microplastics (plastics <5 mm) contamination is of worldwide concern and represents a threat to the environment, biota, and humans. Also, they are potential carriers of other contaminants, increasing their adverse effects. In this study, it was analyzed for the first time the chemical composition and abundance of microplastics (MPs) in the commercial shrimp Pleoticus muelleri. Fibers were the predominant plastics (mean: 1.31 fibers g⁻¹ wet weight) in the abdominal muscle of the shrimps being black, the dominant colour. μ-Raman showed that fibers were composed of polyethylene (PE), polypropylene (PP), and cellulose. Also, weathering and topography of the fibers were analyzed through wide-field confocal microscopy. C, O, Si, Al, K, as well as Fe, Zn, S, Ba, Br, and Ti on the plastic surface were detected with SEM/EDS, indicating potential carriers of contaminants.The shrimp Pleoticusmuelleri ingests fibers with different chemical elements adsorbed on the plastic surface.

Within Southern California, east Pacific green sea turtles (Chelonia mydas) forage year-round, taking advantage of diverse food resources, including seagrass, marine algae, and invertebrates. Assessing persistent organic pollutants (POP) in green turtle aggregations in the Seal Beach National Wildlife Refuge (SBNWR, n = 17) and San Diego Bay (SDB, n = 25) can help quantify contamination risks for these populations. Blood plasma was analyzed for polychlorinated biphenyls (PCBs), organochlorinated pesticides (OCPs), and polybrominated diphenyl ethers (PBDEs). PCBs and body size explained much of the separation of turtles by foraging aggregation in a principal component analysis. Turtles from SDB had significantly (p < 0.001) higher total PCBs than SBNWR turtles. Most PCBs detected in turtles were non-dioxin-like PCB congeners (153, 138, 99) that are associated with neurotoxicity. Recaptured turtles' POP levels changed significantly over time indicating significant variation in POP levels through time and space, even among adjacent foraging locations.

Un-restored (R₀) and restored (in 2006 (R₂₀₀₆) and in 2002, (R₂₀₀₂)) coastal wetlands were selected to study phosphorus (P) storage capacity and the risk of P loss in the Yellow River Delta (YRD). The results showed that the maximum P sorption capacity (Qₘₐₓ) in the wetland sediments varied between 201.8–1168.6 mg kg⁻¹; the average value was 576.2 mg kg⁻¹. Qₘₐₓ increased with increasing time since restoration (R₂₀₀₂ > R₂₀₀₆ > R₀). The eutrophication risk index (ERI) ranged between 0.27–2.07% and decreased with increasing time since restoration, but the relationship was not statistically significant (P > 0.05). A correlation analysis demonstrated that Feₒₓ, Mg, and Alₒₓ are the main P sorption agents in wetland sediments, whereas TOC, pH, and clay particles have an important effect on P sorption and release. The analysis suggests that we should restore degraded coastal wetlands to help reduce the P load to offshore waters.

The Arabian or Persian Gulf is recognized as one of the warmest estuaries globally. The sea surface temperature (SST) has been utilized in several studies to gauge the global warming associated with climate change. In the current investigation we present detailed in situ SST measurements for five consecutive years (2016, 2017, 2018, 2019, 2020) in the northwest of the Gulf, specifically in Kuwait Bay. Results of data analyses were compared with the historical records for the region, revealing that the SST reached an extreme level never previously recorded either in the Gulf. The extreme SST in Kuwait Bay reached 37.6 °C, recorded by the offshore station KISR01 located in the middle of the Bay. The event was associated with heatwave, neap tides, and an extended period of Kous winds which are characterized by high humidity levels and accompanied by large-scale intermittent fish kill incidents that extended the full length of the Kuwait coastline. Several fish kill incidents were reported also at the northern edge of the Gulf along Shatt Al Arab stretch in Iraq. The species found dead during the incident varied considerably, unlike those found in the frequent summer incidents. The records presented in this study may provide evidence to the effects of global warming, aid further research, and encourage the concerned international government bodies to deliver urgent environmental policies.

