Impact of textile microfiber ingestion on the tissue integrity of the mangrove oyster Crassostrea gasar.

Oysters are crucial in coastal ecosystems and are vulnerable to ingesting textile microfibers (MFs) from their environment, which can accumulate in their gills and digestive glands. This study examines the effects of MFs at concentrations of 0.11 mg. L and 1.00 mg. L on Crassostrea gasar (C. gasar) over 7, 14, and 21 days of exposure, using different types of fiber: conventional cotton, polyester, mixed, and organic cotton. The digestive gland was identified as the primary site of microfiber (MF) accumulation, with polyester showing the highest retention, which may impair digestive function. Gill morphometric analyses revealed significant reductions in filament length, width, and interlamellar space, indicating severe tissue atrophy with possible consequences for respiration and immune defense. An increase in mucocyte density and a reduction in the condition index observed after 7 days of exposure suggest a rapid decline in organism health, likely associated with digestive gland damage. Histopathological analyses further demonstrated severe lesions in the gills and alterations in digestive tubules, including hyperplasia and necrosis. Overall, the results indicate that all tested textile MFs can be retained and accumulate in bivalve tissues, causing histopathological damage and reducing physiological condition, thereby highlighting bivalves' high susceptibility to MF pollution in coastal environments.