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.

Surface sediments were sampled seasonally along the Samsun coastline to assess the source, distribution, and ecological risk of 16 polycyclic aromatic hydrocarbons (PAHs). The total PAHs levels, varied between 71.64 and 1186.87 ng g⁻¹ with the mean of 295.79 ng g⁻¹, were consistent with sediment studies worldwide. Diagnosis rates revealed that PAHs in sediments along the Samsun coastline are primarily sourced from biomass, coal and petroleum combustion and petroleum at lesser extent. The three-ring PAHs (34.9 %) were proportionally high, followed by 4-ring PAHs (25 %). Sediment quality guidelines (SQGs), administered to evaluate biological effects of individual PAH, indicated adverse biological effects (≥TEL and < PEL) seasonally in some stations. With respect to the risk quotient, the risk arisen by PAHs in the coastal sediments of Samsun found to be moderate to high ecological risk.

Investigate the growth adaptation law of the Tamarix chinensis root system in response to the groundwater level in a muddy coastal zone. The high groundwater level (0.7–0.9 m), medium groundwater level (1.1–1.3 m) and low groundwater level (1.5–1.7 m) T. chinensis forests on the beaches of the Yellow River Delta were used as the research objects. Full excavation methods were used to excavate root systems with different groundwater levels; then, the aboveground biomass, root biomass, root spatial distribution, root topological structure and fractal characteristics of T. chinensis response characteristics to groundwater level were measured and analysed. The results showed that with the decrease in the groundwater level, the soil water content and soil salt content showed upward trends. At high groundwater levels, T. chinensis reduced root biomass allocation to reduce the damage to roots caused by salinity. At low groundwater levels, T. chinensis strengthened the development of root systems, which greatly enhanced the ability of T. chinensis to balance its water intake. The root biomass at the high groundwater level was 43.06% lower than that at the low groundwater level. The relationship between root and shoot growth of T. chinensis at high groundwater levels and medium groundwater levels indicated allometric growth, and at low groundwater levels, roots and shoots grew uniformly. The root distribution of T. chinensis tended to be shallow at the different groundwater levels, showing the characteristics of a horizontal root type. At high groundwater levels, the root topological structure tended to be dichotomous, and the fractal dimension and fractal abundance values were both large, at 1.31 and 2.77, respectively. The branch complexity increased to achieve spatial expansion and increase plant stability. However, the topological structure of the medium and low groundwater level T. chinensis tended to be herringbone-like, the fractal dimension and fractal abundance values were small, the second branch was limited, and the structure was simple. The topological structure and fractal characteristics of the T. chinensis root system responded to different groundwater levels in a coordinated manner. Based on the differences in the growth and architecture of the T. chinensis root system, the T. chinensis root system has strong phenotypic plasticity to the heterogeneous water-salt habitat of the groundwater-soil system, and the T. chinensis root system shows strong root adaptability to water and salt stress.

To investigate the impacts of sub-lethal concentrations of antibiotic agents in mariculture, culturable approach and DNA based detection were employed to isolate and analyse resistant bacteria and resistant genes in this study. Milkfish (Chanos chanos), the target rearing animal was exposed to sulfamethoxazole (SMX; 2 mg/L) for 8 weeks and resulted in reduced survival rate and weight gain to 61.9 % and 28.4 %, respectively compared to control milkfish (p < 0.001). The composition of SMX-resistant bacteria isolated from the culture water and the gastrointestinal tracts of milkfish underwent changes in response to SMX treatment with a reduced diversity. The prevalence of SMX resistant genes sul in bacterial isolates was elevated from 2.8 % of control to 100 % of SMX-administrated water. Exposure to SMX at a sub-lethal dosage enhanced the prevalence of resistance genes sul1 and sul2 in resistant bacteria, thus implying high frequency of resistance dissemination in the marine environment and surrounding ecosystems.

Estuaries experience variable physicochemical conditions, especially after hurricanes and due to anthropogenic sources of pollution. Their microbial communities are not as well understood in terms of community structure and diversity, particularly in response to stresses from pollution and severe events. This study presents a 16S rRNA-based description of sediment microbial communities in the Houston Ship Channel-Galveston Bay estuary after Hurricane Harvey in 2017. A total of 11 sites were sampled, and microbial genomic DNA was isolated from sediment. The presence and abundance of specific bacterial and archaeal taxa in the sediment indicated pollutant inputs from identified legacy sources. The abundance of certain microbial groups was explained by the mobilization of contaminated sediment and sediment transport due to Harvey. Several microorganisms involved in the biodegradation of xenobiotics were observed. The spatial occurrence of Dehalococcoidia, a degrader of persistent polychlorinated compounds, was explained in relation to sediment properties and contaminant concentrations.

