WOLCOTT, T.G.*; KAMYKOWSKI, D.; JANOWITZ, G.S.; NC State Univ., Raleigh: Red Tides: what’s good behavior for a bad alga?

How do mobile phytoplankton make �decisions� about the migrations that allow them to temporally stitch together spatially separated essential resources? We are exploring the rules that drive vertical migration of red-tide dinoflagellates (Karenia brevis) between well-lit but nutrient-depleted shallow layers in the Gulf of Mexico and deeper, more eutrophic layers. The goal is to understand how slow vertical swimming by algal cells interacts with different horizontal velocities of the water at different depths to initiate, transport and eventually dissipate harmful algal blooms. The multidisciplinary study involves laboratory observations of cell physiology and behavior, numerical modeling of water column physics, and synthesis of behavior and physics in real-world experiments using �plankton mimics�. The mimics are a redesign of our �behaving� autonomous Lagrangian drifters, enhanced with abilities to sense photosynthetically active radiation (PAR), salinity, vertical advection, and geographic position (obtained by on-board GPS during brief surface intervals). They have more datalogging memory, and GPS-encoded radio beacons to facilitate recovery for data upload. Mimics will drift freely in the Gulf, integrating PAR, temperature, and nutrient gradients (stored in memory) to calculate running tallies of photosynthate and nutrient pools, and of cell growth. By migrating vertically (at biologically realistic rates) according to different �rules�, and logging the resultant trajectories, mimics will allow us to compare the consequences of several control schemes that have been proposed (e.g., ones based on diel cycles alone, on changing light levels, or on physiological state). Results from the first mimic cruise (between abstract submission time and the SICB meetings) will be presented. (Supported by EPA)