Seabed litter composition, distribution and sources in the Northern and Central Adriatic Sea (Mediterranean)

Not only in the crowd: Benthic litter characterization in a low population density area still reveals widespread pollution and local malpractices

Various anthropogenic activities affect marine coastal habitats, leading to heavy litter pollution. However, whilst high litter concentrations are nowadays common in the proximity of metropolises, few studies investigated the magnitude of this phenomenon around coastal villages and small towns. We hereby characterized the benthic litter occurring in the trawlable grounds of the Gulf of Policastro (Tyrrhenian Sea, central-western Mediterranean), a low population density area that becomes a popular tourist destination during summer. We furthermore tested differences between two depths (∼100-200 and ∼500-600 m) and the impact of tourism on the shallower waters. The area was characterized by a litter abundance of 651.12 ± 130.61 item/km2, with plastic being almost totalitarian (93%). The shallower waters hosted two-thirds of the litter found. Almost all (∼95%) the litter items had a land-based origin, while the sea-based litter was mostly found at higher depths. About 14% of the litter was found to be fouled, with the development of litter-associated communities that somehow mimic the natural ones living on hard substrates. The higher litter presence noticed during the touristic peak (July-August) suggests that tourism is an important source of local litter, although it contributed to the local accumulation in a synergic way with other factors. The majority of the litter items presumably originated from the nearby coastline, while the deeper waters were or are used as a dumping site by the local trawling fleet. The discovery of such a critical waste accumulation and management in a somehow remote area contributes to widen the perspectives on the presence of benthic litter mostly in territories characterized by wide anthropization. Moreover, it confirms that appropriate local policies and communication plans are urged even at a regional level to stimulate citizen consciousness and mitigate the ever growing litter pollution.

Assessing marine litter in a highly polluted area in the Mediterranean: A multi-perspective approach in the Saronikos Gulf, Greece

Marine litter poses a significant environmental challenge in the Saronikos Gulf, Greece. Employing an integrated approach, data from both beach and underwater sites were analyzed. The average litter density on beaches was 2.61 items m-2, with plastic being the most common material, notably small polystyrene fragments and cigarette butts. The western part of the Gulf exhibited higher litter density, mainly due to surface circulation patterns. Most beaches fell short of meeting Good Environmental Status criteria for marine litter. Higher litter densities were observed in autumn. Benthic litter density decreased with depth, being 23 times higher in shallower waters, with plastic being the predominant type. This extensive study offers crucial insights into the pollution status and litter distribution in the Saronikos Gulf, contributing significantly to the global understanding of marine litter distribution on coastal ecosystems. Such information is crucial for raising awareness, informing policy decisions, and driving environmental actions.

Fragmented marine plastics as the prevalent litter type on a small island beach in the Adriatic

The issue of plastic pollution has dramatically intensified in the recent years. Our study investigates extensive plastic contamination of a sandy beach on a small Adriatic island. The beach was sampled on three occasions, in 2013, 2020 and 2022, using 1 m2 quadrats placed along the lower and upper strandlines, resulting in average litter concentrations of 385 ± 106, 1095 ± 522 and 129 ± 37 item m-2, respectively. The lower size limit of collected litter was 1 mm, thus including large microplastics. Plastic fragments (49-74 %) and plastic pellets (15 %-37 %) were predominant litter categories. The proportion of fragments is significantly higher during the tourist season with a more intensive cleaning regime (April-October), as opposed to the off-season (November-March). Fisheries and aquaculture litter was identified as a relevant source of pollution. More research is needed in the future into the microplastics smaller than 1 mm.

Distribution and composition of seafloor litter and associated macrofouling organisms in the Northeastern Mediterranean Sea

Composition, and density of marine litter and associated macrofouling organisms was assessed in the continental shelf of the Northeastern Mediterranean Sea. A total of 943 litter items weighing 388 kg were collected during 34 hauls. Plastic comprised 72 % of the total litter found on the seafloor. The mean number and weight of ML was 4241 ± 1333 items/km2 and 368 ± 87 kg/km2. Depth and distance from the shore were not identified as a significant factor affecting both the number and weight of litter. A total of 20 fouling species and eggs belonging to Mollusca, Porifera, Cnidaria, Bryozoa, Annelida, Arthropoda, and Chordata were found on marine litter. An alien Mollusca species Pinctada imbricate was also found on plastic litter. Our results confirmed that marine litter is a vector transporting a variety of organisms including alien species and being a threat for the biodiversity and human health in the Mediterranean Sea.

Top 10 marine litter items on the seafloor in European seas from 2012 to 2020

We studied the ten most frequently encountered litter items from the seafloor in European seas to advance actions and inform future mitigation measures to reduce marine litter and the associated social, economic and environmental impacts it has on European seas and beyond. Data were collected during trawl surveys from 2012 to 2020 as part of national and regional marine litter monitoring programmes in the Greater North Sea (5652 trawls), Celtic Seas (3505), Bay of Biscay (651), and Baltic Sea (3688). A Bayesian approach is used to quantify the variation in the item rankings. Overall, plastic items predominate in the top positions in each area. Synthetic rope, plastic sheets, monofilament fishing line and plastic bags occupy four of the top five positions for each of the Greater North Sea, Celtic Seas and the Bay of Biscay. Items from fishing and rope (representing mainly other maritime activities) are strongly represented in the top ten lists from three of our four areas, with synthetic rope, fishing nets, and tangled and untangled monofilament fishing line listed in the top seven positions for the Greater North Sea, Celtic Seas and the Bay of Biscay. The top ten items in the Baltic Sea are of a different profile to the other regions, but the most commonly caught items are still predominantly plastic, with plastic sheets, other plastic items and plastic bags occupying three of the top four positions. The findings in this study highlight the need to address sea-based sources to try and eliminate litter from fishing and maritime activities. Measures such as improved port reception facilities, marking of fishing gear, promoting reporting of the loss of fishing gear and increasing public awareness should be introduced.

