The Black Sea is unfortunately globally established as a highly polluted sea, with contaminants from various sources polluting its marine sediments. This study aimed at analyzing heavy metal resistance levels by heterotrophic bacteria colonizing marine sediments across Black Sea shores within Turkey. Twenty-nine bacterial samples from marine sediments were investigated through exposure to sixteen heavy metal salts using the microdilution method. The minimum inhibitory concentration values for bacterial colonies within such marine sediment samples ranged from <0.97 mM/L to >1000 mM/L. Trough and peak minimum inhibitory concentration values were determined at <0.17 mg/mL and > 331 mg/mL. Peak tolerated and peak toxic heavy metals were identified as iron and cadmium, respectively. Resistance ratios were also obtained in this study. Bacillus wiedmannii was identified as the most resistant bacterial population when exposed to heavy metal salts. This study shows occurrence of heavy metal resistant bacteria within Black Sea sediments.

This study assessed the seasonal variation in the magnitude of marine litter along the Gulf of Guinea coastline, Araromi seaside, Nigeria with a survey of twenty sampling sites. The total number of litter items collected was 29,029 comprising 7358 and 21,671 items in the dry and rainy season respectively. The average number of items per square meter was higher in the rainy season (1.80 ± 0.35) than in the dry season (0.61 ± 0.19). Plastic materials dominated the litter composition with 86 % and 91.8 % in the dry and rainy season respectively. The beach cleanliness assessed as clean coast index (CCI) depicted the beach as dirty (12.26 ± 3.74) during the dry season and extremely dirty (36.13 ± 6.91) in the rainy season. The hazardous item index (HII) also showed the coastline was littered with hazardous items. These results provide baseline data for marine litter management along the Gulf of Guinea coastlines and other coastlines in Africa.

The Gulf contains important biodiversity, but is also heavily impacted. While studies have measured seawater contaminants and toxicity, we are not aware of discrete sampling of the sea surface microlayer (SML). This ocean-atmosphere interface is important environmentally, but also sensitive to marine and atmospheric contaminant inputs. We sampled the SML and subsurface seawater (SSW) from the Gulf in August 1991 and 1992. The SML exhibited significant enrichment of petroleum hydrocarbons, Cu, Cd and Pb, which persisted more than one year after the massive 1991 Gulf War oil spill. Toxicity to echinoderm larvae was also greater in the SML. This likely reflects effects of contaminants measured and other stressors. Sophisticated techniques used over recent decades to determine biological effects of contaminants in the Gulf could usefully extend to the SML. Our study has demonstrated its sensitivity and could serve as a ‘baseline’ for determining long-term persistence of seawater contamination and toxicity.

Metal contamination has never been assessed in Ampullae of Lorenzini. This study employed Rhizoprionodon lalandii, as an ecotoxicological model to investigate potential metal accumulation in Ampullae of Lorenzini jelly. No differences between sexes were observed regarding jelly metal concentrations at Rio das Ostras (RJ) or Santos (SP). Statistically significant correlations were noted between total lengths (TL) and condition factors and several metals at both sampling sites, demonstrating the potential for Chondrichthyan sensory capacity disruption and possible effects on foraging success. Maternal metal transfer to Ampullae jelly was confirmed. Rhizoprionodon lalandii is thus, a good model to assess Ampullae of Lorenzini contamination, as this electrosensory organ seems to be highly vulnerable to metal contamination.

Carbon fixation by chemoautotrophic microorganisms in the dark ocean has a major impact on global carbon cycling and ecological relationships in the ocean's interior. At present, six pathways of autotrophic carbon fixation have been found: the Calvin cycle, the reductive Acetyl-CoA or Wood-Ljungdahl pathway (rAcCoA), the reductive tricarboxylic acid cycle (rTCA), the 3-hydroxypropionate bicycle (3HP), the 3-hydroxypropionate/4-hydroxybutyrate cycle (3HP/4HB), and the dicarboxylate/4-hydroxybutyrate cycle (DC/4HB). Although our knowledge about carbon fixation pathways in the ocean has increased significantly, carbon fixation pathways in the cold seeps are still unknown. In this study, we collected sediment samples from two cold seeps and one trough in the south China sea (SCS), and investigated with metagenomic and metagenome assembled genomes (MAGs). We found that six autotrophic carbon fixation pathways present in the cold seeps and trough with rTCA cycle was the most common pathway, whose genes were particularly high in the cold seeps and increased with sediment depths; the rAcCoA cycle mainly occurred in the cold seep regions, and the abundance of module genes increased with sediment depths. We also elucidated members of chemoautotrophic microorganisms involved in these six carbon-fixation pathways. The rAcCoA, rTCA and DC/4-HB cycles required significantly less energy probably play an important role in the deep-sea environments, especially in the cold seeps. This study provided metabolic insights into the carbon fixation pathways in the cold seeps, and laid the foundation for future detailed study on processes and rates of carbon fixation in the deep-sea ecosystems.

