Potential interaction between plastic litter and green turtle Chelonia mydas during nesting in an extremely polluted beach

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.

A macroplastic vulnerability index for marine mammals, seabirds, and sea turtles in Hawai'i

Plastic pollution is having devastating consequences for marine organisms across the planet. However, the population level effects of macroplastic pollution remain difficult and costly to quantify. As a result, there is a need for alternative approaches to evaluate species risk to plastic pollution and inform management needs. We apply a trait-based framework for macroplastic pollution to develop a relative vulnerability index-informed by three dimensions: likelihood of exposure, species' sensitivity, and population resilience-for marine mammals, seabirds, and sea turtles found in Hawai'i. This index ranks 63 study species based on their population level vulnerability to macroplastic pollution, with the highest scoring species being the most vulnerable. Our results indicate that ducks, waders, and noddies with large populations were the least vulnerable to macroplastics, while the most vulnerable were the Hawaiian monk seal, sea turtles, baleen whales, and some albatross and petrel species. This index can inform species in need of population monitoring in Hawai'i, and direct other management priorities (e.g., locations for clean-ups or booms). More broadly, this work exemplifies the value of qualitative risk assessment approaches for better understanding the population level effects of macroplastic pollution and showcases how vulnerability indices can be used to inform management priorities.

Investigation on beach debris on the historical nesting grounds of green turtles (Chelonia mydas) in Hainan Island, South China

Hainan Island used to be the most important nesting ground of green turtles in China before they disappeared about 37 years ago. Habitat degradation is one of the main reasons for the disappearance of sea turtles. Therefore, it is necessary to take action to evaluate and recover the historical nesting grounds if we hope for sea turtles to return in the future. In this study, we surveyed the beach debris on 13 historical nesting grounds of green sea turtles on Hainan Island. The beach debris on these nesting grounds mainly consisted of plastic, cigarette butts, foam, glass, and nylon, with plastic (including plastic blocks, cigarette butts, and foam) being the dominant type, accounting for 78.92% in number, followed by glass. The average density of beach debris was 0.314 pieces·m^-2. Compared to other nesting grounds, the average quantity and density of beach debris in Hainan was lower, but the proportion of plastic debris was extremely high. After categorizing debris type, we found that most was from human coastal activities (35.54%), with debris at tourist beaches having the biggest proportion of debris from smoking supplies. The distribution characteristics of beach debris were related to the function of the beach, density of tourist, and the intensity of beach debris cleaning. It is recommended to further strengthen the emission reduction and clean-up of beach debris in Hainan Island, so as to restore the nesting habitat of sea turtles as soon as possible.

Microplastics: A Matter of the Heart (and Vascular System)

Plastic use dramatically increased over the past few years. Besides obvious benefits, the consequent plastic waste and mismanagement in disposal have caused ecological problems. Plastic abandoned in the environment is prone to segregation, leading to the generation of microplastics (MPs) and nanoplastics (NPs), which can reach aquatic and terrestrial organisms. MPs/NPs in water can access fish's bodies through the gills, triggering an inflammatory response in loco. Furthermore, from the gills, plastic fragments can be transported within the circulatory system altering blood biochemical parameters and hormone levels and leading to compromised immunocompetence and angiogenesis. In addition, it was also possible to observe an unbalanced ROS production, damage in vascular structure, and enhanced thrombosis. MPs/NPs led to cardiotoxicity, pericardial oedema, and impaired heart rate in fish cardiac tissue. MPs/NPs effects on aquatic organisms pose serious health hazards and ecological consequences because they constitute the food chain for humans. Once present in the mammalian body, plastic particles can interact with circulating cells, eliciting an inflammatory response, with genotoxicity and cytotoxicity of immune cells, enhanced haemolysis, and endothelium adhesion. The interaction of MPs/NPs with plasma proteins allows their transport to distant organs, including the heart. As a consequence of plastic fragment internalisation into cardiomyocytes, oxidative stress was increased, and metabolic parameters were altered. In this scenario, myocardial damage, fibrosis and impaired electrophysiological values were observed. In summary, MPs/NPs are an environmental stressor for cardiac function in living organisms, and a risk assessment of their influence on the cardiovascular system certainly merits further analysis.

