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In this study, it was proposed to design, build, analyze and evaluate a stack of 9 Sediment Microbial Fuel Cells (SMFC) with a depth in the sediment of 10 cm and separation between anode and cathode of 100 cm, using floating cathodes aerated with saturated oxygen, sediments and seawater were collected from the Campeche bay (Mexico). Maximum power density and current density were 101.28 mW/m2 and 899.51 mA/m2 respectively, and organic matter removal was 9.25%, obtaining aromatic structures. Using a circuit storage energy from ultra-low power. Our findings revealed that the implementations of SMFC stack proposal could be a candidate for real scale.

The balance between synoptic and sea breeze atmospheric phenomena can profoundly influence atmospheric circulation in coastal regions. In this paper, a comprehensive study to understand the quasi-permanent patterns of such variability over the surface wind field of the Yucatan Peninsula is described. We performed a Complex Empirical Orthogonal Function (CEOF) analysis on 10 years (May 2007-May 2017) of modeled surface winds from the North American Mesoscale Forecast System (hereafter, NAM). High-pass/low-pass filtering was applied to the time series obtained from the CEOF analysis, to study the high and low-frequency temporal behavior that can be associated with the modes. Results show that for the period from October to March, cold fronts dominate in two different patterns (first two modes), which damp the local winds that show higher amplitude during the nighttime (land breezes) than during the daytime (sea breezes). By the end of this season, the influence of tropical systems, although smaller, is noticeable (third mode). From April to September the peninsula is dominated by sea breezes accentuated at the western shelf (first mode) while land breezes exhibit lesser dominance than sea breezes (third mode). In this period cold fronts and tropical systems (mode 2) exert milder influence over local winds. A distinctive phenomenon seen in the high frequencies of the second mode during this period is the occurrence of peninsula-wide sea breeze. The results of this work have important implications for atmospheric pollutant dispersion, wind wave generation and coastal erosion, among others.

Background Coastal ecosystems are prone to hydrocarbon pollution due to human activities, and this issue has a tremendous impact on the environment, socioeconomic consequences, and represents a hazard to humans. Bioremediation relies on the ability of bacteria to metabolize hydrocarbons with the aim of cleaning up polluted sites. Methods The potential of naturally occurring microbial communities as oil degraders was investigated in Sisal and Progreso, two port locations in the southeast Gulf of Mexico, both with a low level of hydrocarbon pollution. To do so, we determined the diversity and composition of bacterial communities in the marine sediment during the dry and rainy seasons using 16S rRNA sequencing. Functional profile analysis (PICRUTSt2) was used to predict metabolic functions associated with hydrocarbon degradation. Results We found a large bacterial taxonomic diversity, including some genera reported as hydrocarbon-degraders. Analyses of the alpha and beta diversity did not detect significant differences between sites or seasons, suggesting that location, season, and the contamination level detected here do not represent determining factors in the structure of the microbial communities. PICRUTSt2 predicted 10 metabolic functions associated with hydrocarbon degradation. Most bacterial genera with potential hydrocarbon bioremediation activity were generalists likely capable of degrading different hydrocarbon compounds. The bacterial composition and diversity reported here represent an initial attempt to characterize sites with low levels of contamination. This information is crucial for understanding the impact of eventual rises in hydrocarbon pollution.

Aquaponics is an integrated system in which the water containing fish waste is used as a nutrient source for plant production in a closed recirculation system. In this study, tilapia (Oreochromis niloticus) and pak choi (Brassica chinensis) culture was tested using two techniques: 1) Root floating (RAFT), and 2) Dynamic root floating (DRFT). Water quality parameters, total ammonia nitrogen, nitrate nitrogen, nitrite nitrogen and phosphate were measured. At the end of the experiment, fish and plants were weighed and the required electric power consumption was calculated. There was no significant difference observed between the effect of each treatment group on either tilapia or pak choi production. Tilapia productivity was 1.69 ± 0.22 kg/m3 and 1.71 ± 0.23 kg/m3 and pak choi yield was 7.43 ± 1.23kg/m2 and 7.32 ± 0.76 kg/m2 for the RAFT and DRFT, respectively. Water quality parameters were within the recommended range for the tilapia culture while pH and conductivity were out of range for the pak choi culture; nevertheless, plant production was good. Total ammonia nitrogen and nitrite nitrogen did not reach concentrations that could impede tilapia growth. The DRFT allows the elimination of active aeration in hydroponic systems for tilapia and pak choi production during most of the cycle, reducing the electric power consumption to 10.3% and electricity costs to 11.4% by using a nature-based solution.

The Southern Gulf of Mexico is an area highly impacted by crude oil extraction, refining activities and the presence of natural petroleum seepage. Oceanic currents in the Gulf of Mexico continually facilitate the transport of hydrocarbons to lagoons and rivers. This research evaluated hexadecane (HXD) degradation in marine sediment samples from lagoons and rivers that are fed by the Southern Gulf of Mexico, specifically six samples from rivers, three samples from lagoons, and one sample from a marine outfall. The highest rates of biodegradation were observed in sediments from the mouths of the Gonzalez River and the Champotón Lagoon. The lowest consumption rate was found in sediment from the mouth of the Coatzacoalcos River. With regards to the Ostión Lagoon and the Grijalva River, there was a low rate of consumption, but a high efficiency of degradation which took place at the end of the experiments. No correlation was found between the consumption rate and the environmental physicochemical parameters.

