Nitrogen metabolic potential in marine shallow hydrothermal vents in Bahia Concepcion, Mexico

Chawalit "Net" Charoenpong, Marine Chemistry & Geochemistry
Advisor: Scott D. Wankel, Marine Chemistry & Geochemistry

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Nitrogen metabolic potential in marine shallow hydrothermal vents in Bahia Concepcion, Mexico

Submarine hydrothermal systems in shallow areas can be important sources of trace elements to surrounding marine ecosystems (Chester, 2003; Tarasov et al., 2005). For some elements, hydrothermal fluxes from these systems might be equal or greater than riverine fluxes to the coastal sea (Edmond et al., 1979). Moreover, biogenic elements (N, P and Si) in shallow-water vents are often enriched compared to the coastal water (Tarasov et al., 2005). Consequently, hydrothermal discharge can play a significant control on the local primary production notably in semi-enclosed bodies of water. 
 
Bahía Concepción is a 23-km-long bay with the north opening to the Gulf of California. The shallow hydrothermal system found within Bahía Concepción is one of several western Mexico coastal vent fields, which are part of tectonic activity of the East Pacific Rise. Both diffuse (more prevalent) and focused venting has been reported from the intertidal zones down to shallow depths of approximately 15 meters (Prol-Ledesma et al., 2004). Elevated abundances of Nostoc pruniforme and Trichodesmium erythraum around the area (Estrada-Romero et al., 2009) demonstrate the effect of shallow hydrothermal activity on the biological community. Notably in the case of the latter, Trichodesmium is a nitrogen-fixer and is capable of producing bioavailable nitrogen compounds supporting the autotrophic growth. 
 
As one of the chapters in my thesis, I will explore the nitrogen transformations from this site both through the use of stable isotope geochemistry and molecular biology (“-omics”) approaches. Despite a few published works on the geochemistry of the vent fluid from this locale (Prol-Ledesma et al., 2004; Acosta et al., 2013), none has described concentrations and isotopic compositions of different biogenic species (especially N and P), which might play a pivotal control on the primary productivity in the area. In addition, work on the microbial community composition is still lacking. In order to effectively plan the sampling and experiments to be conducted, some preliminary data are necessary and this is the basis of this proposal.
 
With the support from this grant, I will be collecting seawater samples both from vent fluids and
surrounding seawater to analyzed for various nitrogen compounds (including NO3 -, NO2-, NH4+, DON, and N2) and their isotopes (δ15N and δ18O), and also PO43- concentration. The concentrations and isotopic compositions of these compounds should allow me to get a broad picture of dominant processes that control the distribution of nitrogenous species and allow me to further plan appropriate sets of experiments and incubations required to establish the rates of different N metabolisms. Moreover, genomic work will provide the window into the composition of microbial diversity in the area and their genetic potential for different metabolic pathways. This will be fundamental for the -omic works (i.e., transcriptomics and proteomics) that I intend to carry out during the actual sampling campaign.
 

Reference:
• Acosta, M. L. L., Shumilin, E., & Mirlean, N. (2013). Sediment geochemistry of marine shallow-water hydrothermal vents in Mapachitos, bahía Concepción, Baja California peninsula, Mexico. Revista Mexicana de Ciencias Geológicas,30(1), 233-245.
• Chester, R., 2003, Marine Geochemistry: London, Unwin Hyman, 506 pp.
• Edmond, J. M., Measures, C., McDuff, R. E., Chan, L. H., Collier, R., Grant, B., ... & Corliss, J. B.
(1979). Ridge crest hydrothermal activity and the balances of the major and minor elements in the ocean: the Galapagos data. Earth and Planetary Science Letters, 46(1), 1-18.
• Estradas-Romero, A., Prol-Ledesma, R.M., Zamudio-Reséndiz, M.E., 2009, Relación de las
características geoquímicas de fluidos hidrotermales con la abundancia y riqueza de especies del fitoplancton de Bahía Concepción, Baja California Sur, México: Boletín de la Sociedad Geológica Mexicana, 61(1), 87-96.
• Prol-Ledesma, R. M., Canet, C., Torres-Vera, M. A., Forrest, M. J., & Armienta, M. A. (2004). Vent fluid chemistry in Bahía Concepción coastal submarine hydrothermal system, Baja California Sur, Mexico. Journal of Volcanology and Geothermal Research, 137(4), 311-328.
• Tarasov, V. G., Gebruk, A. V., Mironov, A. N., & Moskalev, L. I. (2005). Deep-sea and shallow-water hydrothermal vent communities: two different phenomena? Chemical Geology, 224(1), 5-39.