Assessing metal(loid)s concentrations and biomarkers in tilapia (Oreochromis niloticus) and largemouth bass (Micropterus salmoides) of three ecosystems of the Yaqui River Basin, Mexico.

Aquatic ecosystems have been suffering deleterious effects due to the development of different economic activities. Metal(loid)s are one of the most persistent chemicals in environmental reservoirs, and may produce adverse effects on different organisms. Since fishes have been largely used in studies of metal(loid)s exposure, tilapia and largemouth bass were collected in three ecosystems from the Yaqui River Basin to measure the concentrations of metal(loid)s (chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn) arsenic (As), mercury (Hg), and selenium (Se)) and some biomarkers (somatic indices, metallothionein expression and histopathological analysis) in tissues of both species. Metal(loid) concentrations varied seasonally among ecosystems in tissues of both species. The elements varied seasonally and spatially in tissues of both species, with a general distribution of liver > gills > gonads. Also, biomarkers showed variations indicative that the fish species were exposed to different environmental stressor conditions. The highest values of some biomarkers were in largemouth bass, possibly due to differences in their biological characteristics, mainly feeding habits. The multivariate analysis showed positive associations between metal(loid)s and biomarkers, which are usually associated to the use of these elements in metabolic and/or regulatory physiological processes. Both fish species presented histological damage at different levels, from SI types (changes that are reversible for organ structure) to SII types (changes that are more severe but may be repairable). Taken together, the results from this study suggest that the Yaqui River Basin is moderately impacted by metals and metalloids.

Risk and Benefit Analysis of Fish Consumption in NW Mexico: Mercury, Selenium, and Fatty Acids.

To balance the risks and benefits of fish consumption, selenium, fatty acids (DHA + EPA), and mercury in fishery products were determined. Analyzed products were canned tuna, frozen tuna (Thunnus albacares), smoked striped marlin (Tetrapturus audax), fresh Pacific sierra (Scomberomorus sierra), fresh dolphinfish (Coryphaena hippurus), fresh tilapia (Gerres cinereus), and fresh bullseye puffer (Sphoeroides annulatus). Mercury (µg g-1 wet weight) ranged from 0.01 (dolphinfish) to 0.23 (bullseye puffer); Se ranged from 0.12 to 0.25. EPA + DHA ranged from 1.16 to 10.72 mg g-1. Intake of EPA + DHA was comparable or above the recommended daily intake; Hg intake was below the reference dose but Se intake was below than recommended values for the different population groups. Considering the HBVSe, fishery products had positive values; i.e., they are healthy food items. According to the interaction of Hg and Se and the rate of fishery product consumption, the risk for consumers is below one percent.

Estimation of metal concentrations in marine biota and associated health risk assessment for inhabitants of a coastal region in Northwestern Mexico.

Marine ecosystems are subject to contamination by metals and metalloids and other elements and compounds that are emitted due to various human activities. These substances subsequently induce changes in marine biota after entering the marine environment. Marine organisms are frequently consumed worldwide because they constitute relatively cheap and accessible food items of high nutrient quality. The aim of this study was to estimate metal accumulation in frequently consumed marine species and to evaluate the associated health risks for particular population groups in a coastal region of northwestern Mexico. The marine species were consumed in different quantities between spring (from 0.29 kg year-1 for white clam, to 38.40 kg year-1 for blue crab) and autumn (from 0.34 kg year-1 for white clam, to 15.02 kg year-1 for leopard grouper). The general distribution of metal concentrations in the marine species (n = 13 in each season) evaluated in this study followed the trend of Fe > Zn > Cu > Mn > Cr with the highest metal concentrations detected during autumn. Although many metal concentrations were above the international standards of the Food and Agriculture Organization of the United Nations (FAO) and the World Health Organization (WHO), the hazard quotient (HQ) and hazard index (HI) values for the women in this study indicated that their health was not at risk due to the consumption of either fish or seafood. In contrast, the HQ and HI values determined for groups of men and children indicated that they are at risk due to the frequent consumption of most species evaluated in this study.

