Plastic pollution is ubiquitous throughout the marine environment, yet estimates of the global abundance and weight of floating plastics have lacked data, particularly from the Southern Hemisphere and remote regions. Here we report an estimate of the total number of plastic particles and their weight floating in the world’s oceans from 24 expeditions (2007–2013) across all five sub-tropical gyres, costal Australia, Bay of Bengal and the Mediterranean Sea conducting surface net tows (N5680) and visual survey transects of large plastic debris (N5891). Using an oceanographic model of floating debris dispersal calibrated by our data, and correcting for wind-driven vertical mixing, we estimate a minimum of 5.25 trillion particles weighing 268,940 tons. When comparing between four size classes, two microplastic ,4.75 mm and meso- and macroplastic .4.75 mm, a tremendous loss of microplastics is observed from the sea surface compared to expected rates of fragmentation, suggesting there are mechanisms at play that remove ,4.75 mm plastic particles from the ocean surface.

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Plastic Pollution in the World's Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea

I. the origin of species by means of natural selection

http://resodema.org/publications/publication9.pdf

The physical impacts of microplastics on marine organisms: a review.

There is a rising concern regarding the accumulation of floating plastic debris in the open ocean. However, the magnitude and the fate of this pollution are still open questions. Using data from the Malaspina 2010 circumnavigation, regional surveys, and previously published reports, we show a worldwide distribution of plastic on the surface of the open ocean, mostly accumulating in the convergence zones of each of the five subtropical gyres with comparable density. However, the global load of plastic on the open ocean surface was estimated to be on the order of tens of thousands of tons, far less than expected. Our observations of the size distribution of floating plastic debris point at important size-selective sinks removing millimeter-sized fragments of floating plastic on a large scale. This sink may involve a combination of fast nano-fragmentation of the microplastic into particles of microns or smaller, their transference to the ocean interior by food webs and ballasting processes, and processes yet to be discovered. Resolving the fate of the missing plastic debris is of fundamental importance to determine the nature and significance of the impacts of plastic pollution in the ocean.

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Plastic debris in the open ocean

https://scholarlypublications.universiteitleiden.nl/access/item%3A2978611/view

Microplastics in freshwater and terrestrial environments: Evaluating the current understanding to identify the knowledge gaps and future research priorities.

This review of 68 studies compares the methodologies used for the identification and quantification of microplastics from the marine environment. Three main sampling strategies were identified: selective, volume-reduced, and bulk sampling. Most sediment samples came from sandy beaches at the high tide line, and most seawater samples were taken at the sea surface using neuston nets. Four steps were distinguished during sample processing: density separation, filtration, sieving, and visual sorting of microplastics. Visual sorting was one of the most commonly used methods for the identification of microplastics (using type, shape, degradation stage, and color as criteria). Chemical and physical characteristics (e.g., specific density) were also used. The most reliable method to identify the chemical composition of microplastics is by infrared spectroscopy. Most studies reported that plastic fragments were polyethylene and polypropylene polymers. Units commonly used for abundance estimates are “items per m2” ...

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Microplastics in the Marine Environment: A Review of the Methods Used for Identification and Quantification

This book describes how manmade litter, primarily plastic, has spread into the remotest parts of the oceans and covers all aspects of this pollution problem from the impacts on wildlife and human health to socio-economic and political issues. Marine litter is a prime threat to marine wildlife, habitats and food webs worldwide.

The book illustrates how advanced technologies from deep-sea research, microbiology and mathematic modelling as well as classic beach litter counts by volunteers contributed to the broad awareness of marine litter as a problem of global significance. The authors summarise more than five decades of marine litter research, which receives growing attention after the recent discovery of great oceanic garbage patches and the ubiquity of microscopic plastic particles in marine organisms and habitats.

In 16 chapters, authors from all over the world have created a universal view on the diverse field of marine litter pollution, the biological impacts, dedicated research activities, and the various national and international legislative efforts to combat this environmental problem. They recommend future research directions necessary for a comprehensive understanding of this environmental issue and the development of efficient management strategies. This book addresses scientists, and it provides a solid knowledge base for policy makers, NGOs, and the broader public.