Hotspots of microplastic accumulation at the land-sea transition and their spatial heterogeneity: The Po River prodelta (Adriatic Sea)

Deltas are the locus of river-borne sediment accumulation, however, their role in sequestering plastic pollutants is still overlooked. By combining geomorphological, sedimentological, and geochemical analyses, which include time-lapse multibeam bathymetry, sediment provenance, and μFT-IR analyses, we investigate the fate of plastic particles after a river flood event providing an unprecedented documentation of the spatial distribution of sediment as well as of microplastics (MPs), including particles fibers, and phthalates (PAEs) abundances in the subaqueous delta. Overall sediments are characterized by an average of 139.7 ± 80 MPs/kg d.w., but display spatial heterogeneity of sediment and MPs accumulation: MPs are absent within the active sandy delta lobe, reflecting dilution by clastic sediment (ca. 1.3 Mm3) and sediment bypass. The highest MP concentration (625 MPs/kg d.w.) occurs in the distal reaches of the active lobe where flow energy dissipates. In addition to MPs, cellulosic fibers are relevant (of up to 3800 fibers/kg d.w.) in all the analyzed sediment samples, and dominate (94 %) with respect to synthetic polymers. Statistically significant differences in the relative concentration of fiber fragments ≤0.5 mm in size were highlighted between the active delta lobe and the migrating bedforms in the prodelta. Fibers were found to slightly follow a power law size distribution coherent with a one-dimensional fragmentation model and thus indicating the absence of a size dependent selection mechanism during burial. Multivariate statistical analysis suggests traveling distance and bottom-transport regime as the most relevant factors controlling particle distribution. Our findings suggest that subaqueous prodelta should be considered hot spots for the accumulation of MPs and associated pollutants, albeit the strong lateral heterogeneity in their abundances reflects changes in the relative influence of fluvial and marine processes.

Monitoring the composition, sources and spatial distribution of seafloor litter in the Adriatic Sea (Mediterranean Sea) through Fishing for Litter initiatives

Although the seafloor is an important sink for marine litter, its less accessible environment makes seafloor litter the least studied component. Nevertheless, detailed monitoring of its composition and spatial distribution is urgently needed to develop appropriate mitigation strategies in areas exposed to multiple anthropogenic pressures, such as the Adriatic Sea. Commercial fisheries such as bottom trawls can serve as an opportunistic platform for collecting data on seafloor litter and help researchers in addressing the lack of data through Fishing for Litter initiatives. In this study, the crews of twelve trawlers from two Italian Adriatic ports collected seafloor litter as part of their Fishing for Litter initiatives. In addition to the classical scheme, the collected litter was sorted on board into different bags, and speed, duration and geographical coordinates of each haul were recorded to allow an assessment of both densities and spatial distribution. More than 600 kg of litter was removed from the seafloor by the fishers in approximately 1 month and characterised by the researchers on the docks. Most of the found items were made of synthetic polymers and related to packaging, fisheries and aquaculture activities. Abandoned, lost or discarded fishing gear and mussel nets were identified as of particular concern in the maritime compartment of Chioggia and Civitanova Marche, respectively. Three hotspots for marine litter were identified: near the Venice lagoon, in the centre of the northern basin and at greater depth in the central Adriatic. This study provides a detailed picture of the spatial distribution and composition of seafloor litter in the areas studied and highlights the importance of increased cooperation between fishermen and scientists to improve the identification of hotspots and sources while removing marine litter from the seafloor and raising awareness of the problem.

Artisanal trawl fisheries as a sentinel of marine litter pollution

Systematic seafloor surveys are a highly desirable method of marine litter monitoring, but the high costs involved in seafloor sampling are not a trivial handicap. In the present work, we explore the opportunity provided by the artisanal trawling fisheries to obtain systematic data on marine litter in the Gulf of Cadiz between 2019 and 2021. We find that plastic was the most frequent material, with a prevalence of single-use and fishing-related items. Litter densities decreased with increasing distance to shore with a seasonal migration of the main litter hotspots. During pre-lockdown and post-lockdown stages derived from COVID-19, marine litter density decreased by 65 %, likely related to the decline in tourism and outdoor recreational activities. A continuous collaboration of 33 % of the local fleet would imply a removal of hundreds of thousands of items each year. The artisanal trawl fishing sector can play a unique role of monitoring marine litter on the seabed.

Fishing for litter, accidental catch in bottom trawl nets along the Catalan coast, Northwestern Mediterranean

The seafloor of the Mediterranean Sea accumulates marine litter (ML), an area where bottom trawlers operate and can accidentally catch the litter from the seafloor. This study aims to describe and quantify the ML caught by bottom trawlers along the Catalan coast (NW Mediterranean Sea) and estimate the potential of the bottom trawl fleet to extract ML from the area as a Fishing for Litter (FFL) initiative to tackle the ML issue. Marine litter was collected from commercial trawlers and was classified as metal, plastic, rubber, textile, wood, and other waste and weighed (kg) from 305 hauls performed during three years (2019-2021) from 9 different ports at 3 different depths. ML was present in 97 % of the hauls, with plastic being the most abundant material. The composition varied according to zone, port and depth, with the highest densities found in highly urbanized areas (13.75 ± 3.25 kg km^-2), which mainly contained plastics (74.3 %). The port of Barcelona had the highest presence of plastics (23.62 ± 6.49 kg km^-2), mainly wet wipes. Regarding depth, the continental shelf had the highest density of ML, with 12.24 ± 2.40 kg km^-2. The potential ML removal (t year^-1) was calculated using fishing effort (hours). It is estimated that the bottom trawlers may potentially remove 237 ± 36 t year^-1 of ML in the Catalan coast. FFL initiatives should be part of a multidisciplinary approach to tackle marine litter, which must include prevention, monitoring, and cleaning actions.

Integrated approach for marine litter pollution assessment in the southern Tyrrhenian Sea: Information from bottom-trawl fishing and plastic ingestion in deep-sea fish

Marine litter pollution threatens marine ecosystems and biodiversity conservation, particularly on seafloors where all anthropogenic waste naturally sinks. In this study, we provide new information on the composition, density and origin of seafloor macrolitter as well as on plastic ingestion in deep-sea fish from bottom-trawling by-catch in the southern Tyrrhenian Sea. Plastic constituted the highest fraction of litter in terms of density (64 %) and weight (32 %) and was also retrieved in the gastrointestinal traits of Chlorophthalmus agassizi, Coelorhynchus coelorhynchus and Hoplosthethus mediterraneus. FT-IR spectroscopy analysis on the seafloor macrolitter and the ingested plastics revealed the presence of artificial polymers including PE, PET/polyester, PA widely used for food packaging, plastic bags and several common products, especially Single Use Plastic (SUP). These results underline how poor waste management schemes or their incorrect application strongly contribute to marine litter accumulation on seafloors and plastic ingestion in deep-sea fish.

