A nutritional perspective on plastic ingestion in wildlife

Photodegradation of Microplastics through Nanomaterials: Insights into Photocatalysts Modification and Detailed Mechanisms

Microplastics (MPs) pose a profound environmental challenge, impacting ecosystems and human health through mechanisms such as bioaccumulation and ecosystem contamination. While traditional water treatment methods can partially remove microplastics, their limitations highlight the need for innovative green approaches like photodegradation to ensure more effective and sustainable removal. This review explores the potential of nanomaterial-enhanced photocatalysts in addressing this issue. Utilizing their unique properties like large surface area and tunable bandgap, nanomaterials significantly improve degradation efficiency. Different strategies for photocatalyst modification to improve photocatalytic performance are thoroughly summarized, with a particular emphasis on element doping and heterojunction construction. Furthermore, this review thoroughly summarizes the possible fundamental mechanisms driving the photodegradation of microplastics facilitated by nanomaterials, with a focus on processes like free radical formation and singlet oxygen oxidation. This review not only synthesizes critical findings from existing studies but also identifies gaps in the current research landscape, suggesting that further development of these photocatalytic techniques could lead to substantial advancements in environmental remediation practices. By delineating these novel approaches and their mechanisms, this work underscores the significant environmental implications and contributes to the ongoing development of sustainable solutions to mitigate microplastic pollution.

Chemically Recyclable, High Molar Mass Polyoxazolidinones via Ring-Opening Metathesis Polymerization

The development of robust methods for the synthesis of chemically recyclable polymers with tunable properties is necessary for the design of next-generation materials. Polyoxazolidinones (POxa), polymers with five-membered urethanes in their backbones, are an attractive target because they are strongly polar and have high thermal stability, but existing step-growth syntheses limit molar masses and methods to chemically recycle POxa to monomer are rare. Herein, we report the synthesis of high molar mass POxa via ring-opening metathesis polymerization of oxazolidinone-fused cyclooctenes. These novel polymers show <5% mass loss up to 382-411 °C and have tunable glass transition temperatures (14-48 °C) controlled by the side chain structure. We demonstrate facile chemical recycling to monomer and repolymerization despite moderately high monomer ring-strain energies, which we hypothesize are facilitated by the conformational restriction introduced by the fused oxazolidinone ring. This method represents the first chain growth synthesis of POxa and provides a versatile platform for the study and application of this emerging subclass of polyurethanes.

Multidimensional trace metals and nutritional niche differ between sexually immature and mature common dolphins (Delphinus delphis)

There is a need to understand the links between metals and nutrition for apex marine predators, which may be subject to different ecotoxicological effects at different life stages. We combined stomach content analyses (SCA), prey composition analysis (PCA), the Multidimensional Niche Framework (MNNF) with Bayesian multivariate ellipses, trace metal analysis and nicheROVER to investigate nutrition and trace metals across sex, age, and sexual maturity status in common dolphins (Delphinus delphis) from New Zealand. A broader prey composition niche breadth (SEAc) was estimated for immature compared to mature conspecifics, showing a higher degree of prey and nutrient generalism driven by protein (P) intake. Cd and Zn niche similarities suggests these metals were incorporated through similar prey in both immature and mature dolphins, whereas Hg and Se niche divergence indicates uptake occurred via different prey. Our multidisciplinary assessment demonstrated how nutrients and metal interactions differ in common dolphins depending upon sexual maturity. This approach has relevance when considering how marine pollution, environmental fluctuations and climate change may affect nutritional and trace metal interactions during different reproductive stages within marine predators.

Acceptability of a behaviour change intervention aimed at increasing the use of a reusable hot drink cup

Plastic pollution is an acute issue, with single-use plastic contributing to it significantly. It is beneficial for the planet if we engage in more sustainable behaviors, such as using reusable items instead of single-use ones, thus reducing plastic pollution. We implemented an intervention to increase the use of reusable coffee cups, by employing behavior change techniques that targeted values towards environment, intention to use a reusable cup, and habit. The intervention was successful in increasing the participants' use of reusable cups. The aim of the current study was to evaluate the acceptability of the intervention and research methods, as well as opinions of participants about the process and intervention effectiveness, using a mixed methods approach. Participants (N = 156) answered open and closed survey questions about the acceptability of the intervention, and 11 participated in interviews regarding their experience of intervention. The intervention was deemed acceptable and useful by all participants, regardless of which intervention condition they were allocated to, according to both survey and interview data. Men, however, evaluated the intervention as less personally relevant than women, with overall participation of men in the intervention being smaller than women. Recommendations for implementing similar interventions and future research are offered.

