Meeting Abstract

68.9  Jan. 7  Control of vertical migration in harmful algal blooms (HABs): field-testing a model using a robot "Plankton Mimic". WOLCOTT, T.G.*; KAMYKOWSKI, D.; WOLCOTT, D.L.; WATERS, L.; NC State Univ., Raleigh; NC State Univ., Raleigh; NC State Univ., Raleigh; NC State Univ., Raleigh

Red Tide dinoflagellates (Karenia brevis) undertake diel vertical migrations (DVM) but not simply as coherent swarms. At cell division, daughter cells may receive different resources, hence have different needs. Many of the field observations can be explained by a fairly simple model of migration control: photosynthate (C) deficiency increases speed upward, and nutrient (N) deficiency increases speed downward. The model's consequences in a dynamic field situation are being explored with the "Plankton Mimic", an autonomous vertically-migrating Lagrangian drifter. It measures in-situ depth, temperature, salinity, and photosynthetically-active radiation (PAR). Based on these measurements, it calculates photosynthesis, photodamage and light inhibition, respiration, and nutrient uptake (using depth and water temperature as surrogates for nutrient concentration.) Velocities of DVM are modulated by fullness of the cellular C and N pools. Each new depth presents different physical conditions, which feed back into swimming behavior. Data logged during a week-long deployment will be presented to show various consequences of behaviors in a context of continuous, dynamic interaction between [pseudo]organism and environment. Migration velocities that were modulated by C and N pools affected amplitude and average depth of DVM, which could lead to vertical distributions and dispersion similar to those exhibited by algae in the field. These adaptive behaviors maximized accumulation in the cellular pool (C or N) that was deficient, leading to "cell division" within biologically realistic times despite differences in initial conditions. (Funded by EPA.)