Breaking the paradigm: Marine sediments hold two-fold microplastics than sea surface waters and are dominated by fibers

We conducted one of the first studies to integrate the quantification and characterization of microplastics (MPs), including fibers, in different habitats (sea surface, seafloor and beach sediments) of a coastal Mediterranean marine protected area, analyzing their ingestion in several marine species. The objectives of the study were to evaluate the distribution of MPs according to shape and polymer, to assess the contribution of fibers to local plastic pollution and to evaluate their ingestion in fish and invertebrates species that inhabit the study area (Pagrus pagrus, Serranus scriba, Spondyliosoma cantharus, Diplodus vulgaris, Oblada melanura, Holothuria forskalii, Holothuria tubularis, Holothuria polis, Arbacia lixula, Paracentrotus lividus, Modiolus barbatus, Mytilus galloprovincialis and Arca noae). A total of 111 environmental samples were analyzed. The mean abundance of MPs (excluding fibers) quantified in beach sediments (13,418.86 ± 28,787.99 MPs/m²) was two orders of magnitude higher than that found in seafloor sediments (76.92 ± 108.84 MPs/m²), which in turn was two orders of magnitude higher than sea surface samples (0.17 ± 0.39 MPs/m²). The fibers were the most abundant shape of MPs identified in all habitats. Variability in MPs ingestion was detected between species, with ingestion rates ranging from 43 % to 100 % for general MPs and ranging from 7 % to 100 % for fibers. The highest ingestion was observed in Holoturians, representing suitable bioindicators for plastic pollution. The composition of the polymer varies weakly depending on habitats and biota, but the result is strongly correlated with the morphology of the plastic. Fibers were mainly composed of cellulose acetate (29 %), styrofoam of polystyrene (18 %), and filaments, films and fragments of polyethylene and polypropylene. The results highlighted the need to expand integrated approaches to effectively study marine plastic pollution and to undertake efficient actions to limit the input of plastics, particularly fibers, into the marine environment.

The nauticAttiva project: A mobile phone-based tool for the citizen science plastic monitoring in the marine and coastal environment

Plastic pollution is involving large coastal areas of the Mediterranean Sea. Innovative methods of plastic monitoring can be addressed through the citizen science approaches integrated with mobile phones. On the other hand, the availability of mobile phones is increasing among several users. Mobile phones can be integrated with a web mobile app, which allows to collect a lot of data for extended areas and in a short temporal range. In this study, the web service of iNaturalist was applied to implement a mobile phone-based tool to collect pictures of plastic items. At present, the web mobile app has been used to collect pictures of plastic debris in the Mediterranean Sea. Results were compared with the Mediterranean hydrodynamic regime, to highlight the pathways and densities of the plastic items. The proposed mobile phone-based tool represented a citizen science approach useful for the acquisition of plastic observations in the marine and coastal environment.

Correlation of metals and degraded marine (micro)plastic litter in geologically similar coastal areas with different anthropogenic characteristics

The association and statistical correlation of anthropogenically important trace metals (TM) Cd, Cu, Pb, Zn and degraded marine microplastic (MP) extracted from the bulk debris samples at two locations from two marine systems, estuarine and coastal, in the Croatian Adriatic coastal area were assessed. The abundance of MP particles at both sites were primarily defined by local wave climate, with the open coastal site containing 9-fold more microplastic particles (>4 mm) as compared to the semi-closed estuarine, or twice as much considering bulk plastics. Generally, the higher abundance of adsorbed metal on MP were observed in the more anthropogenically influenced estuary than in the open coastal site and followed the order: polystyrene > polypropylene > low density polyethylene. The amounts of adsorbed zinc were the highest on all types of plastics at both sites, while the affinity of polystyrene for metals followed: Zn > Pb ≈ Cu > Cd.

Microplastics in the Deep: Comparing Dietary and Plastic Ingestion Data between Two Mediterranean Bathyal Opportunistic Feeder Species, Galeus melastomus, Rafinesque, 1810 and Coelorinchus caelorhincus (Risso, 1810), through Stomach Content Analysis

Marine plastic pollution is currently an issue of mounting concern around the world. Stomach content of marine fish has been increasingly used as a valid proxy for detecting the presence of such a pollutant in marine biota, both for coastal and deep-water environments. Although ingestion of microplastics has been reported in an increasing number of species, the patterns of ingestion still remain unclear, depending closely on the interaction between the species and types of microplastics involved. In this context, we analysed and compared the stomach contents of two bathyal dwelling opportunistic feeder species namely Galeus melastomus and Coelorinchus caelorhincus. In particular, we analysed microplastic items according to their dimension, morphology and colour, and diet’s variation with size obtained through prey identification. Both species showed a higher frequency of occurrence of the blue filament-like middle-sized microplastics (1.01–4.75 mm) compared with the other categories, although this pattern was much more marked in C. caelorhincus than in G. melastomus. The latter conversely showed a larger array of ingested plastic items in terms of shape and colour. Matching plastic ingestion with dietary data suggested potential predator confusion occurring in C. caelorhincus through active mis-selection of a defined type of microplastic instead of some particular family of polychaetes, which resemble in shape, size, and color to that type. Otherwise, G. melastomus appeared more prone to a random ingestion of a larger array of microplastic items because of a more generalistic and less selective feeding strategy. Although further validation is needed, stomach contents of the two species showed evidence strong enough to be considered as potential bioindicator species of microplastic pollution, as required by the Marine Strategy Framework Directive for monitoring this pollutant in the marine environment.

Microplastic accumulation in commercial fish from the Adriatic Sea

We assessed the presence and concentration of microplastics in fishes from the Northern Adriatic Sea on sale for human consumption. Microplastics were extracted from the digestive tract of 180 specimens, belonging to 6 different species (2 pelagic, and 4 demersal). Microplastics were identified through Nile red staining, and selected particles were analyzed by μ-Raman spectroscopy. The 47.8% of examined fish were found to contain microplastics (233 fragments). The mean concentration of microplastics in the 6 species ranged between 4.11 ± 2.85 items/individual in Adriatic soles, and 1.75 ± 0.71 items/individual in pilchards. Microplastics ranged in size between 0.054 mm and 0.765 mm. Polyethylene and polypropylene were the polymer types identified through μ-Raman spectroscopy. Despite our estimates are underestimations, these results are of particular concern, as the fish analyzed are consumed without being eviscerated, and the microplastics they contain are transferred directly to humans.

Composition and abundance of benthic marine litter in the fishing grounds of Iskenderun Bay, northeastern Levantine coast of Turkey

The anthropogenic marine debris in the Mediterranean Sea represents a growing concern because of its potentially harmful impact on marine ecosystems. In this paper, we investigated the composition of marine debris in the Iskenderun Bay seafloor. Between November 2009 and April 2010, a total of 34 trawl operations were conducted. Hauls lasted 60-385 min, and the towing speed varied between 2.7 and 2.8 knots. The estimated average marine litter concentration was 450.94 item/km² (90.34 kg/km²). Plastic was the dominant material type (87%) at all stations. Single-use plastic items represented about 74.9% of the total marine litter. Our results showed that there is severe plastic pollution on the seafloor of Iskenderun Bay that may cause significant damage to both the fisheries sector and the marine environment.

