Alejandro Estradas-Romero

Marine pigments are more commonly used in food, pharmaceuticals, aquaculture and cosmetics industries. Marine pigments have a significant economic importance, constituting a multimillion-dollar industry that is still growing. Considering this, we decided to conduct a descriptive study of the photosynthetic pigments in surface sediments from the continental shelf and slope of 14 sites located in the northwestern Gulf of Mexico, obtained during October-November 2012. These pigments were analyzed using high-performance liquid chromatography. At least one pigment was detected in 10 of the samples examined, and a total of six pigments were identified, including three photosynthetic pigments and three chlorophyll-a degradation products: pheophorbide-a, pyrophaeophytin-a and phaeophytin-a. The pigments with the highest concentration were β-carotene and pheophorbide-a. Significant pigment concentrations were observed in inshore areas exposed to the influence of river discharge (Bravo and Soto La Marina) and Laguna Madre. The pigment composition and concentration were influenced by depth, temperature, salinity, and nickel concentration. Finally, a correlation between Ni, an indirect hydrocarbon contaminant marker, and pigment concentrations was observed. A deeper understanding of marine pigments certainly will fuel advances in biotechnology and bioengineering. We find it crucial to recognize the interactions between marine pigments and other ecosystem components. Despite pigment diversity, exploration in this field is still in its first stages, with many marine compounds awaiting further exploration.

Meiofauna are an excellent assemblage for studying how environmental changes affect numerous invertebrates. Meiofaunal distribution can be influenced by several key environmental factors which may differ among habitats and could be too numerous to evaluate. The Wagner and Consag shallow basins are located at the northern end of the Gulf of California. These basins are a young rift system where intense gas discharge has been reported and correlated to anomalously high heat flow (105 W/m²) and temperature (50.2°C in this study). The aim of this study is to evaluate the effects of environmental conditions on the abundance and biomass distribution of the meiofauna in these two shallow and geologically anomalous basins and to determine which of the measured variables are key factors. Sediment samples were collected during the “Sísmica 2015” expedition aboard R/V “Alpha Helix” during September 2015, within a depth range of 39–237 m. A total of 609 organisms were separated and six taxonomic groups were identified: Gastropoda, Polychaeta, Nematoda, Kinorhyncha, Ostracoda, and Harpacticoida. Meiofauna abundance ranged from 0 to 114.11 ind/10 cm² and biomass ranged from 0 to 300.02 μg Corg/10 cm². Though abundance and biomass were found to be correlated to sediment temperature, the main factor associated with the observed meiofaunal distribution was grain size temperature, however, was confirmed as the most important environmental factor as it was responsible for the greatest spatial variation in meiofaunal composition throughout the Wagner and Consag basins, where high temperature stations showed lower abundances. There is still very little known about meiofauna from extreme environments and their clear responses to these extreme conditions is lacking in the published literature. There is an urgent need to understand the biology and ecology of the meiofauna taxa that thrive in these natural environments. The findings in this study may provide some insights into these ecological processes, but more importantly they may be of use in assessing the vulnerability of benthic communities to future anthropogenic disturbances.

Indigenous bacterial populations play an important role in the restoration of crude oil-polluted marine environments. The identification and characterization of these bacteria are key in defining bioremediation strategies for the mitigation of possible future oil spills. In this work, we characterized Pseudomonas aeruginosa strain GOM1, which was isolated from the water column in the southwestern Gulf of Mexico. Phylogenetic analysis revealed that GOM1 strain was most closely related to P. aeruginosa WC55, a strain isolated from the northern Gulf of Mexico after the Deepwater Horizon oil spill. The hydrocarbon-degrading capacity of P. aeruginosa GOM1 was investigated using various approaches. This strain degraded 96% of the aliphatic fraction (C12-C38) of crude oil during a 30-day incubation period, exhibiting a high activity on long-chain alkanes, and expressing alkane hydroxylases AlkB1, AlkB2 and AlmA. Addition of nitrogen and phosphate to seawater culture medium enhanced hexadecane degradation by GOM1. Additionally, the strain exhibited high surfactant/rhamnolipid production and emulsifying activity when grown in a complex medium in the presence of hexadecane. Comparisons of growth kinetics, hydrocarbon degradation and gene expression between GOM1 and the closely related P. aeruginosa laboratory strain PAO1 revealed that the marine isolate is better adapted to degrade alkanes. Taken together, our results place P. aeruginosa GOM1 as a potentially effective candidate to be included in a consortium for use in the bioremediation of oil-polluted sites.

