Spatial distribution of marine macro-litter on the seafloor in the northern Mediterranean Sea: the MEDITS initiative




marine macro-litter, plastic, Mediterranean Sea, GAM modelling, accumulation areas, MEDITS


Marine litter is one of the main sources of anthropogenic pollution in the marine ecosystem, with plastic representing a global threat. This paper aims to assess the spatial distribution of plastic macro-litter on the seafloor, identifying accumulation hotspots at a northern Mediterranean scale. Density indices (items km–2) from the MEDITS trawl surveys (years 2013-2015) were modelled by generalized additive models using a Delta-type approach and several covariates: latitude, longitude, depth, seafloor slope, surface oceanographic currents and distances from main ports. To set thresholds for the identification of accumulation areas, the percentiles (85th, 90th and 95th) of the plastic spatial density distribution were computed on the raster data. In the northern Mediterranean marine macro-litter was widespread (90.13% of the 1279 surveyed stations), with plastic by far the most recurrent category. The prediction map of the plastic density highlighted accumulation areas (85th, 90th and 95th percentiles of the distribution, respectively, corresponding to 147, 196 and 316 items km–2) in the Gulf of Lions, eastern Corsica, the eastern Adriatic Sea, the Argo-Saronic region and waters around southern Cyprus. Maximum densities were predicted in correspondence to the shallower depths and in proximity to populated areas (distance from the ports). Surface currents and local water circulation with cyclonic and anticyclonic eddies were identified as drivers likely facilitating the sinking to the bottoms of floating debris.


Download data is not yet available.


Andrady A.L. 2011. Microplastics in the marine environment. Mar. Pollut. Bull. 62: 1596-1605. PMid:21742351

Andrady A.L. 2015. Persistence of Plastic Litter in the Oceans. In: Bergmann M., Gutow L., Klages M. (eds), Marine Anthropogenic Litter. Springer, Cham, pp. 57-72.

Angiolillo M., di Lorenzo B., Farcomeni A., et al. 2015. Distribution and assessment of marine debris in the deep Tyrrhenian Sea (NW Mediterranean Sea, Italy). Mar. Pollut. Bull. 92: 149-159. PMid:25604749

Anonymus. 2017. MEDITS-Handbook. Version n. 9. MEDITS Working Group. 106 pp. htm

Artegiani A., Bregant D., Paschini E., et al. 1997. The Adriatic Sea general circulation. Part II: Baroclinic circulation structure. J. Phys. Oceanogr. 27: 1515-1532.<1515:TASGCP>2.0.CO;2

Barnes D.K.A., Galgani F., Thompson R.C., et al. 2009. Accumulation and fragmentation of plastic debris in global environments. Philos. Trans. R. Soc. Lond. B. 364: 1985-1998. PMid:19528051 PMCid:PMC2873009

Camedda A., Marra S., Matiddi M., et al. 2014. Interaction between loggerhead sea turtles (Caretta caretta) and marine litter in Sardinia (Western Mediterranean Sea). Mar. Environ. Res. 100: 25-32. PMid:24388284

Carlson D.F., Griffa A., Zambianchi E., et al. 2016. Observed and modeled surface Lagrangian transport between coastal regions in the Adriatic Sea with implications for marine protected areas. Cont. Shelf Res. 118: 23-48.

Carlson D.F., Suaria G., Aliani S., et al. 2017. Combining Litter Observations with a Regional Ocean Model to Identify Sources and Sinks of Floating Debris in a Semi-enclosed Basin: The Adriatic Sea. Front. Mar. Sci. 4: 78.

