DDTs were detected in yellowfin tuna (Thunnus albacares, 92.1–221.8 ng‧g⁻¹ lipid weight) and their prey (54.9–93.5 ng‧g⁻¹ lipid weight) from the South China Sea (SCS). DDT levels reported in this study were lower than those of the previous studies indicated the recent mitigation of DDT contamination in the SCS. Higher DDT levels were observed in fat abdominal muscle than lean dorsal muscle in adult yellowfin tuna. Meanwhile, DDT levels in adult yellowfin tuna were higher than the young ones. The composition profiles of DDT and its metabolites suggested DDTs in fish in the SCS were mainly derived from the historical use of technical DDTs. DDTs were biomagnified through food chains with the trophic magnification factor of 2.5. Risk assessment results indicated that dietary exposure to DDTs through lifetime fish consumption from the SCS would pose little cancer and noncarcinogenic risk to coastal residents.

The pressing need to solve marine plastics pollution as a multi-source and multi-stakeholder problem is an ongoing global issue. This presents a challenge to policy makers tasked with understanding and accommodating different stakeholder perceptions and weighting their alternative propositions for solutions. In the case of Hong Kong, pollution of the marine environment by discarded plastics, polystyrenes and other items is a cumulative and accelerating problem that has yet to be resolved. We demonstrate how a geostatistical mapping approach can achieve joint stakeholder prioritization at any such regional scale. Joint prioritized area mapping is a methodology that links perspectives of otherwise disparate stakeholders to ecosystem-based-management, thereby balancing ecological, socio-economic and governance principles across temporal and spatial scales. It can serve as a generic scoping tool to help assess any marine spatial planning problem.

This study investigates Polycyclic Aromatic Hydrocarbons (PAHs) and Bisphenol-A (BPA) pollution in coastal sediments and bivalves of Hormozgan Province coastline. The results indicated that the BPA concentration in some bivalves reached up to 340.16 ng g⁻¹. The mean BPA concentration in the sediment samples was also 787.01 ng g⁻¹. The ∑PAHs content in sediments ranged from 14.54 to 85.00 ng g⁻¹, while values for bivalves ranged from 5.37 to 16.40 ng g⁻¹. Individual PAH concentrations in sediments exceeded those in bivalves for which only LMW PAHs were detected. A combination of techniques including Self-Organizing Maps (SOM), Positive Matrix Factorization (PMF), and Cluster Analysis (CA) were applied and both petrogenic and pyrogenic sources were identified. The risk of PAHs in the sediments was relatively low according to the sediment quality guidelines. The health risk indices suggest that exposure to PAHs through bivalve consumption does not impose harmful health effects upon consumers.

Functional diversity/distinctness measure based trait has been proved to be a robust indicator to summarize the description of community structures and to assess water quality in different types of aquatic environment. In this study, for identifying the shielding effect of microalgae against protozoan grazing, a nine-day survey was conducted by exposing protozoan communities to a series of concentration gradients (10⁰ (control), 10⁴, 10⁵, 10⁶ and 10⁷ cells ml⁻¹) of two microalgae, respectively. Our results showed clear resistance of two test microalgae against protozoan grazing in five treatments. The functional distinctness measures commonly represented a decreasing trend along the gradient of concentrations of both microalgae. Ellipse tests based on the paired functional distinctness indices revealed that community functioning represented an uptrend departure from the expected pattern with the concentrations of both microalgae increase. Therefore, we suggest that the functional distinctness measures might be a reliable approach to detect the ecological effect of microalgae against protozoan grazing.

Antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) are worldwide considered as emerging contaminants of large interest, and a primary threat to human health. It is becoming clear that the environment plays a central role in the transmission, spread, and evolution of antibiotic resistance. Although marine systems have been largely investigated, only a few studies have considered the presence of ARGs in meso- and bathypelagic waters. To date, no molecular based studies have yet been made to investigate the occurrence of ARGs in the Black Sea, the largest meromictic basin in the world, receiving water from a number of important European rivers and their residues of anthropogenic activities in permanently stratified mesopelagic water masses. In this study, we determined the presence and the abundance of five ARGs (blaCTXM, ermB, qnrS, sul2, tetA) and of the heavy metal resistance gene (HMRG) czcA, in different sampling sites in the eastern and western Black Sea, at several depths (up to 1000 m) and various distances from the shoreline. Three ARGs (blaCTXM, sul2, and tetA) and czcA were present in at least 43% of the analysed samples, whereas ermB and qnrS were never detected. In particular, sul2 abundances increased significantly in coastal location, whereas tetA increased with sampling depth. These findings point out the Black Sea as a source of ARGs and HMRGs distributed along the whole water column.