In the exploration of the hydrothermal system of the Guaymas Basin (GB) between 27° 00′ 35′′ and 27° 00′ 50′′ N and 111° 24′ 15′′ and 111° 24′ 40′′ W in the Gulf of California, carried out on the R/V Atlantis and of the DSRV/Alvin in October 2008, four cores of surface sediments were obtained to analyse photosynthetic pigments at two locations with contrasting extreme conditions: Oil Town and Great Pagoda. We identified nine pigments: Chlorophyll-a, Phaeophytin-a, Phaeophorbide-a, Pyropheophytin-a (degradation Chlorophyll-a products), β-Carotene, Alloxanthin, Zeaxanthin, Diadinoxanthin, and Prasinoxanthin (carotenoids). The maximum pigment concentration was registered in the Great Pagoda (10,309 ng/g) and the minimum in Oil Town (918 ng/g). It is demonstrated that photosynthetic pigment profiles in surface sediments depend on the heterogeneity of the extreme conditions of each site caused mainly by temperature and bacterial substrates. Therefore, there were significant differences (p 0.05) in the concentration of pigments have been detected. We conclude that the photosynthetic pigments contained in the surface sediments of the hydrothermal vents in the Guaymas Basin are primarily of chemoautotrophic bacterial origin.

Ecological services provided by the Gulf of Mexico constitute vital assets for the socioeconomic development of the USA, Mexico, and Cuba. This ecosystem houses vast biodiversity and significant fossil fuel reserves. However, its ecological stability and resilience have been jeopardized by anthropogenic disturbances. Massive oil spills (Ixtoc-I, 1979; Deepwater Horizon, 2010) caused severe environmental injuries and unveiled the vulnerability of coastal and deep-sea habitats. Baseline and monitoring studies are actions implemented by the Gulf stakeholders to cope with such disturbances. The 3-year monitoring program implemented by Mexico in 2010 to assess the environmental damage caused by the Deepwater Horizon (DWH) event confirmed the void of knowledge on the complexity of physical and biological processes susceptible of being altered by oil spills. Between the pelagic and benthic compartments, the latter proved to be a better option in establishing the baseline concentration and trends of oil compounds. Surficial sediments exhibited an increasing concentration trend of PAH, AH, and trace metals throughout the 3-year monitoring. The macroinfauna and selected biomarkers experienced interannual variability attributed to critical hydrocarbon and trace metal thresholds. Sediment toxicity bioassays added support to the distribution and potential sources of oil contaminants dispersed from the northern gulf toward Mexican waters.

A single specimen of the anemone Paraphelliactis pabista was recovered from the Southern Trough of Guaymas Basin during the deep-sea expedition Extreme 2008 conducted onboard the R/V Atlantis/DSRV-2 ALVIN. We studied the bioaccumulation capacity of heavy metals in various tissues of the anemone (oral disk–columella–pedal disk), and retention or adhesion of mineral particles in the epidermis, mesoglea, and gastrodermis. The digested tissues were analyzed for As, Ba, Co, Cu, Cr, Fe, Mn, Ni, Pb, Se, Sb, Sr, Ti, V, and Zn by inductively coupled plasma mass spectrometry. This analysis revealed the capacity of P. pabista for accumulating heavy metals. The predominant mineral particles identified in tissue samples was barite followed by Fe, aluminum-silicates, Sr, and with less presence Cr, Ti, and pyrite. Of the three body compartments analyzed of this anemone, the oral and pedal disks show a greater capacity of bioaccumulation of heavy metals than the columella.

Thermophilic and metal-oxidizing bacteria were identified in shallow hydrothermal vents on the western Mexican coast. The role of these bacteria in biomineralization processes observed in the vents is explained, and the effect of the vents on biodiversity of prokaryotes is discussed. Research was done at two shallow hydrothermal vent sites: Bahía Concepción (BC) in the Baja California Peninsula and Punta Mita (PM), on the central Pacific coast. Temperature at the sediments proximal to the vents was similar, but the redox potentials (0.5 V in BC and −0.3 V in PM) and pH (6.2 in BC and as low as 4.5 in PM) differed. The composition of the discharged water ranged from nearly seawater to lower-salinity fluids, and the gas phase was mainly CO₂ at BC and N₂ and CH₄ at PM. The study focuses on the biogeochemical processes related to the different species of bacteria present in the studied sites, which are involved in the anaerobic oxidation of methane (AOM), seawater sulfate reduction, and metal oxidation. The detected bacterial lineages represented typical deep vent species, which disproves a previous hypothesis that proposed that different consortia were populating deep and shallow hydrothermal vents. The results obtained here show that the main parameter affecting the bacterial groups present in shallow vents was the redox potential: gamma-, delta-, and epsilon proteobacteria as well as Bacteriodetes are present under the oxidizing conditions of BC, and Thermotogae, Aquificae, and Planctomycetes are present in PM. Sunlight abundance favored the prevalence of halophilic and Chlorofleaxae bacteria in both areas.