Marine litter and climate change: Inextricably connected threats to the world's oceans

The global issues of climate change and marine litter are interlinked and understanding these connections is key to managing their combined risks to marine biodiversity and ultimately society. For example, fossil fuel-based plastics cause direct emissions of greenhouse gases and therefore are an important contributing factor to climate change, while other impacts of plastics can manifest as alterations in key species and habitats in coastal and marine environments. Marine litter is acknowledged as a threat multiplier that acts with other stressors such as climate change to cause far greater damage than if they occurred in isolation. On the other hand, while climate change can lead to increased inputs of litter into the marine environment, the presence of marine litter can also undermine the climate resilience of marine ecosystems. There is increasing evidence that that climate change and marine litter are inextricably linked, although these interactions and the resulting effects vary widely across oceanic regions and depend on the particular characteristics of specific marine environments. Ecosystem resilience approaches, that integrate climate change with other local stressors, offer a suitable framework to incorporate the consideration of marine litter where that is deemed to be a risk, and to steer, coordinate and prioritise research and monitoring, as well as management, policy, planning and action to effectively tackle the combined risks and impacts from climate change and marine litter.

Hydrometeorological assessments of the transport of microplastic pellets in the Eastern Mediterranean

Microplastic pellets were sampled in May and November 2018 during one-week surveys at 13 coastal beaches in Iskenderun Bay/Turkey. Pellet pollution index (PPI) was calculated for the beaches as a tool to assess beach pollution by microplastic pellets. Hydrometeorological conditions, including wind, current, wave, surface run-off, and precipitation, were examined during 2018 to reveal the effect on the transport of microplastic pellets within the study area. Sea-surface heights, including the astronomical tide and the storm surge and the wave runup heights, were also considered in the analysis to study the extent of hydrodynamic forcing on the beach. Hydrometeorological assessments indicated that the pellet concentrations in the coastal zone are mostly related to wind-induced transport. Three major river discharges are considered as the main source of microplastic pellets effluents. A Lagrangian particle transport model was conducted to reveal the possible beaching hotspots of microplastic pellets released from these river mouths. Average microplastic pellets were calculated as 126.04 ± 54.08 items/m² for May 2018 and 70.22 ± 18.25 items/m² for November 2018. An overall mean PPI for May 2018 was calculated as 1.13, indicating a moderate degree of pellet pollution, and 0.56 for November 2018, indicating a low degree of pellet pollution. The simulations showed that Orontes River effluents affected the inner Iskenderun Bay coasts more than the Seyhan and Ceyhan River.

A review of plastic pollution in aquatic ecosystems of Turkey

Turkey is one of the major plastic pollution sources in the Mediterranean and the Black Sea. This review summarizes present information, data, and legislation on plastic pollution in Turkish aquatic ecosystems. According to results derived from reviewed studies, both macro- and microplastic pollutions were documented in Turkish aquatic ecosystems. Most of the studies on plastic pollution in Turkish waters were performed in the marine environment while only four were conducted in freshwater environments. Spatially, the majority of these studies, which were on levels in the marine environment, were conducted on the northeastern Mediterranean coasts of Turkey, especially Iskenderun and Mersin Bays. Additional studies were carried out on either the ingestion/presence/impact of microplastics by/to aquatic organisms or the entanglement of marine organisms in plastics. There were also studies assessing the microplastic content of commercial salt, and another has reported microplastic presence in traditional stuffed mussels sold in Turkish streets. Some studies were conducted on microplastic presence and/or their removal in wastewater treatment plants in Mersin, Adana, Mugla, and Istanbul cities. Macro- and microliter loading from a few Turkish rivers to the sea was also estimated. All these investigations indicate that Turkish aquatic environments have significant plastic pollution problems, which were also underlined by the legislative studies. The need for further studies in this field still exists, especially in freshwater environments.

Microplastics and Their Impact on Reproduction—Can we Learn From the C. elegans Model?

Biologically active environmental pollutants have significant impact on ecosystems, wildlife, and human health. Microplastic (MP) and nanoplastic (NP) particles are pollutants that are present in the terrestrial and aquatic ecosystems at virtually every level of the food chain. Moreover, recently, airborne microplastic particles have been shown to reach and potentially damage respiratory systems. Microplastics and nanoplastics have been shown to cause increased oxidative stress, inflammation, altered metabolism leading to cellular damage, which ultimately affects tissue and organismal homeostasis in numerous animal species and human cells. However, the full impact of these plastic particles on living organisms is not completely understood. The ability of MPs/NPs to carry contaminants, toxic chemicals, pesticides, and bioactive compounds, such as endocrine disrupting chemicals, present an additional risk to animal and human health. This review will discusses the current knowledge on pathways by which microplastic and nanoplastic particles impact reproduction and reproductive behaviors from the level of the whole organism down to plastics-induced cellular defects, while also identifying gaps in current knowledge regarding mechanisms of action. Furthermore, we suggest that the nematode Caenorhabditis elegans provides an advantageous high-throughput model system for determining the effect of plastic particles on animal reproduction, using reproductive behavioral end points and cellular readouts.

