Distribution of Hg and Se in Muscle and Liver of the Thornback Guitarfish Platyrhinoidis triseriata from the Eastern Pacific Ocean.

Human consumption of the thornback guitarfish (Platyrhinoidis triseriata) is concentrated in coastal populations of the Pacific coast of Mexico as its meat is prized for its high quality. This study analyzes the distribution of mercury and selenium in the muscle and liver of Platyrhinoidis triseriata and the risk to human health associated with its consumption. In order to conduct these estimates, specimens were collected from the Eastern Pacific Ocean in 2015 and 2016 and found mean concentrations (µg g-1 wet weight) of mercury ranging from 0.02 to 0.58 in muscle and 0.10 to 0.31 in liver. Selenium ranged from 0.14 to 1.31 in muscle and from 0.93 to 4.52 in liver. Mercury levels in the muscle of P. triseriata were significantly correlated (positive correlation) with the total length of the specimens. The predominant prey of P. triseriata was the shrimp Pleuroncodes planipes and according to the biomagnification factor, only mercury was biomagnified. The risk to consumers associated with the simultaneous presence of mercury and selenium in the muscle and liver of rays under the selenium health benefit value approach indicated that consumption of P. triseriata from this area is beneficial to human health.

Mercury levels in myliobatid stingrays (Batoidea) from the Gulf of California: tissue distribution and health risk assessment.

With the aim of knowing Hg distribution in selected tissues of myliobatid stingrays and assessing health risk to Mexican population, Hg concentration was determined in the muscle and liver of four ray species. Total Hg levels were determined by cold vapor atomic absorption spectrophotometry. With respect to the muscle, devil rays (Mobula spp.) showed lower Hg levels (<0.22 µg g(-1)) than Rhinoptera steindachneri (0.37 ± 0.25 µg g(-1) wet weight). In the case of the liver, the highest Hg concentration was found in Mobula japanica (0.22 ± 0.01 µg g(-1)). Hg levels in the muscle and liver varied according to the species; in some case, the liver accumulated more Hg than the muscle and the opposite pattern in other cases. R. steindachneri showed a significant difference between both tissues. No significant differences of Hg levels between males and females and between juveniles and adult specimens of R. steindachneri were found. Positive correlation between Hg concentrations and disc width and total weight was not significant for R. steindachneri (Rs < 0.36, p > 0.05). Batoids showed Hg values below the Mexican (NOM-027-SSA1-1993) limits (1.0 µg g(-1)) in fishes for human consumption. The species with the highest potential of Hg transfer to human population is R. steindachneri; however, an adult (70 kg) could consume approximately 943 g per week without representing a health risk. Nevertheless, further and continuous monitoring is needed since batoids support an important fishery in Mexican waters, being a food resource and income to coastal communities.

Mercury in muscle and liver of ten ray species from Northwest Mexico.

We determined total mercury (Hg) distribution in muscle and liver of ten ray species and assessed health risk considering Hg levels in muscle and average consumption of rays in Mexico. Rays were collected from five sites in NW Mexico between March and November 2012. Hg concentrations ranged from 4.465 µg g(-1) in muscle of the longtail stingray Dasyatis longa to 0.036 µg g(-1) in liver of the diamond stingray Dasyatis dipterura. Considering all the individuals, Hg in muscle (1.612±1.322 µg g(-1)) was significantly (p<0.05) higher than in liver (0.745±0.616 µg g(-1)). Regarding local health risk assessment, none of the ray species may cause adverse effects on consumers.