The intestinal microbiota of a Risso's dolphin (Grampus griseus): possible relationships with starvation raised by macro-plastic ingestion.

Ingesting marine plastics is increasingly common in cetaceans, but little is known about their potential effects. Here, by utilizing 16S rRNA gene sequencing, we profiled the intestinal bacterial communities of a stranded Risso's dolphin (Grampus griseus) which died because of the ingestion of rubber gloves. In this study, we explored the potential relationships between starvation raised by plastic ingestion with the dolphin gut microbiota. Our results showed significant differences in bacterial diversity and composition among the different anatomical areas along the intestinal tract, which may be related to the intestinal emptying process under starvation. In addition, the intestinal bacterial composition of the Risso's dolphin showed both similarity and divergence to that of other toothed whales, suggesting potential roles of both host phylogeny and habitat shaping of the cetacean intestinal microbiome. Perhaps, the microbiota is reflecting a potentially disordered intestinal microbial profile caused by the ingestion of macro-plastics which led to starvation. Moreover, two operational taxonomic units (0.17% of the total reads) affiliated with Actinobacillus and Acinetobacter lwoffii were detected along the intestinal tract. These bacterial species may cause infections in immunocompromised dolphins which are malnourished. This preliminary study profiles the intestinal microbiota of a Risso's dolphin, and provides an additional understanding of the potential relationships between starvation raised by ingesting macro-plastics with cetacean gut microbiota.

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.

Micro(nano)plastics and plastic additives effects in marine annelids: A literature review.

Plastic debris are dispersed in the marine environment and are consequently available to many organisms of different trophic levels, including sediment-dwelling organisms such as polychaetae. Plastic degradation generates micro (MPs) and nanoplastics (NPs) and as well as releases bounded plastic additives, increasing the ecotoxicological risk for marine organisms. Therefore, this review summarizes current knowledge on the accumulation and effects of MPs and NPs and plastic additives in polychaetes, derived from laboratory and field evidences. Thirty-six papers (from January 2011 to September 2021) were selected and analysed: about 80% of the selected works were published since 2016, confirming the emerging role of this topic in environmental sciences. The majority of the analysed manuscripts (68%) were carried out in the laboratory under controlled conditions. These studies showed that polychaetes accumulate and are responsive to this contaminant class, displaying behavioural, physiological, biochemical and immunological alterations. The polychaetes Hediste diversicolor and Arenicola marina were the most frequent used species to study MPs, NPs and plastic additive effects. The consideration of field studies revealed that MP accumulation was dependent on the plastic type present in the sediments and on the feeding strategy of the species. Polychaetes are known to play an important role in coastal and estuarine food webs and exposure to MPs, NPs and plastic additives may impair their behavioural, physiological, biochemical and immunological responses. Thus, the estimated global increase of these contaminants in the marine environment could affect the health of these benthic organisms, with consequences at population and ecosystem levels.

Microplastic presence in the pelagic fish, Seriola dumerili, from Balearic Islands (Western Mediterranean), and assessment of oxidative stress and detoxification biomarkers in liver.

Microplastics (MPs) are characterized by their high persistence in marine ecosystems, and due to their small size, they can be easily ingested by very diverse organisms. Although the presence of MPs in wild fish is well documented, there is still limited information on their potential to induce adverse effects. Pelagic fish species, because of their wide distribution, are considered good bioindicators for monitoring environmental pollution of marine ecosystems. This study investigated the presence of MPs in the gastrointestinal tract of the predatory pelagic fish (Seriola dumerili) in the Balearic Islands (Mediterranean Sea), and the possible relationship with oxidative stress through the analysis of biomarkers in liver tissue. The results showed the presence of MPs in 98% of total samples examined (n = 52) with an average of 12.2 ± 1.3 MPs/individual. A greater amount of fibre-like particles was isolated compared to fragments. No correlation between the presence of MPs in the gastrointestinal contents and the size of the fishes was noted. Antioxidant enzymes (superoxide dismutase and catalase) and the phase II detoxification enzyme glutathione-S-transferase showed increased activities in fish with higher MPs load. The activity ethoxyresorufin-O-deethylase and the levels of malondialdehyde were similar in both groups. In conclusion, the present results provide an important database on the assessment of the presence of MP debris in S. dumerili gastrointestinal tract and, the potential capability to cause oxidative stress.

Beached seabirds as plastic biomonitors in Brazil from the Beach Monitoring Project of the Santos Basin (PMP-BS).

