Total mercury in female Pacific sharpnose sharks Rhizoprionodon longurio and their embryos

Abstract

We determined the Hg content of blood, placenta and umbilical cord of 20 pregnant females of the viviparous Pacific sharpnose shark, Rhizoprionodon longurio and of the livers of the embryos contained in their right and left uterus, aiming to provide information on the amount of this metal offloaded during pregnancy by the mother to the embryos. Hg content varied by close or higher than one order of magnitude in all tissues and showed the decreasing trend: maternal blood > umbilical cord > placenta > embryonic livers, with placenta and embryonic livers significantly lower than maternal blood. There were highly significant correlations (P < 0.001) between the Hg content of maternal blood, cord, and placenta. Those between embryonic livers and maternal blood, cord and placenta were not significant (P > 0.05). The results suggest transplacental Hg transfer and that the liver is not the main site of Hg accumulation.

Essential and non-essential trace element concentrations in muscle and liver of a pregnant Munk’s pygmy devil ray (Mobula munkiana) and its embryo

“…A wide variety of reproduction modes across elasmobranch species can lead to different patterns of maternal transference during gestation, complicating its understanding. Most of the maternal transfer studies carried out on elasmobranchs are focused on Hg (Lyons and Lowe 2013a;Le Bourg et al 2014;Frías-Espericueta et al 2015;van Hees and Ebert 2017) and little is known about the transference of other trace elements (Frías-Espericueta et al 2014;Dutton and Venuti 2019;Lopes et al 2019;Souza-Araujo et al 2020).…”