Native microbial communities (microbiomes) of the vertebrate gut exert vital effects on host ecology, physiology, and evolution. This project explores the potential that the gut microbiome of herbivorous fish plays a vital role in biochemically degrading algal toxins consumed by the host fish, and therefore structuring diet choice and ecology. The student will work jointly between the labs of Drs. Mark Hay and Frank Stewart to test this broad hypothesis, likely focusing on the microbiomes of specific coral reef herbivores.
The characterization of sediment biogeochemistry at high spatial and temporal resolution is a necessary step in predicting the overall pathways and extent of hydrocarbon degradation in areas affected during and after an oil spill. However, geochemical data for sediments from deeper environments are scarce, and most studies do not measure the full suite of terminal electron acceptors involved in sediment diagenesis.
Plastic marine debris or the plastisphere impacts marine organisms through ingestion, entanglement, and as a source of toxic chemicals. The plastisphere could also have a major impact on biogeochemical cycles in the oceans. Plastics are transported via major ocean currents to central gyres, where they reside for decadal time scales. The amount of plastic waste is large, exceeding 2 kg/ km2 in central gyres. Even the most recent ocean surveys cannot account for the amount of debris estimated to enter the ocean, with inputs and outputs differing by orders of magnitude.
The sustainability of human civilization and its evolving lifestyle depends fundamentally on a sustainable food and energy supply. This can largely be linked to the availability of reactive nitrogen (Nr), phosphorus (P) and trace-element nutrient availability for natural and managed ecosystems. Nr, P and Fe are known to stimulate productivity while other elements, like Cu and Mn, can be toxic for ecosystems. Nr is also a critical link for the carbon cycle, and directly/indirectly impacts climate and human/ecosystem health.
Ocean dynamics constantly generates seismic and acoustic noise (e.g. vie wave-seafloor interaction, surface wave activities, ice-noise and anthropogenic sources). This ubiquitous ambient noise waves, which can be measured continuously with hydrophones and seismic stations, travel around the earth and can be used to monitor their generating sources and image the propagating medium. This project will characterize the spatial and temporal generation mechanism of seismic and acoustic ocean noise sources which can be used for passive remote sensing and monitoring purposes.
Advection and biological consumption are both important sinks for oil and gas released from natural seeps in the Gulf of Mexico. We will use a combination of stable isotope measurements and high resolution modeling with both passive and positively buoyant tracers to study the interaction between physical and biological processes in distributing and transporting the carbon released from natural seeps. We will focus on three major seep fields in the Northern Gulf with different water depths –GC185 (ca. 400 m), GC600 (ca. 1200 m), and GC767 (ca.
Many densely populated coastal areas around the world are low lying and susceptible to relative sea level rise (SLR) associated with climate change, land level subsidence or tectonic subsidence. Coastal defense structures have been constructed as barriers to certain design storm surge, storm wave or tsunami heights. Typically even without SLR the design criteria change over time as hazards get reanalyzed or remodeled. The decrease in risk reduction due to relative SLR and the performance of existing defense barriers under loading conditions beyond the design need to be determined.
Deep subsurface methane hydrate-bearing sediments contain microbial communities that are distinct from shallow marine sediments and hydrate-free environments. DNA evidence suggests that novel bacterial phyla (e.g. Atribacteria) are highly enriched in methane hydrate-bearing sediments. Recent genome assemblies by the Glass group at Georgia Tech are providing insights into the metabolic potential of samples drilled from gas hydrate stability zone 70 mbsf below Hydrate Ridge (IODP Leg 204).
The recently completed resource assessment for ocean current energy (Haas et al. 2013) utilized fairly simplistic analytical methods to estimate the extractable energy from the Gulf Stream System as well as to analyze the relative impacts of large scale energy extraction. This level of analysis can be considered to be accurate to an order of magnitude and only provides an idea on the overall trends of the impacts of extraction. Much higher resolution modeling is required to accurately determine the overall impacts of extraction for both localized and far field effects.
Single-celled marine algae are especially chemically rich, producing toxins that kill fish, marine mammals, and seabirds, contaminate shellfish, and threaten human health. Many predators of these algae – copepods – selectively consume less toxic algae, which in turn sense copepods via an excreted blend of copepod-specific molecules. These algae then become up to 20X more toxic when they sense copepod cues in the open ocean.