Mercury and selenium biomagnification in a coastal food web from the Gulf of California influenced by agriculture and shrimp aquaculture.

The biomagnification of Hg and Se was studied using nitrogen stable isotope analysis during four seasons in a coastal lagoon of the eastern central Gulf of California. This lagoon receives agricultural, municipal, and shrimp aquaculture effluents. The species were categorized into organism groups and presented a significant accumulation of Hg and Se with respect to the sources, while the concentration of both elements in sediment and suspended particulate matter (SPM) was low. Our data confirms the positive transfers (biomagnification factors >1) of Hg and Se in the entire studied food web, and it was structured in five trophic levels across all seasons. Additionally, there were no linear correlations between the molar Se:Hg ratios and the trophic levels of the organism groups. However, the Se:Hg ratios among organism groups were >1, which indicates that there is an excess of Se and that it is not a limiting factor for the detoxification of Hg.

Anthropogenic and climate induced trace element contamination in a water reservoir in northwestern Mexico.

Water reservoirs are essential for regional economic development, as populations depend on them for agriculture irrigation, flood control, hydroelectric power generation, water supply for human consumption, and subsistence fishing activities. However, the reservoir environmental quality can be disturbed by enhanced sediment input and trace metal contamination, affecting human health as a consequence of contaminated water and fish consumption. With the purpose to understand the trends and extent of sediment accumulation and trace element contamination in the Oviachic reservoir (OV, northwestern Mexico) since its construction, the temporal variations of sediment accumulation, and As, Cr, Cu, Hg, Ni, Pb, and Zn concentrations, enrichment, and fluxes, were evaluated through the study of two 210Pb-dated sediment cores. We assumed that siltation and trace element contamination were driven by the development of anthropogenic activities in the region within the past ~ 70 years. Elemental concentrations accounted from null to minor enrichment for most elements, but moderate to significant enrichment by Hg. Mercury, As, and Cu fluxes have notably increased since the past decade, most likely because of a combination of anthropogenic and natural processes, including catchment erosion, artisanal gold mining, and recent drought conditions in the region. Arsenic and Hg concentrations may pose deleterious risks to biota in the reservoir, and consequently to humans through fish consumption, for which further biological and toxicological tests are advisable. This study highlights the importance of using sediment dating to assess historical trends of metal contamination and identify possible sources, to support decision-making in programs addressed to reduce environmental and health risks in aquatic ecosystems.

Comparative Assessment of Metal Bioaccumulation in Tilapia and Largemouth Bass from Three Dams of the Yaqui River.

In the present paper, we investigated the accumulation of six metals in tilapia (Oreochromis nilocticus) and largemouth bass (Micropterus salmoides) as indicators of the environmental pollution present at three constructed dams in the Yaqui River basin in Sonora, Mexico. The La Angostura (ANG), El Cajon de Onapa (ECO), and El Oviachic (OVI) dams are ecosystems under different degrees of anthropogenic stress. The collected fishes were dissected to obtain liver, gonad, stomach, gill, and muscle samples to determine the metal concentrations of Fe, Mn, Ni, Cu, Zn, and Cr. The results of a PERMANOVA showed that the concentrations of Fe, Cu, and Zn were significantly higher in tilapia liver, stomach, and gill tissues compared with those of the largemouth bass. Also, differences were detected between seasons, with the metal concentrations during the dry season being significantly higher than those of the rainy season (p < 0.001). The results of a principal component analysis showed an association between metals, tissues, and dams with significantly higher (p < 0.001) concentrations in tilapia from the ECO dam compared with those from the ANG and OVI dams. The general distribution of metals in the tissues was as follows: liver > stomach-gills > gonads > muscle. Variations in metal concentrations may be indicative of the different sources of anthropogenic stress in each ecosystem.