Benzo[α]pyrene (BaP), a lipophilic polycyclic aromatic hydrocarbon (PAH), is a contaminant widely distributed in aquatic systems. Its presence in freshwater organisms is of great concern; particularly in Nile tilapia (Oreochromis niloticus), due to its economic relevance. The aim of this study is to evaluate the effects of acute and sub-chronic BaP exposures on molecular growth/development responses, toxicity to DNA pathways and xenobiotic metabolism. Negative morphometric changes (the growth condition factor, hepatosomatic and gonadosomatic indices), the fluorescent aromatic compounds (FACs) in bile were also studied in order to understand the mechanisms of action of BaP. Genes involved in the growth hormone GH/insulin-like growth factor 1 (IGF-1) were measured, such as IGF1–2 with the growth hormone receptor gene expression GHR1–2, and the endocrine disruption biomarker vitellogenin (VTG). Acute exposure elicited changes in the GH/IGF axis, mainly in the GHR1 and in IGF1 mRNA levels without affecting the GHR2 expression. While sub-chronic exposure had less effect on both GHR and IGF genes. The most notable tissue-specific effects and morphometric endpoints were observed upon sub-chronic exposure, such as changes in key genes involved in detoxification, DNA damage, and altered reproductive morphological endpoints; showing that sub-chronic BaP doses have longer-lasting toxic effects. This study shows that sub-chronic BaP exposure may compromise the health of Nile tilapia and sheds light on the changes of the GH/IGF axis and the biotransformation of the xenobiotics due to the presence of this contaminant.

Since 2011, massive inflows of pelagic Sargassum have been recorded in the Caribbean region, which has affected coastal ecosystems, mainly water quality and the flora and fauna that inhabit these areas. The aim of this study is to evaluate the temporal dynamics of Sargassum arrival and its relationship on water quality in three sites of the Mexican Caribbean (Mahahual, Xahuayxol and Xcalak). We used remote sensing tools to estimate Sargassum coverage and turbidity to know if these parameters vary throughout the year and are related. We measured in situ water quality parameters to identify variations, depending on the Sargassum quantity and leachate concentration. Our results of 26 Landsat 8-OLI images show higher Sargassum coverage and turbidity during the winter months and a high relationship between Sargassum coverage and turbidity in areas near the coast. Additionally, turbidity calculated from multispectral bands complemented satellite detection of Sargassum, as high turbidity values were identified in near-shore areas where satellite images could not detect the alga. Finally, water quality parameters showed an increase in ammonium concentration and decreased pH and oxygen levels in the areas with higher Sargassum accumulation and leachate concentration. This study provides a better understanding about temporal dynamics of Sargassum influx in the southern Mexican Caribbean and its relationship with water turbidity in order to develop strategies, management plans and harvesting policies that could prevent huge masses of Sargassum reaching the coast.

Sediment microbial fuel cells (SMFCs) are devices that generate electrical energy through sediments rich in organic matter (OM). The present study assessed the potential of sediments collected at two sites in Yucatan, Mexico, (the swamp of Progreso port and Yucalpeten dock) to be used in these electrochemical devices. Sediments were collected during the rainy and winter seasons and were monitored in the SMFC for 120 days through electrochemical and physicochemical characterization. OM removal in the SMFC ranged from 8.1–18.01%, generating a maximum current density of 232.46 mA/cm2 and power density of 95.85 mW/cm2. SUVA analysis indicated that with a young soil, the ratio E4/E6 presented evidence directly related to the degradation of aromatic and aliphatic compound formation, implying humification and, therefore, sediment enrichment.

In the Yalahau coastal lagoon, Quintana Roo, we analyzed spatial (Outer, Sea-lagoon, South, and North zones) and temporal weather-season variations (rainy, nortes, and dry), in physicochemical characteristics of water and sediment. The salinity, soluble reactive silicate (SiRS), and sediment grain size were the variables with the highest spatial and temporal variability: (1) The Outer zone is characterized by marine salinity with little temporal variation, low concentrations of SiRS ( 10 ?M during the three seasons that increased up to six times in dry weather, when increased concentrations of ammonium and soluble reactive phosphorus were also observed, and predominantly fine sand. The relatively pristine condition of this protected area suggests that natural factors such as the presence of Thalassia testudinum meadows, the magnitude of freshwater inputs, the decomposition of organic matter, and the entry of exogenous nutrients (e.g., seabird droppings) have a great influence on the environmental heterogeneity of the Yalahau lagoon.

