Bioaccumulation and Biomagnification of Total Mercury in Four Exploited Shark Species in the Baja California Peninsula, Mexico A. Maz-Courrau • C. Lo ´pez-Vera • F. Galva ´n-Magan ˜a • O. Escobar-Sa ´nchez • R. Rosı ´les-Martı ´nez • A. Sanjua ´n-Mun ˜oz Received: 5 June 2011 / Accepted: 12 December 2011 / Published online: 21 December 2011 Ó Springer Science+Business Media, LLC 2011 Abstract The present study determined the average mer- cury bioaccumulation in the muscle tissue of four shark species (Carcharhinus falciformis, Prionace glauca, Sphyrna zygaena and Isurus oxyrinchus) captured in the Baja California Peninsula. We also evaluated biomagnification of some prey consumed by sharks. All sharks’ species had mercury levels over the limit specified by the Mexican government for human consumption. Blue shark (P. glauca) presented highest mercury values (1.96 ± 1.48 lg/g Hg d.w.) and it was the unique specie that showed a negative correlation with mercury content (Rs =-0.035, p = 0.91). Scomber japonicus was the prey with high content of mer- cury (0.57 ± 0.02 lg/g). Keywords Mercury Á Bioaccumulation Á Biomagnification Á Shark Á Pacific Ocean Á Mexico Industrialization and artisanal mining of precious metals have contributed to the increment of toxic contaminants in the environment, affecting mainly coastal areas. One such contaminant is mercury, which is an element not essential to life (Nu ´n ˜ez-Nogueira et al. 1998); it is, however, natu- rally present in the environment due to geological pro- cesses like erosion, degasification of the earth’s crust and volcanic emissions. Mercury can be found under two essential forms in aquatic systems: inorganic (Hg ?1 , Hg ?2 ) and organic (HgCH 3 ). The latter form is the result of biomethylation reactions in biological systems; where the methyl-B12 co-enzime transforms inorganic mercury salts into methylmercury and dimethylmercury. The high tox- icity of ionic mercury and of methylmercury is due to their great affinity for amino and sulphydril protein groups, forming metallic complexes that hinder the ability of enzymes to control metabolic reactions (Campos 1987). Aquatic organisms can absorb mercury through biotic and abiotic processes, concentrating these substances in their tissues and organs (bioaccumulation) (Rand et al. 1995). This bioaccumulation occurs mainly in fishes, especially in large long-lived predators like sharks, whose muscular tissues can present high mercury levels through the union of metal to the proteins (Gomes et al. 2004). So, mercury is transferred through the trophic web, and their concentration increases at each level (biomagnifica- tion); they are present in marine mammals and humans, causing negative health effects. It is important to evaluate mercury levels in aquatic animals in order to alert the public to the effects of consuming contaminated animals, and to determine the physiological differences among species relating to different elimination mechanisms and metal accumulation. The present study determined: (1) mercury bioaccumulation in smooth hammerhead shark (Sphyrna zygaena), blue shark (Prionace glauca), mako A. Maz-Courrau Universidad de Ca ´diz, Campus Rı ´o San Pedro s/n, 11510 Puerto Real, Ca ´diz, Spain C. Lo ´pez-Vera Á A. Sanjua ´n-Mun ˜oz Faculty of Natural Sciences, Universidad de Bogota ´ Jorge Tadeo Lozano, Carrera # 2, 11-68, Edificio Mundo Marino, El Rodadero, Santa Marta, Colombia F. Galva ´n-Magan ˜a (&) Á O. Escobar-Sa ´nchez Laboratory of Fish Ecology, Centro Interdisciplinario de Ciencias Marinas, Av. Instituto Polite ´cnico Nacional s/n, 23096 La Paz, BCS, Mexico e-mail: galvan.felipe@gmail.com R. Rosı ´les-Martı ´nez Laboratory of Toxicology, Veterinary Medicine and Zootechny Faculty, Universidad Nacional Auto ´noma de Mexico, 04510 Mexico, D. F., Mexico 123 Bull Environ Contam Toxicol (2012) 88:129–134 DOI 10.1007/s00128-011-0499-1