Mercury (Hg) and selenium (Se) content in the shark Mustelus henlei (Triakidae) in the northern Mexican Pacific.

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 (< 1.0 µg g-1 Hg). The average Se concentration was 0.03 ± 0.01 µg g-1 in muscle and 0.13 ± 0.05 µg g-1 in liver. The Se/Hg molar ratio of muscle was 1.83; however, the selenium health benefit value (HBVSe) was of 0.08. We calculated that an adult man (70 kg), an adult woman (60 kg), and a child (16 kg) could consume 1595, 838, and 223 g/week of M. henlei muscle, respectively, without risks to health. In conclusion, the concentrations and molar ratio of Hg and Se in M. henlei muscle mean that consumption of this shark's meat does not represent neither a benefit nor a public health risk.

Selenium and mercury in dolphinfish (Coryphaena hippurus) from the Gulf of California: inter-annual variations and selenium health benefit value.

With the aim of determining the benefit from consumption of dolphinfish Coryphaena hippurus from La Paz and Cabo San Lucas in the southern area of the Gulf of California, mercury (Hg) and selenium (Se) were measured in liver and muscle of specimens (n = 362) collected between 2006 and 2013. Mean levels of Hg in muscle (0.61 µg g-1) and liver (0.42 µg g-1) of all individuals from La Paz were significantly higher (p < 0.05) than in fish from Cabo San Lucas; in the case of Se, mean concentrations in liver (1.54 µg g-1) of all individuals from La Paz were significantly higher (p < 0.05) than in fish from Cabo San Lucas. Hg levels in muscle were positively and significantly (p < 0.05) correlated with fork length and weight of fish; in liver, Hg and Se were significantly (p < 0.05) correlated with fork length and weight of specimens. Levels of Hg and Se in muscle and liver among years varied significantly (p < 0.05); although there was not a defined pattern of temporal fluctuations for both elements, the lowest Hg levels occurred in 2009 when surface water temperatures were the highest for the sampled years. With respect to the Se health benefit value (HBVSe), results were positive and above the unit in all cases; it implies that consumption of dolphinfish in the southern Gulf of California is beneficial.

The influence of anthropogenic organic matter and nutrient inputs on the food web structure in a coastal lagoon receiving agriculture and shrimp farming effluents.

In this study, we elucidated the impacts of allochthonous organic matter (OM) and nutrients (N and P) inputs coming from agriculture and shrimp aquaculture activities on food web structure in a subtropical coastal lagoon located on the central-east of the Gulf of California. This coastal lagoon is highly influenced by OM and nutrients inputs by a large agriculture district and aquaculture development center in Mexico. We also selected a second coastal lagoon, without direct OM and nutrients inputs, considered as a 'pristine' ecosystem. We evaluated the quantity of OM, N and P in both ecosystems and reconstructed the food webs using isotopic tools of C and N from the base to top. We collected and analyzed autochthonous and allochthonous OM, and organisms including primary producers, and primary to tertiary consumers. Overall, specimens of the same species and/or functional groups showed higher δ15N values in the ecosystem receiving agriculture and shrimp aquaculture effluents than the pristine. Food webs were composed of four and five trophic levels, where fish and birds occupied the top-predator levels. Seasonal increases in OM and N and P quantities in lagoons affected by anthropogenic activities produced high δ15N values in primary producers and consumers.

Bioaccumulation of arsenic and selenium in bycatch fishes Diapterus peruvianus, Pseudupeneus grandisquamis, and Trachinotus kennedyi from shrimp trawling in the continental shelf of Guerrero, México.

