Contamination des poissons pélagiques et récifaux par les microplastiques et mésoplastiques (cas d’Andrevo, Toliara et Sarodrano, Sud-Ouest de Madagascar)

Abstract

Plastics have become a ubiquitous pollutant in all seas and oceans. However, they
can be ingested by marine organisms. The present study evaluates the presence of plastic
particles (microplastics and mesoplastics) in the digestive tracts and gills of pelagic
(Herklotsichthys quadrimaculatus, Selar crumenophtalmus) and reef (Siganus sutor,
Lethrinus harak) fishes from Andrevo, Toliara and Sarodrano, southwest of Madagascar. It
was carried out between August 2021 and August 2022 and aims to evaluate amount and
composition of plastic particles ingested by fishes. On the whole, 690 specimens were
sampled and examined. A total of 1245 particles were extracted from examined fishes, of
which 446 were found in the gills and 799 in the digestive tracts. They mainly consisted of
filaments (95.02%), followed by fragments (4.02%); film and foam were rare (0.56% and
0.40% respectively). Plastic particles were mostly blue. The results show that 65.07% (n =
449) of the individuals examined are contaminated by plastic, with an average of 1,80 ±
0,10 items.ind-1. In addition, there was variability between sites, with contamination being
higher in Toliara which is an urbanized area. This study therefore provided evidence of
microplastic and mesoplastic contamination in fish caught off Andrevo, Sarodrano and
Toliara in southwest of Madagascar. Microplastics are present in the digestive tract and gills
of all studied species.