Mercury levels in muscle tissue of four common elasmobranch species from the Pacific coast of Costa Rica, Central America

Abstract

Mercury (Hg) is a non-essential and toxic element that is ubiquitous in the marine environment and biomagnifies through food webs. Given the high trophic position of many elasmobranch species, it is important to quantify potentially harmful trace elements like Hg in their tissues, as this is an indicator of the level of contamination in the ecosystem. This study provides the first examination of total mercury (THg) concentrations in muscle tissue of four common demersal elasmobranchs (Mustelus henlei, Raja velezi, Torpedo peruana and Zapteryx xyster) from the Pacific coast of Costa Rica. All four species showed a positive relationship between THg concentration and body size, but THg concentration did not vary with trophic position. Torpedo peruana showed the highest THg concentration (mean ± SD: 0.52 ± 0.25 mg/kg wet weight) but Z. xyster had the highest slope for the THg-size relationship. The THg concentrations found in this study were lower than those reported for similar elasmobranch species in other regions, and only one sample exceeded the concentration limit suggested for human consumption. Our results suggest that THg contamination off the Pacific coast of Costa Rica, and possibly Central America is minimal.