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RNA/DNA index in populations of the clam Tivela mactroides (Bivalvia: Veneridae) from localities with different pollution levels

Abstract:

Three developmental stages in the Tivela mactroides clam: juvenile (10-20 mm), juvenile with reproductive capacity (20-30 mm) and adults (30-45 mm) were evaluated to determine the physiological condition of clams related to environmental pollution levels using the RNA/DNA index. The populations evaluated were obtained from Playa Güiria (Sucre state, northeastern coast of Venezuela), which has no sign of pollution, and from Río Chico and Boca de Paparo (Miranda state, central coast of Venezuela), which showed high pollution levels due to urban and industrial waste disposal through the Tuy river. The RNA and DNA concentrations were determined in the adductor muscle by fluormetric techniques. The three populations showed significant differences in the RNA/DNA index. The clams of Playa Güiria showed the highest RNA/DNA index, followed by Río Chico and Boca de Paparo specimens. This pattern was related to pollution levels in each locality. The RNA/DNA index was inversely proportional to bivalve sizes. The results showed that the RNA/DNA index can be used as a physiological index to estimate conditions of environmental pollution stress on Tivela mactroides.