Behzad Mortazavi

Mortazavi Photo Associate in Research

Biological Oceanography
Ph.D., Florida State University, 1998

My research interest over the last decade has been on the effect of water availability on ecosystem processes. I have investigated the impact of water stress in both marine and terrestrial ecosystems. I have examined the impact of hydrology and nutrient cycling and food web processes in Apalachicola Bay, a river-dominated estuary in Florida. I coupled the output from a three-dimensional hydrodynamic circulation model of the estuary with water column variables and benthic flux measurements to construct a nitrogen and a phosphorus budget for the estuary. These budgets allowed me to highlight the impact of the proposed freshwater withdrawal on nutrient cycling and the productivity of the estuary.

I have used the stable isotopes of CO2 in terrestrial systems to investigate the effect of water stress on the 13C of ecosystem-respired CO2, a parameter used in global carbon budget for partitioning of the biospheric carbon sink into terrestrial and oceanic uptakes. Our investigations in the southeastern U.S. forests clearly demonstrate the dynamic nature of this parameter. The 13C of ecosystem respired CO2 is related to water availability, with more enriched values measured during periods of moisture deficit. In addition, a manipulative experiment with sapling of the dominant species in the southeast is underway to determine the turnover time of foliage carbon pools.