Abundance and Composition of Marine Litter on the Seafloor of the Gulf of Sant Jordi (Western Mediterranean Sea)

This article analyzes the abundance and composition of marine litter in the Gulf of Sant Jordi (Catalonia, Spain). Marine litter was removed from the sea by a fishing trawler operating from the port of L’Ametlla de Mar; 56 hauls were performed between July and September 2018. The marine litter was classified following UNEP/IOC Guidelines on Survey and Monitoring of Marine Litter and EU MSFD Technical Group on Marine Litter Joint List, with a total of 2691 items collected and an average number by haul of 48 (SD 28.24). The density was 130 items km−2 but with significant differences according to trawling depth: 192 items km−2 (≤100 m) and 71.5 items km−2 (>100 m). As expected, plastic was the most commonly found material, comprising almost 80% of the total. The relative presence of plastics declined as trawling depth increased. An alarmingly high amount of sanitary waste was found. Further studies are necessary to compare summer results with those of smaller seasonal populations and to analyze what happens to sanitary waste.

Temporal variation of floatable plastic particles in the largest Italian river, the Po

We investigated the temporal concentration of floatable plastic particles in the Po river, the largest contributor of freshwater to the Adriatic Sea. Surface waters were sampled in 2019 with a Manta trawl, with almost bimonthly frequency. In total, 5063 plastic particles were collected, 80.6% of which were microplastics (<5 mm). Characterization through FT-IR spectroscopy evidenced 7 polymers, of which polyethylene, polypropylene and polystyrene accounted for 40.5%, 25.7%, and 14.9%, respectively. The highest plastic concentration was recorded in December (3.47 particles m^-3; 5.89 mg m^-3), while the lowest in August (0.29 ± 0.01 particles m^-3; 0.22 ± 0.08 mg m^-3). We estimated the annual load of floatable plastic particles carried by the Po river to be 145 tons. Plastic particle load was correlated with the hydraulic regime, and was higher in autumn and spring months.

Marine litter on the shallow seafloor at Natura 2000 sites of the Central Eastern Adriatic Sea

Shallow seafloor marine litter (ML) is the least studied component of ML, and a better understanding of its distribution and accumulation patterns is needed to develop efficient management practices. Abundance and composition of seafloor ML were quantified in two eastern Adriatic Natura 2000 sites (Vis Island and Pakleni Islands), applying a structured sampling design to test whether the intensity of nautical tourism or exposure to prevailing winds and currents are significant drivers determining the ML distribution on shallow, coastal seafloor. ML was widespread and present in considerable amounts across the entire studied area, regardless of the remoteness from most known potential ML sources. Tourism intensity and exposure seem not to be significant predictors of ML accumulation in the investigated Natura 2000 sites. ML abundances displayed large small-scale spatial variation, while for ML composition at a larger scale, regional differences between the two Natura 2000 sites were detected. The Pakleni Islands are mainly polluted by glass items, suggesting a local vessel-based source. The ML composition on Vis Island, with a predominance of plastics, is more determined by long-distance transport. The study indicates the complexity and multi-layeredness of processes driving the patterns of seafloor ML accumulation. Hence, it is suggested to mitigate the issue by addressing the root causes: inadequate waste management and lack of public awareness.

Temporal trends of marine litter in a tropical recreational beach: A case study of Mkomani beach, Kenya

Six marine litter standing stock surveys were carried out to determine the influence of monsoon on the temporal abundance and composition of macro-litter in Mkomani beach, Mombasa Kenya. Foam (0.073 items m^-2) and plastic (0.042 items m^-2) fragments had the highest densities. The brand audit indicated that 66.9% of branded marine litter was of Kenyan origin. Food product packaging contributed 78.4% of the branded litter with PET bottles being the most abundant type of packaging (48.2%). Foreign products contributed 35.6% of branded marine litter during South East Monsoon (SEM) whereas only 11.7% during North-East Monsoon (NEM). Worth noting, PET packaging dominated during SEM (53.6%) compared to NEM (20.2%). Mkomani beach could be considered "extremely dirty" with a Clean-Coast Index greater than 20. The study concludes that monsoons influences litter diversity, richness and evenness.

Preliminary results on the occurrence and anatomical distribution of microplastics in wild populations of Nephrops norvegicus from the Adriatic Sea

This study reports the shapes, dimensional classes, types and counts of microplastics (MPs) found in 23 individuals of N. norvegicus collected from two wild populations of the Adriatic Sea (Mediterranean basin). The focus was on three different anatomical compartments (gut, hepatopancreas and tail), which were analysed separately. MPs were found in all the investigated individuals with an average of about 17 MPs/individual. Fragments were predominant over fibers with a ratio of about 3:1. The majority of MPs were in the dimensional range 50-100 μm. The predominant polymers were polyester, polyamide 6, polyvinyl chloride and polyethylene, which together constitute about 61% of all the MPs found. Fragments were more concentrated in the hepatopancreas, with no significant difference between gut and tail, while fibers were more concentrated in the gut than in the tail with hepatopancreas somehow in between. The dimensional class of the MPs influences their anatomical distribution. There were no statistical differences among individuals from the two sampling sites. Sex of the individual did not influence the level of retained MPs, while length had a very marginal effect. The information reported here contributes to understanding of the possible risks linked to human consumption of different tissues from contaminated Norway lobsters.

Micro- and macro-plastics in beach sediment of the Algerian western coast: First data on distribution, characterization, and source

The accumulation of plastic debris in the Algerian coasts is due to inadequate solid waste management and the inhabitants' behavior. To quantify and characterize the plastic pollution, we collected plastic items (≥1 mm) in the sediment of nine beaches covering 124 km of the Algerian western coast. The plastic concentration varied between 7.6 ± 18.8 and 66 ± 107.28 items/m². With 83.27%, fragments were the predominant items as micro- and macro-plastics, whereas pellets were mainly present as microplastics (14.93%); films represented 1.03%. We recorded the highest values for the number of plastic items/m² in beaches located close to coastal villages. Regarding the number and the weight of the plastic debris, we registered significant differences between the locations. Although the plastic pollution is currently moderate in the study area, local authorities are compelled to be aware of its increase. Therefore, the improvement of the solid waste management is urgently needed.

