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

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.

Plastics are the most abundant form of marine debris, with global production rising and documented impacts in some marine environments, but the influence of plastic on open ocean ecosystems is poorly understood, particularly for microbial communities. Plastic marine debris (PMD) collected at multiple locations in the North Atlantic was analyzed with scanning electron microscopy (SEM) and next-generation sequencing to characterize the attached microbial communities. We unveiled a diverse microbial community of heterotrophs, autotrophs, predators, and symbionts, a community we refer to as the “Plastisphere”. Pits visualized in the PMD surface conformed to bacterial shapes suggesting active hydrolysis of the hydrocarbon polymer. Small-subunit rRNA gene surveys identified several hydrocarbon-degrading bacteria, supporting the possibility that microbes play a role in degrading PMD. Some Plastisphere members may be opportunistic pathogens (the authors, unpublished data) such as specific members of the genus Vib...

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Life in the “Plastisphere”: Microbial Communities on Plastic Marine Debris

Microplastics in freshwater systems: A review of the emerging threats, identification of knowledge gaps and prioritisation of research needs

Microplastics are a pollutant of environmental concern Their presence in food destined for human consumption and in air samples has been reported Thus, microplastic exposure via diet or inhalation could occur, the human health effects of which are unknown The current review article draws upon cross-disciplinary scientific literature to discuss and evaluate the potential human health impacts of microplastics and outlines urgent areas for future research Key literature up to September 2016 relating to accumulation, particle toxicity, and chemical and microbial contaminants was critically examined Although microplastics and human health is an emerging field, complementary existing fields indicate potential particle, chemical and microbial hazards If inhaled or ingested, microplastics may accumulate and exert localized particle toxicity by inducing or enhancing an immune response Chemical toxicity could occur due to the localized leaching of component monomers, endogenous additives, and adsorbed enviro

Plastic and Human Health: A Micro Issue?

Somatic growth of pelagic invertebrates is controlled by temperature and food, both of which vary in space and time. Species-specific growth rate responses to environmental variabil- ity may affect populations through changes in reproductive potential; therefore, measuring spatial and temporal variability in growth rates of highly abundant zooplankton is critical to predict the impact of climate change on pelagic ecosystems. Here, we used length frequencies from bi-annual surveys conducted 1 month apart to estimate growth rates of one the most abundant euphausiids in the Southern Ocean, Thysanoessa macrura. We analyzed summer data from 4 separate years (1995, 1998, 2001, and 2004) that varied widely in temperature and primary production. Stations within the surveys were grouped by water characteristics: warm, low salinity Antarctic Circum - polar Current (ACC) water, and cold, saline Bransfield Strait and Weddell Sea (MBW) water, to assess inter-annual and spatial variability in cohort growth. Mid-summer cohort growth rates of T. macrura varied between years and water masses, ranging from �0.037 mm d �1 in MBW water in 2004 to 0.081 mm d �1 in ACC water in 1995. Growth rates were faster in ACC water than in MBW water during all years. Growth rates were strongly correlated with temperature (R 2 = 0.82) but weakly correlated with copepod density (R 2 = 0.38), and were not correlated with chl a con- centration (R 2 = 0.11). These results suggest that the growth rates of T. macrura may increase in regions exhibiting warming trends, such as the Antarctic Peninsula. This contrasts with published data on the growth rates of Euphausia superba, which is predicted to be impacted negatively by climate warming.

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Temperature-dependent growth of Thysanoessa macrura: inter-annual and spatial variability around Elephant Island, Antarctica

The effect of a tube-building phoronid on associated infaunal species diversity, composition and community structure

Growth rates of interface-feeding spionid polychaetes in simulated tidal currents

Sublethal predation can be a significant trophic pathway in sediment communities, and the regeneration of damaged tissue affects the activity, growth, and reproduction of prey. A field experiment was conducted 12–18 July 2010 in the Tijuana Estuary, California (+32.56617°, −117.13152°), to measure in situ rates of body growth and palp regeneration of the polychaete Polydora cornuta after simulating sublethal predation by removing 2, 1, or 0 palps from labeled individuals. After 3 days in the field, individuals that had 2 palps removed grew significantly slower than worms that had 0 palps removed; 1-palp worms had intermediate growth. After 6 days in the field, rates of body growth were faster than those of worms recovered after 3 days, with similar trends among the three palp treatments. During the 3-day transplantation, removed palps regenerated to half the initial length of unmanipulated palps. After 6 days, palp lengths did not differ significantly among treatment groups, indicating complete regeneration. The regeneration rate of removed palps was significantly faster than the growth rate of undamaged palps, and palp regeneration rate did not differ significantly between worms that had 1 or 2 palps removed.

In situ rates of body growth and palp regeneration of a spionid polychaete following simulated sublethal predation

We developed methods to measure juvenile growth rates of the spionid polychaete Polydora cornuta in nature. We transplanted and recovered small vials containing labeled individuals and measured each worm’s body volume before and after worms spent a week in field sediments. We transplanted labeled individuals to 3 elevations on an intertidal mudflat in Oneonta Slough within the Tijuana River National Estuarine Research Reserve: a high elevation 0.7 m above mean lower low water (MLLW), a mid-elevation 0.4 m above MLLW, and a low elevation 0.1 m above MLLW. To include a range of environmental conditions, we performed two 7 d transplantations in July 2009 and 2 in November 2009. On average, we recovered one-third of the transplanted juveniles. Mean relative growth rates (RGR) declined significantly from 7.7% d−1 at the low elevation to 2.4% d−1at the high elevation. There was a positive correlation between RGR and the time each elevation was submerged, suggesting the decline in RGRs with increasing elevation was due to a reduction in the time available for suspension feeding. RGRs during 1 transplantation (12 to 19 November) were significantly slower than RGRs during the other 3 transplantations, especially at the high and mid elevations. Due to seasonality in the mixed semidiurnal tides, the 12 to 19 November period was the only transplantation that experienced lower low tides during the afternoon. The slower RGRs during this time of exposure to afternoon sunlight and air temperatures suggest physiological stress might have contributed to reduced RGRs during this transplantation.

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Brian T. Hentschel

Papers

Temperature-dependent growth of Thysanoessa macrura: inter-annual and spatial variability around Elephant Island, Antarctica

The effect of a tube-building phoronid on associated infaunal species diversity, composition and community structure

Growth rates of interface-feeding spionid polychaetes in simulated tidal currents

In situ rates of body growth and palp regeneration of a spionid polychaete following simulated sublethal predation

Measuring in situ growth rates of an infaunal polychaete at different intertidal elevations