Plastic ingestion by fishing cats suggests trophic transfer in urban wetlands

Recent studies have suggested that plastic contamination in some terrestrial and freshwater environments is estimated to be greater than that detected in marine environments. Urban wetlands are prone to plastic pollution but levels of contamination in their wildlife are poorly quantified. We collected 276 fishing cat (Prionailurus viverrinus) scat samples in Colombo, Sri Lanka for a dietary study of urban fishing cats. We used traditional dietary analysis methodology to investigate the contents of the scats by washing, isolating, and identifying prey remains; while sorting prey remains of individual scats, we unexpectedly detected macroscopic (>1 mm) plastic debris in six (2.17%) of the samples. Across all scat samples, we detected low occurrences of microplastics (0.72%), mesoplastics (1.09%) and macroplastics (1.45%). All three plastic types were found in scats containing rodent remains, while meso-, and macroplastics were found in scats with avian remains, and micro- and macroplastics in scats containing freshwater fish remains. Given that felids are obligate generalist carnivores that eat live or recently dead prey and do not consume garbage, our findings suggest that trophic transfer of plastics occurred whereby fishing cats consumed prey contaminated with plastic. Although macroscopic plastic detection was low, our findings suggest that accumulation of plastics is occurring in wetland food webs, and plastic pollution in freshwater terrestrial systems could pose a risk to predators that do not directly consume plastics but inhabit contaminated environments.

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.

Diet and debris ingestion of skuas on Fildes Peninsula, King George Island, Antarctica

Using pellet analysis, we characterized the diet and plastic and non-plastic debris ingestion of skuas (Catharacta spp.) during 2017-2020 summer seasons along the coastal sector of Fildes Peninsula (King George Island, Antarctica). In addition, we conducted the same analysis during the 2020 breeding season on reproductive territories of south polar (Catharacta maccormicki) and brown (Catharacta antarctica lonnbergi) skua. Our results confirm the generalist and opportunistic habits of both skua species. Additionally, it has been proposed that brown skua displaces south polar skua from penguin breeding colonies given its higher competitive abilities, and our results suggest this might not have happened during the study period. Along with evidence from other studies, this work underlines the idea that potential local anthropogenic sources of plastic and non-plastic debris at Fildes Peninsula need to be further addressed to improve current mitigation efforts.

Plastics in the environment as potential threat to life: an overview

Plastics have become inevitable for human beings in their daily life. Million tons of plastic waste is entering in oceans, soil, freshwater, and sediments. Invasion of plastics in different ecosystems is causing severe problems to inhabitants. Wild animals such as seabirds, fishes, crustaceans, and other invertebrates are mostly effected by plastic entanglements and organic pollutants absorbed and carried by plastics/microplastics. Plastics can also be potentially harmful to human beings and other mammals. Keeping in view the possible harms of plastics, some mitigation strategies must be adopted which may include the use of bioplastics and some natural polymers such as squid-ring teeth protein. This review focuses on the possible sources of intrusion and fate of plastics in different ecosystems, their potential deleterious effects on wildlife, and the measures that can be taken to minimize and avoid the plastic use.

Towards a Circular Economy of Plastics: An Evaluation of the Systematic Transition to a New Generation of Bioplastics

Plastics have become an essential part of the modern world thanks to their appealing physical and chemical properties as well as their low production cost. The most common type of polymers used for plastic account for 90% of the total production and are made from petroleum-based nonrenewable resources. Concerns over the sustainability of the current production model and the environmental implications of traditional plastics have fueled the demand for greener formulations and alternatives. In the last decade, new plastics manufactured from renewable sources and biological processes have emerged from research and have been established as a commercially viable solution with less adverse effects. Nevertheless, economic and legislative challenges for biobased plastics hinder their widespread implementation. This review summarizes the history of plastics over the last century, including the most relevant bioplastics and production methods, the environmental impact and mitigation of the adverse effects of conventional and emerging plastics, and the regulatory landscape that renewable and recyclable bioplastics face to reach a sustainable future.

