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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 Maria La Reforma (SMLR), Urias (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.

The present study shows the human health risk of Cd, Cu, Hg and Zn by consumption of clams Megapitaria squalida from Northwest Mexico, collected in 2013. The mean concentration for each metal in the soft tissue was: Zn > Cu > Cd > Hg; and mean values of 68.89 ± 37.59—30.36 ± 27.19, 8.77 ± 1.35—6.80 ± 0.36, 4.47 ± 0.21—3.18 ± 0.63 and 0.99 ± 0.81—0.52 ± 0.16 µg/g, respectively. Clam age was significantly negatively correlated (p

Adult sharpnose sharks (Rhizoprionodon longurio) with a mean total length of 110.93 ± 5.30 cm were obtained from a local fishery in Mazatlan (Southeast Gulf of California, Mexico). The total mercury content in muscle was analyzed by cold vapor atomic absorption spectrophotometry. The minimum and maximum total mercury content were 0.77 ± 0.23 and 2.33 ± 0.57 µg/g (dry weight), respectively. Only 6.6 % of the organisms did show mercury content higher than the permissible limit. No significant relationship was observed between weight and total mercury content in edible muscle of the sharks (r = 0.364, p > 0.05). The Hazard Quotient values for total mercury (0.005–0.015) and methyl mercury (0.022–0.065) indicated no risk by edible muscle consumption of the shark Rhizoprionodon longurio.

The objective of this review is to synthetize knowledge of the relationship between metals and oxidative stress in aquatic crustaceans (mainly shrimp and crabs) to analyze antioxidant responses when organisms are exposed to metals because the direct metal binding to the active site of enzymes inactivates most of the antioxidant systems. This study reviewed over 150 works, which evidenced that: (i) antioxidant defense strategies used by aquatic decapod crustaceans vary among species; (ii) antioxidant enzymes could be induced or inhibited by metals depending on species, concentration, and exposure time; and (iii) some antioxidant enzymes, as superoxide dismutase increase their activity in low metal levels and time exposures, but their activities are inhibited with higher metal concentrations and exposure time.

Mercury and selenium were assessed in Mustelus henlei, which is a carnivorous predatory shark that is important for the coastal communities of the northern Mexican Pacific (NMP). Sixty-two individuals were sampled; muscle and liver were isolated and analyzed by atomic absorption spectrophotometry. The mean Hg concentrations (wet weight) obtained for muscle (0.08 ± 0.10 μg g−1) and liver (0.09 ± 0.26 μg g−1) were below the allowed limits (

The White and Striped mullets (Mugil curema and M. cephalus) are highly abundant and commercially important estuarine fish in northwest (NW) Mexico. Because of their feeding habits and habitat, they are likely to accumulate mercury (Hg) in their muscle and liver. The objectives of this study were to determine total Hg distribution in the tissues of interest, to correlate Hg levels between tissues and with length and weight of fish, to estimate the percentage weekly intake (PWI) of total Hg and methyl Hg (MeHg) through consumption of both mullet species, and to compare total Hg levels with mullets from other areas. The highest total Hg concentration (1.031 µg g−1 dry weight) was measured in liver of White mullet. In both species, the order of averaged Hg concentrations (M. curema liver 0.272, muscle 0.184; M. cephalus liver 0.211, muscle 0.129 µg g−1 dry weight) were liver>muscle. Correlations of Hg in muscle and liver with total weight of M. curema were significant. In M. cephalus, Hg levels in li...

Shrimp of Farfantepenaeus californiensis (78 groups) and Litopenaeus stylirostris (14 groups) were caught in the northwestern fishing zones in Mexico during the 2014–2015 fishing season (September–February); both shrimp species have high commercial value. Muscle, hepatopancreas and exoskeleton were analyzed to determine their metal contents. For F. californiensis, the highest Cd, Pb and Zn contents were determined in specimens caught off the State of Baja California Sur (BCS) with 22.4 ± 8.9 (hepatopancreas), 2.83 ± 4.63 (muscle), and 748.5 ± 1567 (muscle) µg/g, in the regions off Mulege, Los Cabos and Los Cabos, respectively. For L. stylirostris, the fishing zone of Comundu (BCS) showed higher Cd (12.3 ± 11.5 µg/g), Cu (569.1 ± 646.5 µg/g) and Zn (549.7 ± 400.7 µg/g) contents; all values were determined in the hepatopancreas. Regarding the hazard quotient and total hazard quotient calculated in this study, the consumption of marine shrimp caught off NW Mexico does not represent a risk to human health (both