Cau A., Alvito A., Moccia D., et al. 2017. Submarine canyons along the upper Sardinian slope (Central Western Mediterranean) as repositories for derelict fishing gears. Mar. Pollut. Bull. 123: 357-364. PMid:28903858

Cau A., Bellodi A., Moccia D., et al. 2018. Dumping to the abyss: single-use marine litter invading bathyal plains of the Sardinian margin (Tyrrhenian Sea). Mar. Pollut. Bull. 135: 845-851. PMid:30301106

Consoli P., Andaloro F., Altobelli C., et al. 2018. Marine litter in an EBSA (Ecologically or Biologically Significant Area) of the central Mediterranean Sea: Abundance, composition, impact on benthic species and basis for monitoring entanglement. Environ. Pollut. 236: 405-415. PMid:29414365

Cooper D., Corcoran P. 2010. Effects of mechanical and chemical processes on the degradation of plastic beach debris on the island of Kauai, Hawaii. Mar. Pollut. Bull. 60: 650-654. PMid:20106491

Corcoran P.L. 2015. Benthic plastic debris in marine and fresh water environments. Environ. Sci. Processes Impacts 17: 1363-1369. PMid:26129903

Cózar A., Sanz-Martín M., Martí E., et al. 2015. Plastic accumulation in the Mediterranean Sea. PLoS ONE 10: e0121762. PMid:25831129 PMCid:PMC4382178

Dameron O.J., Parke M., Albins M.A., et al. 2007. Marine debris accumulation in the Northwestern Hawaiian Islands: An examination of rates and processes. Mar. Pollut. Bull. 54: 423-433. PMid:17217968

European Commission (EC). 2013. Green paper on a European strategy on plastic waste in the environment, COM(2013) 123 final. 20 pp.

European Commission (EC). 2015. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions. Closing the loop - An EU action plan for the Circular Economy, COM/2015/0614 final. 21 pp.

European Commission (EC). 2018. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions, SWD (2018) 16 final. 17 pp.

Eriksen M., Lebreton L.C.M., Carson H.S., et al. 2014. Plastic Pollution in the World's Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea. PLoS ONE 9: e111913. PMid:25494041 PMCid:PMC4262196

Fiorentino F., Lefkaditou E., Jadaud A., et al. 2013. Protocol for Litter Data Collection during the Medits Trawl Surveys. 40th CIESM Congress, Marseille, France, 28 Oct-1 Nov 2013.

Fiorentino F., Gancitano V., Giusto G.B., et al. 2015. Marine litter on trawlable bottoms of the strait of Sicily. Biol. Mar. Mediterr. 22: 225-228.

Frias J.P.G.L., Otero V., Sobral P. 2014. Evidence of microplastics in samples of zooplankton from Portuguese coastal waters. Mar. Environ. Res. 95: 89-95. PMid:24461782

G20. 2017. Leaders' Declaration - Shaping an interconnected world, 7-8 July 2017. 15 pp.

G7. 2015. Leaders' declaration: G7 summit, 7-8 June 2015. 17 pp.

Galgani F., Souplet A., Cadiou Y. 1996. Accumulation of debris on the deep sea floor off the French Mediterranean coast. Mar. Ecol. Prog. Ser. 142: 225-234.

Galgani F., Leaute J.P., Moguedet P., et al. 2000. Litter on the sea floor along European coasts. Mar. Pollut. Bull. 40: 516-527.

Galgani F., Fleet D., Van Franeker J., et al. 2010. Marine Strategy Framework Directive: task group 10 report: marine litter. European Commission Joint Research Centre. Office for Official Publ. EC, Luxembourg. 48 pp.

Galgani F., Clarob F., Depledgec M., et al. 2014. Monitoring the impact of litter in large vertebrates in the Mediterranean Sea within the European Marine Strategy Framework Directive (MSFD): constraints, specificities and recommendations. Mar. Environ. Res. 100: 3-9. PMid:24612883

Galgani F., Hanke G., Maes T. 2015. Global distribution, composition and abundance of marine litter. In: Bergmann M., Gutow L., Klages M. (eds), Marine Anthropogenic Litter. Springer, Cham, pp. 29-56.

Gall S.C., Thompson R.C. 2015. The impact of debris on marine life. Mar. Pollut. Bull. 92: 170-179. PMid:25680883

GFCM. 2009. Establishment of Geographical Sub-Areas in the GFCM area amending the resolution GFCM/31/2007/2, GFCM/33/2009/2.

