Microplastics in marine sediments near Rothera Research Station, Antarctica

Antarctica and surrounding waters are often considered pristine, but may be subject to local pollution from tourism, fishing and governmental research programme activities. In particular, the quantification of microplastic pollution within the Antarctic Treaty area (south of latitude 60°S) has received little attention. We examined microplastic particle concentrations in sediment samples from 20 locations up to 7 km from Rothera Research Station. The highest concentrations of microplastic (<5 particles 10 ml−1) were recorded in sediment collected near the station sewage treatment plant outfall. The concentrations were similar to levels recorded in shallow and deep sea marine sediments outside Antarctica. The detected microplastics had characteristics similar to those commonly produced by clothes washing. We recommend further research on microplastics around Antarctic stations to inform policy discussions and the development of appropriate management responses.

Sarah Reed, Marlon Clark, Richard Thompson, Kevin A. Hughes, Marine Pollution Bulletin, Volume 133, August 2018, Pages 460–463

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Spatial occurrence and effects of microplastic ingestion on the deep-water shrimp Aristeus antennatus

Microplastic (MP) ingestion has been reported in a wide variety of organisms, however, its spatial occurrence and effects on wild populations remain quite unknown. The present study targets an economically and ecologically key species in the Mediterranean Sea, the shrimp Aristeus antennatus. 39.2% of the individuals sampled had MP in their stomachs, albeit in areas close to Barcelona city the percentage reached values of 100%. Overall, MP ingestion was confirmed in a wide spatial and depth (630–1870 m) range, pointing out the great dispersion of this pollutant. The benthophagous diet and close relationship with the sea bottom of A. antennatus might enhance MP exposure and ultimately lead to accidental ingestion. Detailed analysis of shrimps’ diet revealed that individuals with MP had a higher presence of endobenthic prey. Microplastic fibers are probably retained for long periods due to stomach’s morphology, but no negative effects on shrimp’s biological condition were observed.

E. Carreras-Colom, M. Constenla, A. SolerMembrives and al., Marine Pollution Bulletin, Volume 133, August 2018, Pages 44-52

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Human footprint in the abyss: 30 year records of deep-sea plastic debris

This study reports plastic debris pollution in the deep-sea based on the information from a recently developed database. The Global Oceanographic Data Center (GODAC) of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) launched the Deep-sea Debris Database for public use in March 2017. The database archives photographs and videos of debris that have been collected since 1983 by deep-sea submersibles and remotely operated vehicles. From the 5010 dives in the database, 3425 man-made debris items were counted. More than 33% of the debris was macro-plastic, of which 89% was single-use products, and these ratios increased to 52% and 92%, respectively, in areas deeper than 6000 m. The deepest record was a plastic bag at 10898 m in the Mariana Trench. Deep-sea organisms were observed in the 17% of plastic debris images, which include entanglement of plastic bags on chemosynthetic cold seep communities. Quantitative density analysis for the subset data in the western North Pacific showed plastic density ranging from 17 to 335 items km−2 at depths of 1092–5977 m. The data show that, in addition to resource exploitation and industrial development, the influence of land-based human activities has reached the deepest parts of the ocean in areas more than 1000 km from the mainland. Establishment of international frameworks on monitoring of deep-sea plastic pollution as an Essential Ocean Variable and a data sharing protocol are the keys to delivering scientific outcomes that are useful for the effective management of plastic pollution and the conservation of deep-sea ecosystems.

S. Chiba, H. Saito, R. Fletcher and al., Marine Policy, Available online 6 April 2018, In Press

The article

Microplastic pollution identified in deep-sea water and ingested by benthic invertebrates in the Rockall Trough, North Atlantic Ocean

Microplastics are widespread in the natural environment and present numerous ecological threats. While the ultimate fate of marine microplastics are not well known, it is hypothesized that the deep sea is the final sink for this anthropogenic contaminant. This study provides a quantification and characterisation of microplastic pollution ingested by benthic macroinvertebrates with different feeding modes (Ophiomusium lymani, Hymenaster pellucidus and Colus jeffreysianus) and in adjacent deep water > 2200 m, in the Rockall Trough, Northeast Atlantic Ocean. Despite the remote location, microplastic fibres were identified in deep-sea water at a concentration of 70.8 particles m−3, comparable to that in surface waters. Of the invertebrates examined (n = 66), 48% ingested microplastics with quantities enumerated comparable to coastal species. The number of ingested microplastics differed significantly between species and generalized linear modelling identified that the number of microplastics ingested for a given tissue mass was related to species and not organism feeding mode or the length or overall weight of the individual. Deep-sea microplastics were visually highly degraded with surface areas more than double that of pristine particles. The identification of synthetic polymers with densities greater and less than seawater along with comparable quantities to the upper ocean indicates processes of vertical re-distribution. This study presents the first snapshot of deep ocean microplastics and the quantification of microplastic pollution in the Rockall Trough. Additional sampling throughout the deep-sea is required to assess levels of microplastic pollution, vertical transportation and sequestration, which have the potential to impact the largest global ecosystem.