Seafloor litter along the Italian coastal zone: An integrated approach to identify sources of marine litter

A heterogeneous amount of waste of different origins is continuously generated along Italian coasts in the Mediterranean Sea. In this paper, using information regarding the quantities and the different types of marine litter based on Project AWARE's "Dive Against Debris" data, we try to identify the main sources of this waste. In particular, the methodological approach used associates the origin of marine litter sources with the dataset of geo-localised state-owned maritime concessions, which are loaded by the granting bodies (regions, municipalities, port authorities) on the State Property Information System (Sid). The sources of marine litter were evaluated using the matrix scoring technique (MST). Then, to assess the weight of each source in each station, the community-level weighted mean (CWM) was calculated. Single-use plastic accounted for the highest percentage (19.13%), followed by glass beverage bottles (10.90%), shopping bags (9.03%), aluminium beverage cans (4.91%), and cigarette butts (4.61%). Tourism and beach users contributed to 42.3% of the litter found, followed by fishing (15.7%) and yachting (11.3%). The overlapping of the data collected by scuba divers with the state concessions of activities from offshore and mainland areas was used to distinguish the anthropic pressures that impact the coast. Policy makers and the local administrator may use these results to define new methods of collection and reuse of anthropic waste through a more harmonised approach in the management of marine waste.

A critical review on marine litter in the Adriatic Sea: Focus on plastic pollution

Marine litter affects various habitats across the world. This review focuses on the Adriatic region, considering the presence of marine litter as well as microplastics (mPs) and macroplastics (MPs) in different environments (water, beach, seabed and biota). Data from 53 scientific papers were critically analysed, providing a snapshot of this type of contamination, and evidencing critical issues. The final part of the review provides considerations on spatial and temporal trends, comparing data with the available information provided by transport forecasting models. It emerges that the most investigated areas are those most subjected to the contribution of rivers, tourism or have the greatest relevance to nature conservation. Our analysis also reveals that, even though many international research projects have played a fundamental role in the creation of shared methods and protocols, currently available data are difficult to compare. Nevertheless, our results enhance knowledge of the state of the art in the research carried out so far, and on the situation regarding pollution due to the marine litter in the Adriatic Sea, as well as highlighting avenues for future investigation.

Abundance, composition and sources of marine debris trawled-up in the fishing grounds along the north-east Arabian coast

The pollution due to marine debris is a serious environmental threat in many parts of the world. The abundance of marine debris, composition and its distribution over the seafloor along north-east coast of Arabian coast was studied through trawl based swept method. Experimental fishing was conducted fortnightly using shrimp bottom trawl and collected debris was categorized as per standard protocols. A total of 1077 pieces of debris (11.7 kg dry weight) were collected from 25 hauls. The average number and weight of debris were 943 items/km² and 10.2 kg/km² respectively. The estimated total marine debris along this coast was 379 t (dry weight). Plastic-based debris contributed maximum (87.1%) to the total debris collected in numbers and among this, plastic bags and food wrappers were dominant. Debris produced by shoreline/recreational activities comprised the major source of debris (88.6%) along this coast. This study provides the evidence that the effective use of available fishing trawlers and co-management practices ("Make fishers friend") can help to remove the seabed debris. The base data generated through this study would facilitate region-based effective control and management of plastic debris pollution.

Microplastic's story

The problem of microplastic pollution is now the order of the day in front of everyone's eyes affecting the environment and the health of leaving creature. This work aims to retrace the history of microplastics in a critical way through a substantial bibliographic collection, defining the points still unresolved and those that can be resolved. Presence of marine litter in different environments is reviewed on a global scale, focusing in particular on micro and macro plastics definition, classification and characterization techniques.

Composition and abundance of macrolitter along the Italian coastline: The first baseline assessment within the european Marine Strategy Framework Directive

The main objective of the Marine Strategy Framework Directive (MSFD) was to achieve a Good Environmental Status (GES) in European waters by 2020, according to 11 descriptors. Descriptor 10 is related to marine litter and envisages that the properties and quantities of marine litter are at a level that does not cause harm to the coastal and marine environment. Even if GES was not achieved by 2020, the first MSFD implementation cycle filled many gaps in knowledge. Here we present the first data (2015-2018) on beach litter densities along Italian coasts and discuss lessons learnt and future perspectives. The beach litter median density was 477 items/100 m (interquartile range: 261-934 items/100 m), but subregional differences emerged both in terms of litter quantities and composition. The Adriatic Sea was the most polluted subregion (590 items/100 m), followed by the Western Mediterranean Sea (491 items/100 m) and the Ionian Sea and Central Mediterranean Sea subregion (274 items/100 m). A high presence of aquaculture-related litter (mainly mussel nets) characterised beaches in the Adriatic Sea. At the same time, the numbers of cotton bud sticks were extremely high in some beaches of the Western Mediterranean Sea. General litter (items discarded or left by the public on the coast or inland and carried by winds and rivers or objects originating from tourism and recreation at land or sea, poor waste management practices, etc.) was the most common litter typology (38.8%). The results of this study represent the first baseline to compare achievement towards GES in the next years and the efficacy of the program of measures which entered into force in 2016, concerning beach litter densities and composition. They also highlight the necessity of a joint effort for deploying harmonised marine litter monitoring methodologies across the European Member States to obtain comparable results.

Seafloor litter sorting in different domains of Cap de Creus continental shelf and submarine canyon (NW Mediterranean Sea)

We analyzed litter occurrence in 68 underwater video transects performed on the middle/outer continental shelf and submarine canyon off Cap de Creus (NW Mediterranean), an area recently declared Site of Community Importance (SCI). Low densities of urban litter were registered on the shelf (7.2 items ha^-1), increasing in abundance towards the deepest part of the submarine canyon, with 188 items ha^-1 below 1000 m depth. We hypothesize that the strong bottom currents that recurrently affect this area efficiently move litter objects from the shelf towards the deep. Of all litter items, approximately 50% had a fishing-related origin, mostly longlines entangled on rocks in the canyon head and discarded trawl nets in deeper areas. Over 10% of cold-water colonies observed had longlines entangled, indicating the harmful effects of such practices over benthic habitats. These results should be considered when designing mitigation measures to reduce litter pollution in Cap de Creus SCI.

The current state of marine debris on the seafloor in offshore area around Japan

Marine debris on the seafloor has not been thoroughly investigated, and there is little information compared to other types of marine debris. We conducted bottom trawl surveys to determine the present situation of marine debris on the seafloor in offshore areas around Japan. The survey was conducted in three sea areas with different characteristics. As a result, it was found that the amount of marine debris in submarine canyons (2926.1 items/km²) was higher than on the continental shelf. It was revealed that most marine debris on the seafloor is comprised of plastic products, and that debris on the seafloor retains its condition for a long time (over 30 years) without deterioration. In addition, the type of marine debris is affected by the industries operating in each area. Continuing to investigate marine debris on the seafloor in more areas will contribute to solving the problem of marine debris.