Gu C., Wahba G. 1991. Minimizing GCV/GML Scores with Multiple Smoothing Parameters via the Newton Method. SIAM J. Sci. Stat. Comput. 12: 383-398.

Iñiguez M.E., Conesa J.A., Fullana A. 2016. Marine debris occurrence and treatment: A review. Renew. Sustain. Energy Rev. 64: 394-402.

Ioakeimidis C., Zeri C., Kaberi H., et al. 2014. A comparative study of marine litter on the seafloor of coastal areas in the Eastern Mediterranean and Black Seas. Mar. Pollut. Bull. 89: 296-304. PMid:25440189

Ioakeimidis C., Fotopoulou K.N., Karapanagioti H.K., et al. 2016. The degradation potential of PET bottles in the marine environment: An ATR-FTIR based approach. Sci. Rep. 6: 23501. PMid:27000994 PMCid:PMC4802224

Jambeck J.R., Geyer R., Wilcox C., et al. 2015. Plastic waste inputs from land into the ocean. Science 347: 768-771. PMid:25678662

Jang Y.C., Hong S., Lee J., et al. 2014. Estimation of lost tourism revenue in Geoje Island from the 2011 marine debris pollution event in South Korea. Mar. Pollut. Bull. 81: 49-54. PMid:24635983

Karimova S. 2017. Observing surface circulation of the Western Mediterranean basin with satellite imagery. Int. Arch. Photogramm. Remote Sens. Spat. Inf. Sci. XLII-3/W2: 97-104.

Law K.L. 2017. Plastics in the Marine Environment. Ann. Rev. Mar. Sci. 9: 205-229. PMid:27620829

Lebreton L.C.M., Greer S.D., Borrero J.C. 2012. Numerical modelling of floating debris in the world's oceans. Mar. Pollut. Bull. 64: 653-661. PMid:22264500

Lebreton L.C.M., Van Der Zwet J., Damsteeg J.W., et al. 2017. River plastic emissions to the world's oceans. Nat. Commun. 8: 1-10. PMid:28589961 PMCid:PMC5467230

Lee D.-I., Cho H.-S., Jeong S.-B. 2006. Distribution characteristics of marine litter on the sea bed of the East China Sea and the South Sea of Korea. Estuar. Coast. Shelf Sci. 70: 187-194.

Lefkaditou E., Karkani M., Anastasopoulou A., et al. 2013. Litter composition on the shelf and upper slope of the Argosaronikos region and the eastern Ionian Sea, as evidenced by MEDITS surveys 1995-2008. ICES C. 2013/A 3357: 1-3. Theme%20Session%20A%20contributions/A0613.pdf

Legendre P., Legendre L. 1998. Numerical ecology, Elsevier Science B.V., Amsterdam. 852 pp.

Leite A.S., Santos L.L., Costa Y., et al. 2014. Influence of proximity to an urban center in the pattern of contamination by marine debris. Mar. Pollut. Bull. 81: 242-247. PMid:24530003

Liubartseva S., Coppini G., Lecci R., et al. 2016. Regional approach to modeling the transport of floating plastic debris in the Adriatic Sea. Mar. Pollut. Bull. 103: 115-127. PMid:26774440

Liubartseva S., Coppini G., Lecci R., et al. 2018. Tracking plastics in the Mediterranean: 2D Lagrangian model. Mar. Pollut. Bull. 129: 151-162. PMid:29680533

Lusher A. 2015. Microplastics in the Marine Environment: Distribution, Interactions and Effects. In: Bergmann M., Gutow L., Klages M. (eds), Marine Anthropogenic Litter. Springer, Cham, pp. 245-307.

