Distribution and composition of floating macro litter off the Azores archipelago and Madeira (NE Atlantic) using opportunistic surveys

Ship-based visual observation underestimates plastic debris in marine surface water

Visual observation surveys from ships are commonly used for monitoring floating marine debris, but their detection performance has not yet been fully verified. Here, simultaneous visual observation surveys and surface trawling were conducted in three coastal areas of South Korea, each with distinct characteristics. The extent of floating debris missed by visual observations was assessed, and the characteristics of overlooked debris were identified. The mean density of floating debris observed visually was five-fold lower than that obtained from surface trawling. Loss of buoyancy and transparent colour of debris were identified as major factors contributing to the significant difference in density between the two survey methods. Our findings suggest that visual observation can underestimate the density of floating debris, especially in areas with abundant plastic bags and sheets. Supplementary methods such as surface trawls with macro-sized mesh are recommended to accurately assess the level of contamination from floating debris.

Anthropogenic particles determination in northern krill (Meganyctiphanes norvegica) from the Azores region: A keystone species for marine food webs

Plastic pollution poses a significant threat to marine ecosystems. Microfibres from fabrics have become the most prevalent shape of microplastic found in the marine environment. The northern krill (Meganyctiphanes norvegica) is the most abundant euphausiid species in the northern hemisphere, playing a crucial role in various pelagic ecosystems. Anthropogenic microparticles in northern krill was assessed for the first time in samples collected in the Azores on two occasions - April 2019 (n = 480) and April 2023 (n = 480). Analysis of all individuals revealed 533 anthropogenic particles, with an average abundance of 0.56 ± 0.14 items per individual and, no significant differences between years. Microfibres were the most common shape (94.8 %), with the remaining items being fragments (5.2 %), and blue and black were the predominant colours. MicroFourier transform infrared spectroscopy analysis (μFTIR) of 22.1 % of the total number of particles, showed that they were mainly cellulosic (65.3 %) - either natural or semisynthetic - followed by polyester (7.6 %). Our finding of microplastics in the northern krill raises important questions due to its crucial role in marine food webs. The intake of anthropogenic particles, particularly those that are 100 % synthetic, suggests that the northern krill may act as a transfer vector of these pollutants to higher trophic levels.

Abundance of Marine Macrodebris on the Northern Coast of Jaffna Peninsula, Sri Lanka

Marine plastic debris has emerged as a pressing concern along the northern coast of Jaffna, Sri Lanka, posing a significant threat to marine resources. A preliminary study was conducted to investigate the abundance and characteristics of marine plastic debris at four major fish landing sites in the northern coast of Jaffna, using the Clean Coast Index (CCI) and Plastic Abundance Index (PAI). The results revealed that the average abundance of marine debris and plastic debris were 1.71 ± 0.42 items/m2 and 1.66 ± 0.57 items/m2, respectively. The most common types of plastic debris represented plastic rope and net pieces (23.2%), followed by unidentified weathered plastic fragments (16.7%), beverage bottles (16.2%), bottle caps and lids (13%), and styrofoam (14.1%). The recognized sources of plastic debris were mainly fishing-based activities, recreation activities, transboundary sources, and unidentified sources. The fish landing sites were classified as exceptionally polluted, with a CCI exceeding 10 and a PAI value exceeding 8. Myliddy had the highest debris density, indicating substantial pollution levels, followed by Point Pedro, Mathagal, and Valveddithurai. These findings underscore the urgency of establishing a comprehensive plastic waste management framework for the northern coast of Jaffna and devising strategies to address buoyant debris within the northern Indian Ocean. Furthermore, this study carries significant implications for the local marine ecosystem, coastal communities, and Sri Lanka's broader environmental policies and practices.

Distribution and composition of floating marine debris in Shiretoko peninsula, Japan, using opportunistic sighting survey

Floating marine debris (FMD) poses several threats to marine species, such as entanglement, ingestion, and the transport of pollutants. The Shiretoko Peninsula, located in northern Japan, is a registered World Natural Heritage Site and a biodiversity hotspot. However, FMD has not yet been thoroughly investigated in this region. In 2022, sighting surveys were conducted in Abashiri (west side of the peninsula) and Rausu (east side) to assess the abundance, composition, and distribution of FMD. The mean densities were notably higher in Abashiri, and there was more fishing-related debris in Rausu. Regarding local human activities, the population and number of tourists are higher in Abashiri, and fishing activities are higher in Rausu. While marine pollution is a global issue, our study suggests that addressing it should commence with community-based management at the local level.