Bioindicator species are useful to monitor wildlife exposure to plastic pollution, and responses to plastic leakage and policy interventions. Here we explore the biomonitoring potential of different seabird and shorebirds species across six years of monitoring in Brazil. Using the necropsy stranding database of the Beach Monitoring Project of the Santos Basin (PMP-BS), we evaluated i) the frequency of birds-plastic interactions in Brazil; ii) whether plastic interactions have changed through time and in different coastal regions; and iii) potential bioindicators for monitoring the exposure of seabirds to plastic in the nearshore South Atlantic Ocean. We found 37 species that had ingested plastic, including ten new records, found that the rates of tube-nosed seabirds increased through time, and suggested two potential species. We discuss the potential for biomonitoring marine pollution in the South Atlantic Ocean using PMP-BS, providing a scheme for a better plastic pollution monitoring in Brazil.

Experimental study on color and texture as cues for plastic debris ingestion by captive sea turtles.

Sea turtles face considerable risks from ingesting marine debris. They are primarily visual feeders, so color may be important for identifying food suitability or enhancing prey detection. Here, we investigated the impacts of color and texture on foraging behavior in relation to plastic consumption. We experimentally assessed the influences of color and texture as attractors for sea turtles using edible jellyfish. The findings showed that the colors of objects significantly affected selective preferences, as evidenced by different behaviors by sea turtles in response to different colors. They exhibited diet-related selectivity toward colors similar to common aquarium food, and texture had a significant impact on complete ingestion. The results suggest that plastic resembling natural prey is more likely ingested. Also, sea turtles were attracted by the color yellow, suggesting that visually distinctive items can attract them. Our results provide fundamental knowledge, helping mitigate the effects of plastic pollution on wildlife.

Cory's shearwater as a key bioindicator for monitoring floating plastics.

The potential of using organisms as bioindicators of marine litter has been an area of general interest in multiple scientific and monitoring programs across the globe. Procellariiformes seabirds are particularly vulnerable to plastic contamination, which makes them a research focus group. This study investigated plastic ingestion in deceased fledglings and adults Cory's shearwaters (Calonectris borealis) collected over eight years (2015 to 2022) at two Atlantic archipelagos: the Azores and the Canaries. Necropsies were carried out in a total of 1,238 individuals showing a high prevalence of plastic ingestion (90%), with approximately 80% of items recovered from the gizzard. Fledglings carried greater plastic loads compared to adults, yet plastic morphologies were similar between both age classes. The temporal analyses conducted with generalised additive mixed-effect models revealed a distinct temporal trend in plastic numbers, but not in terms of plastic mass. In addition, the spatial analyses showed that Cory's shearwaters from the Canary Islands ingest a higher quantity of plastic and a greater proportion of threadlike items than the Azorean birds. These results suggest higher contamination at the NW Africa foraging grounds next to the Canaries and highlight fisheries as a potential source of marine litter in that region. On the other hand, the information gathered from the Azorean birds suggests they would be able to monitor changes in the composition of the plastic items floating in the North Atlantic Subtropical Gyre. Overall, our outcomes support the use of Cory's shearwater fledglings that are victims of light pollution as a key bioindicator of plastic contamination in the North Atlantic. For its policy application, the presented threshold value in combination with the assessment method will enable effective tracking of floating plastic litter in the framework of the MSFD and OSPAR.

Beyond the surface: Seabirds and plastics as indicators in a large, remote marine protected area.

Marine protected areas (MPAs) are an important conservation tool for species and habitats; however, they are not a panacea solution. For example, MPAs provide little protection from plastic pollution which travels vast distances on ocean currents. Here we document exposure of juvenile Christmas Shearwaters (Puffinus nativitatis) to plastics on uninhabited Ducie Atoll in the remote South Pacific. Despite being surrounded by the very large Pitcairn Islands MPA, most birds (68.7 %; n = 16) contained 3.8 ± 4.1 pieces of ingested plastic. Unexpectedly, the number, mass and frequency of occurrence of plastic in two age classes (young downy chicks and fledglings) was similar. While the reason for this is unknown, it may suggest birds do not acquire new plastic items, or are able to rid themselves of plastics, beyond a certain age. We discuss the potential health consequences of plastic ingestion in Christmas Shearwaters and call for further research of this poorly studied species.

Regurgitated skua pellets containing the remains of South Atlantic seabirds can be used as biomonitors of small buoyant plastics at sea.