What is in our seas? Assessing anthropogenic litter on the seafloor of the central Mediterranean Sea

Abundance, composition, and distribution of macro-litter found on the seafloor of the Strait of Sicily between 10 and 800 m depth has been studied using data collected by bottom trawl surveys MEDITS from 2015 to 2019. Three waste categories based on the items use were considered: single-use, fishing-related and generic-use. Over 600 sampling sites, just 14% of these were litter-free. The five-years average density of seafloor litter was 79.6 items/km² and ranged between 46.8 in 2019 and 118.1 items/km² in 2015. The predominant waste type was plastic (58% of all items). Regardless of material type, single-use items were a dominant (60% of items) and widespread (79% of hauls) fraction of litter with a mean density of 48.4 items/km². Fishing-related items accounted for 12% of total litter items. Percentage of dirty hauls and litter density increased with depth. Analysis of the relation density-depth indicates a progressive increase of litter density beyond depth values situated within the interval 234-477 m depending on the litter category. A significant decrease in litter density by categories was observed over the period. Patterns of spatial distribution at the higher depths (200-80 0m) resulted stable over the years. Density hotspots of fishing-related items were found where the fishing activity that uses fish aggregating devices (FADs) is practised and in the proximity of rocky banks. Single-use and generic-use objects densities were greater on the seafloor along main maritime routes than other areas. Comparisons between the percentage of hauls littered with anthropic waste from the mid-1990s against those in 2018-19 highlighted an increase of about 10.8% and 15.3% for single-use items and fishing-related items respectively, and a decrease of 18.6% for generic-use items. This study provides a snapshot of the current situation of littering in the central Mediterranean Sea and represents a solid baseline against which the effectiveness of current and future mitigation strategies of the litter impact on marine environment can be measured.

Exploring the relation between plastic ingestion in species and its presence in seafloor bottoms

In order to have a wider understanding of the impacts of plastics on marine ecosystems, studies should approach different environmental compartments, such as seafloor and biota, at the same time. The aim of this research is to study the relation between microplastic ingestion in species and the amount of seafloor plastics caught in the same bottom trawls hauls of the western Mediterranean Sea to describe a potential overlap between these two indicators of plastic pollution. According to results, 15% of the sampled individuals ingested microplastics with a mean value of 0.30 ± 0.40 microplastics/individuals. Regarding seafloor plastics, these were present in 58% of the hauls with a mean value of 1.31 ± 0.09 kg/km². The highest overlap between ingestion of microplastic in species and seafloor plastics was observed in the bay of Palma, the most urbanized area, but also in areas close to Marine Protected Areas (MPAs).

Investigating Detection of Floating Plastic Litter from Space Using Sentinel-2 Imagery

Plastic litter floating in the ocean is a significant problem on a global scale. This study examines whether Sentinel-2 satellite images can be used to identify plastic litter on the sea surface for monitoring, collection and disposal. A pilot study was conducted to determine if plastic targets on the sea surface can be detected using remote sensing techniques with Sentinel-2 data. A target made up of plastic water bottles with a surface measuring 3 m × 10 m was created, which was subsequently placed in the sea near the Old Port in Limassol, Cyprus. An unmanned aerial vehicle (UAV) was used to acquire multispectral aerial images of the area of interest during the same time as the Sentinel-2 satellite overpass. Spectral signatures of the water and the plastic litter after it was placed in the water were taken with an SVC HR1024 spectroradiometer. The study found that the plastic litter target was easiest to detect in the NIR wavelengths. Seven established indices for satellite image processing were examined to determine whether they can identify plastic litter in the water. Further, the authors examined two new indices, the Plastics Index (PI) and the Reversed Normalized Difference Vegetation Index (RNDVI) to be used in the processing of the satellite image. The newly developed Plastic Index (PI) was able to identify plastic objects floating on the water surface and was the most effective index in identifying the plastic litter target in the sea.

Macro litter distribution of the Turkish Mediterranean coasts dominated by pleasure crafts

Litters are the most pollutants in progress of the interests in marine environments. Macro litter samples were collected from 66 stations to estimate litter contribution from pleasure crafts along bays of the most Turkish touristic coasts (Antalya-Muğla) by the divers in June/July 2019. Average abundance and weight were 19 items/km² and 18 kg/km², respectively. The most abundant litter was plastics and the most contributors in weight were metals, followed by glass/ceramics. Abundance of the litters increased with number of pleasure crafts in active in summer. Pleasure crafts contributed most abundantly with the personal wares to the total litter, particularly in the coasts of Muğla. Litters were differentiated with interaction of region × bottom depths. The litter composition and abundance were different between region of Antalya in active mostly by tour boats and region of Muğla by private yachts. The litter types were however correlated with sea surface temperature.

Characterization of seafloor litter on Mediterranean shallow coastal waters: Evidence from Dive Against Debris®, a citizen science monitoring approach

Citizen science programs carried out by volunteers are fundamental for the collection of scientific data on a wide spatial scale. From 2011 to 2018, 468 survey dives were conducted in 172 coastal locations of the Mediterranean Sea through Project AWARE's citizen science program, Dive Against Debris®. During the dives, information was collected on quantity, typology and distribution of seafloor litter in shallow coastal waters. Overall, the observed average density was 43.55 items/100 m² and plastic was largely the dominant material (55% of the total collected items) on basin scale. The most abundant seafloor litter items were plastic fragments with 9.46%, followed by beverage cans (7.45%). Single-use plastic items constituted 33% of the total marine litter. The results of the study can be used to inform policymakers of the European Community towards specific management action to contrast the marine litter in relation to the distribution of the recorded litter category.

Modeling transport of microplastics in enclosed coastal waters: A case study in the Fethiye Inner Bay

In this study, transport and possible accumulation of microplastic marine litter in enclosed coastal waters are modeled numerically. The model is applied to the Fethiye Inner Bay, located in Fethiye-Göcek Specially Protected Area. In modeling studies, three dimensional coastal hydrodynamics, transport and water quality numerical model HYDROTAM-3D was used. The current climate was prepared by modeling long-term circulation patterns due to wind, wave and density stratifications. Following the hydrodynamic studies, the advection and diffusion of 3 mm size polystyrene particles by the coastal currents in the surface waters of Fethiye Inner Bay were simulated. The coastal regions where the microplastic pollution will be concentrated and transported were determined by the modeling scenarios. It has been found that microplastic accumulation is expected in the southwest and east coastal waters of the Fethiye Inner Bay. The results of the model will contribute to the databases for sustainable protection of the marine environments.

A trawl survey of seafloor macrolitter on the South African continental shelf

Demersal trawls provide an index of seafloor macrolitter abundance, but there are no published data from sub-Saharan Africa. We collected litter items from 235 trawls conducted to assess fish abundance off South Africa. Only 17% of trawls contained litter (3.4 items·km^-2, 2.1 kg·km^-2 but only 0.2 kg·km^-2 excluding four megalitter items). Plastic items predominated (88%), of which 77% floated once cleaned of epibionts. One LDPE bag manufactured three months before being caught carried pelagic goose barnacles Lepas anserifera, confirming that biofouling leads to rapid sinking of floating plastics. Fishery/shipping wastes comprised 22% of litter items (98% by mass; 73% excluding megalitter items); the remainder was general waste - mostly packaging or other single-use items - that could come from land- or ship-based sources. Litter was more abundant in deep water close to Cape Town. The annual demersal trawl survey is a useful way to monitor seafloor litter off South Africa.