Total mercury (T-Hg) was examined in 8 threadfin bream species (Nemipterus spp.) caught in the Gulf of Thailand (GoT). The T-Hg contents ranged from 11.3 to 374 μg kg⁻¹ wet weight, with the lowest in Nemipterus peronii and the highest in Nemipterus nemurus and Nemipterus tambuloides. Accumulation of T-Hg in fish tissue was found to be related to fish size, trophic levels, feeding habits and habitat. Threadfin bream caught in the upper GoT exhibited significantly (p < 0.05) lower T-Hg than those in the middle and lower parts of GoT, which possibly due to local mercury sources e.g., internal anthropogenic activities in the GoT and external from terrestrial input via river discharge. The estimated daily intakes were ranged from 0.03 to 0.07 μg kg⁻¹ bodyweight day⁻¹. All threadfin breams in the GoT have HQ <1. To prevent the associated potential risk, the maximum safe daily consumption is recommended at 95.3 g day⁻¹.

China is one of the largest waste importers and producers in the world, with land-based discharges mainly from domestic sewage and industrial wastes being the main source of marine debris (MD) including three distributional types as stranding on the beach (BMD), floating on the water surface (FMD), and submerging into sediments (SMD). Fishery-related activities are also one of the main sources of marine debris: intensive aquaculture, fishing, and related household activities. Marine debris, showing different ways of leaching, degradation and fragmentation, can be ingested, incorporated and accumulated by marine organisms through the food chain, and ultimately pose risks to the ecological environment, economic benefits and human health. Comprehensive countermeasures, from awareness to practices and from the government to the public, are now being implemented in China and have achieved remarkable results especially in domestic waste incineration, but greater commitment and stronger execution are urgently required.

Three ²¹⁰Pb-dated sediment cores were used to evaluate the contamination degree and flux ratios of potentially toxic elements (PTEs; As, Cd, Cr, Cu, Ni, Pb, V, and Zn) in seagrass meadows from the northern margin of Términos Lagoon (TL), southern Gulf of Mexico. The sediments displayed minor Cd, Ni, V, and Zn enrichments but moderate to strong enrichment by As. Results from a chemometric analysis revealed that: 1) salinization and grain size, along with 2) the terrigenous inputs are the major factors influencing the PTEs accumulation. The historical trends of PTEs flux ratios nearly follow the large-scale land-use changes around TL, linked to the growth of the Mexican oil industry in the area since the 1970s. Our findings showed the critical role of seagrass meadows as PTEs sinks. This information is useful for decision-makers to develop restoration projects for a vulnerable site within the largest coastal lagoon ecosystem in Mexico.

Single-use plastics (SUPs) represent a major threat to marine environments and require proactive policies to reduce consumption and mismanagement. Many SUP management strategies exist to reduce SUP use and mitigate environmental impacts, including extended producer responsibility (EPR), deposit-return schemes, SUP bans or taxes, and public outreach and education. This study analyzed brand audit and beach cleanup data in four densely populated Canadian cities (Vancouver, Toronto, Montréal, Halifax) and a remote island (Sable Island) to determine efficacy of ongoing SUP mitigation measures. Cities were found to have similar litter type proportions, and six brands were found to disproportionally contribute to Canadian SUP litter, comprising 39% of branded litter collected. Results confirm that current Canadian SUP management appears to be insufficient to address leakage of SUPs into the environment. Recommendations to strengthen SUP management strategies and mitigate plastic pollution are recommended to improve future Canadian SUP reduction policies.

So far, the adverse effects of excess Fe in shrimp have been ignored for years as it was thought that extra Fe supplementation was not needed in the practical diets. Nowadays, Fe concentration in commercial shrimp feed from feed enterprises could be around 301.34–545.5 mg/kg, which is mainly due to the fish meal containing up to 1500 mg/kg Fe. Therefore, the purpose of this experiment was to investigate the effects of Fe supplementation on the growth performance, tissue Fe deposition, hepatopancreas lipid metabolism, intestinal function in L. vannamei. The results showed that although growth performance was not influenced by the dietary Fe supplementation, excess Fe supplementation (955.00 mg/kg) significantly increased hepatopancreas Fe deposition and induced lipolysis. Moreover, excess Fe supplementation impaired intestinal immune function and disrupted microbiota homeostasis. These findings might provide partial theoretical evidence for the effect of dietary Fe supplementation on physiological metabolism in L. vannamei.