It has been proven that there is an extensive bulk of plastic debris in marine ecosystems. The present study analyzed solid waste generation, its management and final disposal methods in Caspian Sea coastal countries, and the amount of plastic waste entering the Caspian Sea. The results showed that, on average, more than 90% of waste in the Caspian Sea coastal countries is mismanaged. According to our estimates, 425 kilotons (Kt) of plastic waste was generated by Caspian Sea coastal countries in 2016, of which, with high probability, 58–155 Kt find their way to the Caspian Sea. It is estimated that without improved waste management infrastructures, the amount of plastic waste entering the Caspian Sea will increase to 68–182 Kt by 2030, an increase of about 15%. Accordingly, the related cumulative environmental and health problems could be more severe. All countries located in the coastal areas of the Caspian Sea should revise their solid waste and plastic waste management programs to protect that sensitive marine ecosystem.

Microplastic pollution status in Kuwait coastal areas was assessed A total of 44 intertidal locations were sampled for beach sediment. Short trawls (40) were conducted. In addition, 87 fish and mussels gastrointestinal contents were examined. Microplastics were characterized by Raman spectroscopy. Contrary to the expectation very few microplastic particles were found. Only 37 MPs were detected in beach sediments at 15 locations. Seawater trawls indicated that MPs were low in the numbers. MPs were found in just two samples from Kuwait Bay and also in two samples from the southern areas. In biota, only 3 pieces of plastics were recovered from gastrointestinal tracks of hamour fish. The identified MPs were dominantly polypropylene, polyethylene and polystyrene. It appeared that the microplastic levels in sediment, water and biota were much lower compared to published values from adjoining areas, however, were comparable to the absolute numbers of particles from Qatar and Oman.

Nowadays, marine ecosystem monitoring and assessment are increasingly depending on variety of molecular tools. With these background, DNA barcoding play a key role in species identification with increasing speed and accuracy, and although the suitability for developing genetic tools like genomic AMBI (gAMBI). Presently we have submitted 13 benthic polychaete species using mtCOI to GenBank. Of these, nine species were newly submitted, and hence they act as a benchmark and reference organism for identifying respective polychaete species worldwide in the near future. Based on that, our study results tend to be helpful for motivating among the researcher in order to implementing the genomic AMBI (gAMBI).

Further to our 2015–16 investigation, this study revealed the repeated presence of microplastics (MPs) in the coastal environment (Deep Bay, Tolo Harbour, Tsing Yi and Victoria Harbour) of Hong Kong from July 2016 to March 2017. The highest level of MPs in coastal surface water (17,182 particles/100 m³) was detected in Tsing Yi. Microplastic abundance in sediments of different sites (59 to 225 plastic particles/kg), however, did not vary significantly. MPs in the size of ≤1 mm were predominated in surface waters (53.3% to 98.6%) and sediments (79.1% to 96.8%). MPs in the shape of pellets and fragments were prevalent in surface waters and sediments respectively. Seasonal pattern of microplastic pollution was consistently observed in Victoria Harbour and Tsing Yi, where the number of MPs was always higher in dry season than in wet season for two consecutive years.

Although marine plastic litter has been recognized as a global problem, there are insufficient data on the extent of plastic pollution in the Black Sea. The results from this pilot study of the floating marine litter and microplastics along the Bulgarian Black Sea coast revealed high quantities of floating litter (60.3–93.8 items.km⁻²). The microplastic concentrations (1.14 × 10⁴–1.91 × 10⁵ items.km⁻², 0.33–490.52 g.km⁻²) were on average lower than those found in other parts of the Black Sea, the Baltic Sea, and the Mediterranean Sea, although the observed ranges were similar. Further studies are needed to elaborate the extent and spatial distribution of this type of pollution in the Black Sea basin.

