Oceanographic and anthropogenic variables driving marine litter distribution in Mediterranean protected areas: Extensive field data supported by forecasting modelling

Microplastic ingestion and Phthalate ester levels as plastic tracers in the Mediterranean Velella velella: a candidate plastic indicator for the pelagic neustonic environment

Bioindicator species can help assess plastic pollution's impact on biodiversity by integrating spatial distribution and temporal trends, highlighting associated ecological risks. To investigate a potential indicator for pelagic neustonic environments, the holoplanktonic hydrozoan V. velella was collected in the Pelagos Sanctuary (SPAMI, NW Mediterranean Sea). A total of 460 individuals from 27 stations were collected alongside manta net trawls. Isolated organisms were digested through an alkaline solution and examined for the presence of microplastics (MPs). The correlation among the abundance of floating microplastics in the area, microplastic ingestion and levels of 11 Phthalate Acid Esters (PAEs) in V. velella have been investigated to provide a comprehensive assessment of the multiple stressors impacting this species. Over 200 MPs were isolated, with an occurrence of 93 % in the sampling stations (0.6 ± 0.7 items/individual). Polyester filamentous-shape particles (including fibres and filaments; 81 %) and polyamide, polyolefin and polystyrene fragments (17 %) were the predominant particle types. PAEs concentration averaged 313 ± 66 ng/g w.w. with Dibutyl-phthalate, Diisobutyl-phthalate, and Diethylhexyl-phthalate, listed as reprotoxic by EU regulation, comprising 95 % of total compounds. Despite no statistical correlation, a slightly positive trend between ingested plastic and total PAEs load was found shedding light on the potential direct release from particles. With its wide distribution, key trophic role, ability to capture smaller MPs fractions (<300 μm) and fibres and to accumulate the chemicals from the surrounding environment, V. velella emerges as a promising bioindicator of MPs pollution in the pelagic areas of the Mediterranean Sea and the other seas and oceans worldwide.

Anthropogenic fibers in the Mediterranean sea: Methods and monitoring of an overlooked category of microparticles in the water column

Anthropogenic particles (APs) are widespread in the marine environment, but knowledge gaps remain regarding anthropogenic fibers. This study aimed to evaluate the presence of APs, including natural and synthetic fibers, in the water column. A literature review on fibers in Mediterranean seawater revealed that current sampling methods are underdeveloped. Two sampling methods were compared to determine the best approach for collecting fibers: a new in-situ pump (20 μm mesh filter) and a WP2 plankton net (200 μm). The in-situ pump was the most effective method and was applied in three areas of the Western Mediterranean Sea (Gulf of Asinara, Capraia Island, Capo Carbonara). The predominant APs, characterized by μFTIR, were cellulose and polyester fibers, reflecting the global textile fiber production. The Asinara area was the most impacted area (average of 393.7 items/m3). This study highlights the ubiquitous presence of fibers in the water column and underscores the need for further investigation of potential impacts on marine biota.

A systematic monitoring approach to assess floating marine macro litter in Italian waters: Baseline, thresholds, good environmental status, and mitigation priorities under the EU MSFD

The EU Marine Strategy Framework Directive (MSFD, 2008/56/EC) requires Member States to establish monitoring programs for Descriptor 10-Marine Litter, to track progress towards achieving a marine Good Environmental Status (GES). Italy conducted systematic monitoring of Floating Marine Macro Litter (FMML) in three Marine Reporting Units: Western, Central Mediterranean, and Adriatic (2018-2022, 534 surveys, 2719 km2 across all seasons). This study assessed baseline values for FMML amount and composition, giving indication for tracking GES progress. Following the beach litter approach and considering the differences between coastal and offshore environment, two threshold values were identified: 14.4 items/km2 (objects >2.5 cm) in coastal environments; 0.6 items/km2 (objects>20 cm) in offshore. Based on mean density values (95.8 ± 6.4 items >2.5 cm/km2 coastal; 20.7 ± 2 items >20 cm/km2 coastal; 2.7 ± 0.18 items >20 cm/km2 offshore), all sub-regions were found to be in non-GES status. Priority for mitigation measures and for the replication of the approach are given.