Marine organisms are exposed to great changes induced by human beings due, among others, to discharges into the oceans, increasing marine pollution. For this study, 294 specimens of Trachurus picturatus from the Canary Islands were analyzed during a period of 2 years. The concentration of 11 anthropic metals and trace elements was determined in each individual using the Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) technique. Statistical analyses were carried out considering the following factors: oceanographic season, maturity of the gonads, size of the specimens, season. Immature specimens had higher concentration in more metals than the mature specimens. This fact may be due to the fact that these specimens require a much higher metabolic rate due to their growth and do not detoxify like mature specimens.

Nitrate is the major chemical form of N-nutrient to sustain primary production in Changjiang Estuary and adjacent seawaters. We employed δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻ to constrain the source, cycling, and sink of nitrate in early spring. Both δ¹⁵N-NO₃⁻ and δ¹⁸O-NO₃⁻ differentiate significantly among Changjiang Diluted Water (CDW), Yellow Sea Coastal Current (YSCC), and Taiwan Warm Current (TWC). In coastal areas, nitrate distribution and its isotopes are mainly affected by Changjiang inputs. Chemical fertilizers and sewage & manure originated nitrate jointly contribute the most nitrate in CDW. In offshore areas, nitrification contributes 44 ± 21% of the nitrate in YSCC and 17 ± 16% in TWC; assimilation is the dominant process to remove nitrate in TWC (35 ± 16%). Overall, nitrification and assimilation are the key nitrate cycling processes in early spring and co-shape the offshore distribution pattern of nitrate and its dual isotopes.

In this study, we characterized plastic debris (PD) found on beaches from Concepción Bay in central Chile during spring 2017 and summer 2018. The identification of polymers was carried out using FT-IR. Persistent organic pollutants (POPs) were extracted with hexane using an ultrasonic bath and further quantified through GC–MS. The highest abundance of PD was obtained during the summer (4.1 ± 3.7 items/m²), with the most common size range between 2.5 and 10 cm (42%) and the most frequent shape were plastic fragments (44%). FT-IR analysis showed that polypropylene was the most recurrent plastic polymer found. The ∑10PBDEs ranged from 2.1 to 1300 ng/g in spring 2017 and 392 to 3177 ng/g in summer 2018. ∑7PCBs ranged from 0.9 to 93 ng/g during the spring 2017 and 0.3 to 4.5 ng/g for summer 2018. This study is the first with information on POPs occurrence in the plastic debris of central Chile.

Hypoxia is often thought of as the key factor responsible for fish kill events in coastal areas but fish kill events are too complex to be governed by a single factor. The events are influenced by a combination of chemical, biological and physical processes. Hydrodynamics play a key role in understanding the formation of hypoxia in shallow waters. This study aims to identify the settings of the physical forces that lead to a large-scale depletion of dissolved oxygen in Kuwait Bay at the northwest of the Arabian Gulf. The assessment, made with a validated three-dimensional numerical model (Alosairi and Alsulaiman, 2019), revealed that the pollution from the outfalls leads to nearfield depletion of dissolved oxygen but has only a minor effect on the bay-scale dissolved oxygen. This is a result of the strong dynamics of Kuwait Bay, which mixes the pollutant rapidly before it is transported seawards. Offshore, a low dynamic region has been identified near Jahra Bay which is susceptible to occasional dissolved oxygen depletion. Assessment of the physical forces revealed that the density-driven current and, to a greater extent the wind regime, controlled the formation of a hypoxic parcel near Jahra Bay. The combination of neap tides and low mixed winds reduced mixing and enabled the longer residence times of Kuwait Bay. These are the most critical circumstances, as the average dissolved oxygen can be reduced by 50% during summer. The circumstance resulting in low dynamics near Jahra Bay were also found to be effective in explaining algal blooms.