The potential effects of microplastic pollution on human digestive tract cells

The level of environmental microplastics in the biosphere is constantly increasing. These environmental microplastics can enter the human body with food, be absorbed through the gut, and have negative effects on the organism health after its digestion. Four sizes (0.1, 0.5, 1, 5 μm) polystyrene microspheres (PS-MPs) and nanospheres (PS-NPs) were selected for this study. The effects of different sizes of polystyrene particles on human colonic epithelial cell CCD841CoN and small intestinal epithelial cell HIEC-6 within 24 h were explored. The uptake of PS-NPs was found to has more potential to enter cells than micro-sized polystyrene PS-MPs that was confirmed by fluorescence microscope, and the intake amount was proportional to the exposure time. PS-MPs had no significant effect on cell viability and apoptosis, but the group treated with high concentration showed low toxicity to oxidative stress level and mitochondrial membrane potential. In addition, the membrane damage caused by PS-MPs was significantly higher than that of PS-NPs. This may be due to the large amount of polystyrene adhering to interstitial, which have a significant negative effect on the cell membrane functions. For the first time human intestinal normal cell lines were used to study the effect of microplastic pollution, which can provide some references for the influence of microplastics on human health in the future.

Composition, sources, abundance and seasonality of Marine Litter in the Çakalburnu lagoon coast of Aegean Sea

The Aegean Sea is one of the most contaminated by marine litter (ML) in the World. In this study, the Turkish Aegean Region was evaluated in light of the sources, abundance and composition of ML along Çakalburnu Lagoon coast. Macroscopic ML with > 3 cm was collected and separated into composition and sources categories. ML abundance was calculated by its density in items/m² (Mean ± SD). Beach cleanliness was evaluated according to Clean-Coast Index (CCI). Seasonality was found as factor for ML composition, sources and abundance at Çakalburnu coast. Plastic was the most abundant material, followed by unidentifiable items. The major sources of ML were mixed packaging, domestic and fisheries activities. The mean ML density was 0.64 ± 0.09 items/m². Çakalburnu coast was classified as dirty during all seasons. Therefore, ML contamination on Çakalburnu coast represent a potential threat to coastal and marine environments. Thus, the present study can serve as a base for the elaboration of mitigating actions urgently needed at Çakalburnu Lagoon.

Dangerous traps: Macroplastic encounters affecting freshwater and terrestrial wildlife

Encounters (or interactions) between plastic debris and wildlife can cause great harm to individuals and populations. The most common encounters are ingestion, entanglement and plastic usage (plastic as nesting material, vector for biota transport and refuge/shelter). Hundreds of plastic-encounters have been reported for marine species. However, there is a lack of studies reporting encounters in other ecosystems, such as freshwater and terrestrial ones. Based on a citizen science approach, we documented and analyzed 90 different cases of macroplastic-fauna encounters for 44 freshwater and terrestrial species. Herein, we provided evidence (photographically documented) of the negative consequences of macroplastic debris discarded in freshwater and terrestrial environments. Birds were by far the taxon most frequently reported in encounters (72.2% of the encounters, 30 different species). The dominant type of plastic-fauna encounter was the use of plastic as nesting material (42% of the total cases) and the second one was entanglement (33%). Most of the entanglements had lethal consequences for the organisms involved (almost 60%). Entanglement in ghost fishing gear and bottle (security) rings were particularly dangerous and comparatively frequent in this study. Some invasive species could benefit from the encounters to the detriment of the environment's health, using plastics as settlement substrata. Finally, we lay the foundation for creating worldwide lists of non-marine species impacted by encounters with plastic debris.

High levels of microplastic ingestion by commercial, planktivorous Alburnus tarichi in Lake Van, Turkey

Microplastic pollution of inland environments has been receiving increased publicity over the last few years. For the first time, this study reports on the presence of microplastics (0.1 mm to <5 mm) in the gastrointestinal tracts of Alburnus tarichi in Lake Van from January to April 2020. In total, 101 fishes were obtained from Citoren, Edremit, Gevas and Dagonu fisheries regions. A total of 3338 pieces of plastic, ranging from 8 to 124 samples per fish with averaging 34 ± 13 MPs/individual, were extracted from gastrointestinal tracts of fish. The majority of the ingested particles consisted of fibres (74%), and blue coloured material was the most consumed microplastic. The polymers identified by Fourier Transform Infrared Spectroscopy (FTIR) were polyethylene and polypropylene. Consequently, this study suggested that the vast majority of A. tarichi were contaminated with microplastics and showed higher abundance in comparison with other worldwide studies so far.