Biodiversity at risk in the SPAMI Pelagos Sanctuary: The impact of marine litter on biota

The Mediterranean basin is the second largest global biodiversity hotspot in the world, which coexists with a plethora of anthropogenic stress. This study examines the risks that marine litter poses to Mediterranean biodiversity, using the Special Protection Area of Mediterranean Importance (SPAMI) "Pelagos Sanctuary" as a case study. In this paper, a new survey method and data analysis strategies to assess the impact of marine litter, including microplastics, on Mediterranean organisms, is proposed. A total of 23 species, from invertebrates to cetaceans, were analysed using two main monitoring approaches. In the first approach, the core density distribution areas of 11 megafauna species (elasmobranchs, sea turtles, seabirds, and cetaceans) and 4 invertebrate species were evaluated through an extended field survey. Simultaneously, monitoring of floating macro- and micro-litter was performed to be overlapped with the species distribution and abundance. The second monitoring approach assessed the ingestion of marine litter, microplastics and the levels of plastic additives in 10 stranded megafauna species and in 7 invertebrate and fish species. The final data processing, merging the data on biodiversity and marine litter abundance and distribution in the environment, with the data of ingested marine litter, microplastics, and plastic additives in sentinel species, allowed to: a) create risk maps for the species inhabiting the Pelagos Sanctuary, identifying critical areas for biodiversity conservation; b) identify the most exposed species to the risk of marine litter by an "exposure score"; c) to select sentinel species for pelagic environment.

Observational requirements for marine litter concentration characterization in the Mediterranean Sea

The pollution of the seas by anthropogenic debris represents a significant environmental and socioeconomic concern. It is of paramount importance to accurately monitor the amount of marine litter in the oceans. However, there is considerable variation in the reported values of marine litter concentrations in certain areas. This uncertainty can be attributed to the inadequacy of the sampling strategies employed. This study analyzes the spatial and temporal requirements for the marine litter sampling in order to obtain accurate estimates of the actual marine litter concentration with the Mediterranean Sea serving as a case study. We conducted a series observing system simulation experiments based on the outputs of a high-resolution modeling system. Our results demonstrate that the strategies employed in the majority of observational campaigns are inadequate for obtaining acceptable uncertainty ranges. The average concentration uncertainty, both spatial and temporal, was quantified in relation to the parameters of the sampling strategies.

A multi-compartment monitoring approach to assess the impact of marine litter in a Mediterranean coastal area

Marine litter, particularly microplastics, is a growing threat to the Mediterranean Sea, impacting biodiversity and ecosystem health. However, most studies conducted in the Mediterranean Sea have focused on monitoring of only specific environmental compartments, and rarely have highlighted the overall impacts affecting an area. Therefore, using a new multi-compartment monitoring approach and a standardized methodology, this study investigates the abundance, distribution, composition and impact of marine litter on beaches, surface waters, fish and mussels in a coastal area of Tuscany (Italy). Concerning beach macro litter values, significant differences were found among the three beaches analysed, with the highest amount in the Feniglia beach (mean value = 1245 items/100 m). The top items found are cotton bud sticks (32.3 %), which in the winter survey at Feniglia beach, reached a remarkable density of 1983 items/100 m. Microlitter (1-5 mm), was detected in the beach sediments with a mean abundance of 130 items/m2. Regarding floating macrolitter, the transect with the highest values was the Feniglia site at 3 nautical miles in autumn (1083 items/km2) while for floating microlitter the highest concentration (832,683 MPs/km2) was found in front of Scarlino. Of the 234 fish analysed from 5 different species, 67 contained microplastics in the gastrointestinal tract (28 %) with a mean value of 0.4 items per individual. The species with the highest occurrence was the European anchovy (Engraulis encrasicolus) (53 %) followed by the bogue (Boops boops) (40 %). Through the application of the Marine Litter Impact Index (MLII), considering all the compartments analysed, the Feniglia area emerges as the ecosystem most impacted by marine litter (mean MLII = 3.5, high). This study highlights how a multi-compartment monitoring approach is crucial for understanding the complex interactions between land, sea, and biota.