Seafloor litter from the continental shelf and canyons in French Mediterranean Water: Distribution, typologies and trends

Seafloor litter has been studied both on the continental shelves (by trawling during 24 years) and in canyons (by ROV) of the French Mediterranean sea Water (FMW). On the continental shelf, mean densities range from 49.63 to 289.01 items/km². The most abundant categories were plastic, glass/ceramics, metals and textiles. Trend analysis shows a significant increase in plastic quantities during the study period. Plastics accumulate at all depths, with heavier items being found in deeper areas, while the continental slope-break appears as a clean area. The spatial distribution of litter revealed the influence of geomorphologic factors, anthropic activities, shipping route, river inputs. All the canyons are affected by debris but coastal canyons (Ligurian Sea and Corsica) were more impacted than offshore canyons in the Gulf of Lion. The FMW appears to be highly polluted with regard to values found in other areas, but lower than those observed in the Eastern Mediterranean.

Study of marine debris around a tourist city in East China: Implication for waste management

Marine debris characterization is fundamental for developing policies aiming at ending the flow of marine debris at the source. China has the largest coastal population in the world. For this emerging economy, the sources of debris might be different from those in regions at different developmental stages. As a typical coastal tourist city and a special economic zone in East China, there are multiple sources of marine debris continuously produced around Xiamen. Marine debris characterization here could provide insights into regulatory measures. Therefore, the abundance and composition of marine debris around Xiamen were investigated. Average densities of floating, beached, benthic macro-debris and floating microplastics (0.5 mm - 5 mm) were 3963 ± 2027 items km^-2, 0.13 ± 0.08 items m^-2, 20,274 ± 15,873 items km^-2 and 36,455 ± 33,935 items km^-2, respectively. Based on the Clean Coast Indexes, the beaches investigated were supposed to be "very clean" most of the time (73.2% ± 34.9%). Wastes with low value for recycling/reuse, such as grocery bags, ropes, and foams, were the main items of marine debris in the study area. Both domestic sources from the upstream and local fishing/aquaculture activities significantly contributed to marine debris. Obvious regional differences in benthic debris categories could be explained by both natural factors and the rural-urban gap in economic levels, waste-management strategies and infrastructure. These might be common features in this emerging market and densely populated economy. The findings provide insights into the sources of mismanaged waste around this tourist city and some neglected deficiencies in China's current solid waste management system.

Marine litter from fishery activities in the Western Mediterranean sea: The impact of entanglement on marine animal forests

The anthropogenic marine debris, especially abandoned, lost or otherwise discarded Fishing Gear (ALDFG), represents a rising concern, because of its potential harmful impact on the marine animal forests. We carried out 13 km of video recordings, by means of a remotely operated vehicle, from 10 to 210 m depth, in an anthropised area of the Tyrrhenian Sea (Mediterranean Sea). This site, for its high ecological importance and biodiversity value, has been identified for the establishment of a new marine protected area (MPA). The aim of this paper was to assess marine litter abundance and its effects on the benthic fauna. The debris density, in the study area, ranged from 0.24 to 8.01 items/100 m², with an average of 3.49 (±0.59) items/100 m². The derelict fishing gear, mainly fishing lines, were the main source of marine debris, contributing 77.9% to the overall litter. The impacts of debris on the benthic fauna were frequently recorded, with 28.5% of the litter entangling corals and impacting habitats of conservation concern. These impacts were exclusively caused by the derelict fishing gear (91.2% by longlines), and the highest percentage (49.1%) of ALDFG causing impacts was observed from 41 to 80 m depth, in the coralligenous biocenosis. The results of the present study will help the fulfilment of "harm" monitoring, as recommended by the Marine Strategy Framework Directive (MSFD) and the UN Environment/MAP Regional Plan on the marine litter management in the Mediterranean Sea. Regarding the actions to reduce the derelict fishing gear, preventive measures are usually preferred instead of the extensive removals based on cost-effectiveness and sustainability. The establishment of a new MPA in the area could be a good solution to reduce ALDFG, resulting in the improvement of the ecological status of this coastal area.

Characterisation of wastes collected from beaches, coastlines, marine surface cleaning processes and ships: A case study of Istanbul

Marine waste management is crucial for Istanbul because of the significant location for intercontinental transition, international trade, tourism, industry and shipping. This study is the first one realised in Turkey for the detailed characterisation of marine waste. The amount and characteristics of solid wastes originating from beaches, coastlines, sea surface cleaning processes and ships (both cargo and cruise ships) were determined. It was observed that marine wastes includes a significant amount of recyclable materials. Although, it was ascertained that the amount and composition of waste differs according to the collecting sources, the majority of wastes are composed of different types of plastics. The average calorific value of marine waste was determined as 2500 kcal kg^-1, which is higher than that of mixed municipal solid waste. There is a lack of studies on the pathways of disposal alternatives of marine waste after collection. As landfilling is the common pathway for disposal after collecting, it is clear that recycle/reuse and energy recovery options are possible for marine waste.

Sources, transport, and accumulation of different types of plastic litter in aquatic environments: A review study

Types of plastic waste in different aquatic environments were assessed to obtain a global framework of plastic waste transport and accumulation, relevant for plastic pollution mitigation strategies in aquatic environments. Packaging and consumer products were the most encountered product categories in rivers, while fishery items dominated in the oceanic environment. Plastics from electronics, building and construction, and transport were barely observed. For polymers, polyethylene and polypropylene contributed most to pollution in all environments. The highest diversity in polymer composition was found in oceanic and freshwater sediments. It is therefore argued that a large fraction of plastic waste accumulates here. This confirms that plastic waste transport and accumulation patterns were most affected by the density, surface area, and size of plastics. Only thick-walled, larger plastic debris from low-density polymers are transported through currents from rivers to ocean, while the larger fraction of plastic litter is likely retained in sediments or beaches.

