Surficial marine sediments were sampled along the south-east coast and in Discover Bay Jamaica. Total elemental composition was determined for the sediments using three techniques. Total mass fractions of Al, As, Br, Ce, Co, Cr, Cs, Eu, Fe, La, Mn, Sb, Sc, Th, U, V, and Zn were determined using instrumental neutron activation analysis; Cu, Ni, Pb, Sr and Zr using energy dispersive X-ray fluorescence; and Hg using a direct mercury analyser. Potential anthropogenic hotspots were assessed using indices including enrichment factor (EF), geoaccumulation index (Igₑₒ), ecological risk (Eᵣ) and potential ecological risk index (Rᵢ). The quality of the sediments was also assessed using the sediment quality guidelines (SQGs). Temperature, pH, salinity, dissolved oxygen and organic carbon content (OC) were determined to assess variation across sample sites. Results indicated moderate to severe ecological risk at sites in Port Royal and Discovery Bay with ecological risk values as high as 381.9.

The faunistic analysis of soft bottom benthic materials collected from the Aegean and Levantine coasts of Turkey in August 2016 and 2017 revealed a total of 7 sipuncula species and 975 individuals belonging to 6 genera. The maximum population density of sipunculans was found to be 1790 ind.m⁻² in the Aegean Sea and 730 ind.m⁻² in the Levantine Sea. Onchnesoma steenstrupii steenstrupii was the most dominant species, comprising 83.1–92.8% of the total number of specimens in the Aegean Sea and 87.2–96.2% of the total number of specimens in the Levantine Sea. Four major sipunculan assemblages were found in the regions, and the main environmental factors controlling these assemblages were depth, temperature, salinity, the sediment grain size, nutrients and total organic carbon. Different abiotic factors affected the distribution of different sipunculan species in the regions. The present study included two cryptogenic sipunculan species; Apionsoma (Apionsoma) misakianum and Aspidosiphon (Aspidosiphon) mexicanus.

Trace metal dynamics were investigated in mangroves developing in semi-arid New Caledonia, where Avicennia and Rhizophora stands grow in the upper and lower intertidal zone, respectively. We collected soil samples and mangrove tissues in an undisturbed site, a mining-influenced site and in a mining and aquaculture-influenced site. Differences in duration of immersion and organic matter (OM) cycling resulted in a sharp decrease of metal concentrations in soils and plants from landside to seaside. Both species were tolerant to metals mainly via exclusion, (i.e. metal bioaccumulation restricted to roots and leaf litter). Strong correlations (p < 0.05) were found between Na and Fe, Mn, Cu and Zn in green and senesced leaves of Avicennia marina, indicating a possible role of those metals in mechanisms to cope with hypersaline conditions.Increasing metal pollution, aridity and sea-level rise are likely to result in a decrease in mangrove efficiency in filtering trace metals seaward.

Marine bivalves are often used as a sentinel species in coastal environmental monitoring since changes in the environmental quality are often well preserved in their cells and tissues. Anadara and Tegillarca species of Arcidae, the blood cockles, are considered to be good sentinel species in monitoring coastal pollution and ecosystem health because they are distributed widely in the subsurface of intertidal mudflats. Internal cellular defense of the blood cockles to physical and biological stresses is mediated by the circulating hemocytes, while their hemocyte types and functions are poorly studied. In this study, we first characterized morphology and immune-related activities of hemocytes of three common blood cockles Anadara broughtonii, A. kagoshimensis, and Tegillarca granosa using flow cytometry. Based on cell morphology and immunological functions, we described five types of hemocytes identically in the three blood cockles: erythrocytes type-I (erythrocytes-I), erythrocytes type-II (erythrocytes-II), granulocytes, hyalinocytes, and blast-like cells. Erythrocytes were round cells containing hemoglobin with numerous granules in the cytoplasm and these cells consist of two central populations. Erythrocytes-I were the most abundant cells accounting for 80–89% of the total circulating hemocytes and exhibited a certain level of lysosome and oxidative capacity. Erythrocytes-II were the largest cells and displayed high lysosome content and the most active oxidative capacity. Both erythrocytes-I and erythrocytes-II did not show phagocytosis capacity. Granulocytes were intermediated-sized hemocytes characterized by granules in the cytoplasm and long pseudopodia on the cell surface, and these cells were mainly engaged in the cellular defense exhibiting the largest lysosome content, the most active phagocytosis, and high oxidative capacity. Contrary to granulocytes, hyalinocytes were comparatively small and round cells and exhibited no granules in the cytoplasm. Hyalinocytes displayed a certain level of lysosome and phagocytosis and oxidative capacities. Blast-like cells characterized by the smallest size and small quantity of cytoplasm and exhibited an absence of phagocytosis and extremely low oxidative capacity, suggesting that this population is not directly involved in the cell-mediated immune activities. In conclusion, flow cytometry indicated that three blood cockles had five types of hemocytes, and the erythrocytes and granulocytes were mainly involved in the immunological activities.