The Pearl River Estuary is an important sink of organochlorine compounds (OCs), and OC pollution levels in surface sediments remain largely unknown at present. We collected and analysed residual DDTs, HCHs and PCBs of 45 surface sediments from the Pearl River Estuary in 2017. The values of DDTs (1.83 to 6.98 ng·g⁻¹) and HCHs (0.43 to 2.14 ng·g⁻¹) were higher in the Humen outlet, and the values of PCBs (4.6 to 187.4 ng·g⁻¹) were higher in the coastal areas of Shenzhen. The DDTs and HCHs have generally decreased while the PCBs have been rapidly increasing in recent decades. The DDTs might originate from technical DDT and dicofol. The major source of HCHs was lindane. The main potential sources of PCBs were increased industrial products, ship painting, E-waste disassembly, maricultural and agricultural pollution. The total PCBs and DDTs had medium ecological risks according to the sediment quality guidelines.

To produce albinism in the marine medaka Oryzias melastigma, we disrupted the solute carrier family 45 (SLC45a2) gene by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 with a single guide RNA (sgRNA). Selected sgRNAs were able to target a SLC45a2 gene as confirmed by genotyping and heteroduplex mobility assay (HMA). Of the survived embryos after injection, 54.2% and 60.0% embryos exhibited albinism phenotype by sgRNA1 and sgRNA2, respectively. Deep sequencing at the on-target sites showed different insertion and deletion (indel) mutation profiles near the DNA cleavage sites, indicating high efficacy of producing SLC45a2 knock-out mutants by this method. Moreover, HMA at the potential off-target sites revealed that off-target activity would be induced at a low rate, or not induced at all. This albino marine medaka will be a good model for marine molecular ecotoxicology in establishment of diverse in vivo endpoints, and the application of this efficient gene targeting method in the marine medaka would be useful tool for mechanistic approaches.

Bulk sedimentary phosphorus (P) is studied to evaluate its source, distribution, preservation and enrichment in relation with organic carbon (OC), sediment textures and moisture contents in the northern Beibu Gulf. Approximately 80% of surface sediments in the investigated sites were composed of coarse sandy texture (>63 μm). Total P (TP), inorganic P (IP) and organic P (OP) contents were lower to medium range compared to the levels reported for other marginal seas. Sedimentary OC and P were derived from mixed sources, with high terrestrial influence in the coastal areas (molar OC/OP ratios >250:1). The distribution of P corroborated with the variation tendency of fine-grained sediments, moisture contents and OC. Both IP and OP may significantly influence the trophic state of seawater if released from surface sediments. Influenced by hydrodynamics, frequent resuspension and high abundance of sand, TP is less preserved, and shows low to moderate enrichment in surface sediments.

Plastics in Colombian marine-coastal ecosystems are being fragmented by various environmental factors, generating microplastics (size < 5 mm), an emerging pollutant that is ingested by marine organisms, representing a threat to ecosystems and potentially also to humans. This study aims to evaluate the incidence of microplastic ingestion by fishes from mangrove ecosystems in Cispata, Colombian Caribbean. The digestive tract content of 302 specimens of 22 fish species were analyzed using the KOH digestion method (500 g/5 L), stereoscopic visual identification and infrared spectroscopy. A total of 69 microplastics were found in the digestive tract of 7% of the analyzed fishes. 55% of the ingested microplastics were filaments, 23% fragments, 19% films, and 3% foam. The results of this study raised concerns about microplastic contamination in the marine environments, a threat to the fishery resource and to public health, which requires actions to prevent and reduce its negative effects.