Wayne Gardner
Job Title
Research Interests

Nitrogen cycling is important in coastal and estuarine ecosystems because nitrogen is transformed to a variety of forms, by autotrophic and heterotrophic processes in the water and sediments, and is a nutrient that often limits the growth of phytoplankton and other plants in these relatively shallow systems. Internal regeneration is a dominant process providing nitrogen to plants whereas denitrification causes available nitrogen to be lost from estuarine and coastal ecosystems. Major goals are to understand and quantify the biotic mechanisms and rates of nitrogen remineralization and the fate of the remineralized products in the water and at the sediment-water interface. This information is needed to understand nitrogen biogeochemistry and to quantify the relative importance of internal nitrogen regeneration processes compared to inputs from other sources in these highly productive ecosystems. Nitrogen regeneration and transformation rates in the water and at the sediment-water interface are measured with 15-N as a tracer. Ammonium concentrations and isotope ratios are measured by high performance liquid chromatography. Denitrification rates will be determined using a Membrane Inlet Mass Spectrometer. Nitrogen cycling studies will be conducted in Laguna Madre and/or other coastal ecosystems.

Affiliated Departments