Mansui J., Molcard A., Ourmières Y. 2015. Modelling the transport and accumulation of floating marine debris in the Mediterranean basin. Mar. Pollut. Bull. 91: 249-257. PMid:25534631

Melli V., Angiolillo M., Ronchi F., et al. 2017. The first assessment of marine debris in a Site of Community Importance in the north-western Adriatic Sea (Mediterranean Sea). Mar. Pollut. Bull. 114: 821-830. PMid:27847167

Mifsud R., Dimech M., Schembri P.J. 2013. Marine litter from circalittoral and deeper bottoms off the Maltese islands (Central Mediterranean). Mediterr. Mar. Sci. 14: 298-308.

Millot C., Taupier-Letage I. 2005. Circulation in the Mediterranean Sea. In: Saliot A. (ed.), The Mediterranean Sea. Springer, Berlin, Heidelberg, pp. 29-66.

Munari C., Corbau C., Simeoni U., et al. 2016. Marine litter on Mediterranean shores: Analysis of composition, spatial distribution and sources in north-western Adriatic beaches. Waste Manage. 49: 483-490. PMid:26725754

Neves D., Sobral P., Pereira T. 2015. Marine litter in bottom trawls off the Portuguese coast. Mar. Pollut. Bull. 99: 301-304. PMid:26231069

O'brien R.M. 2007. A Caution Regarding Rules of Thumb for Variance Inflation Factors. Qual. Quant. 41: 673-690.

Pace R., Dimech M., Camilleri M., et al. 2007. Litter as a source of habitat islands on deep water muddy bottoms. Rapp. Comm. Int. Mer Médit. 38 pp.

Pasquini G., Ronchi F., Strafella P., et al. 2016. Seabed litter composition, distribution and sources in the Northern and Central Adriatic Sea (Mediterranean). Waste Manage. 58: 41-51. PMid:27614560

Pellini G., Gomiero A., Fortibuoni T., et al. 2018. Characterization of microplastic litter in the gastrointestinal tract of Solea solea from the Adriatic Sea. Environ. Pollut. 234: 943-952. PMid:29665634

Pham C.K., Ramirez-Llodra E., Alt C.H.S., et al. 2014. Marine litter distribution and density in European seas, from the shelves to deep basins. PLoS ONE 9: e95839. PMid:24788771 PMCid:PMC4005782

Pinardi N., Masetti E. 2000. Variability of the large scale general circulation of the Mediterranean Sea from observations and modelling: a review. Palaeogeogr. Palaeoclimatol. Palaeoecol. 158: 153-173.

Politikos D.V, Ioakeimidis C., Papatheodorou G., et al. 2017. Modeling the Fate and Distribution of Floating Litter Particles in the Aegean Sea (E. Mediterranean). Front. Mar. Sci. 4: 191.

QGIS Development Team. 2017. Geographic Information System. Open Source Geospatial Foundation Project.

R Development Core Team. 2013. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria.

Renault L., Oguz T., Pascual A., et al. 2012. Surface circulation in the Alborán Sea (western Mediterranean) inferred from remotely sensed data. J. Geophys. Res. 117: C08009.

Robinson A.R., Hecht A., Michelato A., et al. 1992. General circulation of the Eastern Mediterranean. Earth-Sci. Rev. 32: 285-309.

Robinson A.R., Leslie W.G., Theocharis A., et al. 2001. Mediterranean Sea Circulation. In: Steele J.H. (ed), Encyclopedia of Ocean Sciences. Academic Press, Oxford, pp. 710-725.

Rubec P.J., Kiltie R., Leone E., et al. 2016. Using delta-generalized additive models to predict spatial distributions and population abundance of juvenile pink shrimp in Tampa Bay, Florida. Mar. Coast. Fish. 8: 232-243.

Sánchez P., Masó M., Sáez R., et al. 2013. Baseline study of the distribution of marine debris on soft-bottom habitats associated with trawling grounds in the northern Mediterranean. Sci. Mar. 77: 247-255.

Serena F., Abella A.J., Baino R.T., et al. 2011. Anthropogenic waste in the marine ecosystem. Biol. Mar. Mediterr. 18: 161-164.

