A number of trace metals in seawater are essential micronutrients for phytoplankton
and heterotrophic bacteria (e.g., Fe, Zn, Co, Cu, Cd, Mn). If the availability of one or
more of these metals is too high they exert toxic effects while too little can limit
productivity. Because phytoplankton species differ in their metal requirements and
tolerances, changes in metal concentration or chemical speciation should have a strong
influence on the composition of plankton assemblages as well as the net carbon transport
from surface to deep waters. My research group studies the chemistry of bioactive metals
in seawater and lake waters, their effects on phytoplankton and bacteria and, in turn,
how these factors may alter ocean optics and the remote sensing of phytoplankton
distributions by satellites. 



Denitrification in the Hypolimnion of Permanently Ice-Covered Lake Bonney, Antarctica (with B. B. Ward, J. Granger, M. T. Maldonado, K. L. Casciotti, and S. Harris), Aquatic Microbial Ecology (2005)

The distribution of denitrification was investigated in the hypolimnion of the east and west lobes...



What Limits Bacterial Production in the Suboxic Region of Permanently Ice-Covered Lake Bonney, Antarctica? (with B. B. Ward, J. Granger, and M. T. Maldonado), Aquatic Microbial Ecology (2003)

Bacterial production assays (thymidine incorporation rates) were used to evaluate the activity of heterotrophic bacteria...



Evaluation of Iron as a Triggering Factor for Red Tide Blooms (with Lawrence Mayer and R. R.L. Guillard), Marine Ecology-Progress Series (1991)

We have examined the relationship between Fe and blooms of the toxic dinoflagellate Alexandrium tamarense...