Microplastics: impacts on corals and other reef organisms

Plastic pollution in a growing problem globally. In addition to the continuous flow of plastic particles to the environment from direct sources, and through the natural wear and tear of items, the plastics that are already there have the potential to breakdown further and therefore provide an immense source of plastic particles. With the continued rise in levels of plastic production, and consequently increasing levels entering our marine environments it is imperative that we understand its impacts. There is evidence microplastic and nanoplastic (MNP) pose a serious threat to all the world's marine ecosystems and biota, across all taxa and trophic levels, having individual- to ecosystem-level impacts, although these impacts are not fully understood. Microplastics (MPs; 0.1–5 mm) have been consistently found associated with the biota, water and sediments of all coral reefs studied, but due to limitations in the current techniques, a knowledge gap exists for the level of nanoplastic (NP; <1 µm). This is of particular concern as it is this size fraction that is thought to pose the greatest risk due to their ability to translocate into different organs and across cell membranes. Furthermore, few studies have examined the interactions of MNP exposure and other anthropogenic stressors such as ocean acidification and rising temperature. To support the decision-making required to protect these ecosystems, an advancement in standardised methods for the assessment of both MP and NPs is essential. This knowledge, and that of predicted levels can then be used to determine potential impacts more accurately.

Fourier transform infrared (FTIR) analysis identifies microplastics in stranded common dolphins (Delphinus delphis) from New Zealand waters

Here we provide a first assessment of microplastics (MPs) in stomach contents of 15 common dolphins (Delphinus delphis) from both single and mass stranding events along the New Zealand coast between 2019 and 2020. MPs were observed in all examined individuals, with an average of 7.8 pieces per stomach. Most MPs were fragments (77%, n = 90) as opposed to fibres (23%, n = 27), with translucent/clear (46%) the most prevalent colour. Fourier transform infrared (FTIR) spectroscopy revealed polyethylene terephthalate (65%) as the most predominant polymer in fibres, whereas polypropylene (31%) and acrylonitrile butadiene styrene (20%) were more frequently recorded as fragments. Mean fragment and fibre size was 584 μm and 1567 μm, respectively. No correlation between total number of MPs and biological parameters (total body length, age, sexual maturity, axillary girth, or blubber thickness) was observed, with similar levels of MPs observed between each of the mass stranding events. Considering MPs are being increasingly linked to a wide range of deleterious effects across taxa, these findings in a typically pelagic marine sentinel species warrants further investigation.

Plastic ingestion as an evolutionary trap: Toward a holistic understanding

Human activities are changing our environment. Along with climate change and a widespread loss of biodiversity, plastic pollution now plays a predominant role in altering ecosystems globally. Here, we review the occurrence of plastic ingestion by wildlife through evolutionary and ecological lenses and address the fundamental question of why living organisms ingest plastic. We unify evolutionary, ecological, and cognitive approaches under the evolutionary trap theory and identify three main factors that may drive plastic ingestion: (i) the availability of plastics in the environment, (ii) an individual's acceptance threshold, and (iii) the overlap of cues given by natural foods and plastics.

100th Anniversary of Macromolecular Science Viewpoint: Redefining Sustainable Polymers

Although Staudinger realized makromoleküles had enormous potential, he likely did not anticipate the consequences of their universal adoption. With 6.3 billion metric tons of plastic waste now contaminating our land, water, and air, we are facing an environmental and public health crisis. Synthetic polymer chemists can help create a more sustainable future, but are we on the right path to do so? Herein, a comprehensive literature survey reveals that there has been an increased focus on "sustainable polymers" in recent years, but most papers focus on biomass-derived feedstocks. In contrast, there is less focus on polymer end-of-life fates. Moving forward, we suggest an increased emphasis on chemical recycling, which sees value in plastic waste and promotes a closed-loop plastic economy. To help keep us on the path to sustainability, the synthetic polymer community should routinely seek the systems perspective offered by life cycle assessment.

