Estimating diapycnal mixing in the ocean: How close are we?

Mixing by turbulent motions in the ocean is important for global ocean circulation, nutrient supply to surface waters, and the global ocean heat budget. Turbulent mixing takes the form of a diffusive process where the vertical flux is proportional to the concentration gradient with an eddy diffusivity coefficient, Kz, as a constant of proportionality. Osborn (1980) suggested that Kz is in turn related to the flux Richardson number (Rif) or mixing efficiency (G) that is commonly assumed to be a constant value of 0.2.

Compositional variations in dissolved organic matter and black carbon across hydrologic and aquatic gradients

Dissolved organic matter (DOM) is viewed as an information-rich set of molecular tracers which carry the chemical signature of its source and subsequent journey to its point of analysis. The overarching goal of my research is to read the molecular signatures of DOM using advanced analytical techniques to reveal its source, reactivity, and environmental fate. Upstream landscapes and rainfall-runoff processes have emerged as major controllers of the quantity and quality of terrestrial DOM exported through inland waters to coastal margins.

Nutrients influence the thermal ecophysiology of an intertidal macroalga: Multiple stressors or multiple drivers?

About Nick: "My graduate research training encompassed a combination of biophysical and physiological tools used to describe how organism responds to changes in environmental conditions. For my masters research, I focused on the effects of the light microenvironment influencing the photophysiology and growth of scleractinian coral. For my dissertation research, I explored the physiological responses of Fucus vesiculosus, a basal primary producer, to environmental drivers (i.e., temperature and nutrient enrichment) through the use of photosynthesis and growth measurements.

Secondary foundation species as drivers of coastal ecosystem structure, resilience and restoration success

Facilitation cascades arise where primary foundation species facilitate secondary (dependent) foundation species and collectively, they increase habitat complexity and quality to enhance species richness and abundance. In this seminar, I will present results from field experiments, lab experiments, correlational studies and models that indicate facilitation cascades created by spatial overlap of cordgrass and ribbed mussel foundation species are powerful drivers of biodiversity and ecosystem resilience to climate change in southeastern US salt marshes.

Numerical modeling of multiphase plumes and their applications: 1) Lagrangian integral near field plumes and 2) Lagrangian far field plumes

Dr. Dissanayake is a postdoctoral researcher working on modeling aggregation and export of marine particle and oil in the water column in Dr. Burd’s lab at UGA. She was previously a postdoctoral researcher working with Dr. Scott Socolofsky at Texas A&M University.

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