G. Izaguirre-Fierro

Trace metal concentrations and their distribution in the lobster Panulirus inflatus (Bouvier, 1895) from the Mexican Pacific coast

The concentration and distribution of Fe, Mn, Ni, Cu, Co, Cd, Cr and Zn among the tissues of female and male lobster Panulirus inflatus from the Pacific coast of México were determined. Distinct inter-tissue and intersize differences in metal concentrations were observed. In general, highest Zn concentrations were found in viscera while highest Cu levels occurred in the gill and gonadal material. The highest Mn, Ni, Cr and Co concentrations were observed in exoskeleton and highest in eggs and gills. Cadmium was undetectable (<0.05 microg g(-1)) in most tissues, only muscle and viscera contained low but detectable amounts. A positive relationship between size and metal concentration was observed only for Zn contained in the muscle of females and males, for Zn contained in the gonad of females, for Mn contained in the gonad of males and for Cu associated with muscle of males. These results are discussed with regard to trace metal concentrations found in temperate and tropical regions.

Cadmium, Copper, Lead and Zinc Contents of the Mangrove Oyster, Crassostrea corteziensis, of Seven Coastal Lagoons of NW Mexico

The ranges of concentrations of Cd, Cu, Pb and Zn of the soft tissues of C. corteziensis collected in seven coastal lagoons of NW Mexico were 1.55–7.45, 17.50–166.36, 4.13–9.49 and 245.34–2,304.12xa0μg/g (dry weight), respectively. Their distributions were not consistent and there were no seasonal trends, indicating different point sources of the metals in each lagoon. The mean Cd and Pb concentrations were 5.34 and 6.30xa0μg/g (dry weight), which are higher than the values indicative of polluted areas. Our data indicate that only the levels of Cd are a possible health risk in six of these lagoons, and only in the case of regular local consumers. In one, Cu and Zn reach levels of concern.

Metal Contents of Four Commercial Fish Species of NW Mexico

The metal contents in tissues of fish species: M. cephalus, Diapterus sp., Scomberomorus sierra and Oreochromis aureus, were determined in order to evaluate if their consumption might become a health risk. The liver and gills of M. cephalus and Diapterus sp. had the highest values of Cu, Fe and Pb. In the muscle, there were no interspecific differences in the Cd, Cu and Pb contents (0.27–0.32, 0.96–1.30 and 2.12–2.80xa0μg/g dw, respectively). Cd and Pb may be of concern, since their mean contents in the edible muscle of the four species are higher than the limits of the European Community.

Toxicity of metal mixtures to the Pacific white shrimp Litopenaeus vannamei postlarvae

According to the literature, the safe level of a toxic substance for any given organism may be calculated from its median lethal concentration multiplied by a suitable application factor (AF: usually 0.1 and 0.01). The medial lethal concentrations for Litopenaeus vannamei postlarvae exposed to the mixtures in equitoxic proportions of Cd-Hg, Hg-Zn and Hg-Pb were close to one order of magnitude lower than the values calculated from individual toxicity tests, indicating a synergistic effect, while the mixture Cd-Zn showed an antagonistic effect. Exposure to the mixture of Cu, Fe, Mn, Zn, Cd, Hg and Pb caused 63.3% and 100% mortality after 21 and 13 days for 0.05 and 0.1 AF, showing that environmental safe concentrations of toxicants should not be calculated from individual toxicity tests.

