High intake rates of microplastics in a Western Atlantic predatory fish, and insights of a direct fishery effect,

Environmental Pollution, Volume 236, May 2018, Pages 706-717, ISSN 0269-7491,

Abstract:
Microplastic contamination was investigated in the gut contents of an economically important estuarine top predator, Cynoscion acoupa, according to spatiotemporal and ontogenetic use of a tropical estuary.

Microplastic contamination was found in more than half of the analysed fish. Ingested microplastics were classified by type, colour and length with most of the particles consisting of filaments (<5 mm). Longer filaments were more frequently ingested in the upper estuary and smaller filaments in the lower estuary, as a result of differences in
hydrodynamic forces and proximity to the probable input sources.
The river is likely an important source of filaments to the estuary and filaments ingested in the upper estuary showed little sign of weathering, when compared with those from the lower estuary, which are subject to intense weathering and consequent break-up of particles to smaller sizes.
Most filaments, of all colours, accumulated in adults of C. acoupa, which are more susceptible to contamination through both direct ingestion and trophic transference as they shift their feeding mode to piscivory. Moreover, the highest ingestion of filaments in adults occurred in the lower estuary, during the late rainy season, likely associated with the intense fishing activities in this habitat, which results in a greater input of filaments from fishing gear, which
are mainly blue in colour.
Overall, 44% of the ingested filaments were blue, 20% purple, 13% black, 10% red and 12% white. The next most common colour, the purple filaments, are most likely blue filaments whose colour has weathered to purple. Red filaments were proportionally more ingested in the lower estuary, indicating a coastal/oceanic source.
White and black filaments were more commonly ingested in the inner estuary, suggesting that they have a riverine origin and/or were actively ingested by juveniles and sub-adults, which inhabit the inner estuary and have zooplankton as an important food resource.

https://drive.google.com/open?id=11dU2qe45pv7Bx2o9FgVQwIEco-gdo-0h

https://doi.org/10.1016/j.envpol.2018.01.095.

(https://www.sciencedirect.com/science/article/pii/S0269749117339143)

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Investigating microplastic trophic transfer in marine top predators,
Environmental Pollution, 2018, ISSN 0269-7491,

Abstract:

Microplastics are highly bioavailable to marine organisms, either through direct ingestion, or indirectly by trophic transfer from
contaminated prey. The latter has been observed for low-trophic level organisms in laboratory conditions, yet empirical evidence in high
trophic-level taxa is lacking. In natura studies face difficulties when dealing with contamination and differentiating between directly and
indirectly ingested microplastics. The ethical constraints of subjecting large organisms, such as marine mammals, to laboratory investigations hinder the resolution of these limitations. Here, these issues were resolved by analysing sub-samples of scat from captive grey seals (Halichoerus grypus) and whole digestive tracts of the wild-caught Atlantic mackerel (Scomber scombrus) they are fed upon. An enzymatic digestion protocol was employed to remove excess organic material and facilitate visual detection of synthetic particles without damaging them.
Polymer type was confirmed using Fourier-Transform Infrared (FTIR) spectroscopy. Extensive contamination control measures were implemented throughout. Approximately half of scat subsamples (48%; n = 15) and a third of fish (32%; n = 10) contained 1–4 microplastics. Particles were mainly black, clear, red and blue in colour. Mean lengths were 1.5 mm and 2 mm in scats and fish respectively. Ethylene propylene was the most frequently detected polymer type in both. Our findings suggest trophic transfer represents an indirect, yet potentially major, pathway of microplastic ingestion for any species whose feeding ecology involves the consumption of whole prey, including humans.

https://www.sciencedirect.com/science/article/pii/S0269749117343294/pdfft?md5=d32001ca555605d234108050d52b4f0d&pid=1-s2.0-S0269749117343294-main.pdf

https://drive.google.com/open?id=1vD0N5JAGw_ehwsWTR-OBq_MQRRFGzces
https://doi.org/10.1016/j.envpol.2018.02.016.(http://www.sciencedirect.com/science/article/pii/S0269749117343294)

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