A critical review of the issue of cigarette butt pollution in coastal environments

Beach anthropogenic litter is a worldwide problem and has been discussed in the specialized literature for decades. Cigarette butts (CB) are the most frequent form of personal item found on beaches. Yearly, 6 trillion cigarettes are smoked worldwide, and 4.5 trillion cigarettes are littered in the environment. The objective of our review was to assess the relevant literature on the issue of CB in costal environments, including urban areas. We compile and discuss studies (1998-2018) of CB sources for coastal environments, composition/degradability, quantification on beaches, toxicity to aquatic organisms and existing strategies to abate the problem. The literature shows that despite the growing interest in marine litter, this specific issue remains little studied and information is limited in time and space. Studies have been undertaken on islands, continental coasts, estuaries and coastal cities. There area wide variety of approaches to classification; for example, CB are considered plastic in 19% of studies and placed in an isolated category in another 16%. It was possible to identify the main sources of CB in coastal environments and access to the marine biota. In conclusion, we list and discuss proposals for reducing smoking, littering and marine pollution as a contribution to reduce the problems caused by CB in coastal and marine environments. CAPSULE: Cigarette butts are a pervasive, toxic and recalcitrant type of marine litter that requires urgent attention from manufacturers, users, authorities and the public to prevent the ingestion of cigarette butts by biota and water pollution from its leachate.

Assessment of seabed litter in the Northern and Central Adriatic Sea (Mediterranean) over six years

Seabed debris is much less investigated in respect to the sea surface and shores due to sampling difficulties and costs. However, detecting marine benthic litter is fundamental for developing policies aimed at achieving the Good Environmental Status in European Seas by 2020, as requested by the Marine Strategy Framework Directive. This study estimates seafloor litter abundance, composition, spatial distribution and main sources in the North-Central Adriatic Sea (FAO GSA 17) over a six-year period (2011-2016) with 67 stations sampled per year, representing the longest data set for the basin. Litter items collected using a "rapido" trawl were classified in six major categories. The average density of the litter collected over six years was 102.66 ± 41.91 kg/km². The highest concentration of litter was found in stations close to the coast within 30 m depth with a mean weight of 142.90 ± 27.20 kg/km², while the lowest value was recorded between 30 and 50 m of depth (41.12 ± 9.62 kg/km²). Plastic was dominant followed by metal and other litter materials. Lost fishing nets and mussel culture debris accounted for 50% of the overall plastic litter collected. These data and the systematic monitoring of marine litter provide useful information to implement necessary measures to manage marine litter and minimize this type of anthropogenic pollution in the Adriatic region.

Shelf-life and labels: A cheap dating tool for seafloor macro litter? Insights from MEDITS surveys in Sardinian sea

The global plastic economy demands to reduce the flow of plastic into oceans and promote remedial actions for already accumulated seafloor litter. In this perspective, baseline levels of contamination and tools for dating litter items in order to assess the efficacy of those actions, are thus needed. In this note we discuss the utility of introducing the acquisition of shelf-life and labels features from litter items into already established standardized protocols such as the one proposed by MEDiterranean International Trawl Survey (MEDITS). Our investigation was conducted on 612 high resolution images of litter items collected in each haul, which was retrieved during 6 years of surveys (2013-2018) around Sardinian sea (central western Mediterranean). While for the majority of items (89%) expiration date or labels were not present or legible, over 50% of dated items were likely dumped at sea from a period <5 years. In this perspective, this sort of data could represent a useful tool for monitoring the effectiveness of input reduction actions that implicitly rely on the gradual reduction of recently dumped items.

A harmonized and coordinated assessment of the abundance and composition of seafloor litter in the Adriatic-Ionian macroregion (Mediterranean Sea)

Marine litter is a threat to marine life and an economic burden for coastal communities, but efforts to address the issue are hampered by the lack of data for many countries. We performed the first harmonized assessment of seafloor litter (trawl and visual surveys) in six countries of the Adriatic-Ionian macroregion. Seafloor litter showed an uneven distribution throughout the area, with large differences in litter densities and composition among countries and locations. An emerging problem in the area resulted in short-term & single-use objects that represented the largest fraction of litter. Packaging was the economic sector contributing most to seafloor litter on the continental shelf and upper slope, while in some areas aquaculture (mussel farming) represented a key activity producing marine litter. In coastal areas and bays (e.g. Boka Kotorska bay, Montenegro), seafloor litter was mainly related to construction activities and electronic goods, which are a consequence of fly-tipping/illegal dumping.

Marine litter in the Croatian part of the middle Adriatic Sea: Simultaneous assessment of floating and seabed macro and micro litter abundance and composition

In this study, abundance, distribution and composition of floating and seabed macro and micro litter in the Central Adriatic Sea were assessed. Floating macro litter observations were made. Floating and seabed micro litter were sampled with manta net and Van Veen grab, respectively. Micro litter particles visually found under the microscope were chemically analyzed with Fourier Transform Infrared microscope. Average calculated concentrations of floating macro (175 items/km²), floating micro (127 thousand particles/km²) and seabed micro litter (36 particles/100 g dry weight) show similar values as other published studies from the Mediterranean Sea. A statistically significant (p < 0.01) correlation between the floating micro and macro litter concentrations was found for the sites located in the channel waters. Disagreement between model and observations revealed gaps in our knowledge concerning the sea circulation and litter sources. Simultaneous samplings and observations of marine litter in different marine compartments proved possible, efficient and informative.

Quantity and spatial distribution of seafloor marine debris in the Moroccan Mediterranean Sea

This paper qualifies, quantifies and localizes seafloor marine debris (SMD) in the Moroccan portion of the Mediterranean Sea. Six scientific trawl surveys were conducted by the Moroccan Institute of Fisheries Research from 2012 to 2015 between Cape Spartel (5°W) and Saidia (2°W), during which a total of 497 kg of SMD has been collected. Statistical analysis show that the mean abundance differed between surveys, generally ranging from 26 ± 68 to 80 ± 133 kg/km². A typology of SMD indicates that plastic represented 73% of the debris collected, followed by rubber (12%), textile (8%), metal (3%), glass (0.32%), and some unidentified materials (2.70%). Analysis of results shows that the abundance and the distribution of SMD were strongly influenced by the local anthropogenic activities and by rivers inputs. The movements and accumulations in the open sea were also shown to be influenced by the geomorphology and the hydrodynamics of the basin.

Spatial and temporal trends of marine litter in the Spanish Mediterranean seafloor

Composition, spatial distribution and temporal evolution of marine litter on the Spanish Mediterranean seafloor were assessed. The data derive from Spanish MEDITS surveys over 11 years and were analysed by GIS. A total amount of 2197.8 kg of litter was collected. Marine litter (by weight) was composed of plastics (29.3%), clinker (28.4%), wood (10.2%), metal (9.7%) and glass (6.2%). Its density varied among Areas (Alboran Sea > Valenciana >Alboran Island > Tramontana). For the last 11 years, the marine litter has remained stable or decreases in some case. The information provided by this study is a useful baseline to study such debris on the Spanish seafloor. The MEDITS survey has proven to be an appropriate monitoring tool, also of use to assess future control measures.