Cadmium, copper, lead, and zinc in Mugil cephalus from seven coastal lagoons of NW Mexico

The increasing order of the mean concentrations of Cd, Cu, and Zn in the tissues of Mugil cephalus of seven coastal lagoons of Sinaloa State (NW Mexico) was liver > gills > muscle, while for Pb it was gills > muscle ≥ liver. There were no differences between the mean concentrations of Cd and Pb of the three tissues determined in the samples of the seven lagoons and, although there were some significant differences, there was no indication of a latitude-related trend in the distribution of Cu and Zn: the Cu content of the muscle tended to be higher in the northern than in the southern lagoons, although in the case of the gills the highest and lowest mean values indicated an opposite trend, with the highest and lowest values in one southern and one northern lagoon. In the case of the liver, there were no differences and no indication of a regional trend. There were no differences in the mean Zn contents of muscle and gills; in the case of the liver, one of the lagoons of the central part of the state had a significantly higher value than one of the southern lagoons and all the rest had similar values. In addition, there was no clear indication of season-related differences in any of the three tissues. According to our results, the metal contents of the muscle of this species are not of concern for human health, since the allowable ingestion would be in the order of 0.9xa0kg/day.

The Effect of Initial Cell and Nutrient Concentrations on the Growth and Biomass Production of Outdoor Cultures of Dunaliella sp.

The final concentrations of non-axenic outdoor mass cultures of Dunaliella sp. grown for two or three days in f/2 and 2f media were found to be dependent on the initial cell concentration, since the cultures started with 80 × 103 cells ml-1 gave better yields than those started with 40 × 103 cells ml-1. There was a correlation between nutrient availability and cell yields: the two and three days-old cultures started with 40 × 103 cells ml-1 and grown in medium f/2 had lower concentrations than those grown in 2f medium, whereas in cultures with 80 × 103 cells ml-1 inoculum the yield was significantly higher only after three days. The lowest dry biomass yields after two and three days were with the inoculum of 40 × 103 cells ml-1 and medium f/2.

The contents of Cd, Cu, Pb and Zn of the white shrimp Litopenaeus vannamei (Boone, 1931) of six coastal lagoons of Sinaloa, NW Mexico

Litopenaeus vannamei is the most importantnshrimp species in the traditional fishery of the coastal lagoonsnof the State of Sinaloa (NW Mexico), and most of the landingsnare consumed locally. Since these lagoons receive importantnvolumes of agricultural, industrial and urban effluents,nconsumption of this shrimp could pose risks to human health.nThe mean content of Cd, Cu, Pb and Zn determined in thenhepatopancreas of shrimp from commercial landings from sixnlagoons of Sinaloa were higher than those of the muscle. Therenwas a weak correlation between the Zn content of the two tissuesn(P.0.05) and the correlations were not significant for Cd, Cunand Pb (P>0.1). The concentrations found in the shrimp musclenwere comparable or lower than those determined in commercialnlandings of different crustaceans from other geographic areas.nAccording to our results the consumption of local shrimp posesnno risks to human health.

Changes in metal contents in shrimp cultured in NW Mexico (2000–2010)

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 15xa0years since leaded gasoline was discontinued in Mexico.

Mercury and selenium concentrations in marine shrimps of NW Mexico: health risk assessment

We determined total Hg and Se contents of hepatopancreas, exoskeleton, and muscle, and the Se:Hg molar ratios in the muscle of shrimps Farfantepenaeus californiensis and Litopenaeus stylirostris caught in NE Pacific Mexican waters. Total Hg mean values in muscle, hepatopancreas, and exoskeleton were 0.31xa0±xa00.26, 0.28xa0±xa00.29, and 0.24xa0±xa00.06xa0μgxa0g−1, and 0.46xa0±xa00.46, 0.41xa0±xa0.034, and 0.24xa0±xa00.06xa0μgxa0g−1 for F. californiensis and L. stylirostris, respectively. In all tissues, the mean concentrations of Se tended to be close to one order of magnitude higher than the respective Hg values. In F. californiensis, the hepatopancreas of the larger commercial size had significantly (pxa0<xa00.05) higher Hg content than smaller sizes, but correlations size-Hg concentration calculated for each tissue of either species were not significant. The Hg content of the muscle of all commercial sizes of both species was lower than the permissible limit and their Se:Hg ratios in all sizes were higher than 1, indicating low risk for human consumption.