Assessing the impact of microplastics on gonadal health of the spadenose shark (Scoliodon laticaudus) on the west coast of India.

Pollutants such as microplastics (MPs) are detrimental to the health of humans, animals and reduce the quality of the environment. These particles can be ingested and accumulate in marine biota through the food chain leading to adverse effects on various physiological processes. Sharks, which typically occupy higher trophic levels in the marine food chain, may exhibit the highest accumulation of MPs. However, the prevalence of MPs in sharks and their potential impact on physiology are not well understood. To address this gap, we investigated MP concentrations in the gastrointestinal tract (GI) and gonads of the spadenose shark (Scoliodon laticaudus) on the west coast of India. MPs were detected in all water samples, 97.9 % of the GI tract samples and 95 % of gonadal tissue samples, with gonads exhibiting the highest MP concentrations. Fibres (85 %) were the dominant type, followed by flakes (11.2 %) and films (3 %). Female gonads had a significantly higher concentration of MPs than males. However, in males, a negative correlation between MP concentration and gonadosomatic index (GSI) indicated potential physiological impacts. Raman spectroscopy identified polyethylene and polyamide polymers along with other contaminants. These findings underscore the widespread presence of MP in shark tissues and their potential impact on reproductive health.