Using seabirds as bioindicators of marine plastic pollution requires an understanding of how the plastic retained in each species compares with that found in their environment. We show that brown skua Catharacta antarctica regurgitated pellets can be used to characterise plastics in four seabird taxa breeding in the central South Atlantic, even though skua pellets might underrepresent the smallest plastic items in their prey. Fregetta storm petrels ingested more thread-like plastics and white-faced storm petrels Pelagodroma marina more industrial pellets than broad-billed prions Pachyptila vittata and great shearwaters Ardenna gravis. Ingested plastic composition (type, colour and polymer) was similar to floating plastics in the region sampled with a 200 µm net, but storm petrels were better indicators of the size of plastics than prions and shearwaters. Given this information, plastics in skua pellets containing the remains of seabirds can be used to track long-term changes in floating marine plastics.

Are we even close? Five years marine litter ingestion monitoring in loggerhead turtles along Italian coast reveals how far we are from the Good Environmental Status.

The loggerhead sea turtle Caretta caretta has been chosen as bioindicator to monitor the amount of litter ingested by marine animals within the European Marine Strategy Framework Directive and the Barcelona Regional Sea Convention. European Member States and Contracting Parties are committed to achieve the Good Environmental Status (GES), which is reached when the quantity of ingested litter does not adversely affect the health of the species concerned. Although the monitoring strategy has been outlined for more than a decade, to date no threshold values have been adopted to verify GES achievement. After five years of extensive monitoring along the Italian coasts, this study evaluates the suitability of five different GES scenarios and proposes a new threshold value (i.e., "there should be less than 33% of sea turtles having more than 0.05 g of ingested plastic in the GI") for its implementation in the European seas and the Mediterranean basin.

Dynamics and effects of plastic contaminants' assimilation in gulls.

Polybrominated diphenyl ethers are persistent disrupters assimilated by organisms, yet little is known about their link to plastic ingestion and health effects. In an experiment, two groups of yellow-legged/lesser black-backed gulls (Larus michahellis/Larus fuscus) were fed plastics with BDE99 to assess leaching into brain, preen oil, liver and fat tissues and evaluate effects on health and stress parameters. Although most plastic was regurgitated, we observed a clear relation between plastic ingestion and chemical leaching. BDE99 exhibited higher levels in brain tissue of gulls from the plastic groups. Also, only values of cholinesterases measured in plasma were significantly reduced in the 'plastic' groups. Cholinesterase activity in the brain also tended to decrease, suggesting a negative effect in gulls' neurofunction. Results indicate that chemical leaching occurs, even when plastics stay in the stomach for a short period of time and showed that this can affect gulls' health.

Microplastics ingestion and chemical pollutants in seabirds of Gran Canaria (Canary Islands, Spain).

Plastic pollution constitutes an environmental problem in the Canary Islands nowadays. Nevertheless, studies evaluating the impact of plastics on its avifauna are still scarce. Gastrointestinal tracts of 88 birds belonging to 14 species were studied for the presence of plastics. Moreover, their livers were analyzed for the determination of bromodiphenyl ethers (BDEs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). Among Cory's shearwaters (n = 45), the frequency of occurrence of plastic ingestion was considerably high (88.89 %). This species had the highest mean value of items (7.22 ± 5.66) and most of them were compatible with lines derived from fishing gear. PCBs and PAHs were detected in all of the samples and OCPs in the great majority of them (98.86 %). Our results highlight the problems that plastic debris (mainly for seabirds) and organic pollutants pose to these species.

Mapping microplastic overlap between marine compartments and biodiversity in a Mediterranean marine protected area.

The Mediterranean Sea is adversely affected by human activities, of which the release of mismanaged waste into the marine environment, primarily plastic pollution, is one of the most omnipresent. The primary goal of this study is to link microplastic ingestion in several bioindicator species and creating hazard maps from microplastics sampled along the seafloor, in the hyperbenthos and along the sea surface layer in a Marine Protected Area (MPA). Considering the connectivity between these layers, the findings of this study identify areas of concern, especially within bay areas, where marine diversity is exposed to microplastic debris ingestion. In terms of exposure to plastic debris, our findings indicate that areas with high species diversity are particularly vulnerable to plastic exposure. The best model integrated the mean exposure of each species to plastic debris across each layer and the nektobenthic species inhabiting the hyperbenthos layer were found to be the most at risk. Furthermore, the cumulative model's scenario indicated a higher risk to plastic ingestion when all habitats were considered jointly. Overall, the findings of this research highlight marine diversity in a Mediterranean MPA are vulnerable to microplastic pollution, and this study's proposed exposure methodology is applicable to other MPAs.