The main objective of this study was to evaluate the total mercury content in hepatopancreas and edible muscle of the whiteleg shrimp Litopenaeus vannamei cultured along the NW coast of Mexico, and to evaluate the potential human health risk due to their consumption. Samples were obtained between May and June 2010 in 26 shrimp farms from the three most important shrimp-producing states of NW Mexico, and total Hg was analyzed after reduction with SnCl 2 in a mercury analyzer. The ranges of Hg concentrations of the hepatopancreas were 0.101 ± 0.03–0.184 ± 0.13 μg g −1 in Sonora, 0.077 ± 0.055–0.813 ± 0.363 μg g −1 in Sinaloa and 0.139 ± 0.037–0.791 ± 0.33 μg g −1 in Nayarit. In the muscle, values were from 0.078 ± 0.02 to 0.539 ± 0.09 μg g −1 in Sonora, 0.154 ± 0.03–0.861 ± 0.423 μg g −1 in Sinaloa and 0.121 ± 0.041–1.48 ± 0.44 μg g −1 in Nayarit. Considering the concentrations of Hg in the muscle and the national consumption rate, shrimp farmed in NW Mexico does not represent a risk for human health (HQ

Total mercury (Hg) concentrations were determined by atomic absorption spectrophotometry in muscles and liver of composite samples of Mugil cephalus and M. curema collected during November 2013 and in January, April, and July 2014 from the coastal lagoons Altata-Ensenada del Pabellón (AEP), Ceuta (CEU), and Teacapán-Agua Brava (TAG) of Sinaloa State. The mean Hg contents and information on local consumption were used to assess the possible risk caused by fish ingestion. Mean total mercury levels in the muscles ranged from 0.11 to 0.39 μg/g, while the range for liver was 0.12-3.91 μg/g. The mean Hg content of the liver was significantly (p 0.001) higher than that of the muscles only in samples collected from AEP. Although total Hg levels in the muscles were lower than the official permissible limit, the HQ values for methyl mercury calculated for the younger age classes of one fishing community were1, indicating a possible risk for some fishing communities of the Mexican Pacific coast.

This study shows the concentrations of Cd, Cu, Pb, and Zn in the muscle and hepatopancreas of Pacific white shrimps, Litopenaeus vannamei, cultured during 2010 in 26 commercial farms of the three main producer states of the Mexican NW, Sonora, Sinaloa, and Nayarit and compares the results to those obtained in 2000 using samples collected in16 farms of the same states. No significant changes were detected in Cd concentrations, but the 2010 Zn levels were significantly higher in all states in the hepatopancreas and in Sinaloa in the case of the muscle. Cu showed a tendency to higher hepatopancreas values in 2010, but differences were significant only in Sonora and for the global mean value. In contrast, Pb was one order of magnitude lower in both organs in 2010, possibly because of the almost 15 years since leaded gasoline was discontinued in Mexico.

The total mercury (Hg) content of the soft tissues of cultured oysters of the genus Crassostrea obtained during the dry and rainy seasons at sampling sites of NW Mexico with different degrees of urbanization, was determined by cold vapor atomic absorption spectrophotometry. Hg levels ranged from 0.05 to 0.37 µg/g (dry weight) and no significant differences (p > 0.05) related to season and sampling site were observed. The values did not exceed the limit of 1.0 µg/g (wet weight) established by Mexican legislation and by the Food and Drug Agency (FDA), and the hazard quotient was between 0.001 and 0.002. The estimated hazard quotient for MeHg ranged approximately from 0.002 to 0.01.

Though mercury (Hg) occurs naturally in the environment, anthropogenic activities have affected its global cycle in ways that mobilize increasing amounts of this metal; currently, such human-related activities mobilize more Hg than do natural processes (Fitzgerald and Lamborg 2005). It has been estimated that the quantity of Hg mobilized into the atmosphere has increased from two to five times (Nriagu and Pacyna 1988) since the beginning of the industrial age. The mercury cycle is complex and involves diverse environmental media that include air, land, and water. For any country that is not landlocked, the estuaries and coastal waters constitute an important link between the terrestrial environment and the open oceanic waters (Mason et al. 1994). However, research thus far performed on Hg as an environmental contaminant has been focused mainly on terrestrial ecosystems (Fitzgerald and Mason 1996). The focus on land contamination by Hg has occurred despite the prominent role played by Hg in the atmosphere (transported by wind and deposited under both dry and wet conditions) and in oceanic processes (horizontal and vertical transportation, accumulation in sediments, and bacterial transformations).