Our studies over the past 3 decades have focused on the ecology of plankton on the U.S. southeastern continental shelf and adjacent ocean regions through interdisciplinary research. To obtain a quantitative understanding we combined oceanographic observations with those under controlled conditions, and modeling studies, ranging in scales from nanometers to 100s of kilometers, and milliseconds to months.
Our oceanographic studies revealed that the driving variables largely originate with atmospheric forcing and the Gulf Stream which provides new nutrients via upwellings and diverging isobaths; and via the Florida Current seed populations from the Gulf of Mexico . Our oceanographic findings over the past decades have implications for other wide continental shelves such as the East China shelf, the Campeche Banks, the Agulhas Bank and the East Australian shelf which are affected by Western Boundary Currents.
Our main findings were that subtropical continental shelves allow rapid colonization by pelagic tunicates like salps and doliolids within 1 to 2 weeks, and similarly by planktonic copepods over a period of a generation time like e.g. 2.5 to 3 weeks.
To understand the mechanisms underlying these processes we conducted experiments / observations under controlled conditions including juvenile stages of copepods, by simulating environmental conditions. Our main findings include that sensing of food particles is a function of food concentration, and that sensing of food particles decreases with increasing stage, thus limiting competition for particles of similar size/signal strength; that energy metabolism is not so much a function of drag but of motion; and that various taxa of proto- and metazooplankton appear to be able to survive temporary food shortages by reducing their metabolic expenditures.
The information obtained so far is not comprehensive, and has led to numerous questions as to how organisms in the water column operate and persist. Those include: Which ranges of variability of interactions of various dominant taxa of metazooplankton with the microbial loop occur in neritic and oceanic environments, and which are the mechanisms governing them? How well can modeling describe the interactions of proto- and metazooplankton with food organisms at limiting abundances? Which signal strengths can be perceived by hydrodynamically-sensing proto- and metazooplankton in order to persist under extremely limiting food abundances? We envision that only interdisciplinary efforts can lead to satisfactory results. |
