ingestion des microplastiques par les especes marines : anadara natalensis, holothuria scabra et holothuria parva dans le sud-ouest de madagascar ingestion des microplastiques par les especes marines : anadara natalensis, holothuria scabra et holothuria parva dans le sud-ouest de madagascar

Abstract

Plastic waste threatens and affects marine biodiversity and also human health. Marine
fauna is a victim of microplastic ingestion as most marine species are destined for human
consommation. This study was carried out to determine the presence of microplastics and
their abundance and characteristics in Holothuria scabra, Holothuria parva and Anadara
natalensis. It was carried out in Toliara and Ranobe Bay, southwestern Madagascar, from
15th December 2021 to 30th july 2022. For each species by site, 30 individuals of various
sizes were collected. After extraction of the digestive tracts and specific organs of the
samples, the organic particles of the organs were dissolved with a KOH solution (10%) for
48h at 18-21°C. The tissue_KOH solution was then filtered through a 0.47µm mesh filter
paper. Finally, the filter paper was dried at room temperature in a Petri dish and observed
under a stereomicroscope. The study showed that 646 microplastics were identified out of
85.92% contaminated samples. They are abondant in Toliara, at 41.02%. It was revealed
that MPs are abundantly observed in Holothuria scabra 2.88±0.23MPs/ind and Anadara
natalensis 2.46±0.18MPs/ind than in Holothuria parva 1.82±0.15MPs/ind. The viscera of
holothurians incorporate more microplastics 1.66 to 3.46 for H. scabra and 0.8 to 1.56 for
H. parva; in contrast, for A. natalensis, it was the gills that were most affected 0.76 to
1.13MPs. The type of microplastics most significantly encountered in the individuals
sampled were fibers at 97.99%. These results showed that microplastics were present and
ingested in the specific organs of holothurians and bivalves. The human health of the
population is threatened by consuming these microplastic-soaked species