Identifying macrofloating debris hotspots in the Mediterranean Sea applying multiplatform methodologies

The Mediterranean Sea is considered the world's sixth greatest hotspot for marine litter; however, quantifying the extent of marine debris in the oceans is a challenge, especially due to variations in survey methodologies. This study aims to assess the spatial abundance and distribution of macrofloating debris (> 2.5 cm) in the Mediterranean basin through visual surveys carried out by methods (research vessel, sailing vessel, and aerial) and approaches (science and citizen science). Aerial and research vessel surveys estimated litter at 1.88 ± 2.3 items·km-2 and 0.89 ± 1.61 items·km-2 respectively for the whole Mediterranean; moreover both methods agreed that the main macrofloating debris hotspots were in the east of Algeria, Tyrrhenian, Adriatic and Alboran Seas. Likewise, for the common blocks analysed aerial surveys estimated greater amounts of macrofloating debris than research vessels (mean 1.92 ± 2.61 items·km-2 vs. 0.94 ± 1.69 items·km-2) highlighting the different detection capacities of the two methods. In the Spanish Mediterranean continental shelf, results obtained from research vessels showed mean values of 8.6 ± 7.8 items·km-2 for 2021 and 3.86 ± 3.96 items·km-2 for 2022. Sailing vessels along the Spanish coastline registered up to 70.87 ± 257.23 items·km-2 in waters of the Cabrera Island, which is a Marine Protected Area. No significant differences between citizen science and scientific methods were found, which suggests that the implementation of this tool could be very useful in obtaining greater datasets. Results on the abundance of macrofloating debris could be attributed to various factors, including the influence of mighty rivers, a dense population in these areas, especially during some seasons like summer, and the effect of some currents and eddies, such as the Algerian and the northern currents, which also influence the transboundary plastics.

Anthropic Pressure on Cetaceans Stranded Along the Ligurian Coast Within the Pelagos Sanctuary: A Case Series

Data collected by C. Re. Di. Ma over a 3-year period (2020-2022) were considered to assess anthropic pressure on cetaceans living in the Ligurian sea. Out of a total of 37 stranded cetaceans, a complete post mortem examination was performed on 23 cases. Of these, 14 were further selected considering at least one of these conditions: (i) confirmed, probable, or suspected interaction with fishing activities through the application of a standardized diagnostic framework (7/14; 50%), (ii) toxicological stress through the evaluation of OCs hazardous levels (14/14; 100%), and (iii) terrestrial pathogen-associated disease (systemic infection and/or associated lesions) (7/14; 50%). For 9 animals out of a total of 14 selected, the cause of death was classified as natural (6/14; 42,8%), anthropic (3/14; 21,4%), or not determined (5/14; 35,7%) based on gross and histological pathology and ancillary testing. These findings extend our knowledge of the anthropic pressure to which cetaceans stranded along the Ligurian coastline are subjected from a multidisciplinary point of view.

Marine macrolitter and cigarette butts hazard multiple-use marine protected area and fishing community at Brazil

Wide marine litter (ML) contamination impacts human health and economic sectors including fishing, navigation, and tourism. Perequê beach, Brazil, is an authentic fishing community within a touristic multiple-use marine protected area. However, no ML contamination monitoring were so far performed in the region. This study evaluated the spatiotemporal abundance, composition, sources, and associated ML hazards at Perequê beach using a multi-index approach. The 2579 items (0.64 ± 0.72 items.m-2) yielded a high contamination level (CCI = 12.6 ± 14.4) with plastic (44.6-50.9 %) and cigarette butts (20.6-28.4 %) prevalence, while primary sources were smoking (cigarette butts, lighters, others-21.2-30.1 %) and packaging (17.8-22.8 %). Levels of pollutants leaked from cigarette butts (CBPI = 30.5 ± 47.5) and hazardous items (HALI = 3.06 ± 2.64) were among the highest globally. Heightened levels occurred in summer, at dry sand strip, where short-term buoyant items prevailed. Multi-indexing approaches offer valuable insights for local authorities to implement mitigation programs, while contributing to global discussions, promoting awareness, and facilitating replicability.

An analysis of suspected microplastics in the muscle and gastrointestinal tissues of fish from Sarasota Bay, FL: exposure and implications for apex predators and seafood consumers

Microplastics have been found in the gastrointestinal (GI) fluid of bottlenose dolphins (Tursiops truncatus), inhabiting Sarasota Bay, FL, suggesting exposure by ingestion, possibly via contaminated fish. To better understand the potential for trophic transfer, muscle and GI tissues from 11 species of dolphin prey fish collected from Sarasota Bay were screened for microplastics (particles <5 mm diameter). Suspected microplastics were found in 82% of muscle samples (n=89), and 97% of GI samples (n=86). Particle abundance and shapes varied by species (p<0.05) and foraging habit (omnivore vs. carnivore, p<0.05). Pinfish (Lagodon rhomboides) had the highest particle abundance for both tissue types (muscle: 0.38 particles/g; GI: 15.20 particles/g), which has implications for dolphins as they are a common prey item. Findings from this study support research demonstrating the ubiquity of estuarine plastic contamination and underscore the risks of ingestion exposure for wildlife and potentially seafood consumers.

