On August 25, Hurricane Harvey made landfall on San Jose Island, TX as a category 4 storm. During the subsequent five days, precipitation reached over 130 cm of rainfall in the Houston area, causing city-wide flooding. The floodwaters/runoff inundation introduced large amounts of terrestrial and freshwater microbes and anthropogenic pollutants into Galveston Bay and ultimately the Gulf of Mexico, causing disruptions to the resident communities. Microbes, composed of viruses, bacteria, and protists, are tightly inter-connected and are constantly adjusting to their environment to maintain a critical balance in global biogeochemical cycles. The main objective of this project is to characterize the effect of Hurricane Harvey on microbial communities in Galveston Bay, with a focus on determining the role of viruses in the ecosystem recovery.
The ocean covers 71% of the planet and deep-sea marine sediments harbor a remarkable microbial biomass. Yet the richness, ecosystem interactions, and functional diversity of subseafloor microbial communities remain poorly understood. This project aims to characterize the subseafloor microbial communities and virus-host interactions in well-dated sediment records spanning the last 3,000 years from an anoxic coastal sinkhole in the Bahamas as an analog for deep-sea anoxic basins. This project is in collaboration with Dr. Pete van Hengstum (Department of Marine Sciences, TAMUG) funded by the Center for Dark Energy and Biosphere Investigation (C-DEBI).
Nitrogen is an important controlling element for marine primary productivity. Until recently, nitrogen loss in the ocean was assumed to proceed only via denitrification or dissimilatory nitrate reduction. It is now known that anaerobic oxidation of ammonia (anammox) accounts for much of the loss of nitrogen from the ocean in water columns, and is likely important in sediments, too. Seasonal riverine discharge on the Louisiana/Texas (LATEX) shelf in the northern Gulf of Mexico by the Mississippi river results in variability in bottom water oxygen concentrations. This variability suggests that denitrification rates will vary seasonally as well, affecting anammox rates. This project will allow for improved modeling estimates of the nitrogen cycle and microbial community members responsible for anammox on the LATEX shelf. The project is a collaboration between Dr. Jason B. Sylvan, Dr. Piers Chapman, and Dr. Jessica Labonté and funded by the Texas A&M Triads for Transformation (T3). More information is available at http://t3.tamu.edu/fundedproject.
All living organisms require energy to synthesize the molecules needed for cell maintenance and growth. The energy needed comes from chemical reactions obtained by electron transfer. While oxygen is the favored electron donor microorganisms can use a wide range of electron donors and acceptors. In sediments, oxygen is quickly depleted, while other electron donors such as sulfate, nitrate, and ferric iron increase in concentration, resulting in a sequence of redox reactions (redox tower) that changes the pH, influences metal cation solubility, the valence ions, and the nature of the molecules dissolved in pore water solution. The gradients of the redox tower can vertically stratify the microbial communities and create interdependent layers of phototrophic, chemotrophic, and heterotrophic microorganisms. A combination of metagenomic sequencing and redox potential is vital to fully understand the ecosystem. The study aims to determine the redox tower to better understand the impact of electron donors and acceptors as well as characterize metabolic genes using metagenomics to understand the metabolic potential and putative roles of microbial communities and their dynamics.