SS1.05 How Will Aquatic Ecosystems Respond to Climate Change?
Date: Tuesday, June 11, 2002
Time: 4:15:00 PM
Location: Oak Bay
 
DenmanKL, CCCMA/U. Victoria, Victoria, Canada, ken.denman@ec.gc.ca
 
THE ROLE OF ZOOPLANKTON AND AMMONIUM CYCLING IN MARINE ECOSYSTEM RESPONSES TO CLIMATE CHANGE - MODEL APPROACHES
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To explore responses to climate change, we are developing models of the marine planktonic ecosystem coupled to 1D vertical mixed layer models and 3D ocean general circulation models. Several forms of ecosystem models coupled to a mixed layer model have been forced with possible climate-related changes: 2 and 5 C temperature warming and changes in the supply of the micronutrient iron. Responses in phytoplankton standing stocks tend to be small. Responses in zooplankton concentrations are much larger, indicating that the recycling of ammonium by zooplankton may play a critical role in determining changes in export production in response to changes related to climate. Here I present a new modelling approach for ammonium uptake based on ideas of relative preference rather than of inhibition of nitrate uptake by ammonium. Model results are compared with in situ concentrations of ammonium in the subarctic Pacific Ocean.