Marine macro-litter mass outweighs biomass in trawl catches along abyssal seafloors of Sardinia channel (Italy)

This study provides new insights onto spatial and temporal trends of seafloor macro-litter in the abyssal seafloor of Sardinian channel, in central western Mediterranean (Italy). Trawl surveys were conducted at depths between 884 and 1528 m, thus focusing on one of the least investigated marine environments. None of the considered sites was litter free, with plastics being numerically dominant (57% of items), followed by metal (11%) and glass (16%). Recorded densities and weight ranged between 49.9 and 499 items km-2 and 1.4 and 1052 kg km-2. In the most contaminated sites, the weight of the litter collected in nets represented up to nine times the biomass of benthic megafauna, and, overall, in 60% of hauls macro-litter mass outweighed the biomass collected. Moreover, we report that megafauna was observed to be more abundant in sites where macro-litter presence was more severe. More studies are needed to elucidate the nature of this correlation, with biota being more abundant in hotspots of accumulation of seafloor macro-litter.

Anthropogenic and environmental factors partly co-determine the level, composition and temporal variation of beach debris

The accumulation of human-derived waste on our coasts is an escalating phenomenon, yet the relative importance and potential interactions among its main drivers are not fully understood. We used citizen-science standardized collections to investigate how anthropogenic and environmental factors influence the level, composition, and temporal variation of beach debris. An average of 58 kg and 803 items/100 m, dominated by single-use items of land (rather than sea) origin, were collected in the 881 beaches sampled. Interactions between anthropogenic and environmental factors (e.g., human use × beach substrate) were the strongest predictors of beach debris, accounting for 34% of the variance explained in its amount and composition. Beach debris showed a highly stochastic temporal variation (adjusted R2 = 0.05), partly determined by interactions between different local and landscape anthropogenic pressures. Our results show that both environmental and anthropogenic factors (at the local and landscape scale) co-determine the level and composition of beach debris. We emphasize the potential of citizen-science to inform environmental policy, showing that land-originated single-use items dominate beach debris, and the importance of considering their multiple anthropogenic and environmental drivers to improve our low predictive power regarding their spatio-temporal distribution.

Paraffin waxes in the North-Western Mediterranean Sea: A comprehensive assessment in the Pelagos Sanctuary, a Specially Protected Area of Mediterranean Importance

Paraffin waxes are widely recognized as emerging marine pollutants, even their classification by the recent monitoring programs and the knowledge of their occurrence, and sources of contamination in marine ecosystems are poorly defined and reported. Wax presence and distribution have been evaluated in different environmental compartments in the Pelagos Sanctuary (Mediterranean Sea) floating on the sea surface and stranded on beaches, focussing on their characterization, accumulation areas and pollution inputs. More than 2500 yellow paraffin residues were detected and analysed in the study area showing a prevailing dimension smaller than 5 mm. The Genoa Canyon and the waters facing Gorgona Island resulted in the more polluted areas representing two distinct hotspots of wax accumulation potentially related to the high density of tanker vessels sailing to and from the harbour of Genova and Livorno. Higher concentrations of beached particles were found along the Tuscan coast (11 items/100 m) and on Pianosa Island (110 items/m2). This study gives valuable insights into paraffin wax pollution in the Pelagos Sanctuary, emphasizing the need for harmonized monitoring and detection methods to elucidate the potential impacts on marine organisms. Moreover, mitigating actions are crucial to prevent and curb the waxes pollution of marine ecosystems.

Model-based estimation of seasonal transport of macro-plastics in a marine protected area

Management of plastic litter in Marine Protected Areas (MPAs) is expensive but crucial to avoid harms to critical environments. In the present work, an open-source numerical modelling chain is proposed to estimate the seasonal pathways and fates of macro-plastics, and hence support the effective planning and implementation of sea and beach cleaning operations. The proposed approach is applied to the nearshore region that includes the MPA of Capo Milazzo (Italy). A sensitivity analysis on the influence of tides, wind, waves and river floods over the year indicates that seasonality only slightly affects the location and extension of the macro-plastic accumulation zones, and that beach cleaning operations should be performed in autumn. Instead, the influence of rivers on plastic litter distribution is crucial for the optimal planning of cleaning interventions in the coastal area.