In the Bay of Biscay, regional monitoring programmes and data on abundance and distribution of floating marine litter are scarce, contrary to many other European marine regions. Here, a joint analysis of multiyear observations (2017–2019) of floating micro and macrolitter and oceanographic conditions was conducted for the Bay of Biscay by combining microlitter samplings with neuston nets and vessel-based macrolitter observations. Results show spatiotemporal abundance and distribution patterns. The density of floating microlitter increased from 26,056 items/km² in 2017 to 1,802,4611 items/km² in 2019; floating macrolitter densities barely varied amongst year (2.52 items/km² in 2017 and 3.70 items/km² in 2019). No significant correlation was found between densities of micro and macrolitter, neither for the oceanographic variables. We conclude that longer micro and macrolitter monitoring periods and standardized datasets based on the cross-border cooperation are needed to collect more comparable information, evaluate trends, and support decision making in the area.

Long non-coding RNAs (lncRNAs) have been demonstrated to participate in plant growth and development as well as response to different biotic and abiotic stresses. However, the knowledge of lncRNA was limited in microalgae. In this study, by RNA deep sequencing, 134 lncRNAs were identified in marine Nannochloropsis oceanica in response to carbon dioxide fluctuation. Among them, there were 51 lncRNAs displayed differentially expressed between low and high CO₂ treatments, including 33 upregulation and 18 downregulation lncRNAs. Cellulose metabolic process, glucan metabolic process, polysaccharide metabolic process, and transmembrane transporter activity were functionally enriched. Multiple potential target genes of lncRNA and lncRNA-mRNA co-located gene network were analyzed. Subsequent analysis had demonstrated that lncRNAs would participate in many biological molecular processes, including gene expression, transcriptional regulation, protein expression and epigenetic regulation. In addition, alternative splicing events were firstly analyzed in response to CO₂ fluctuation. There were 2051 alternative splicing (AS events) identified, which might be associated with lncRNA. These observations will provide a novel insight into lncRNA function in Nannochloropsis and provide a series of targets for lncRNA-based gene editing in future.

Release from the sediment is an important nutrient source to the water column of global oceans, especially for marginal seas with active biogeochemical processes. Benthic nutrient biogeochemistry and its responses to environmental changes were investigated in the eastern marginal seas of China using a two-layer diffusion-advection-reaction diagenetic model. Overall, the sediment represented the primary nutrient source with fluxes of ~−342 ± 197, −1.25 ± 0.50, and −114 ± 56 × 10⁸ mol/month for dissolved inorganic nitrogen (DIN), phosphate, and silicate, respectively. This could contribute up to ~42% of nutrients requested by primary production (PP), with a DIN/SiO₃²⁻/PO₄³⁻ molar ratio of 273:91:1, which was higher than that in the overlying water (49:47:1). Future benthic nutrient fluxes were predicted under two environmental change scenarios (increasing and decreasing PP and biogenic silica). Our study may help rebuild nutrient budgets in the future and formulate environmental management policies in marginal seas.

While pollution due to nano- and micro-sized plastics (NMPs) and hypoxic conditions both occur in coastal areas, the deleterious potential of co-exposure to hypoxia and NMPs (hypoxia and micro-sized plastics, HMPs; hypoxia and nano-sized plastics, HNPs) is largely unclear. Here, we provide evidence for multigenerational effects of HMP and HNP in the marine rotifer Brachionus plicatilis by investigating changes in its life traits, antioxidant system, and hypoxia-inducible factor (HIF) pathway using an orthogonal experimental design, with nanoscale and microscale particles measuring 0.05 μm and 6.0 μm in diameter, respectively, and hypoxic conditions of 0.5 mg/L for six generations. Combined exposure to NMPs and hypoxia caused a significant decrease in fecundity and overproduction of reactive oxygen species (ROS). The HIF pathway and circadian clock genes were also significantly upregulated in response to HMP and HNP exposure. In particular, synergistic deleterious effects of HNP were evident, suggesting that size-dependent toxicity can be a major driver of the effects of hypoxia and NMP co-exposure. After several generations of exposure, ROS levels returned to basal levels and transcriptomic resilience was observed, although rotifer reproduction remained suppressed. These findings help eluciating the underlying molecular mechanisms involved in responses to plastic pollution in hypoxic conditions.

Exposure risk is assessed based on modeling suitable habitat of large pelagic fish and oil spill scenarios originating at three wells located in the western GM's deep waters. Since the fate of the oil depends on the oceanographic conditions present during the accident, as well as the magnitude and duration of the spill, which are not known a priori, the scenarios used are a statistical representation of the area in which oil spilled from the well could be found, given all possible outcomes. The ecological vulnerability assessment identified a subset of bony fish with low-medium vulnerability and elasmobranchs with medium-high vulnerability. The oiling probability and exposure risk of both bony fish and elasmobranchs hotspots vary by well analyzed. Thus, these results provide essential information for a risk management plan for the assessed species and others with economic or conservation importance distributed in the GM and worldwide.