Exploring plastic-induced satiety in foraging green turtles

In the last decade many studies have described the ingestion of plastic in marine animals. While most studies were dedicated to understanding the pre-ingestion processes involving decision-making foraging choices based on visual and olfactory cues of animals, our knowledge in the post-ingestion consequences remains limited. Here we proposed a theoretical complementary view of post-ingestion consequences, attempting to connect plastic ingestion with plastic-induced satiety. We analyzed data of plastic ingestion and dietary information of 223 immature green turtles (Chelonia mydas) from tropical Brazilian reefs in order to understand the impacts of plastic ingestion on foraging behavior. Generalized linear mixing models and permutational analysis of variance suggested that plastic accumulations in esophagus, stomach and intestine differed in their impact on green turtle's food intake. At the initial stages of plastic ingestion, where the plastic still in the stomach, an increase in food intake was observed. The accumulation of plastic in the gastrointestinal tract can reduce food intake likely leading to plastic-induced satiety. Our results also suggest that higher amounts of plastics in the gastrointestinal tract may led to underweight and emaciated turtles. We hope that adopting and refining our proposed framework will help to clarify the post-ingestion consequences of plastic ingestion in wildlife.

Linking cadmium and mercury accumulation to nutritional intake in common dolphins (Delphinus delphis) from Patagonia, Argentina

Bioaccumulation of Hg and Cd from food is a complex ecological process that has been oversimplified in the past. Common dolphins (Delphinus delphis) provide a powerful model to biomonitor metal concentrations in marine environments worldwide. We combined proportions-based nutritional geometry with metal analysis, stomach content analysis and the proximate composition of prey, to yield novel insights into the accumulation of Hg and Cd. Our analysis showed an age-related accumulation trend for Cd and Hg in kidney and liver, with highest concentrations found at 18 years of age. When viewed through the lens of nutritional ecology, Argentine anchovy (58.1 Mass %) and South American long-finned squid (22.7 Mass %), provided most of the dietary intake of protein (P) and lipids (L) (P:L ratio = 2.6:1.0) and also represented the main source for Cd and Hg levels accumulated in their bodies. This study presents unprecedented evidence on metal accumulation in relation to age and nutritional intake in a marine predator.

Debris ingestion and nutritional niches in estuarine and reef green turtles

Little attention has been drawn toward the effects of marine debris ingestion in relation to nutrient acquisition and fitness consequences. We tested whether anthropogenic debris ingestion influence the nutritional niches of endangered green turtles (Chelonia mydas) in estuarine and reef habitats on the Brazilian coast. Our results showed that estuarine turtles consumed diets with lower proportional wet mass composition of protein (P) and water (W) than their reef conspecifics. The amounts of debris, mostly plastics, retrieved from the digestive tracts of estuarine turtles were higher compared with those individuals from reefs. The realized nutritional niche from estuarine turtles was subject to the debris density in the environment, lack of benthic food resources available and the surface foraging behavior, likely preventing them from reaching their nutritional goals and resulting in lower fitness. The study provides critical information for the management and conservation of ecologically threatened individuals, populations, and their natural habitats.

Thorough Multianalytical Characterization and Quantification of Micro- and Nanoplastics from Bracciano Lake’s Sediments

Lake basins can behave as accumulators of microplastics released in wastewaters as such or resulting from degradation of larger items before and/or during their journey toward the marine environment as a final sink. A novel multianalytical approach was adopted for the detection and quantification of microplastics with size < 2 mm in the sediments of the volcanic lake of Bracciano, Italy. Simple analytical techniques such as solvent extraction/fractionation (for polyolefins and polystyrene) or depolymerization (for polyethylene terephthalate, PET), along with chromatographic detection (SEC and HPLC), allowed quantitative and qualitative determination of the main synthetic polymer contaminants. In particular, PET microplastic concentrations of 0.8–36 ppm were found, with variability related to the sampling site (exposure to incoming winds and wave action). Proton Nuclear Magnetic Resonance (1H-NMR) and Attenuated Total Reflectance Fourier Transformed InfraRed (ATR-FTIR spectroscopic investigations supported the identification and chemical characterization of plastic fragments and polymer extracts. The average molecular weight of solvent extractable polymers was evaluated from 2D 1H-NMR diffusion ordered spectroscopy (DOSY) experiments. The proposed, easily accessible multianalytical approach can be considered as a useful tool for improving our knowledge on the nature and the concentration of microplastics in sediments, giving insights on the impact of human activities on the health status of aquatic ecosystems.

