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Concern is rising about widespread contamination of the marine environment by microplastics. Plastic debris in the marine environment is more than just an unsightly problem. Images of beach litter and large floating debris may first come to mind, but much recent concern about plastic pollution has focused on microplastic particles too small to be easily detected by eye (see the figure). Microplastics are likely the most numerically abundant items of plastic debris in the ocean today, and quantities will inevitably increase, in part because large, single plastic items ultimately degrade into millions of microplastic pieces. Microplastics are of environmental concern because their size (millimeters or smaller) renders them accessible to a wide range of organisms at least as small as zooplankton, with potential for physical and toxicological harm.

The loss of animal species in terrestrial environments has been well documented and is continuing. Loss of species in marine environments has been slower than in terrestrial systems, but appears to be increasing rapidly. McCauley et al. review the recent patterns of species decline and loss in marine environments. Though they note many worrying declines, they also highlight approaches that might allow us to prevent the type of massive defaunation that has occurred on land. Science , this issue 10.1126/science.1255641 Marine defaunation, or human-caused animal loss in the oceans, emerged forcefully only hundreds of years ago, whereas terrestrial defaunation has been occurring far longer. Though humans have caused few global marine extinctions, we have profoundly affected marine wildlife, altering the functioning and provisioning of services in every ocean. Current ocean trends, coupled with terrestrial defaunation lessons, suggest that marine defaunation rates will rapidly intensify as human use of the oceans industrializes. Though protected areas are a powerful tool to harness ocean productivity, especially when designed with future climate in mind, additional management strategies will be required. Overall, habitat degradation is likely to intensify as a major driver of marine wildlife loss. Proactive intervention can avert a marine defaunation disaster of the magnitude observed on land.

Microplastics in the environment are a subject of intense research as they pose a potential threat to marine organisms. Plastic fibers from textiles have been indicated as a major source of this type of contaminant, entering the oceans via wastewater and diverse non-point sources. Their presence is also documented in terrestrial samples. In this study, the amount of microfibers shedding from synthetic textiles was measured for three materials (acrylic, nylon, polyester), knit using different gauges and techniques. All textiles were found to shed, but polyester fleece fabrics shed the greatest amounts, averaging 7360 fibers/m−2/L−1 in one wash, compared with polyester fabrics which shed 87 fibers/m−2/L−1. We found that loose textile constructions shed more, as did worn fabrics, and high twist yarns are to be preferred for shed reduction. Since fiber from clothing is a potentially important source of microplastics, we suggest that smarter textile construction, prewashing and vacuum exhaustion at production sites, and use of more efficient filters in household washing machines could help mitigate this problem.

At the 62nd Meeting (2011) of the Marine Environment Protection Committee (henceforth MEPC), the IMO had adopted the proposed amendment adding to the MARPOL Annex Chapter Ⅵ making it mandatory the EEDI (Energy Efficiency Design Index) for new ships as well as the SEEMP (Ship Energy Efficiency Management Plan) for all ships. This was eventually for reducing GHG emissions from international shipping vessels, and has been effective since the 1st of January 2013 for ships weighing 400GT. Notably, at the 70th MEPC, the plan to develop a roadmap for the comprehensive IMO strategy on reducing GHGs from ships was approved, and as such, the plans including its short-term, mid-term and long-term measures have been arranged in order to adopt the pertinent strategy by 2023. Following the approved roadmap, at the 72 nd MEPC (April, 2018), the first stage of reducing GHG emissions from ships was selected/passed as the Initial IMO strategy for the reduction of GHGs from ships (henceforth Initial IMO GHG Strategy), and at the 73 rd MEPC (October, 2018), subsequent programs following the Initial IMO GHG Strategy were arranged. In this paper, the following issues will be introduced and discussed 1) the initial IMO strategy for the reduction of GHG from ships, 2) the contents of the 73 ~ 74 MEPC meeting regarding the follow-up actions related GHG reduction programs until 2023 to be executed (including specific matters concerning the execution of potential short-term, mid-term and long-term measures) 3) the GHG reduction strategies, GHG response policies of IMO member states and 4) finally, trends in technological developments for GHG reduction from ships.

Antibiotics, as pollutants of emerging concern, can enter marine environments, rivers, and lakes and endanger ecology and human health. The purpose of this study was to review the studies conducted on the presence of antibiotics in water, sediments, and organisms in aquatic environments (i.e., seas, rivers, and lakes). Most of the reviewed studies were conducted in 2018 (15%) and 2014 (11%). Antibiotics were reported in aqueous media at a concentration of <1 ng/L–100 μg/L. The results showed that the highest number of works were conducted in the Asian continent (seas: 74%, rivers: 78%, lakes: 87%, living organisms: 100%). The highest concentration of antibiotics in water and sea sediments, with a frequency of 49%, was related to fluoroquinolones. According to the results, the highest amounts of antibiotics in water and sediment were reported as 460 ng/L and 406 ng/g, respectively. In rivers, sulfonamides had the highest abundance (30%). Fluoroquinolones (with an abundance of 34%) had the highest concentration in lakes. Moreover, the highest concentration of fluoroquinolones in living organisms was reported at 68,000 ng/g, with a frequency of 39%. According to the obtained results, it can be concluded that sulfonamides and fluoroquinolones are among the most dangerous antibiotics due to their high concentrations in the environment. This review provides timely information regarding the presence of antibiotics in different aquatic environments, which can be helpful for estimating ecological risks, contamination levels, and their management.

