The emergence of the COVID-19 pandemic has caused worldwide health constraints. This study was conducted to establish a baseline monitoring survey to describe the distribution of PPE litters during the COVID-19 pandemic in the province of Palawan, Philippines. A total of 386 COVID-19-related PPE items were present in 83 % of coastal sampling sites with over a cumulative area of 48,200 m², with a density of 8 × 10⁻³ items m⁻². The facemask (98 %; n = 377) was the primary type of PPE, followed by face shield (2 %; n = 9). Meanwhile, the daily density of PPE litters in San Manuel, Puerto Princesa ranged from 0 to 9.9 × 10⁻² items m⁻², with a mean density of 8 × 10⁻³ items m⁻². The accumulation rates of PPE items ranged from 3.27 × 10⁻¹ items to 1.143 items d⁻¹, with an average rate of 7.29 × 10⁻¹ items d⁻¹.

17α-ethinylestradiol (EE2) is an anthropogenic estrogen that is widely used for hormone therapy and oral contraceptives. It was reported that EE2 exposure induced reproductive impairments through processes affecting reproduction behavior and inducing ovotestis. However, the effects of continuous EE2 exposure on the reproductive performance remain largely unknown. In this study, adult marine medaka fish (Oryzias melastigma) were exposed to EE2 (85 ng/L) for one (F₀) and two (F₁) generations. Our results indicate that continuous EE2 exposure reduced fecundity and sperm motility. The testicular transcriptome, followed by bioinformatic analysis revealed the dysregulation of pathways related to steroidogenesis, sperm motility, and reproductive system development. Collectively, our findings indicate that continuous EE2 exposure directly affected sperm quality via the alteration of steroidogenesis and dysregulation of reproductive system development. The identified key factors including DNM1, PINK1, PDE7B, and SLC12A7 can serve as biomarkers to assess EE2-reduced sperm motility.

It is essential to evaluate secondary migration caused by riverine input and resuspension from seabed sediments to estimate the future distribution of radioactive cesium (¹³⁷Cs) in the coastal area off Fukushima Prefecture. In particular, the inflow from rivers cannot be ignored because most of the ¹³⁷Cs inflow from rivers is deposited on the coast without elute into seawater. Two mooring systems were installed near the Ukedo River's mouth (Fukushima Prefecture) from February 2017 to February 2018. The first contained a sediment trap system, collecting sinking particles during the period. The second comprised a turbidity sensor and a current sensor. The contribution of resuspension and inflow from the river to the mass flux was quantitatively evaluated using multiple regression equations. The results showed that resuspension caused 79%–83% of secondary ¹³⁷Cs migration in nearshore areas, whereas the influence of riverine ¹³⁷Cs input on the sediment was only 7% per year.

Interactions between microplastic (MP) and fine-grained suspended sediment in natural waters are important for the environmental fate of plastic particles. Estuaries are transitional areas between freshwater and open marine systems and are recognized as important accumulation zones for MPs. However, there is a knowledge gap on the processes driving the sedimentation of MPs in estuaries, especially with regard to positively buoyant MPs. Here we show from settling tube experiments that positively buoyant and non-spherical MP HDPE particles in different size-fractions (63–500 μm) and concentrations (1 and 5 mg l⁻¹) rapidly flocculate and settle with natural fine-grained sediment in natural seawater. Our results demonstrate that flocculation is a key process for the vertical transport of MP in estuaries. The implication is that land-based sources of positively buoyant HDPE MP transported by rivers will likely settle and accumulate in estuarine environments and thereby increase the concentration of MP in the benthic zone.

Globally, nutrient river discharges drive water quality of coastal ecosystems, and excess nutrients can cause eutrophication impacts. The Grijalva-Usumacinta River System (GURS) discharges in the southern Gulf of Mexico (SGoM) and it is the second largest riverine input to the Gulf. To study how contrasting GURS freshwater flow between rainy and dry seasons affects nutrients concentrations in the receiving coastal ecosystem, we evaluated nutrient variability in the water column during both seasons. High inorganic nutrients and total phosphate outline the rivers discharge plumes during rainy season, and were significantly higher than during the dry season throughout the study area, suggesting contrasting seasonal nutrient discharge of the GURS to coastal waters. On average the GURS discharged 141,123 t N yr⁻¹ 6893 t P yr⁻¹ and 928,904 t Si yr⁻¹ to SGoM. These results contribute with a nutrient baseline in the SGoM that could be useful for GURS decision-makers.

