Physiological and histological effects of cadmium, lead, and combined on Artemia franciscana.

This study analyzed the effects of cadmium (Cd) and lead (Pb) on growth, sexual couples, and histological structures of Artemia franciscana exposed to individual concentrations of these metals and combined. No histological effects were observed at tissue level in digestive, respiratory, nervous, and reproductive systems (i.e., necrosis, loss of regular structure) in individual and mixed applications on A. franciscana for 20 days of exposure. No significant differences (p > 0.05) were determined in final size and growth rate among the organisms exposed to Cd and those of control. For Pb, only the final size (3.59 ± 0.59 mm) of organisms exposed to the highest concentration was significantly lower (p < 0.05) than those of the control (4.53 ± 0.34 mm) group, whereas for the combined experiment, no significant differences (p > 0.05) were observed in final size and growth rate. At all Cd concentrations, mean sexual couples were significantly lower (p < 0.05) than those of the control, as well as for Pb. For the combined experiment (8 µg/L of Cd + 8 µg/L of Pb), sexual couples were not observed, indicating synergism and negative reproduction effects. The results showed that Cd and Pb aquatic environmental regulations (as the Criterion of Continuous Concentration) proposed by the US Environmental Protection Agency (EPA) should include their interactions with other metals.

Mercury and selenium concentrations in the crab Callinectes arcuatus from three coastal lagoons of NW Mexico.

Mercury and selenium concentrations and Se:Hg molar ratio in edible muscle and hepatopancreas of the crab Callinectes arcuatus from coastal lagoons of northwest Mexico were determined using atomic absorption spectrophotometry. The three coastal lagoons were Santa María La Reforma (SMLR), Urías (UR), and Huizache-Caimanero (HC); samplings were carried out from December 2016 to October 2017. The mercury ranges in the muscle of C. arcuatus in SMLR, UR, and HC lagoons were 0.31-0.52, 0.15-0.45, and 0.22-0.55 µg g-1, respectively. In hepatopancreas, the values ranged from 0.08 to 0.15, 0.06 to 0.15, and 0.05 to 0.12 µg g-1 in SMLR, UR, and HC lagoons, in that order. For selenium concentrations in C. arcuatus muscle, the ranges 11.64-20.14, 14.88-19.71, and 15.27-29.51 µg g-1 were determined in SMLR, UR, and HC lagoons, respectively. While for hepatopancreas, the ranges were 34.34-44.13, 27.77-40.45, and 15.16-49.80 µg g-1, in that order. No significant relationships (p > 0.05) between mercury and selenium concentrations (in white meat and hepatopancreas) were observed in C. arcuatus carapace width and length. Se:Hg molar ratio values were 98.1 ± 20.8, 171.4 ± 81.6, and 176.8 ± 51.2 for SMLR, UR, and HC lagoons, in that order. This high ratio (> 1) in C. arcuatus edible muscle indicated that selenium concentration was sufficient to neutralize possible mercury toxicity, so it does not represent danger to humans when it is consumed.