Microplastic ingestion ubiquitous in marine turtles

As a consequence of the global ubiquity of plastic pollution, scientists, decision‐makers, and the public often ask whether macroplastics (>5 mm) and microplastics (<5 mm) have a realized ecological threat. In 2016, we conducted a systematic review of the literature and made a call for further research testing hypotheses about ecological effects. In the subsequent years, the amount of relevant research has risen tremendously. Here, we reassess the literature to determine the current weight of evidence about the effects of plastic pollution across all levels of biological organization. Our data spans marine, freshwater, and terrestrial environments. We extracted data from 139 lab and field studies testing 577 independent effects across a variety of taxa and with various types, sizes, and shapes of plastic. Overall, 59% of the tested effects were detected. Of these, 58% were due to microplastics and 42% were due to macroplastics. Of the effects that were not detected, 94% were from microplastics and 6% were from macroplastics. We found evidence that whether or not an effect is detected, as well as the severity and direction of the effect, is driven by dose, particle shape, polymer type, and particle size. Based on our analyses, there is no doubt that macroplastics are causing ecological effects, however, the effects of microplastics are much more complex. We also assessed the environmental relevancy of experimental studies by comparing the doses used in each exposure to the concentrations and sizes of microplastics found in the environment. We determined that only 17% of the concentrations used in experimental studies have been found in nature, and that 80% of particle sizes used in experiments fall below the size range of the majority of environmental sampling. Based on our systematic review and meta‐analysis, we make a call for future work that recognizes the complexity of microplastics and designs tests to better understand how different types, sizes, shapes, doses, and exposure durations affect wildlife. We also call for more ecologically and environmentally relevant studies, particularly in freshwater and terrestrial environments.

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“…), turtles (Duncan et al. ), sea birds (Reynolds and Ryan ), seals (Donohue et al. ), and whales (Nelms et al.…”

Section: Introductionmentioning

confidence: 99%

What is known and unknown about the effects of plastic pollution: A meta‐analysis and systematic review

Bucci

Túlio

Rochman

2020

Ecological Applications

383

263

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“…This is important because prey type may be a crucial factor that determines the extent to which plastic is ingested, particularly for top predators for which trophic transfer is potentially the main route of entry (Nelms et al, ). Although both metabarcoding and microplastic extraction from faeces/gut content have been applied separately to a variety of marine and terrestrial taxa, including zooplankton, fish, turtles, birds and marine mammals (metabarcoding; Bucklin & Lindeque, ; Berry et al, ; McInnes et al, , microplastics; Cole et al, ; Zhao, Zhu, & Li, ; Huerta Lwanga et al, ; Duncan et al, ; Nelms et al, ), they usually require different sample processing methods and have not been used concurrently. Here, for the first time, we combine existing DNA extraction techniques for determination of diet composition using molecular scatology methods, with specialist methods designed to isolate microplastics in the same protocol, providing a stream‐lined methodology pipeline to assess diet and microplastic abundance simultaneously.…”

Section: Introductionmentioning

confidence: 99%

What goes in, must come out: Combining scat‐based molecular diet analysis and quantification of ingested microplastics in a marine top predator

et al. 2019

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Microplastics (plastic particles <5 mm in size) are highly available for ingestion by a wide range of organisms, either through direct consumption or indirectly, via trophic transfer, from prey to predator. The latter is a poorly understood, but potentially major, route of microplastic ingestion for marine top predators. We developed a novel and effective methodology pipeline to investigate dietary exposure of wild top predators (grey seals; Halichoerus grypus) to microplastics, by combining scat‐based molecular techniques with a microplastic isolation method. We employed DNA metabarcoding, a rapid method of biodiversity assessment, to garner detailed information on prey composition from scats, and investigated the potential relationship between diet and microplastic burden. Outcomes of the method development process and results of both diet composition from metabarcoding analysis and detection of microplastics are presented. Importantly, the pipeline performed well and initial results suggest the frequency of microplastics detected in seal scats may be related to the type of prey consumed. Our non‐invasive, data‐rich approach maximizes time and resource–efficiency, while minimizing costs and sample volumes required for analysis. This pipeline could be used to underpin a much‐needed increase in understanding of the relationship between diet composition and rates of microplastic ingestion in high trophic level species.

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“…Gastrointestinal obstruction by debris such as plastic are a clear risk for turtles [ 110 , 111 ]. Macroplastic ingestion is ranked at the same level as other anthropogenic pressures such as by-catch [ 112 ]. The risk of plastic ingestion has been documented for decades and has affected different age groups of sea turtles [ 113 – 115 ].…”

Section: Resultsmentioning

confidence: 99%

“…Generally, the risk of macroplastic ingestion is documented more than microplastics and in some cases is reported to have higher impacts. Micronising plastic can accumulate in coastal sediments and in ocean beds but the consequences for sea turtles is still unclear [ 112 ].…”

Section: Resultsmentioning

confidence: 99%

Disease risk analysis in sea turtles: A baseline study to inform conservation efforts

et al. 2020

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The impact of a range of different threats has resulted in the listing of six out of seven sea turtle species on the IUCN Red List of endangered species. Disease risk analysis (DRA) tools are designed to provide objective, repeatable and documented assessment of the disease risks for a population and measures to reduce these risks through management options. To the best of our knowledge, DRAs have not previously been published for sea turtles, although disease is reported to contribute to sea turtle population decline. Here, a comprehensive list of health hazards is provided for all seven species of sea turtles. The possible risk these hazards pose to the health of sea turtles were assessed and “One Health” aspects of interacting with sea turtles were also investigated. The risk assessment was undertaken in collaboration with more than 30 experts in the field including veterinarians, microbiologists, social scientists, epidemiologists and stakeholders, in the form of two international workshops and one local workshop. The general finding of the DRA was the distinct lack of knowledge regarding a link between the presence of pathogens and diseases manifestation in sea turtles. A higher rate of disease in immunocompromised individuals was repeatedly reported and a possible link between immunosuppression and environmental contaminants as a result of anthropogenic influences was suggested. Society based conservation initiatives and as a result the cultural and social aspect of interacting with sea turtles appeared to need more attention and research. A risk management workshop was carried out to acquire the insights of local policy makers about management options for the risks relevant to Queensland and the options were evaluated considering their feasibility and effectiveness. The sea turtle DRA presented here, is a structured guide for future risk assessments to be used in specific scenarios such as translocation and head-starting programs.

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Microplastic ingestion ubiquitous in marine turtles

Cited by 222 publications

References 82 publications

What is known and unknown about the effects of plastic pollution: A meta‐analysis and systematic review

What is known and unknown about the effects of plastic pollution: A meta‐analysis and systematic review

What goes in, must come out: Combining scat‐based molecular diet analysis and quantification of ingested microplastics in a marine top predator

Disease risk analysis in sea turtles: A baseline study to inform conservation efforts

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