Spatial and temporal variations and trends of SST and Chl-a in the Persian Gulf were evaluated using MODIS data from 2002 to 2018. Trend indicator and key features were built up based on Mann-Kendall test, Hurst exponents and Wavelet Transform (WT) techniques to investigated the volatilities, trend estimation and persistence of original and WT signals. The key features revealed that the Chl-a pattern is heterogeneous in both time and spatial scale, whereas SST pattern is more homogenous. Trend analysis of the study area showed identifiable and sustainable trend with maximum tendency to decrease of Chl-a, and increase of SST. More than 48% of the study area is under slight decrease, and about 20% area mostly located at the northern parts show slight increase of Chl-a values. The presented methodology is applicable to the data signals that keep the range of inter-annual approximation components of DWT not less than scale level-4.

We report the occurrence and genomic analysis of extended-spectrum β-lactamase (CTX-M)-producing Escherichia coli in anthropogenically polluted coastal waters of Southeast Brazil. E. coli strains belonging to sequence types (STs) ST10, ST38, ST155 and ST1284 exhibited a wide resistome, with genes conferring resistance to medically relevant antimicrobials and heavy metals, and a halophilic behavior (tolerance to 9–10% NaCl). These findings suggest a heavy contamination in this area by critical priority bacteria adapted to marine environments, which might have negative impacts on human and ocean health.

The chromium (Cr) pollution in Bali gained public attention because the textile and screen-printing industry was reportedly dumping their waste into the river. Benoa Bay is the estuary of six rivers in Bali and is thought to be contaminated by Cr. In this research, we investigated the presence of Cr in surface water, sediment and plankton (as a base trophic level) in Benoa Bay, Bali. Thirty stations were used to investigate Cr in Benoa Bay. The results showed that at almost all stations, surface waters of Benoa Bay were not contaminated by Cr, meanwhile Cr was detected in plankton and sediment. This research found that the range of Cr concentrations was sediment > plankton > water. The Bioaccumulation Factor (BCF) between plankton-water was much higher than plankton-sediment.

Jellyfish are voracious planktonic predators that may be susceptible to ingesting microplastics. We measured rates of ingestion and egestion of microbeads by Aurelia aurita (Scyphozoa) and evaluated whether ingesting microbeads affected metabolism or gut epithelia. Ingestion rates were measured by exposing medusae to microbeads and randomly sampling them 6 times over a 32 h period to determine the number of microbeads in their tissues. Egestion rates were measured by exposing medusae to microbeads for 1 h before transferring them to kreisels without microbeads and sampling them 6 times over 8 h. Respiration rates of medusae were determined using incubations and potential damage to gut epithelia was evaluated using histopathology. Medusae ingested few microbeads and egested them within 8 h. Microbeads had no effect on respiration and the histology. We concluded that the medusae may recognise microbeads as non-food particles and that their ingestion caused undetectable physiological and histological harm.

A statistical oil spill risk forecast model in support of emergency response and environmental risk assessment is presented by combing the deterministic model, probabilistic strategy and frequency estimation. When applied to evaluate various potential spill sources (oil port, fairway, anchorage and pipeline) in the Zhoushan offshore area, the model provides the probability of slick spatial position, oil slick thickness, and exposure duration of floating slick. An oil spill risk map is generated after integrating multiple spill sources, which is a powerful tool for identifying high-risk areas and developing contingency plan. Impact scope and damage degree vary among different sources because of special local topographical, hydrological, and meteorological conditions, where generally exists high pollution intensity of point-source and wide range of line-source. Huge Changjiang River runoff prevents coastal sea in the north from being contaminated by spilled oil from the southern Zhoushan offshore area.

Microplastics' (MPs) abundance, small size, and global distribution render them bioavailable to a variety of organisms directly or by trophic transfer, yet examinations in marine apex predators are currently limited. The present study investigated the occurrence of MPs sized 125 μm–5 mm in the gastrointestinal tract (GIT) of bottlenose dolphins (Tursiops truncatus) stranded in South Carolina, USA from 2017 to 2018. MPs, mostly fibers, were detected in all GITs (n = 7) of stranded bottlenose dolphins. Total suspected MPs ranged between 123 and 422 particles/individual, a high range among international studies. Comparison to other studies likely reflects differences in both methods and location. This is the first study from North America to quantify MPs in a small coastal cetacean outside Arctic waters and the first specifically in bottlenose dolphins (southeastern United States). Findings and methodology from this investigation can aid future studies examining MP in marine apex predators.