Long term trends in floating plastic pollution within a marine protected area identifies threats for Endangered northern bottlenose whales

"The Gully", situated off Nova Scotia, Canada, is the largest submarine canyon in the western North Atlantic. This unique oceanographic feature, which became a Marine Protected Area (MPA) in 2004, is rich in marine biodiversity and is part of the critical habitat of Endangered northern bottlenose whales (Hyperoodon ampullatus). To understand the potential impact of plastic pollution in the MPA and on this Endangered cetacean, we evaluated trends over time in the abundance and composition of plastics and compared these to the stomach contents of recently stranded northern bottlenose whales. From the 1990s-2010s, the median abundance of micro-sized (<5 mm) and small plastics (5 mm-2.5 cm) increased significantly, while the median abundance of large plastics (>2.5 cm) decreased significantly. Plastic abundance from the 2010s for micro-sized and small plastics varied from 5586-438 196 particles km-2, higher than previously measured estimates for surrounding offshore areas. Polymers identified using FTIR spectroscopy included polyethylene, polypropylene, polyethylene terephthalate polyester, nylon, alkyds (paint), and natural and semi-synthetic cellulosic fibers. The abundance of large debris ranged from 0 to 108.6 items km-2 and consisted of plastic sheets and bags, food wrappers and containers, rope, fishing buoys, and small plastic fragments. Whale stomach contents contained fragments of fishing nets, ropes, bottle caps, cups, food wrappers, smaller plastic fragments, fibers, and paint flakes, consistent with the composition and character of items collected from their critical habitat. Despite being far from centres of human population, the unique oceanographic features of The Gully (i.e. currents and bathymetric complexity) may concentrate plastic debris, increasing exposure rates of whales to plastic pollution. The increase in micro-sized and small plastics over time suggests associated health and welfare impacts of ingested plastics should be accounted for in future recovery plans for this Endangered species.

Bacterial Colonization of Microplastics at the Beaches of an Oceanic Island, Tenerife, Canary Islands

(1) Isolated systems, such as oceanic islands, are increasingly experiencing important problems related to microplastic debris on their beaches. The formation of microbial biofilm on the surface of microplastics present in marine environments provides potential facilities for microorganisms to survive under the biofilm. Moreover, microplastics act as a vehicle for the dispersion of pathogenic organisms, constituting a new route of exposure for humans. (2) In this study, the microbial content (FIO and Vibrio spp. and Staphylococcus aureus) of microplastics (fragments and pellets) collected from seven beaches of the oceanic island of Tenerife, in the Canary Islands (Spain), was determined. (3) Results showed that Escherichia coli was present in 57.1% of the fragments and 28.5% of the pellets studied. In the case of intestinal Enterococci, 85.7% of the fragments and 57.1% of the pellets tested positive for this parameter. Finally, 100% of the fragments and 42.8% of the pellets analyzed from the different beaches contained Vibrio spp. (4) This study shows that microplastics act as reservoirs of microorganisms that can increase the presence of bacteria indicating faecal and pathogenic contamination in bathing areas.

Marine litter on the beaches of the Kanyakumari, Southern India: An assessment of their abundance and pollution indices

The problem of marine litter is increasing along the Indian coast. For conducting a baseline study to identify and assess the abundance, clean-coast index (CCI), and plastics abundance index (PAI) of marine litter were calculated on the beaches of Kanyakumari, Southern India. A total of 11,439 marine litter items were collected and classified into 33 groups along the 7 beaches of Kanyakumari. From the results, plastics were the most abundant items (65.08 %) followed by foam (21.93 %), along with cloths (4.59 %), rubber (3.09 %), papers (2.26 %), glass (2.16 %), metal (0.38 %), wood (0.26 %), and others (0.26 %). The average CCI value (27.24) indicates that all beaches are 'extremely dirty'; however, the PAI average value (4.37) indicates 'high abundance'. About 96.87 % of the marine litter originates from the land-based sources. This study provides an interpretive framework for further plastic pollution assessment, which could lead to a better marine litter management on Indian beaches.