Winnie Courtene-Jones, Brian Quinn, Stefan F. Gary, Andrew O.M. Mogg, Bhavani E. Narayanaswamy, Environmental Pollution, Volume 231, Part 1, December 2017, Pages 271-280

The article

High quantities of microplastic in Arctic deep-sea sediments from the HAUSGARTEN observatory

Although mounting evidence suggests the ubiquity of microplastic in aquatic ecosystems worldwide, our knowledge of its distribution in remote environments such as Polar Regions and the deep sea is scarce. Here, we analyzed nine sediment samples taken at the HAUSGARTEN observatory in the Arctic at 2,340 – 5,570 m depth. Density separation by MicroPlastic Sediment Separator and treatment with Fenton’s reagent enabled analysis via Attenuated Total Reflection FTIR and µFTIR spectroscopy. Our analyses indicate the wide spread of high numbers of microplastics (42 – 6,595 microplastics kg-1). The northernmost stations harbored the highest quantities, indicating sea ice as a transport vehicle. A positive correlation between microplastic abundance and chlorophyll a content suggests vertical export via incorporation in sinking (ice-) algal aggregates. Overall, 18 different polymers were detected. Chlorinated polyethylene accounted for the largest proportion (38 %), followed by polyamide (22 %) and polypropylene (16 %). Almost 80 % of the microplastics were ≤ 25 µm. The microplastic quantities are amongst the highest recorded from benthic sediments, which corroborates the deep sea as a major sink for microplastics and the presence of accumulation areas in this remote part of the world, fed by plastics transported to the North via the Thermohaline Circulation.

Melanie Bergmann, Vanessa Wirzberger, Thomas Krumpen, Claudia Lorenz, Sebastian Primpke, Mine B. Tekman, and Gunnar Gerdts, Environ. Sci. Technol., Volume 51, Issue 19, Page 11000-11010, October 3, 2017

Benthic litter distribution on circalittoral and deep sea bottoms of the southern Bay of Biscay: Analysis of potential drivers

We analyze marine litter densities in soft bottoms of the southern Bay of Biscay using five years of demersal trawling data (2006- 2010). Marine litter densities amounted to 43 ± 33 kg·km−2 and 74 ± 28 items·km−2, with plastics and fisheries derived litter being the most widespread categories. Litter densities generally decreased along the water depth axis. To identify possible drivers for the observed litter distribution we performed a generalised additive model, which explained 14.8% of the variance and pointed to densely populated areas, number of fishing ports, geographical sector and fishing activity as the main explanatory factors. The most important driver for the benthic litter distribution was human population, as litter density linearly increased along this variable. Similarly, the number of ports in neighbouring areas had a positive effect on litter densities. Fishing effort had a negative and non-linear effect on benthic litter density which could be explained by litter delocalization during fishing operations. We hypothesise that litter might accumulate preferentially on the periphery of rocky bottoms, out of reach for our sampling methodology. Litter distribution differed among geographical sectors, pointing to other variables such as shipping traffic and oceanographic currents, which were not explicitly considered in the analysis. Our study sets a reference level for benthic macro-litter in the southern Bay of Biscay and identifies factors driving its distribution, which can be extrapolated to other continental shelf seas. Our findings lay the foundations to develop measures aiming to reduce macro-litter densities on the seafloor.

L. Lopez-Lopez, J.M. Gonzalez Irusta, A. Punzón, A. Serrano, Continental Shelf Research, Volume 144, 15 July 2017, Pages 112-119

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Marine litter on deep Arctic seafloor continues to increase and spreads to the North at the HAUSGARTEN observatory

The increased global production of plastics has been mirrored by greater accumulations of plastic litter in marine environments worldwide. Global plastic litter estimates based on field observations account only for 1% of the total volumes of plastic assumed to enter the marine ecosystem from land, raising again the question ‘Where is all the plastic? ’. Scant information exists on temporal trends on litter transport and litter accumulation on the deep seafloor. Here, we present the results of photographic time-series surveys indicating a strong increase in marine litter over the period of 2002–2014 at two stations of the HAUSGARTEN observatory in the Arctic (2500 m depth).

Plastic accounted for the highest proportion (47%) of litter recorded at HAUSGARTEN for the whole study period. When the most southern station was considered separately, the proportion of plastic items was even higher (65%). Increasing quantities of small plastics raise concerns about fragmentation and future microplastic contamination. Analysis of litter types and sizes indicate temporal and spatial differences in the transport pathways to the deep sea for different categories of litter. Litter densities were positively correlated with the counts of ship entering harbour at Longyearbyen, the number of active fishing vessels and extent of summer sea ice. Sea ice may act as a transport vehicle for entrained litter, being released during periods of melting. The receding sea ice coverage associated with global change has opened hitherto largely inaccessible environments to humans and the impacts of tourism, industrial activities including shipping and fisheries, all of which are potential sources of marine litter.

Mine B. Tekman, Thomas Krumpen, Melanie Bergmann,  Deep Sea Research Part I: Oceanographic Research Papers, Volume 120, February 2017, Pages 88–99

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