Shapiro S.S., Wilk M.B. 1965. An Analysis of Variance Test for Normailty (Complete Samples). Biometrika 52: 591-611.

Spedicato M.T., Massutí E., Merigot B., et al. 2019. The MEDITS trawl survey specifications in an ecosystem approach to fishery management. Sci. Mar. 83S1: 9-20.

Spengler A., Costa M.F. 2008. Methods applied in studies of benthic marine debris. Mar. Pollut. Bull. 56: 226-230. PMid:18082846

Stefatos A., Charalampakis M., Papatheodorou G., et al. 1999. Marine debris on the seafloor of the Mediterranean Sea: Examples from two enclosed gulfs in western Greece. Mar. Pollut. Bull. 38: 389-393.

Strafella P., Fabi G., Spagnolo A., et al. 2015. Spatial pattern and weight of seabed marine litter in the northern and central Adriatic Sea. Mar. Pollut. Bull. 91: 120-127. PMid:25560999

Suaria G., Avio C.G., Mineo A., et al. 2016. The Mediterranean Plastic Soup: synthetic polymers in Mediterranean surface waters. Sci. Rep. 6: 37551. PMid:27876837 PMCid:PMC5120331

Thompson R., Moore C., Andrady A., et al. 2005. New Directions in Plastic Debris. Science 310: 1117. PMid:16293739

UNEP. 2016. Draft Integrated Monitoring and Assessment Guidance. UNEP(DEPI)/MED WG.429/Inf.6. 270 pp.

UNEP/MAP. 2009. Plan Bleu: State of the Environment and Development in the Mediterranean, UNEP/MAP-Plan Bleu, Athens. 204 pp.

UNEP/MAP. 2012. State of the Mediterranean Marine and Coastal Environment, UNEP/MAP-Barcelona Convention, Athens, 96 pp.

UNEP/MAP. 2015. Marine Litter Assessment in the Mediterranean, UNEP/MAP, Athens. 88 pp.

United Nations. 2016. The First Global Integrated Marine Assessment. United Nations.

Watters D.L., Yoklavich M.M., Love M.S., et al. 2010. Assessing marine debris in deep seafloor habitats off California. Mar. Pollut. Bull. 60: 131-138. PMid:19751942

Werner S., Budziak A., Van Franeker J.A., et al. 2016. Harm caused by marine litter. MSFD GES TG marine litter - Thematic report; JRC Technical report; EUR 28317 EN. 92 pp.

Williams A.T., Simmons S.L. 1985. Estuarine Litter at the River/ Beach Interface in the Bristol Channel, United Kingdom. J. Coast. Res. 13: 1159-1165.

Wood S.N. 2001. mgcv: GAMs and generalized ridge regression for R. R News 1: 20-25.

Wood S.N 2006. Generalized Additive Models: An Introduction with R. Chapman Hall/CRC, Boca Raton, FL. 410 pp.

Zambianchi E., Trani M., Falco P. 2017. Lagrangian Transport of Marine Litter in the Mediterranean Sea. Front. Environ. Sci. 5: 5.

Zuur A.F. 2012. A beginner's guide to generalized additive models with R. Highland Statistics Limited, Newburgh. 206 pp.

Zuur A.F., Ieno E.N., Elphick C.S. 2010. A protocol for data exploration to avoid common statistical problems. Methods Ecol. Evol. 1: 3-14.



How to Cite

Spedicato MT, Zupa W, Carbonara P, Fiorentino F, Follesa MC, Galgani F, García-Ruiz C, Jadaud A, Ioakeimidis C, Lazarakis G, Lembo G, Mandic M, Maiorano P, Sartini M, Serena F, Cau A, Esteban A, Isajlovic I, Micallef R, Thasitis I. Spatial distribution of marine macro-litter on the seafloor in the northern Mediterranean Sea: the MEDITS initiative. scimar [Internet]. 2019Dec.30 [cited 2021Jan.22];83(S1):257-70. Available from:




Most read articles by the same author(s)

1 2 3 4 5 > >>