Microplastic ingestion by marine organisms presents a challenge to both ecosystem functioning and human health. We
characterized microplastic abundance, shape, size, and polymer types ingested by the West African mangrove oyster,
Crassostrea tulipa (Lamarck, 1819) sampled from estuaries and lagoons from the Gambia, Sierra Leone, Ghana, Benin,
and Nigeria using optical microscopy and Fourier transform infrared (FTIR) techniques. A total of 780 microplastics were
isolated in the whole tissues of the 250 oysters (n = 50 oysters per country). The abundance and distribution of microplastics
in the oysters followed the pattern: the Gambia > Ghana > Sierra Leone > Nigeria > Benin. The Tanbi wetlands in the
Gambia recorded the highest average of 10.50 ± 6.69 per oyster while the Ouidah lagoon in Benin recorded the lowest
average of 1.80 ± 1.90 per oyster. Overall, microplastic numbers varied significantly (p < 0.05) among the five countries.
Microfibers, particularly those within 1001–5000 μm size, dominated the total microplastic count with a few fragments
and films. No spherical microplastics were isolated in the oysters. In the Sierra Leone and Benin oysters, fragments and
films were absent in the samples. Microplastic between the 1001 and 5000 μm size class dominated the counts, followed by
501–1000 μm, 101–500 μm, and 51–100 μm. Five polymer groups namely polyethylene, polyester, nylon, polypropylene,
and polyamide were identified across the five countries, with polyethylene occurring in oysters from all five countries and
polyester occurring in all but the oysters from Nigeria. This diversity of polymers suggests varied sources of microplastics
ingested by the studied oysters. The absence of microspheres across the five supports findings from other studies that they
are the least ingested and highly egested by the oysters. |
University of Cape Coast