The abundance of radionuclides in the Arctic Actiniaria has limited study despite their environmental importance in coastal food chains. Although the Arctic has incurred relatively little contamination by anthropogenic radionuclides as a result of nuclear weapons tests, there are still detectable levels of radionuclide activity observed in marine species. In this study of anthropogenic radionuclide activity in Actiniaria from Spitsbergen we observed levels of ⁹⁰Sr from 0.92 Bq kg⁻¹dw to 18 Bq kg⁻¹dw and for ¹³⁷Cs from 1.2 Bq kg⁻¹dw to 12 Bq kg⁻¹dw. The highest values of ⁹⁰Sr and ¹³⁷Cs were observed in organisms at stations close to seabird colonies and a river mouth, suggesting that fecal material and melting glaciers may be sources of radionuclides in the Arctic environment. The body mass of individual organisms affected bioaccumulation of ⁹⁰Sr and ¹³⁷Cs in Actiniaria, with radionuclide bioaccumulation occurring most intensively in the smaller specimens.

Microplastics are a group of ubiquitous persistent pollutants that have rapidly attracted much attention from the scientific community as well as the general public due to the growing awareness of the environmental risks they pose. However, due to limitations and variations in sampling, analytical measurement methods, and the different units used for reporting data, reliable comparisons between studies in the Gulf region and internationally are not straightforward. This study proposes standardized protocols for marine sediment, seawater, marine biota and aerosol (1) sampling, (2) sample processing, (3) sample identification and (4) reporting units to be used. An attempt has been made to highlight the limitations of the widely employed strategies for sampling microplastics in seawater, where a large portion of the microplastics is not sampled due to the mesh sizes used. The issues with the processing of biota samples and aerosols are likewise addressed, and recommendations are also made for standardization of units for reporting microplastic quantification. Protocols for collection of bottom sediments and aerosols are also proposed. These are the environmental matrixes for which there are no harmonized protocols in the Gulf region; hence if a standardized approach is adopted, it will enable and improve comparisons between the studies within this region and can be useful for similar studies in other marine areas as well.

Recurrent thermal stress events and intensified precipitation alter the ocean environment resulting in the decline of coral populations. However, the influence of these changes on larval survival and settlement is not well understood. We examined the effect of salinity (15, 20, 25, 30, 35, and 40 ppt) and temperature (27 °C, 30 °C, and 33 °C) on settlement and survival of larvae of the octocoral, Heliopora coerulea. Larvae settled successfully at salinities from 25 to 30 ppt. On the other hand, larval survival and settlement decreased with increasing temperature. A combination of 25–35 ppt and 27–30 °C resulted in highest survival and settlement. These results indicate that early life stages of H. coerulea are negatively impacted by thermal stress but may be able to survive at reduced salinity. The wider tolerance range of H. coerulea larvae compared to most scleractinian larvae may thus contribute to the success of this coral on disturbed reef ecosystems.

Population growth around water bodies is deteriorating environmental quality. The benthic foraminiferal and trace element concentration in a pair of short sediment cores were used to establish the quality of the sedimentary environment in a tropical coastal lagoon in the southwestern Gulf of California. From 25 cm depth towards the surface of the sediment core, Ammonia beccarii was dominant over nontolerant species and the concentrations of V, Ni, Co, Zn, Cu, Hg and Pb in the sediments increased compared with the lower depth intervals. This finding suggests a deterioration in the environmental quality of the lagoon since 1980, associated with an increase in the sizes of the population and vehicle fleet in the city of La Paz, Baja California Sur, and with the operation of three fossil fuel-based thermoelectric plants since 1985.

Diluted bitumens are produced by adding lower viscosity diluent to highly viscous bitumen to enable it to flow through pipelines and thus may behave differently than conventional oils when spilled into coastal seawater. Simulated surface spills using three different diluted bitumen products were carried out in May, July and November and water column hydrocarbons were monitored over a 14 day period. Volatile and total petroleum hydrocarbons varied in the water column depending on season and type of diluent. In summer, products diluted with synthetic crude or a mixture of condensate and crude released droplets into the water column. Diluted bitumen did not sink to the bottom of the enclosures with surface slicks showing a range of weathering after 14 d. With most of the diluted bitumen product remaining on the surface for 14 d, a rapid conventional clean up response may be effective in low energy, coastal waters.

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.

Microplastics in shoreline sediments were investigated from Da Nang beach for the first time. Sediment samples at the two depth strata (0–5 cm and 5–10 cm) at eight sites along the entire coast were collected for identifying the characteristics of microplastics, including their concentration, size, shape, color, and nature. The synthetic fiber was the predominant type of microplastics, accounting for 99.2% of the total items. Blue (59.9%) and white (22.9%) were the most common colors of the fibers. Synthetic fibers showed a homogenous distribution at all sampling sites with a mean concentration of 9238 ± 2097 items kg⁻¹ d.w. Meanwhile, the fibers tended to concentrate much more at the surface stratum than the deeper stratum. A large number of synthetic fibers (81.9%) were in the size range of 300–2600 μm, which might pose a threat to marine biota and human health.

The issue of plastic in the marine environment is a growing concern. Images of floating plastic island are often found in mainstream press publications. In this study, we focus on such an episode that occurred in October 2017 near the island of Roatan in the Gulf of Honduras. Our objective is to find out if Lyapunov Exponents, a type of Lagrangian Coherent Structure diagnostic can characterize such plastic accumulations. We use routinely available weather and ocean model data as inputs to a Lagrangian drift model. With the drift simulation outputs we compute the Lyapunov exponents. We perform sensitivity studies by varying the separation ratio value, the wind coefficient, the start date and the simulation duration to investigate the ability of the Lyapunov exponents to provide useful information. We find that with the right settings, Lyapunov Exponents can indeed highlight areas of plastic accumulation and their transient nature in coastal seas.

Eleven organophosphate esters (OPEs) in air and seawater were investigated from the Northwestern Pacific to the Arctic Ocean. The concentration of Σ₁₁OPEs in air and seawater ranged from 231.56 to 1884.25 pg/m³ and from 8.47 to 143.45 ng/L, respectively. Halogenated OPEs dominated in both two media. The slight decreasing trend was observed for OPEs in gaseous air, no obvious trend for particle-bound OPEs and in seawater. The net air-seawater exchange flux ranged from −792.68 to 590.29 pg/m²/day. The dry deposition flux ranged from 16.4 to 185 ng/m²/day with high value observed at the Bering Strait (64.70 ng/m²/day). The relationship between temperature and OPEs particle-bound fractions suggests that temperature might be a driving factor of OPEs long-range atmospheric transport (LRAT). This research highlighted that OPEs are subject to LRAT from the Asian continent to the northwestern Pacific and Arctic Oceans and demonstrated the “sink” in polar regions of OPEs atmospheric transportation.

We report here for the first time the effectiveness of Reteporella bryozoan genus in the early stage of coralligenous reefs recolonization through the analysis of the settlement and the population size structure over a two-years period at two impacted and two control sites. Results highlighted how Reteporella spp. colonies strongly recolonized, from 2017 to 2019, the bare coralligenous reefs subjected to the Costa Concordia shipwreck and its related anthropogenic disturbances, notably increasing both their density and percentage coverage. We recorded differences in colony size among impacted and control sites. Overall, large-sized colonies were reported at impacted sites exclusively, where Reteporella settlement and growth patterns differed if compared to control areas. This study highlights implications for the maintenance of the ecological functions, for the recovery processes, and for the future ecological shifts affecting one of the most important Mediterranean coastal ecosystems, the coralligenous reefs.