The Nutritional Ecology of Marine Apex Predators

Apex predators play pivotal roles in marine ecosystems, mediated principally through diet and nutrition. Yet, compared with terrestrial animals, the nutritional ecology of marine predators is poorly understood. One reason is that the field has adhered to an approach that evaluates diet principally in terms of energy gain. Studies in terrestrial systems, by contrast, increasingly adopt a multidimensional approach, the nutritional geometry framework, that distinguishes specific nutrients and calories. We provide evidence that a nutritional approach is likewise relevant to marine apex predators, then demonstrate how nutritional geometry can characterize the nutrient and energy content of marine prey. Next, we show how this framework can be used to reconceptualize ecological interactions via the ecological niche concept, and close with a consideration of its application to problems in marine predator research.

Making citizen science count: Best practices and challenges of citizen science projects on plastics in aquatic environments

There is considerable scientific and societal concern about plastic pollution, which has resulted in citizen science projects to study the scale of the issue. Citizen science is a cost-effective way to gather data over a large geographical range while simultaneously raising public awareness on the problem. Because the experiences of researchers involved in these projects are not yet adequately covered, this paper presents the findings from ten semi-structured qualitative interviews with researchers leading a citizen science project on micro- or macroplastics. Our results show it is important to specify the goal(s) of the project and that expertise on communication and data science is needed. Furthermore, simple protocols, quality control, and engagement with volunteers and the public are key elements for successful projects. From these results, a framework with recommendations was drafted, which can be used by anyone who wants to develop or improve citizen science projects.

Diet and macronutrient niche of Asiatic black bear (Ursus thibetanus) in two regions of Nepal during summer and autumn

Relatively little is known about the nutritional ecology of omnivorous Asiatic black bears (Ursus thibetanus) in Nepal. We characterized the diet of black bears in two seasons (June-July, "summer"; and October-November "autumn") and two study areas (Dhorpatan Hunting Reserve [DHR]; and Kailash Sacred Landscape [KSL]). We then conducted nutritional analysis of species consumed by black bears in each study area, in combination with nutritional estimates from the literature, to estimate the proportions of macronutrients (i.e., protein [P], lipid [L], and carbohydrate [C]) in the seasonal bear foods and diets, as well as their macronutrient niche breadth. We found that bamboo (Arundinaria spp.) had the highest relative frequency in both study areas and seasons. Ants and termites were found in DHR diets, but not KSL diets. One anthropogenic crop was found in DHR summer diets (Zea mays) and two were found in KSL summer diets (Z. mays; and Kodo millet [Paspalum scrobiculatum]). Other than insects, no animal prey was found in either diet. The proportions of macronutrients in diets (i.e., realized macronutrient niches) were relatively high in carbohydrate for both study areas and seasons: DHRsummer 24.1P:8.7L:67.2C; KSLsummer 16.7P:8.2L:75.1C; DHRautumn 21.1P:10.5L:68.4C; KSHautumn 19.0P:11.0L:70.0C. Macronutrient niche breadth was 3.1 × greater in the DHR than KSL during summer, and 4.0 × greater in the autumn, primarily due to the higher proportion of lipid in ants and termites relative to plant foods. Within-study area differences in niche breadth were greater during summer than autumn; in the KSH the macronutrient breadth was 1.4 × greater in summer, while in the DHR it was 1.1 × greater in summer. Similarity in dietary macronutrient proportions despite differences in foods consumed and niche breadth are suggestive of foraging to reach a preferred macronutrient balance.