My research interests span the intersection of plankton ecology and biogeochemical cycling. Phytoplankton living in the surface ocean are responsible for roughly half of the planet's photosynthesis, but most of the CO2 taken up by phytoplankton is rapidly released back into the joint surface ocean-atmosphere system after respiration by grazers and bacteria. Efficient storage of the fixed carbon is dependent on assorted mechanisms that transport organic material into the deep ocean. Of particular importance are particle packaging processes that create or destroy large particles capable of sinking rapidly into the ocean. These processes are mediated by complex interactions between phytoplankton, zooplankton, bacteria, and physical aggregation mechanisms.
Elucidating these relationships, which are key to understanding how the ocean's ability to sequester carbon will adapt to a changing climate, is the focus of my research and requires the use of many different methods. In study regions across the globe, I've used diversemethods (sediment traps, 234Th:238U disequilibrium, microzooplankton dilutions, mesozooplankton gut pigments, 15NO3 and H14CO3- uptake) to measure relevant in situ rates. I have then used a series of analytical tools varying from simple trophic models to inverse ecosystem models and three-dimensional coupled biogeochemical models to synthesize these results.
Specifc research interests can be found on the left.