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Marine Anthropogenic Litter

Rafting of marine and terrestrial organisms has been reported from a variety of substrata and from all major oceans of the world. Herein we present information on common rafting organisms and on ecological interactions during rafting voyages. An extensive literature review revealed a total of 1206 organisms, for which rafting was confirmed or inferred based on distributional or genetic evidence. Rafting organisms comprised cyanobacteria, algae, protists, invertebrates from most marine but also terrestrial phyla, and even a few terrestrial vertebrates. Marine hydrozoans, bryozoans, crustaceans and gastropods were the most common taxa that had been observed rafting. All major feeding types were represented among rafters, being dominated by grazing/boring and suspension-feeding organisms, which occurred on all floating substrata. Besides these principal trophic groups, predators/scavengers and detritus-feeders were also reported. Motility of rafting organisms was highest on macroalgae and lowest on abiotic substrata such as plastics and volcanic pumice. Important trends were revealed for the reproductive biology of rafting organisms. A high proportion of clonal organisms (Cnidaria and Bryozoa) featured asexual reproduction, often in combination with sexual reproduction. Almost all rafting organisms have internal fertilisation, which may be due to the fact that gamete concentrations in the rafting environment are too low for successful fertilisation of external fertilisers. Following fertilisation, many rafting organisms incubate their offspring in/on their body or deposit embryos in egg masses on rafts. Local recruitment, where offspring settle in the immediate vicinity of parents, is considered an important advantage for establishing persistent local populations on a raft, or in new habitats. Some organisms are obligate rafters, spending their entire life cycle on a raft, but the large majority of reported rafters are considered facultative rafters. These organisms typically live in benthic (or terrestrial) habitats, but may become dispersed while being confined to a floating item. Substratum characteristics (complexity, surface, size) have important effects on the composition of the rafting community. While at sea, ecological interactions (facilitation, competition, predation) contribute to the community succession on rafts. Organisms capable to compete for and exploit resources on a raft (space and food) will be able to persist throughout community succession. The duration of rafting voyages is closely related to rafting distances, which may cover various geographical scales. In chronological order, three features of an organism gain in importance during rafting, these being ability to (1) hold onto floating items, (2) establish and compete successfully, and (3) develop persistent local populations during a long voyage. Small organisms that do not feed on their floating substratum and with asexual reproduction or direct development combine all these features, and appear to be most suited for long-distance dispersal on rafts and successful colonisation after reaching new habitats. All available evidence suggests that rafting is an important process for the population dynamics of many organisms and that it also has had and continues to have a strong influence on coastal biodiversity.

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The Ecology of Rafting in the Marine Environment. II. The Rafting Organisms and Community

Rafting has been inferred as an important dispersal mechanism in the marine environment by many authors. The success of rafting depends critically on the availability of suitable floating substrata. Herein currently available information on floating items that have been reported to carry rafting organisms is summarised. Floating items of biotic origin comprise macroalgae, seeds, wood, other vascular plants, and animal remains. Volcanic pumice (natural) and a diverse array of litter and tar lumps (anthropogenic) are the main floating items of abiotic origin. Macroalgae, wood, and plastic macrolitter cover a wide range of sizes while pumice, microlitter, and tar lumps typically are <10 cm in diameter. The longevity of floating items at the sea surface depends on their origin and likelihood to be destroyed by secondary consumers (in increasing order): nonlignified vascular plants/animal carcasses < macroalgae < driftwood < tar lumps/skeletal remains < plastic litter < volcanic pumice. In general, abiotic substrata have a higher longevity than biotic substrata, but most abiotic items are of no or only limited food value for potential rafters. Macroalgae are most abundant at mid-latitudes of both hemispheres, driftwood is of major importance in northern and tropical waters, and floating seeds appear to be most common in tropical regions. Volcanic pumice can be found at all latitudes but has primarily been reported from the Pacific Ocean. Plastic litter and tar lumps are most abundant near the centres of human population and activities. In some regions of abundant supply or zones of hydrography-driven accumulation, floating items can be extremely abundant, exceeding 1000 items km –2 . Temporal supply of floating items is variable, being seasonal for most biotic substrata and highly sporadic for some items such as volcanic pumice. Most reported velocities of floating items are in the range of 0.5–1.0 km h –1 , but direct measurements have shown that they occasionally are transported at much faster velocities. Published trajectories of floating items also coincide with the main oceanic currents, even though strong winds may sometimes push them out of the principal current systems. Many studies hint toward floating items to link source regions with coastal sinks, in some cases across long distances and even entire ocean basins. Fossil evidence suggests that rafting has also occurred in palaeooceans. During recent centuries and decades the composition and abundance of floating items in the world’s oceans have been strongly affected by human activities, in particular logging, river and coastline regulation, and most importantly oil exploitation and plastic production. The currently abundant supply and the characteristics of floating items suggest that rafting continues to be an important dispersal mechanism in present-day oceans. 182 M. Thiel & L. Gutow

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The ecology of rafting in the marine environment - i - the floating substrata

Plastic pollution is an emerging global threat for marine wildlife. Many species of birds, reptiles, and fishes are directly impaired by plastics as they can get entangled in ropes and drown or they can ingest plastic fragments which, in turn, may clog their stomachs and guts. Microplastics of less than 1 mm can be ingested by small invertebrates, but their fate in the digestive organs and their effects on the animals are yet not well understood. We embedded fluorescent microplastics in artificial agarose-based food and offered the food to marine isopods, Idotea emarginata. The isopods did not distinguish between food with and food without microplastics. Upon ingestion, the microplastics were present in the stomach and in the gut but not in the tubules of the midgut gland which is the principal organ of enzyme-secretion and nutrient resorption. The feces contained the same concentration of microplastics as the food which indicates that no accumulation of microplastics happens during the gut passage. Long-...

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Lars Gutow

Papers

Microplastics in the Marine Environment: A Review of the Methods Used for Identification and Quantification

Marine Anthropogenic Litter

The Ecology of Rafting in the Marine Environment. II. The Rafting Organisms and Community

The ecology of rafting in the marine environment - i - the floating substrata

Fate of Microplastics in the Marine Isopod Idotea emarginata