Several methods to quantify the complexity of a time series have been proposed in the literature, which can be classified into three categories: structure/self-affinity, attractor in the phase space, and randomness. In 2009, Lacasa et al. proposed a new method for characterizing a time series called the natural visibility algorithm, which maps the data into a network. To further investigate the capabilities of this technique, in this work, we analyzed the monthly ambient temperature of 4 cities located in different climatic zones on the Peninsula of Yucatan, Mexico, using detrended fluctuation analysis (structure complexity), approximate entropy (randomness complexity) and the network approach. It was found that by measuring the complexity of the dynamics by structure or randomness, the magnitude was very similar between the cities in different climatic zones; however, by analyzing topological indices such as Laplacian energy and Shannon entropy to characterize networks, we found differences between those cities. With these results, we show that analysis using networks has considerable potential as a fourth way to quantify complexity and that it may be applied to more subtle complex systems such as physiological signals and their high impact on early warnings.

Benthic microbial fuel cells (BMFC) are devices that remove organic matter (OM) and generate energy from sediments rich in organic nutrients. They are composed of electrodes with adequate different distances and floating air cathodes in an aqueous medium with saturated oxygen. In this study we proposed to design, build, analyze and evaluate a set of BMFCs with floating air cathodes to test the optimal distance between the electrodes, using sediment from the Bay of Campeche as a substrate. For the analysis of OM removal, COD tests, volatile solids (VS), E4/E6 study and FTIR analysis were performed. Power generation was evaluated through polarization curves, cyclic voltammetry and electrochemical impedance spectroscopy (EIS). We achieved a current density and power density at 10 cm depth of 929.7 &plusmn, 9.5 mA/m2 and 109.6 &plusmn, 7.5 mW/m2 respectively, with 54% removal of OM from the sediment, obtaining formation of aliphatic structures. BMFCs are proposed as adequate systems for bioremediation and power generation. The system at 10 cm depth and 100 cm distance between sediment and the floating air cathode had a good performance and therefore the potential for possible scaling.

Aquatic hypoxia is a seasonal condition in some coastal and continental wetlands where co-exposure with polycyclic aromatic hydrocarbons (PAHs) pollution may be detrimental to the biota. In the present study, adult tilapia, an euryoxic fish of high economic importance, were intraperitoneally injected with benzo[a]pyrene (BaP) (20 mg kg(-1)) and then exposed to graded hypoxia to assess combined effects on some detoxification and fitness parameters. Seventy-two hours after a stepped decrease in dissolved oxygen (

The discharge of nutrients, phytoplankton and pathogenic bacteria through ballast water may threaten the Cayo Arcas reef system. To assess this threat, the quality of ballast water and presence of coral reef pathogenic bacteria in 30 oil tankers loaded at the PEMEX Cayo Arcas crude oil terminal were determined. The water transported in the ships originated from coastal, oceanic or riverine regions. Statistical associations among quality parameters and bacteria were tested using redundancy analysis (RDA). In contrast with coastal or oceanic water, the riverine water had high concentrations of coliforms, including Vibrio cholerae 01 and, Serratia marcescens and Sphingomona spp., which are frequently associated with "white pox" and "white plague type II" coral diseases. There were also high nutrient concentrations and low water quality index values (WQI and TRIX). The presence of V. cholerae 01 highlights the need for testing ballast water coming from endemic regions into Mexican ports.

ZOOPLANKTON SAMPLING WAS CARRIED OUT IN THE NORTHERN COAST OF THE MEXICAN CARIBBEAN SEA, FROM PUERTO MORELOS TO CANCUN. CAPTURES WERE MADE WITH A CONIC NET 0.4M DIAMETER, 1.40M LENGTH AND 0.330 MM MESH FROM JANUARY TO DECEMBER 2004 AT TWELVE LOCATIONS. A TOTAL OF 41 ZOOPLANKTON GROUPS WERE IDENTIFIED. COPEPODS WERE THE MOST ABUNDANT TAXA MAKING UP 61%, FOLLOWED BY ECHINODERMS (17%) AND DECAPODS (5%). ACARTIA TONSA AT THE NICHUPTE LAGOON SYSTEM (SLN) OVER NUMBERED THE COPEPOD FAUNA AND OCCASIONALLY THE WHOLE ZOOPLANKTON POPULATION. ALONG THE COAST ACARTIA SPINATA, PSEUDOCALANUS SP, AND CALANOPIA AMERICANA WERE THE MOST IMPORTANT COPEPODS. ECHINODERMS LARVAE SUCH AS ECHINOPLUTEUS-OPHIOPLUTEUS WERE PRESENT AT ALL SAMPLED STATIONS BUT WERE MORE ABUNDANT AT THE NLS. FOR CHAETOGNATHS, FEROSAGITTA HISPIDA DOMINATED, THE SPECIES WAS THE MOST ABUNDANT AND IN FACT THE ONLY SPECIES FOUND WITHIN THE NLS. DECAPOD LARVAE WERE MAINLY REPRESENTED BY ZOEA LARVAE (BRACHIURA). FISH LARVAE WERE MADE UP BY 54 FAMILIES, FROM THOSE, GOBIDS OF THE GENERA CTENOGOBIUS SP., GOBIONELLUS SP. AND GOBIOSOMA SP. WERE THE MOST ABUNDANT, PARTICULARLY FOR SLN. BIOMASS WAS HIGHER AT STATIONS LOCATED WITHIN THE SLN.