Assessing plastic size distribution and quantity on a remote island in the South Pacific

Plastics are an environmental threat; however, their fate once in the pelagic environment is poorly known. We compare results from assessments of floating plastics in the South Pacific Ocean with accumulated beach plastics from Henderson Island. We also compare accumulated plastic mass on Henderson during 2015 and 2019 and investigate the presence of nanoplastics. There were differences between the size classes of beach and pelagic plastics, and an increase in microplastics (0.33-5 mm) on the beach between 2015 and 2019. Micro- and nanoplastics were found at all sites (mean ± SE: 1960 ± 356 pieces/kg dw). Across the whole beach this translates to >4 billion plastic particles in the upper 5 cm. This is concerning, particularly given Henderson is uninhabited and distant from urban centres (~2350 km from Pape'ete, French Polynesia). The vast number of small particles on Henderson may make nearshore filter feeders susceptible to ingestion and subsequent detrimental impacts.

The Way of Macroplastic through the Environment

With the focus on microplastic in current research, macroplastic is often not further considered. Thus, this review paper is the first to analyse the entry paths, accumulation zones, and sinks of macroplastic in the aquatic, terrestrial, and atmospheric environment by presenting transport paths and concentrations in the environment as well as related risks. This is done by applying the Source–Pathway–Receptor model on macroplastic in the environment. Based on this model, the life cycle of macroplastic is structurally described, and knowledge gaps are identified. Hence, current research aspects on macroplastic as well as a sound delimitation between macro- and microplastic that can be applied to future research are indicated. The results can be used as basic information for further research and show a qualitative assessment of the impact of macroplastic that ends up in the environment and accumulates there. Furthermore, the applied model allows for the first time a quantitative and structured approach to macroplastic in the environment.

Toxicity of Microplastics and Nanoplastics in Mammalian Systems

Fragmented or otherwise miniaturized plastic materials in the form of micro- or nanoplastics have been of nagging environmental concern. Perturbation of organismal physiology and behavior by micro- and nanoplastics have been widely documented for marine invertebrates. Some of these effects are also manifested by larger marine vertebrates such as fishes. More recently, possible effects of micro- and nanoplastics on mammalian gut microbiota as well as host cellular and metabolic toxicity have been reported in mouse models. Human exposure to micro- and nanoplastics occurs largely through ingestion, as these are found in food or derived from food packaging, but also in a less well-defined manner though inhalation. The pathophysiological consequences of acute and chronic micro- and nanoplastics exposure in the mammalian system, particularly humans, are yet unclear. In this review, we focus on the recent findings related to the potential toxicity and detrimental effects of micro- and nanoplastics as demonstrated in mouse models as well as human cell lines. The prevailing data suggest that micro- and nanoplastics accumulation in mammalian and human tissues would likely have negative, yet unclear long-term consequences. There is a need for cellular and systemic toxicity due to micro- and nanoplastics to be better illuminated, and the underlying mechanisms defined by further work.

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.

Mediterranean dirty edge: High level of meso and macroplastics pollution on the Turkish coast

It has become apparent that the coastal zones of aquatic environments are significantly affected by plastics pollution. The accumulation of marine plastic litter on beaches is an important problem due to their significant environmental impacts. In this study, 13 coastal areas in Iskenderun Bay (NE Levantine coast of Turkey) were sampled in May 2018 to investigate meso and macroplastic (0.5-123.4 cm) pollution. A total of 1424 meso and macroplastic items in five categories (filament, film, foam, fragments, and pellets) were collected. The average meso and macroplastic concentration was 12.2 ± 3.5 pcs m^-2 (12.3 ± 3.5 g m^-2) and the mean size for all stations was 3.7 ± 0.16 cm. The highest meso and macroplastic concentration was found in the Dörtyol location (46.2 ± 7.6 pcs m^-2) and the lowest concentration was found in the Y. Lagün location (2.3 ± 0.2 pcs m^-2). Plastics were separated into 14 different groups based on their origins. The most dominant type was hard plastics (broken, fragmented, and deformed) with 59.8% and greenhouse coverage films with 11%. Our results shows that regardless their source plastics fluxes at beaches from various pathways. Results of this study provide useful information for designing monitoring strategies and setting management goals.

Abundance, characteristics and surface degradation features of microplastics in beach sediments of five coastal areas in Tamil Nadu, India

This study undertook to investigate the occurrence of microplastics (MPs) in the high and low-tide sediments of five coastal areas in Tamil Nadu, India. The abundance of microplastics vary from 439 ± 172 to 119 ± 72 (HTL) and 179 ± 68 to 33 ± 30 (LTL) items kg^-1 of sediments. The MP polymers found in the study sites are Polyethylene (73.2%), polypropylene (13.8%), nylon (8.2%), polystyrene (2.8%) and polyester (2%). The weathered surfaces might act as high-capacity carriers and this was confirmed by SEM-EDAX. The results of an analysis of the textures of the sediments do not ascribe any influence on microplastic abundance. The recreation, religious and fishing activities are the major contributors to plastic pollution in these beaches, which is borne out by the high abundance of MPs in the study sites. A regular and permanent waste management system should be put in place for the protection of beaches.