In 2020, the global cap of maximum allowable sulphur content in marine fuel will be reduced from the current 3.5% to 0.5%. Another way to reduce the sulphur emissions is to install a seawater scrubber that cleans exhausts but instead release acidic water containing nutrients and contaminants back to the marine environment. In the current study, scrubber washwater was tested on a Baltic Sea microplankton community. A significant increase in chlorophyll a, particulate organic phosphorus (POP), carbon (POC) and nitrogen (PON) were observed when the community was exposed to 10% scrubber washwater for 13 days as compared to the control. A laboratory experiment with the filamentous cyanobacteria Nodularia spumigena and the chain-forming diatom Melosira cf. arctica showed negative responses in photosynthetic activity (EC10 = 8.6% for N. spumigena) and increased primary productivity (EC10 = 5.5% for M. cf. arctica), implying species-specific responses to scrubber washwater discharge.

As small pieces of plastics known as microplastics pollute even the remotest parts of Earth, research currently focuses on unveiling how this pollution may affect biota. Despite increasing awareness, one potentially major consequence of chronic exposure to microplastics has been largely neglected: the impact of the disruption of the symbiosis between host and the natural community and abundance pattern of the gut microbiota. This so-called dysbiosis might be caused by the consumption of microplastics, associated mechanical disruption within the gastrointestinal tract, the ingestion of foreign and potentially pathogenic bacteria, as well as chemicals, which make-up or adhere to microplastics. Dysbiosis may interfere with the host immune system and trigger the onset of (chronic) diseases, promote pathogenic infections, and alter the gene capacity and expression of gut microbiota. We summarize how chronically exposed species may suffer from microplastics-induced gut dysbiosis, deteriorating host health, and highlight corresponding future directions of research.

This study examines how dissolved oxygen (DO) responds to tropical cyclones (TCs) "Wind Pump" in a pre-existing cyclonic and an anticyclonic eddy over the Bay of Bengal (BoB) based on Argo and satellite data. Both TCs induced DO temporal decreases in the subsurface waters (Deep Depression BOB 04 with a pre-existing cyclonic eddy and cyclonic storm Roanu with a pre-existing anticyclonic eddy) owing mainly to the storm-induced upwelling. The deeper oxycline caused by the pre-existing anticyclonic eddy relieved the storm-induced shallow of oxycline during Roanu. On the contrary, the pre-existing cyclonic eddy shoaled the oxycline, intensifying the storm-induced shallow of oxycline during BOB 04. Furthermore, the pre-existing cyclonic eddy induced a long time of DO decrease after BOB 04. This study suggests that the subsurface DO concentrations in the BoB are affected mainly by storm-induced physical processes, and the mesoscale eddies also play an important role.

Cyst abundance and identity are essential for understanding and predicting blooms, and for assessing the dispersal of toxic target dinoflagellate species by natural or human mediated ways, as with ballast waters. The aim of this study was to apply rapid, specific and sensitive qPCR assays to enumerate toxic dinoflagellate cysts in sediment samples collected from Adriatic harbours. The molecular standard curves of various target species allowed obtaining the rDNA copy number per cyst. The analytical sensitivity for specific standard curves was determined to be 2 or 10 rDNA copies per reaction. The abundance varied in the range of 1–747 dinoflagellate cysts g⁻¹ dry weight. The assays showed greater sensitivity as compared to counts by light microscopy. This qPCR method revealed a powerful tool for the quantification of cysts from toxic dinoflagellate resting stages in sediment samples from Adriatic ports.

The zooplankton community was analyzed in ten Adriatic ports as part of the port biological baseline surveys carried out within the framework of the BALMAS project. We provide the first inventory of resident zooplankton taxa and five detected non-indigenous zooplankton species (NIS), and their spatial and seasonal distribution patterns. Copepoda and meroplankton larvae, particularly of Mollusca, dominated the zooplankton in all sampled ports. We recorded a total of 76 indigenous copepod species and five NIS, among which Parvocalanus crassirostris detected in Šibenik and Rijeka ports and Oithona davisae in Venice port, are new for the Adriatic. All detected NIS were widely distributed within the recipient ports. Co-occurrences of NIS were observed in the ports of Venice, Bari, Ancona and Trieste. The results are expected to contribute to the quality of practical monitoring of zooplankton NIS and facilitate the synchronization of efforts in creating NIS-related policies for the Adriatic sub-region.

