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We determined the levels of Cd and Pb in liver and muscle of demersal fish from three lagoon systems (Urías, Huizache, and Teacapán) in the SE Gulf of California with the purpose of comparing the studied metals in fish from the three ecosystems and to assess the potential human health risk. Considering the number of individuals, the sequence of fish abundance was Teacapán > Huizache > Urías. Length and size at maturity of collected species showed that 76.5% of the individuals were juveniles. Overall, Cd and Pb were more accumulated in liver than in muscle. After multivariate analyses, considering fish tissue and locality, Cd and Pb levels were different (p < 0.05) between fish from Teacapán and Huizache. In general, the hazard quotients (HQs) of Pb were higher than the corresponding values of Cd; the highest HQ for Cd (0.0051) corresponded to Mugil curema, and the highest HQ for Pb (0.0099) was estimated in Diapterus peruvianus. With respect to the hazard index (accumulative risk from Cd and Pb), the most elevated value (HI = 0.0124) was estimated for Pomadasys macracanthus. Estimated HI does not represent a health risk at the consumption rates of the Mexican population.

Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed‐batch glass tubular reactor (7 L) at 200 μmol E m−2 s−1, yielding 3.5 × 108 cells ml−1, followed by fed‐batch Erlenmeyer flask (1 L) at 650 μmol E m−2 s−1 with 1.7 × 108 cells ml−1. The highest total lipid contents (% g lipid × g dry biomass−1) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m−2 s−1 and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m−2 s−1, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m−2 s−1) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m−2 s−1, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n‐3) and (20:4n‐3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed‐batch tubular reactor (7 L) at 200 μmol E m−2 s−1 contains major FAs (16:0; 38.06 ± 0.16%), (16:1n‐7; 30.74 ± 0.58%), and (18:1n‐9; 17.15 ± 0.91%).

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We assessed human health risk due to mercury (Hg) concentrations in fish from three coastal lagoons (Urías, Huizache, and Teacapán) in the SE Gulf of California. We also determined Hg distribution in muscle and liver of analyzed ichthyofauna and compared the results among studied areas according to tissue, season, and lagoon system by using multivariate analyses. Levels of Hg in most of the analyzed fish followed the sequence liver > muscle. The highest Hg levels in muscle (2.80 µg g dw) and liver (9.51 µg g dw) were measured in Cynoscion reticulatus and Pomadasys macracanthus, respectively, although according to the multivariate analyses, statistical differences of Hg concentrations were not found according to the season and the tissue but were found according to the system. It seems that the higher concentrations were associated with areas where the hydrological regime is lower. With respect to health risk assessment, the highest hazard quotients were estimated for Cynoscion reticulatus (0.45) and Stellifer furthii (0.29) from Urías and Pomadasys macracanthus (0.35) from Huizache. None of the studied fish represent a risk for consumers in terms of Hg levels in the edible portion.