Heavy metal assessment and natural radioactivity determination in sediments of North Cyprus (Mediterranean coast) were carried out using different analysis methods. The average activity concentrations (range) of ²²⁶Ra, ²³²Th, and ⁴⁰K were found to be 20.1 (30.6–9.2) Bq kg⁻¹dry weight, 18.4 (26.9–12.4) Bq kg⁻¹dw, and 467.3 (619.9–147.6) Bq kg⁻¹dw, respectively. The average activity concentrations of ²²⁶Ra and ²³²Th in the sediment samples were less than the acceptable limits, whereas the average activity concentration of ⁴⁰K in the sediment samples was higher than the worldwide average concentration. With regard to the studied heavy metals, the corresponding decreasing average concentration orders were found to be Mn > Zn > Cr > Ni > Cu > Pb. The heavy metal concentration values that were determined for sediment samples were compared with the values obtained in other studies. According to contamination indexes, the results (except for Cu in S-9) indicated no significant contaminated area.

Effects of microplastics on marine taxa have become a focal point in marine experimental biology. Almost all studies so far, however, assessed the influence of microplastics on animals only in relation to a zero-particle group. Documented microplastic impacts may thus be overestimated, since many marine species also experience natural suspended solids as a stressor. Here, we compared the effects of polyvinyl chloride (PVC) and red clay (mean for both particles: ~12–14 μm) on the Mediterranean mussel Mytilus galloprovincialis across three particle concentrations (1.5, 15, 150 mg l⁻¹). Exposure to PVC for 35 days lowered mussel body condition index by 14% in relation to clay, but no difference in byssus production, respiration and survival rates emerged between the two particle types. This suggests that the effects of synthetic particles on filter feeders may emulate those of natural suspended solids, and highlights the importance of including natural particles in microplastic exposure studies.

The use of trace metals and rare-earth elements (REEs) is increasing in the mining, metallurgic, electronic, and automobile industries due to their magnetic, heat-resistant, and phosphorescent properties. While large amounts of these metals are released to the environment, the toxic consequences in marine organisms are poorly understood. In Chile a mass stranding event of long-finned pilot whales (LFPW) (Globicephala melas) occurred in 2016 due to unknown consequences. Al, Ce, Cr, Cu, Tl, and Zn concentrations were analyzed in LFPW blubber tissue and correlated with body size and age class of individuals. While Al and Zn were higher in juvenile individuals, Ce, Cu, Cr, and Tl were higher in adults. This study provides the first base line of trace metals and REE in LFPW from the southern hemisphere and demonstrates the existence and persistence of trace elements in marine top predators from remote ecosystems like the Chilean Patagonia.

Element concentration (Fe, Mn, Pb, Zn, Cu, Cr, Ni and Co) in the surface sediments of Ashtamudi estuary, Southwest coast of India, has been analyzed to understand the spatial variation and potential ecological risk status. The sediment pollution index and Potential Ecological Risk index suggest that the northeastern part of the estuary exhibits low to moderate polluted sediments with moderate ecological risk. The results of correlation analysis indicate that the natural weathering process and river input play an important role in the distribution of the elements in the surface sediments of the estuary. The extracted factor results indicate that the fine sediment fractions supporting for accumulation of the trace elements, whereas the enriched level of Fe and Mn is chiefly controlled by the riverine process, and other elements are contributed by anthropogenic influences.

We studied the effects of chronic exposure to metals on energy reserves and reproduction in the clam Megapitaria squalida in two nearby populations exposed to different levels of pollution from mining operations in the Gulf of California, Mexico. Female M. squalida from San Lucas beach had good reproductive health status, whereas Santa Rosalia specimens consistently showed low energy reserves, massive oocyte resorption throughout the year, high frequencies of undifferentiated individuals, low proportions of ripe and spawning organisms, smaller and fewer oocytes per follicle, and significantly lower follicular areas. Ovarian levels of Co, Cu, Pb, Mn, and Zn were consistently higher in clams from Santa Rosalia. The poor reproductive health of clams inhabiting this site may be attributed to their long-term exposure to high Co, Cu, and Pb concentrations, as these have been shown to cause toxicity and reproductive impairments in other marine organisms.