During the last years, the oil and gas explorations, extractions and refineries have led to severe ecological damages into the sensitive environment of the Persian Gulf. In this study, the level of oil contamination, the source of hydrocarbons and the degree of weathering or degradation extent were investigated in the Surface Sediments of Pars Special Zone, Persian Gulf. Fifteen sediment samples were collected. The Gas Chromatography-Mass Spectrometry used to analyze Aliphatic Hydrocarbons (AHC) and EPA's sixteen compounds of Polycyclic Aromatic Hydrocarbons (PAHs). The total concentration of Aliphatic Hydrocarbons found to be in the range of 693 to 3752 μg/g and the 16 EPA PAHs compounds varied between 46.6 and 84.7 ng/g dry weight in the region. The concentration of hydrocarbons found to be lower than the level of threshold effects. The source of compounds was also identified by developing the multiple indices.

Previous studies on PCDD/Fs and PCBs in dugong (Dugong dugon) blubber reported unexpectedly elevated TEQ levels. This study analysed archived blubber, muscle, liver and faeces obtained from dugongs from two areas along the Queensland coast. All samples showed detectable levels of PCDDs and PCBs, while PCDFs were consistently near or below LOQ. PCDD levels in dugongs contributed to a large proportion (<95%) of sum TEQ levels in all tissues (blubber: 6.7–38 pg g−1 lw, muscle: 5.7–96 pg g−1 lw, liver: 3.3–42 pg g−1 lw, faeces: 203 pg g−1 lw). Liver/blubber tissue ratios show that PCDDs are preferentially accumulated in the liver with higher degree of chlorination. The same trend was not so obvious with PCBs, which occasionally showed higher hepatic sequestration of lower chlorinated PCBs such as PCBs 28 and 77. PCDD congeners were dominated by OCDD which is similar to the profiles from the dugongs' food source, namely sediment and seagrass.

Several country–wide bans have recently been implemented for microbeads, which are a form of microplastics that are found in our oceans. The effect of the ban on reducing the overall quantity of microplastics in our oceans, however, may not be significant. This paper explores the scientific data related to microbeads to evaluate whether an underlying risk or combination of risks led to the ban, what impact public perception and activism had on this issue, and how this case study may be extrapolated to other emerging issues, such as per- and polyfluoroalkyl substances (PFAS). In some cases, the strategy for communicating with the public and managing the outrage can be equally as important as the regulatory and technical strategies.

Dredging poses a potential threat to coral reefs, yet quantifying impacts is often difficult due to the large spatial footprint of potential effects and co-occurrence of other disturbances. Here we analyzed in situ monitoring data and remotely-sensed sediment plumes to assess impacts of the 2013–2015 Port of Miami dredging on corals and reef habitat. To control for contemporaneous bleaching and disease, we analyzed the spatial distribution of impacts in relation to the dredged channel. Areas closer to dredging experienced higher sediment trap accumulation, benthic sediment cover, coral burial, and coral mortality, and our spatial analyses indicate that >560,000 corals were killed within 0.5 km, with impacts likely extending over 5–10 km. The occurrence of sediment plumes explained ~60% of spatial variability in measured impacts, suggesting that remotely-sensed plumes, when properly calibrated against in situ monitoring data, can reliably estimate the magnitude and extent of dredging impacts.

Today, four decades past peak anthropogenic lead emissions in the 1970s, dissolved lead (DPb) concentrations in the surface ocean remain elevated. To constrain contemporary sources and sinks of DPb, we studied high latitude surface waters of the North Atlantic and the Southern Ocean. We observed high concentrations of surface DPb (46 pmol kg⁻¹) near South Georgia in the Southern Ocean, sourced from glacial flour, while offshore DPb concentrations of 3–9 pmol kg⁻¹ were attributable to aeolian Pb inputs mainly from Patagonia. Dissolved Pb in the North Atlantic (4–29 pmol kg⁻¹) originated from aeolian particles from Northern Hemisphere sources. Extremely low DPb concentrations of <5 pmol kg⁻¹ found in both polar regions were the result of scavenging of DPb onto biogenic particles formed during spatially confined phytoplankton blooms, indicating that changes in phytoplankton abundance may alter the residence time and distribution of DPb in the surface ocean.