Clayton, T. D. Old Dominion University,
Hofmann, E. D. Old Dominion University,

A time-dependent, nutrient-based model was constructed to investigate ecosystem behavior when Trichodesmium spp. is included as a component of an open-ocean ecosystem model. Of particular interest are those aspects of Trichodesmium's ecology which might afford it a unique role within the ecosystem: it is diazotrophic, copiously exudes DOM, and is only lightly grazed. Values were taken from the literature to characterize this organism's rates of growth, exudation, physiological death, and grazing by herbivores. The initial model has focused on the supplies of nitrogen and phosphorus, and the resulting role of Trichodesmium. Model simulations emphasize the point that this organism is a poor competitor for phosphate; the model Trichodesmium population does not survive when nutrients are supplied in Redfield ratio. This result points to the need for phosphate to be supplied preferentially to the system, or for Trichodesmium to obtain its phosphorus from other sources or to suppress the success of its phosphate-competitors by outcompeting them for other essential resources (e.g., light, iron). The impact of exudate fate and M. gracilis grazing on Trichodesmium were also examined within this simple framework.
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
Code: CS62TH0453S