Resumen del producto

The oceanic manta rays, Mobula birostris, filter big volumes of water while feeding on zooplankton. Thus, they are potentially exposed to the growing threat of plastic pollution. Ingested plastics can leach adsorbed toxic pollutants and plastic additives (e.g. phthalates, used as indicators of plastic contamination in animal tissues) that are recognized as endocrine disruptors and toxic for many species. The oceanic manta ray population of the Gulf of California has been drastically reduced in recent decades, making the Revillagigedo Archipelago (RA) and Banderas Bay (BB) its last refuge and aggregation areas in the Mexican Pacific Ocean. Tissue samples (skin and muscle biopsies) of manta rays were collected during scuba and freediving using a spear pole and underwent chemical extraction and subsequent analysis to measure the concentration of phthalates monoesters as indicators of plastic ingestion. In addition, samples from surface waters were collected in RA and BB using zooplankton and manta nets with 333µm mesh: floating plastics were found in both areas and the abundance, size and polymer composition of the plastic debris were determined through Fourier transform infrared spectroscopy (FT-IR). In the biopsy samples, none of the analyzed phthalates were detected, indicating that in the study area mantas are less vulnerable to plastic ingestion than previously thought, or microplastics are rapidly excreted. Measuring phthalates in manta ray biopsies is a valid non-lethal method to investigate possible plastic ingestion occurrence in this species, that is considered vulnerable to extinction and is protected in Mexico. This research is a baseline study for plastic debris contamination in the area and for possible ingestion by oceanic manta rays.

Palabras clave: Mobula birostris; Pollution; Gulf of California

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