With the aim of determining arsenic (As) and selenium (Se) concentrations in bycatch fishes from SW Mexico and comparing elemental concentrations with limits for human consumption set in the national and international legislation, three fish species (Diapterus peruvianus, Pseudupeneus grandisquamis, and Trachinotus kennedyi) were collected from Guerrero state during trawling operations. Additionally, As and Se levels in muscle tissue were compared with similar species from diverse areas. The order of As and Se concentrations was T. kennedyi>P. grandisquamis>D. peruvianus. In Mexico, there is no regulation of As and Se levels in fish. In comparison to the legal limit (0.1 µg g(-1) wet weight) set by legislation in Venezuela, As levels in the edible portion of T. kennedyi (0.632 µg g(-1) wet weight), P. grandisquamis (0.166 µg g(-1) wet weight), and D. peruvianus (0.157 µg g(-1) wet weight) were above this limit. In the case of Se, average concentrations in T. kennedyi (0.323 µg g(-1) wet weight) were above the maximum permissible limit (0.30 µg g(-1) wet weight) set in the Chilean legislation. Se concentrations in Carangoides bajad from Saudi Arabia were comparable to values in T. kennedyi (this study). In relation to As, concentrations varied in magnitude orders; the highest As concentration (range 10.35 to 23.71 µg g(-1) wet weight) corresponded to Mullus barbatus from the Iberian Mediterranean.

Fractionation and risk assessment of Fe and Mn in surface sediments from coastal sites of Sonora, Mexico (Gulf of California).

The aim of this study was to evaluate Fe and Mn distribution in geochemical fractions of the surface sediment of four oyster culture sites in the Sonora coast, Mexico. A selective fractionation scheme to obtain five fractions was adapted for the microwave system. Surface sediments were analyzed for carbonates, organic matter contents, and Fe and Mn in geochemical fractions. The bulk concentrations of Fe ranged from 10,506 to 21,918 mg/kg (dry weight, dry wt), and the bulk concentrations of Mn ranged from 185.1 to 315.9 mg/kg (dry wt) in sediments, which was low and considered as non-polluted in all of the sites. The fractionation study indicated that the major geochemical phases for the metals were the residual, as well as the Fe and Mn oxide fractions. The concentrations of metals in the geochemical fractions had the following order: residual >> Fe and Mn oxides > organic matter > carbonates > interchangeable. Most of the Fe and Mn were linked to the residual fraction. Among non-residual fractions, high percentages of Fe and Mn were linked to Fe and Mn oxides. The enrichment factors (EFs) for the two metals were similar in the four studied coasts, and the levels of Fe and Mn are interpreted as non-enrichment (EF < 1) because the metals concentrations were within the baseline concentrations. According to the environmental risk assessment codes, Fe and Mn posed no risk and low risk, respectively. Although the concentrations of Fe and Mn were linked to the residual fraction, the levels in non-residual fractions may significantly result in the transference of other metals, depending on several physico-chemical and biological factors.

Bulk and bioavailable heavy metals (Cd, Cu, Pb, and Zn) in surface sediments from Mazatlán Harbor (SE Gulf of California).

This work evaluates current metal concentrations (Cd, Cu, Pb and Zn) and the operational bio-available chemical extraction fraction in surface sediments in Mazatlán Harbor in Northwest México. Sediment samples were also analyzed for organic carbon, carbonates and particle size. Ranges of bulk metal were as follows: Cd from 3.1 to 3.3 microg/g, Cu from 31.9 to 44.9 microg/g, Pb from 49.6 to 54.0 microg/g, and Zn from 217.8 to 323.5 microg/g. In terms of biological effects, metals concentrations in the sediments lie between the low and median ranges of the mean quality guideline criteria. Comparatively, the metals concentrations increased from 1983 to 1994 and then for 2006, except Pb and Cd that decreased in the last period of time. The bio-available fraction of metals increased from 1983 to 1994, but only bio-available Cu increased from 1994 to 2006, due to mobilization of this metal from the organic matter-sulfide phase.

Content and daily intake of copper, zinc, lead, cadmium, and mercury from dietary supplements in Mexico.