In eutrophic coastal waters, harmful algal blooms (HAB) often occur and present challenges to environmental and fisheries management. Despite decades of research on HAB early warning systems, the field validation of algal bloom forecast models have received scant attention. We propose a daily algal bloom risk forecast system based on: (i) a vertical stability theory verified against 191 past algal bloom events; and (ii) a data-driven artificial neural network (ANN) model that assimilates high frequency data to predict sea surface temperature (SST), vertical temperature and salinity differential with an accuracy of 0.35ᵒC, 0.51ᵒC, and 0.58 psu respectively. The model does not rely on past chlorophyll measurements and has been validated against extensive field data. Operational forecasts are illustrated for representative algal bloom events at a marine fish farm in Tolo Harbour, Hong Kong. The robust model can assist with traditional onsite monitoring as well as artificial-intelligence (AI) based methods.

Concentration of bacterial species indicative of fecal contamination in the gut of mangrove oysters (Crassostrea gasar) is a major concern for public health and food surveillance. Our work aimed to determine the occurrence, antibiotic-resistance, phylogenetic profile and virulence of Escherichia coli strains isolated from C. gasar farmed in four estuaries of Amazonia. Santo Antônio de Urindeua was the sampling point with the highest number of E. coli cells in oyster samples (10⁴ per 100 g of sample). Twenty-four isolates (52.2%) showed resistance to cephalotin and 18 to amoxicillin (39.1%). Eighteen clonal populations were determined by rep-PCR and were mainly affiliated to the pathogenic and commensal phylo-groups B1 and D. The presence of elt genes suggests that 10 of these clones belong to the Enterotoxigenic Escherichia coli pathotype. Plasmids, mostly of the F incompatibility group, were detected in the majority of the strains. All isolates were susceptible to last-resort antibiotics.

Hemocyte parameters have been used as a proxy to characterize the health condition of marine bivalves, as the effects of external and internal stresses are reflected well in these parameters. Marine bivalve hemocyte functions are often depressed during the post-spawning period due to physiological stress and energy depletion. In this study, we analyzed temporal changes in hemocyte parameters of the oyster Saccostrea kegaki on Jeju Island, off the south coast of Korea, using flow cytometry. Total hemocyte count (THC), hemocyte types, hemocyte mortality, and phagocytosis capacity were analyzed. S. kegaki spawned during June and August, when the sea surface temperature increased from 18 to 23 °C. Most of the oysters were in the spent and resting phases from September to January. THC dropped dramatically from September to October, when most oysters completed spawning. Histology revealed that the residual eggs or sperm were actively resorbed through phagocytosis by hemocytes during the spent stage. Hemocyte mortality also showed its annual peak in October, possibly due to increased resorbing activities. The phagocytosis capacities of the granulocytes decreased dramatically from September to February. The level of energy reserves (glycogen) in post-spawning tissues was significantly lower than that prior to spawning. The low energy level reserve during the post-spawning period likely reduced the THC and immune capacities, as oysters may have been unable to acquire sufficient food from the ambient environment.

Based on field survey in the southwestern Yellow Sea (SWYS) during April–September 2017, the spatiotemporal variations in the hydrological characteristics and nutrient conditions were coupled and analyzed; the intra-seasonal variations in the upwelling in the front of the Yellow Sea Cold Water Mass (YSCWM) and impacts on nutrient transport were explored. The coastal area was controlled by the low-salinity high-nutrient Lubei Coastal Current, Subei Coastal Current, and Yangtze River Diluted Water from north to south; at bottom, the northeastern SWYS was controlled by the low-temperature high-salinity high-nutrient YSCWM. Temperature, salinity and nutrient fronts formed around YSCWM. The upwelling velocity in the front increased during April to late June and decreased in early September; the upwelled fluxes of dissolved inorganic nitrogen (0.29×10³-7.77×10³ μmol·m⁻²d⁻¹), phosphate (0.02×10³-0.27×10³ μmol·m⁻²d⁻¹) and silicate (0.98×10³-8.75×10³ μmol·m⁻²d⁻¹) showed similar variations during April–September. The upwelled nutrients could potentially contribute to local green tide development and phytoplankton growth during spring–summer.