Heavy-metal contents in oysters (Crassostrea gigas) cultivated on the southeastern coast of the Gulf of California, Mexico

Abstract

Heavy-metal contents in oysters (Crassostrea gigas) cultivated on the southeastern coast of the Gulf of California, Mexico Contenido de metales pesados en ostiones (Crassostrea gigas) cultivados en la costa sureste del Golfo de California, México ABSTRACT Background. For its flesh and flavor, the Pacific oyster Crassostrea gigas is cultivated worldwide, but as filter feeders, this bivalve bioaccumulates heavy metals from different pollution sources, rendering them unsafe for human consumption. Goals. We carried out this study to assess the heavy metal concentrations in cultivated oysters from a farm located on the southeastern coast of the Gulf of California during 2011. Methods. Oyster samples were analyzed monthly (March-December 2011) for cooper (Cu), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), zinc (Zn), arsenic (As), and mercury (Hg). Results. The mean values (µg g -1 , dry weight) for each metal were Cu = 51.42 ± 25.92, Cr = 24.97 ± 32.38, Cd = 13.84 ± 4.22, Ni = 10.26 ± 12.18, Pb = 2.18 ± 1.28, As = 0.37 ± 0.08, Zn = 267.42 ± 92.29, and Hg = 0.02 ± 0.01. Conclusions. The results suggest that metal burdens could be influenced by anthropogenic activities such as agriculture and aquaculture surrounding the culture zone. Cu, Cr, Cd, and Pb levels (µg g -1 , fresh weight) were above the maximum permissible values and thus pose a threat to human health. Metal concentrations must be monitored periodically. RESUMENAntecedentes. El ostión del pacífico, Crassostrea gigas, es cultivado en el mundo por su sabor y textura de la carne, pero por ser un organismo que se alimenta mediante filtración, puede acumular metales pesados haciéndolo peligroso para su consumo. Objetivos. El presente estudio evaluó la concentración de metales pesados en ostiones cultivados en una granja localizada en la costa sureste del Golfo de California durante 2011. Métodos. Se tomaron muestras de ostión cada mes (marzo-diciembre 2011) para analizar el contenido de cobre (Cu), cadmio (Cd), cromo (Cr), níquel (Ni), plomo (Pb), zinc (Zn), arsénico (As) y mercurio (Hg). Resultados. Los valores promedio (µg g -1 , peso seco) de cada metal fueron: Cu = 51.42 ± 25.92, Cr = 24.97 ± 32.38, Cd = 13.84 ± 4.22, Ni = 10.26 ± 12.18, Pb = 2.18 ± 1.57, As = 0.37 ± 0.26, Zn = 267.42 ± 92.29 and Hg = 0.02 ± 0.01. Conclusiones. Los resultados obtenidos sugieren que la carga de metales pudo haber sido influenciada por actividades antropogénicas desarrolladas en los alrededores del área de cultivo, como agricultura y acuacultura. Los niveles de Cu, Cr, Cd y Pb en peso húmedo rebasaron los límites máximos permitidos representando un riesgo para la salud humana. La carga de los metales estudiados debe ser monitoreada periódicamente.