Legacy mining facilities pose significant risks to aquatic resources. From March 30th to April 9th, 2021, 814 million liters of phosphate mining wastewater and marine dredge water from the Piney Point facility were released into lower Tampa Bay (Florida, USA). This resulted in an estimated addition of 186 metric tons of total nitrogen, exceeding typical annual external nitrogen load estimates to lower Tampa Bay in a matter of days. An initial phytoplankton bloom (non-harmful diatoms) was first observed in April. Filamentous cyanobacteria blooms (Dapis spp.) peaked in June, followed by a bloom of the red tide organism Karenia brevis. Reported fish kills tracked K. brevis concentrations, prompting cleanup of over 1600 metric tons of dead fish. Seagrasses had minimal changes over the study period. By comparing these results to baseline environmental monitoring data, we demonstrate adverse water quality changes in response to abnormally high and rapidly delivered nitrogen loads.

To understand the transport of Fukushima Dai-ichi Nuclear Power Plant Accident (FDNPPA)-derived nuclear contaminated water, which will be discharged into the Pacific Ocean in the future, the distributions of ¹³⁴Cs and ¹³⁷Cs in seawater in the public areas east of Japan in winter 2011 were reported in this study. The ranges of ¹³⁴Cs and ¹³⁷Cs activities were <MDA (Minimum Detectable Activity) -68.9 Bq/m³ and 1.3–85.9 Bq/m³, respectively. The average decay corrected FDNPPA-derived ¹³⁴Cs/¹³⁷Cs activity ratio was 0.97. The FDNPPA-derived radiocesium existed in the seawater at a relatively high level at most stations. The ¹³⁴Cs and ¹³⁷Cs activities were comparable throughout the upper 50 m at each station. The FDNPPA-derived radiocesium was mainly distributed north of 36.5°N due to the boundary formed by the Kuroshio Extension. The temporal variations of FDNPPA-derived ¹³⁴Cs and ¹³⁷Cs suggested that their environmental half-lives in the study area were 61 d and 63 d in the period of June 2011 to June 2012, respectively.

We assessed microplastics (MPs) contamination in water, sediments, and tissues (gills, digestive tract, and muscle) of two intertidal crab species with different ecological traits and commercial importance (Menippe mercenaria and Callinectes sapidus), from a coastal lagoon in the southeastern Gulf of Mexico. There were significant differences between MP abundances in the abiotic matrices and between crab species. The burrower, sedentary and carnivorous M. mercenaria bioaccumulates 50 % more MPs than the free-swimming, omnivorous C. sapidus. However, no differences were observed between species' tissues. Fragments were the predominant shape in the tissues of both species, with the exception in the digestive tract of M. mercenaria. We identified polyethylene, and polyethylene terephthalate in water samples and Silopren® in sediment. In both crab species, Silopren and polyethylene predominated. Differences in ecological traits resulted in different bioaccumulation patterns in intertidal crabs.

Horseshoe crabs (HSCs) are a group of ancient chelicerates with great ecological and biomedical importance. Food poisonings caused by the consumption of Asian HSCs have significant impacts on public health and safety. This study measured tetrodotoxin (TTX) concentrations in two HSC species across various life stages in May 2020 from the northern Beibu Gulf, their most important spawning and nursery habitats in China. The average TTX contents in both Carcinoscorpius rotundicauda and Tachypleus tridentatus ranged 6.2–8.0 μg/kg and 3.8–8.4 μg/kg, respectively. While sampling location, growth and molt stages have little influence on TTX distribution in both species, significantly higher levels of TTX were detected in hemolymph, but lower in pooled tissues of early-instar juvenile T. tridentatus. These results provide a regional view of TTX occurrence and distribution in HSCs during their spawning season, which are critical for future studies to enhance understanding of TTX dynamics and formation in HSCs.

The present study aims to analyze the level and total toxicity of the most common pollutants in surface sediments and assess their impact on the occurrence of antibiotic resistance genes (ARGs) in the Sea of Azov. Biotesting using the whole-cell bacterial lux-biosensors showed high integral toxicity of surface sediments and the presence of genotoxicants and substances that cause oxidative stress and protein damage. Using cluster analysis, it was shown that the distribution of pollutants in the Sea of Azov depends on the type of surface sediments. The relative abundance and distribution of 14 ARGs in surface sediments were shown. Principle component analyses results suggest that non-corresponding contaminants do not exert direct influence on the ARGs abundance in the surface sediments of the Sea of Azov. Thus, the need to investigate the significance of non-corresponding pollutants in the selection and distribution of ARGs in the aquatic environment remains a pressing problem.