Solid waste ingestion by marine megafauna on Southeast Brazilian coast.

The disparities in the ecology and behavior of marine megafauna may influence their susceptibility to solid waste ingestion; however, this relationship has been underestimated along the Brazilian coast. We analyzed a dataset of 7261 marine megafauna (45 species) necropsied to investigate the influence of their foraging strategies on solid waste ingestion. A total of 1240 specimens ingested solid waste with over 55 % (689) that ingested plastic. Sea turtles were the most impacted taxa, while cetaceans present the lowest frequency. Some characteristics such as regurgitation (e.g., Suliformes and Charadriiformes seabirds) or possess complex foraging strategies (e.g., cetaceans echolocation) may mitigate the negative effects of solid waste ingestion. Also, the variability over the monitoring program likely was influenced by the volume of pollutants transported to the ocean during flood periods, and level of staff training. This study serves as a valuable baseline for solid waste management actions and marine megafauna conservation efforts.

Cetaceans playing with single-use plastics (SUPs): A widespread interaction with likely severe impacts.

Play is a common behaviour in wild cetaceans that includes the manipulation of natural, as well as artificial objects such as marine debris. Yet, very little is known about these interactions despite the potential impacts on cetacean health. We combined a detailed review of the scientific literature and social media with 12 years of observations to examine cetacean interactions with plastic litter. A total of 11 odontocete species (Tursiops truncatus, Stenella longirostris, Delphinus delphis, Grampus griseus, Steno bredanensis, Stenella frontalis, Sotalia guianensis, Pseudorca crassidens, Orcinus orca, Globicephala melas and Physeter macrocephalus) were documented in 59 events carrying or throwing plastic litter with their head and/or flippers suggesting a form of play. Interactions occurred in the Atlantic, Pacific, Indian Ocean, Mediterranean, and Red Sea, with single-use plastics composing the main typology registered. While these interactions appeared harmless to the observers, they can pose a significant risk through subsequent entanglement or ingestion.

The use of an alimentary index to assess anthropogenic debris on green turtles (Chelonia mydas).

Studies on novel methodologies addressed to quantification of anthropogenic marine debris (AMD) types ingested by green turtles (Chelonia mydas) is not common in the scientific literature. To fill this gap, we used the alimentary index (IAi) to quantify and classify AMD ingested by green turtles stranded in the Potiguar Basin, northeastern Brazil. We classified 295 green turtles as juveniles (JUV-I (n = 190) and JUV-II (n = 58)) and adults (ADU (n = 47)). We collected gut contents during necropsy and analyzed them using the IAi. The IAi values were categorized as main (IAi ≥ 0.5), secondary (0.25 ≤ IAi < 0.5), and accessory (IAi < 0.25). The results revealed that transparent soft plastic was an accessory item for the three size groups and the second most frequent item (IAi = 0.23) for JUV-I. Our study brings insights into the application of the IAi to evaluate the amount and types of AMD ingested by green turtles.

First documentation of plastic ingestion in the arctic glaucous gull (Larus hyperboreus).

Arctic wildlife is facing multiple stressors, including increasing plastic pollution. Seabirds are intrinsic to marine ecosystems, but most seabird populations are declining. We lack knowledge on plastic ingestion in many arctic seabird species, and there is an urgent need for more information to enable risk assessment and monitoring. Our study aimed to investigate the occurrence of plastics in glaucous gulls (Larus hyperboreus) breeding on Svalbard. The glaucous gull is a sentinel species for the health of the arctic marine ecosystem, but there have been no studies investigating plastic occurrence in this species since 1994. As a surface feeder and generalist living in an area with high human activity on Svalbard, we expected to find plastic in its stomach. We investigated for plastic >1 mm and documented plastic ingestion for the first time in glaucous gulls, with a frequency of occurrence of 14.3% (n = 21). The plastics were all identified as user plastics and consisted of polypropylene (PP) and polystyrene (PS). Our study provides new quantitative and qualitative data on plastic burden and polymer type reported in a standardized manner establishing a reference point for future research and monitoring of arctic gulls on national and international levels.

A systematic review and risk matrix of plastic litter impacts on aquatic wildlife: A case study of the Mekong and Ganges River Basins.