Drivers of litter ingestion by sea turtles: Three decades of empirical data collected in Atlantic Europe and the Mediterranean

Sea turtles are considered as bio-indicators for monitoring the efficiency of restoration measures to reduce marine litter impacts on health. However, the lack of extended and standardised empirical data has prevented the accurate analysis of the factors influencing litter ingestion and the relationships with individual health. Historic data collected from 1988 and standard data collected from 2016 were harmonised to enable such analyses on necropsied loggerhead turtles (Caretta caretta) in eight Mediterranean and North-East Atlantic countries. Litter was found in 69.24 % of the 1121 individuals, mostly single-use and fishing-related plastics. Spatial location, sex and life history stage explained a minor part of litter ingestion. While no relationships with health could be detected, indicating that all individuals can be integrated as bio-indicators, the mechanistic models published in literature suggest that the high proportion of plastics in the digestive contents (38.77 % per individual) could have long-term repercussions on population dynamics.

Floating marine macro litter in the Black Sea: Toward baselines for large scale assessment

The Black Sea is a semi-enclosed basin subject to major anthropogenic pressures, including marine litter and plastic pollution. Due to numerous large rivers draining into the basin and a population settled along the coast, the region could accumulate significant amounts of floating litter over time. Until now, only limited field data were available, and litter quantities and distribution remained unknown. In this study, floating marine macro litter (FMML) was assessed at the regional Black Sea scale for the first time, showing relatively high litter densities across the basin that reached a weighted mean of 81.5 items/km². Monitoring data revealed an accumulation of floating items offshore in the eastern part of the basin, resembling on a small scale a 'garbage patch', where litter items were trapped, showing elevated densities in comparison to their surrounding areas. Most of these items were made of plastic materials (ca. 96%) and included large numbers of plastic and polystyrene fragments of small size ranges (2.5-10 cm). Harmonised field data collection through consistent and regular monitoring programmes across the region is essential to establish baselines and thresholds for large scale assessment at international level.

Close-range remote sensing-based detection and identification of macroplastics on water assisted by artificial intelligence: A review

Detection and identification of macroplastic debris in aquatic environments is crucial to understand and counter the growing emergence and current developments in distribution and deposition of macroplastics. In this context, close-range remote sensing approaches revealing spatial and spectral properties of macroplastics are very beneficial. To date, field surveys and visual census approaches are broadly acknowledged methods to acquire information, but since 2018 techniques based on remote sensing and artificial intelligence are advancing. Despite their proven efficiency, speed and wide applicability, there are still obstacles to overcome, especially when looking at the availability and accessibility of data. Thus, our review summarizes state-of-the-art research about the visual recognition and identification of different sorts of macroplastics. The focus is on both data acquisition techniques and evaluation methods, including Machine Learning and Deep Learning, but resulting products and published data will also be taken into account. Our aim is to provide a critical overview and outlook in a time where this research direction is thriving fast. This study shows that most Machine Learning and Deep Learning approaches are still in an infancy state regarding accuracy and detail when compared to visual monitoring, even though their results look very promising.

First assessment of floating marine litter abundance and distribution in the Bay of Biscay from an integrated ecosystem survey

In the Bay of Biscay, regional monitoring programmes and data on abundance and distribution of floating marine litter are scarce, contrary to many other European marine regions. Here, a joint analysis of multiyear observations (2017-2019) of floating micro and macrolitter and oceanographic conditions was conducted for the Bay of Biscay by combining microlitter samplings with neuston nets and vessel-based macrolitter observations. Results show spatiotemporal abundance and distribution patterns. The density of floating microlitter increased from 26,056 items/km² in 2017 to 1,802,4611 items/km² in 2019; floating macrolitter densities barely varied amongst year (2.52 items/km² in 2017 and 3.70 items/km² in 2019). No significant correlation was found between densities of micro and macrolitter, neither for the oceanographic variables. We conclude that longer micro and macrolitter monitoring periods and standardized datasets based on the cross-border cooperation are needed to collect more comparable information, evaluate trends, and support decision making in the area.