This study investigates the presence of Cu, Zn, Cd, Pb, and Hg in 24 dietary supplements purchased in different health stores across the city of Hermosillo, located in the northwest of Mexico. Analysis of metals was done by microwave digestion and atomic absorption spectroscopy. The most abundant elements in dietary supplements were Cu (<0.19-137.85 microg/g) and Zn (<2.83-4785.71 microg/g), followed by Pb (<0.003-66.32 microg/g), Cd (<0.001-2.90 microg/g), and Hg (<0.24-0.85 microg/g). The estimated daily intakes of metals were below those recommended by WHO and the Institute of Medicine, showing that little risk from heavy metals is associated with the consumption of the dietary supplements analyzed. However, some products presented more than 10% of the tolerable daily intake of Pb, indicating that production processes should be improved.

Concentrations of heavy metals in sediment and organisms during a harmful algal bloom (HAB) at Kun Kaak Bay, Sonora, Mexico.

In early April 2003, fishermen from Kino Bay Sonora alerted us about a massive die-off of fish and mollusks occurring at Kun Kaak Bay. Phytoplankton samples taken on 17 May 2003 reported the presence of a harmful algal bloom composed of Chatonella marina, Chatonella cf. ovata, Gymnodinium catenatum and Gymnodinium sanguineum. On 22 of May, we collected samples of water, sediment and organisms at the affected area. Physicochemical parameters and nutrients were measured in water samples from different depths. Sediment and benthic organisms were analyzed for Cd, Cu, Zn, Pb and Hg. We found concentrations of heavy metals higher than background levels for this area. Cadmium and Lead concentrations in sediment from the HAB area were up to 6x greater than background levels and Cd in mollusks was 8x greater than regulations allow. A relationship between elevated Cd and Pb concentrations in sediment and the survival of toxic dinoflagellates is suspected.

Modificación enzimática de las propiedades funcionales, nutricias y sensoriales de la soya para alimentación especial / Enzimatic modification of the functional, nutritional and sensorial properties of soy protein for special nutrition

En la producción de fórmulas hipoalergénicas, bebidas fortificadas y nutracéuticos para alimentación especial, se requieren ingredientes ideales. En este estudio, se obtuvieron ingredientes proteicos por medio de hidrólisis y síntesis enzimática con metionina a la proteína de soya. La hidrólisis se realizó al 4 por ciento (p/v) con enzimas pancreáticas porcinas al 4 por ciento (p/p), 50ºC, 6h y pH 8. El hidrolizado seco se resuspendió al 20 por ciento (p/v) e incubó con 7,6 por ciento de metiléster de metionina (p/p), quimotripsina al 1 por ciento (p/p) y glicerol 3 M, 37ºC, 3 h y pH 7.0. Ates y después del enriquecimiento (E), el hidrolizado se fraccionó en 3 partes por ultrafiltración (UF): FI>10, 10>FII>3 y 3>FIII>1 kDa. A la proteína nativa y todas las fracciones se les evaluaron propiedades funcionales, aminoácidos, factores antifisiológicos y antigenicidad; así como la calidad proteica y características sensoriales a 2 de ellas. La hidrólisis y síntesis modificaron las propiedades proteicas y el enriquecimiento se dio en un mínimo de tiempo y metionina añadida. Después de la UF, las fracciones menores de 10 kDa presentaron solubilidad completa (pH 4 y 7), buena claridad y regular capacidad espumante. La FIII-E por su calidad nutricia, nulas antigenicidad y actividad antifisiológica, puede utilizarse en fórmulas infantiles hipoalergénicas. La FII-E por su composición de aminóacidos es adecuada para formúlas fortificadas solubles y como única proteína en nutracéuticos. La FI, semejante al aislado comercial, es utilizable amortizando costos. La FI-E por su contenido de metionina, la estabilidad de su espuma, su actividad emulsificante y buen sabor, puede utilizarse en papillas infantiles