Beaches on Henderson Island, one of the Pitcairn Islands in the central South Pacific, have been reported to have some of the highest standing stocks of stranded plastic recorded. Surveys of floating debris at sea show that this is not related to high densities of plastic in the area. Only 19 macroplastic items were observed during 905 km of at-sea transects (0.5 items·km⁻²; 135 g·km⁻²). This low density confirms previous microplastic surveys which show that the Pitcairn group lies west of the South Pacific Gyre. Plastic loads on beaches at other islands in the Pitcairn group are not exceptional. The east coast of Henderson Island appears to be particularly effective at accumulating drifting debris, but many small plastic fragments on these beaches probably result from degradation in situ, so removing macroplastics will reduce the formation of microplastics.

A total of 23 sediment samples are collected from Ross Sea and Drake Passage to investigate the distribution characteristics of polychlorinated biphenyls (PCBs) in the Antarctic marine sediments. Over 51 kinds of PCBs are detected through exhaustive searches using multiple reaction monitoring system. The results show that the concentration of individual PCB congener and total PCBs vary greatly among sampling sites, ranging from not detected to 49.75 ng g⁻¹ and 3.77 to 246.86 ng g⁻¹, respectively. The average PCBs level in Ross Sea is ten times higher than that in Drake Passage. Two different homologues, hexa- and tetra-CBs, give high contributions to ∑PCBs level in most samples from Ross Sea and Drake Passage, respectively. Our results support that the marine sediments might be an important sink for PCBs. Besides, the biological pump and the primary productivity might be responsible for the distribution differences of PCBs between Ross Sea and Drake Passage.

Here, we examined the coral bleaching responses during the 2016 thermal stress event and post-bleaching changes in coral communities in the heavily disturbed reefs of the Bolinao-Anda Reef Complex (BARC), northwestern Philippines. Less than 25% of colonies bleached, with 77% attributed to five genera (Dipsastrea, Porites, Fungia, Seriatopora, and Montipora). Coral bleaching prevalence was associated with site location, coral composition, and coral abundance, suggesting that small-scale variation (<20 km) in coral communities (taxa and density) influences spatial variation in coral bleaching prevalence. There was no noticeable change in coral composition and cover two years after the bleaching event as exposure to chronic disturbance likely selected for the dominance of stress tolerant coral taxa and communities. Results show that the 2016 thermal stress event caused coral bleaching but with low prevalence at the BARC, which suggests that disturbed reefs may provide spatial refuge to coral communities from thermal stress.

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.

In this study, the amount of heavy metals such as Ni, Cd, Pb and Cu and some physiochemical factors including pH, temperature and total organic carbon (TOC) in the ballast water of the ships entering the Bushehr Port were measured for two years (cold and hot seasons) before and after the ballast water convention was enforced. The mean concentrations of Ni, Cd, Pb and Cu, before and after implementation of the convention were 46.55, 3.93, 5.36, 58.83 and 26.41, 2.12, 2.59, 23.54 ppb. It became clear that the concentrations of heavy metals after the implementation of the convention was lower in comparison and there was a significant difference (p < .05). It seems that continuous monitoring of the quality of the ballast water and determination of locations free of pollution and contamination in the Persian Gulf are necessary for ships that intend to exchange their ballast water in this Gulf.

A model is proposed for the beach process of buoyant marine plastics, specifically its beaching and backwashing, by introducing beaching and backwashing diffusion coefficients and the onshore-offshore advection-diffusion equations of plastics for the upper layers in the beach and adjacent coastal sea. The backwashing diffusion coefficient was estimated from the average residence time of the beached plastics and the beach width, and then the beaching diffusion coefficient was estimated from the flux-balance assumption between the beaching and backwashing fluxes. Finite difference calculations in the staggered-grid system demonstrated that the amount of beached plastics responds as predicted by the linear system analysis when the beach had an exponential decay type of unit impulse response regardless of the ratio between the residence time and the period of beaching flux fluctuation from the nearshore. The condition in which the flux balance assumption holds was also discussed.