Arenas Blancas (El Hierro island), a new hotspot of plastic debris in the Canary Islands (Spain)

The present work has studied the incidence and type of micro (1-5 mm), meso (5-25 mm) and macroplastics (>25 mm) that have reached Arenas Blancas beach, located in the north coast of El Hierro island, in the Canary Islands (Spain), from October 2019 to May 2020 (13 sampling dates with 3 sampling points each). Taking into consideration the three studied plastic debris fractions (macro, meso and microplastics), a total of 9206 items were found, which had a total weight of 1169.7 g and a concentration of 891.3 ± 91.5 items/m² (118.3 ± 17.8 g/m² and 2.3 ± 0.4 g/L). Regarding their colour, most of them were transparent/white/clear, especially in the microplastic fraction in which they accounted for a 68% of the total. Attenuated Total Reflectance Fourier Transform Infrared spectroscopy of meso and microplastic fractions indicated that most of the particles were either polypropylene and polyethylene followed by polystyrene in a much lower amount. In general, the total amount of plastic debris that arrives to the beach by the persistent oceanic current pattern linked to the easternmost branch of the North Atlantic Subtropical Gyre is comparable to those of the most contaminated beaches of the Canary Islands archipelago, suggesting that a new hotspot of plastic debris arrival has been found.

The distribution of microplastics in the surface layer of the Atlantic Ocean from the subtropics to the equator according to visual analysis

This study reports the levels of plastic contamination in the Atlantic Ocean between 35°N and 32°S during the 1st stage of the 79th cruise of the "Akademik Mstislav Keldysh" from December 12, 2019, to January 4, 2020. A subsurface pump system and a Manta net were used for seawater filtration. Twenty-seven samples were visually analyzed with a microscope. It was found that almost every subsurface sample contained potentially plastic particles, which were classified according to their type and size. Plastic fragments were more commonly found in the samples taken from the surface. In the subsurface layer, the majority of the detected particles were fibers. These results also indicate that minimal concentrations of plastics tend to be found near the equator and to the north of the Canary Islands. The maximum microplastic concentrations were found in tropical zones. The obtained results are in good agreement with previous models and field studies.

Basic principles for development and implementation of plastic clean-up technologies: What can we learn from fisheries management?

Plastic pollution compromises ocean health, with large amounts of plastics continuing to enter marine and coastal environments. Various mitigative engineering solutions are being developed and implemented in response to this threat. While recognising the positive impacts of clean-ups, we highlight two perspectives given little attention to date, which are vital to evaluating the cost-benefit ratio of clean-ups: firstly, clean-up efficiency where density and accessibility of litter are key, and secondly, potential negative externalities that implementation of clean-up technologies may have. These principles, catch per unit effort and the impact on non-target species, are well known from fisheries management. We argue they should also be applied in evaluating marine litter removal schemes.

Microplastic in the stomachs of open-ocean and deep-sea fishes of the North-East Atlantic

The presence of microplastic in marine fishes has been well documented but few studies have directly examined differences between fishes occupying contrasting environmental compartments. In the present study, we investigated the gut contents of 390 fishes belonging to three pelagic (blue jack mackerel, chub mackerel, skipjack tuna) and two deep-sea species (blackbelly rosefish, blackspot seabream) from the Azores archipelago, North-East Atlantic for microplastic contamination. Our results revealed that pelagic species had significantly more microplastic than the deep-water species. In all of the species studied, fragments were the most common plastic shape recovered and we found a significant difference in the type of polymer between the pelagic and deep-water species. In deep-sea fish we found almost exclusively polypropylene, whereas in the pelagic fish, polyethylene was the most abundant polymer type. Overall, the proportion of fish containing plastic items varied across our study species from 3.7% to 16.7% of individuals sampled, and the average abundance of plastic items ranged from 0.04 to 0.22 per individual (the maximum was 4 items recovered in one stomach). Despite the proximity of the Azores archipelago to the North Atlantic subtropical gyre, a region of elevated plastic abundance, the proportion of individuals containing plastic (9.49%) were comparable with data reported elsewhere.