Superoxide and other reactive oxygen species (ROS) originate from several natural sources and profoundly influence numerous elemental cycles, including carbon and trace metals. In the deep ocean, the permanent absence of light precludes currently known ROS sources, yet ROS production mysteriously occurs. Here, we show that taxonomically and ecologically diverse heterotrophic bacteria from aquatic and terrestrial environments are a vast, unrecognized, and light-independent source of Superoxide, and perhaps other ROS derived from Superoxide. Superoxide production by a model bacterium within the ubiquitous Roseobacter clade involves an extracellular oxidoreductase that is stimulated by the reduced form of nicotinamide adenine dinucleotide (NADH), suggesting a surprising homology with eukaryotic organisms. The consequences of ROS cycling in immense aphotic zones representing key sites of nutrient regeneration and carbon export must now be considered, including potential control of carbon remineralization and metal bioavailability.

Corrosion had aroused extensive concern and attention because it was an unavoidable problem for marine equipment and facilities in service. However, the current status and development trend of marine environment corrosion research had seldom been systematically studied. Therefore, it was encouraged to use bibliometrics and information visualization analysis methods to conduct bibliometric analysis of related publications in the field of marine environment corrosion based on HistCite, CiteSpace, and VOSviewer software programs. Compared with the traditional comments of researchers in this field, this research provided a direction for the development of quantitative analysis and visualization of marine environment corrosion on a large scale. The results showed that the overall focus of research in the field of marine environment corrosion continued to increase from 1900 to 2019. China had the highest publication productivity, the USA had the highest h-index value and the second highest average citations per item value, Materials Science was the most popular subject category, Corrosion Science was the main journal and Melchers RE was the author with the most output contributions. This research also exhibited four hot spots in this field. In addition, this work could help new researchers to find research directions and identify research trends and frontiers in the field of marine environment corrosion by tracing the research hotspots of topic categories, countries, institutions, journals, authors, and publications in recent years.

Bacteria are widespread in nature as they can adapt to any extreme environmental conditions and perform various physiological activities. Marine environments are one of the most adverse environments owing to their varying nature of temperature, pH, salinity, sea surface temperature, currents, precipitation regimes and wind patterns. Due to the constant variation of environmental conditions, the microorganisms present in that environment are more suitably adapted to the adverse conditions, hence, possessing complex characteristic features of adaptation. Therefore, the bacteria isolated from the marine environments are supposed to be better utilized in bioremediation of heavy metals, hydrocarbon and many other recalcitrant compounds and xenobiotics through biofilm formation and production of extracellular polymeric substances. Many marine bacteria have been reported to have bioremediation potential. The advantage of using marine bacteria for bioremediation in situ is the direct use of organisms in any adverse conditions without any genetic manipulation. This review emphasizes the utilization of marine bacteria in the field of bioremediation and understanding the mechanism behind acquiring the characteristic feature of adaptive responses.

Microplastics are ubiquitous within the marine environment. The last 10 years have seen research directed at understanding the fate and effect of microplastics within the marine environment; however, no studies have yet addressed how concentrations of these particles could affect sedimentary processes such as nutrient cycling. Herein we first determine the concentration and spatial distribution of microplastics within Baynes Sound, a key shellfish-growing area within coastal British Columbia (BC). We also determined sediment grain size and % organic matter (OM) such that we could relate spatial patterns in sediment microplastic concentrations to sedimentary processes that determine zones of accretion and erosion. Using field-determined concentrations of microplastics, we applied laboratory microcosms studies, which manipulated sediment concentrations of microplastics, OM, and bivalves to determine the influence of sediment microplastics on ammonium cycling within intertidal sediments. Concentrations of microplastics determined within the intertidal sediment varied spatially and were similar to those found in other coastal regions of high urban use. Concentrations were independent of grain size and OM suggesting that physical processes other than those that govern natural sediment components determine the fate of microplastics within sediments. Under laboratory conditions, concentrations of ammonium were significantly greater in the overlying water of treatments with microplastics, clams, and OM compared with treatments without microplastics. These preliminary studies suggest that high concentrations of microplastics have the potential to alter key sedimentary processes such as ammonium flux. This could have serious implications, for example, contributing to eutrophication events in regions of the coast that are highly urbanized.

Viruses are the most common biological entities in the marine environment. There has not been a global survey of these viruses, and consequently, it is not known what types of viruses are in Earth's oceans or how they are distributed. Metagenomic analyses of 184 viral assemblages collected over a decade and representing 68 sites in four major oceanic regions showed that most of the viral sequences were not similar to those in the current databases. There was a distinct \"marine-ness\" quality to the viral assemblages. Global diversity was very high, presumably several hundred thousand of species, and regional richness varied on a North-South latitudinal gradient. The marine regions had different assemblages of viruses. Cyanophages and a newly discovered clade of single-stranded DNA phages dominated the Sargasso Sea sample, whereas prophage-like sequences were most common in the Arctic. However most viral species were found to be widespread. With a majority of shared species between oceanic regions, most of the differences between viral assemblages seemed to be explained by variation in the occurrence of the most common viral species and not by exclusion of different viral genomes. These results support the idea that viruses are widely dispersed and that local environmental conditions enrich for certain viral types through selective pressure.