SEMINAR: MGG Student Seminar - Tuesday, April 19 at 12 pm, CIMAS Conference Room

[Scott Baker <sbaker@rsmas.miami.edu>]

MGG Student Seminar

Tuesday, April 19

12:00 pm - 1:00 pm

CIMAS Conference Room, 3rd floor

See titles and abstracts below:

The coral-zooxanthellae symbiosis and the delicate balance of algal density: too much of a good thing?

Quinn B. Devlin           

Coral reefs are currently threatened by a combination of environmental stressors including increased sea surface temperatures, elevated pCO₂, nutrient inputs and several other anthropogenically induced conditions. Understanding the response of corals to an individual environmental condition may provide insight to the mechanism through which corals are degraded by a stressor independently; however, knowledge of the synergistic interactions of stressors is extremely important. Nutrients are most generally understood to lead to reef degradation through macroalgal overgrowth and dominance on a reef. This is certainly the case; however, nutrients appear to play an underlying role in decreasing coral growth. While coral bleaching involves reduced zooxanthellae populations and can be detrimental to zooxanthellate corals, elevated levels of inorganic nutrients can result in increased zooxanthellae populations. Preliminary data suggest that inputs of elevated levels of nitrate or ammonium result in increased zooxanthellae densities and a change in the recycling of nitrogen and carbon between the coral host and photosynthetic symbiotic zooxanthellae in the branching coral Pocillopora damicornis. This change in cycling is accompanied by decreased rates of coral extension. Several experiments will be further carried out to understand responses of corals to elevated nutrient levels in combination with increased temperature and increased pCO₂. This study will focus on understanding the mechanism underlying any measured decline in coral growth.  

Ambient Noise-a New Method for exploring interior of the Earth

Peng Li

To know the interior of the earth is important for us understanding the evolution of the earth. Seismic tomography is a powerful tool to investigate the structures of the earth. Traditional tomography methods use earthquake as signal sources which is not convenient for all the time and all the places (Earthquakes are not happen every time and every place). And sometimes the signals of earthquakes are not good enough to utilize. Ambient noise tomography method can use signals extracted from sources of the ocean wave, which avoid the disadvantage of the traditional methods. The basic steps of ambient noise tomography include: do cross-correlation of each pairs of 1 day length station records to extract surface wave signals from ambient noise; stacking 6 month-1 year cross-correlation results to improve signal-noise ratio; inversing group and phase velocities of surface wave.