Environmental status of (micro)plastics contamination in Portugal

Plastics and microplastics are ubiquitous contaminants in aquatic ecosystems. This critical review is the first attempt at analyzing sources, concentration, impacts and solutions of (micro)plastic litter in Portugal based on all currently available literature. We found that, besides sea-based sources (e.g. shipping, fishing), 5717 t of mismanaged waste and 4.1 trillion microplastics from wastewater, mostly from untreated wastewater, are released to the environment every year. The highest concentrations are found in the North, Center and Lisbon regions, mostly comprised of consumer products, fishing gear and microplastics (<5 mm), especially fragments and pellets. This contamination has resulted in ingestion of plastics by organisms, including mussels, fishes, birds and turtles. Thus, every Portuguese citizen may consume 1440 microplastics a year based on the consumption of mollusks. Awareness campaigns, improvements in waste management and reductions in the release of untreated wastewater are recommended measures to reduce plastic pollution in Portugal.

First evaluation of neustonic microplastics in the Macaronesian region, NE Atlantic

Marine microplastic pollution is an issue of great concern nowadays since high concentrations have been detected in the ocean, mainly in the subtropical gyres that accumulate this type of debris. The long-term effects of this pollution on ecosystems and marine biota are still unknown. The aim of this study is to quantify and characterise microplastics and neustonic zooplankton in sub-surface waters of the Macaronesian region, an area that has been little studied to date. Our results show a great variability in the concentration of microplastics with values between 15,283 items/km² in Los Gigantes (Tenerife, Canary Islands) and 1,007,872 items/km² in Las Canteras (Gran Canaria, Canary Islands). The main types of debris found were plastic fragments and fibres. The abundances of neustonic zooplankton were also very variable between the different sampling areas, being the main components copepods and eggs. Regarding the microplastics-zooplankton ratio, values were obtained between 0.002 and 0.22. In Las Canteras, the highest accumulation zone, was found twice as much microplastics as zooplankton for the 1-5 mm fraction in dry weight. These values highlight the potential hazard of microplastics - and its associated chemical contaminants - for marine biota, especially for large filter feeders.

First record of 'plasticrusts' and 'pyroplastic' from the Mediterranean Sea

We report the presence of 'plasticrusts' and 'pyroplastic' from coastal habitats in Giglio island, Tyrrhenian Sea, Italy. These novel plastic debris types have only recently been described for the first time from Madeira island (NE Atlantic Ocean) and the United Kingdom, respectively. While 'plasticrusts' are generated by sea waves smashing plastic debris against intertidal rocks, 'pyroplastic' derives from (un)deliberately burnt plastic waste. Using Fourier-transform infrared (FTIR) spectroscopy, we identified the 'plasticrust' material as polyethylene (PE) and the 'pyroplastic' material as polyethylene terephthalate (PET). These polymers are widely used in everyday products and, therefore, contribute heavily to plastic pollution in aquatic and terrestrial environments worldwide. Furthermore, our field surveys suggest that 'plasticrust' abundance is related to wave-exposure and that the 'pyroplastic' derived from beverage bottles which we frequently found along the Giglio coast. Overall, our findings corroborate the notion that 'plasticrusts' and 'pyroplastic' are common debris types in marine coastal habitats.

Low abundance of floating marine debris in the northern Baltic Sea

We determined the spatial and seasonal distribution of Floating Marine Debris (FMD) by visual ship surveys across the northern Baltic Sea between Finland and Sweden. FMD density was comparatively low, and we found the highest debris density close to major port cities. The seasonal variation in debris density was not pronounced although we observed more FMD items during the summer surveys. Plastic bags were the most common identifiable litter items, and we also found other consumer items (plastic bottles and cups). Styrofoam items suggest fishing or aquaculture activities as potential sea-based sources of FMD. These are the first data on FMD density in the Baltic Sea, and they are substantially lower than those reported for other coastal waters, which may be due to (i) lower human population densities, and (ii) higher environmental awareness in the Scandinavian countries.

Identifying floating plastic marine debris using a deep learning approach

Estimating the volume of macro-plastics which dot the world's oceans is one of the most pressing environmental concerns of our time. Prevailing methods for determining the amount of floating plastic debris, usually conducted manually, are time demanding and rather limited in coverage. With the aid of deep learning, herein, we propose a fast, scalable, and potentially cost-effective method for automatically identifying floating marine plastics. When trained on three categories of plastic marine litter, that is, bottles, buckets, and straws, the classifier was able to successfully recognize the preceding floating objects at a success rate of ≈ 86%. Apparently, the high level of accuracy and efficiency of the developed machine learning tool constitutes a leap towards unraveling the true scale of floating plastics.