Plastic litter is a pollutant of aquatic environments worldwide, with some of the world's highest litter densities occurring in freshwater ecosystems. Little information about the risk that plastic litter poses to aquatic wildlife is available across the world's most polluted waterways. To help assess the risk to aquatic species where empirical data is lacking, our review presents i) a risk assessment methodology for predicting plastic litter impacts on aquatic wildlife in data poor environments, ii) a case study demonstrating this risk assessment methodology for wildlife across two heavily polluted river basins in Asia, the Mekong and Ganges River Basins; and iii) a broad review summarising common trends in litter interactions and risk to freshwater fish, aquatic birds, cetaceans and raptors. This risk analysis unites a systematic review approach with risk matrices following International Standards Organization's risk assessment criteria, evaluating the risk of plastic entanglement and ingestion and the potential for harm to the animal. In the Mekong and Ganges River Basins, we found that the risk of litter entanglement is higher than litter ingestion. Four species were forecast to be at high risk of entanglement: Ganges River dolphin, Gharial, Mekong giant catfish and Irrawaddy dolphin. The eastern imperial eagle and greater spotted eagle were noted to be at moderate risk of entanglement. Both the Ganges River dolphin and Irrawaddy dolphin were predicted to have a moderate risk of plastic ingestion. Interestingly, cranes, waterfowl and wading birds were deemed at low or negligible risk from plastic litter. This risk matrix methodology can be applied to other waterways and taxa to assess the risk posed by plastic. It can also be readily updated as more information becomes available. This review enables decision makers to bridge a data gap by providing a tool for conservation and management before comprehensive empirical data is available.

The role of mesopelagic fishes as microplastics vectors across the deep-sea layers from the Southwestern Tropical Atlantic.

Microplastics (MPs; <5 mm) are a macro issue recognised worldwide as a threat to biodiversity and ecosystems. Widely distributed in marine ecosystems, MPs have already been found in the deep-sea environment. However, there is little information on ecological mechanisms driving MP uptake by deep-sea species. For the first time, this study generates data on MP contamination in mesopelagic fishes from the Southwestern Tropical Atlantic (SWTA) to help understand the deep-sea contamination patterns. An alkaline digestion protocol was applied to extract MPs from the digestive tract of four mesopelagic fish species: Argyropelecus sladeni, Sternoptyx diaphana (Sternoptychidae), Diaphus brachycephalus, and Hygophum taaningi (Myctophidae). A total of 213 particles were recovered from 170 specimens, and MPs were found in 67% of the specimens. Fibres were the most common shape found in all species, whereas polyamide, polyethylene, and polyethylene terephthalate were the most frequent polymers. The most contaminated species was A. sladeni (93%), and the least contaminated was S. diaphana (45%). Interestingly, individuals caught in the lower mesopelagic zone (500-1000 m depth) were less contaminated with MPs than those captured in the upper mesopelagic layer (200-500 m). Our results highlight significant contamination levels and reveal the influence of mesopelagic fishes on MPs transport in the deep waters of the SWTA.

Microplastic contamination in terrestrial ecosystems: A study using barn owl (Tyto alba) pellets.

Microplastics (MPs) are recognised as an emerging environmental problem that needs to be carefully monitored. So far, MPs have been widely recorded in marine and freshwater ecosystems. Still, few studies have focused on MP occurrence in terrestrial ecosystems, although soils are suspected to be one of the main MP reservoirs. To test a non-invasive method for assessing MP contamination in terrestrial ecosystems, we analysed the pellets of a top terrestrial predator, the barn owl (Tyto alba). Sixty pellets were collected from three agricultural areas (20 pellets each) and analysed to assess both barn owl diet and MP content. Thirty-four MPs were confirmed by micro-Fourier Transform Infrared Spectroscopy (µ-FTIR) analysis in 33% of the pellets (min-max 1-5 MPs per pellet). Most of the detected items were microfibres (88.2%). Polyethylene terephthalate, polyacrylonitrile and polyamide were the most abundant polymers. One of the three sites was significantly less contaminated. In the two sites with the highest MP occurrences, barn owl diet was characterised by predation on synanthropic rodents, particularly brown rats (Rattus norvegicus), which may indicate habitat degradation and increased exposure to MPs. Analyses also suggest that Savi's pine vole (Microtus savii) is the prey least at risk of MP contamination, probably due to its strictly herbivorous diet. We argue that the analysis of barn owl pellets may represent a cost-effective method for monitoring MP contamination in terrestrial ecosystems.