Since my last modeling update on this blog, I have made a combination of tiny steps and leaps of progress on understanding Dynamic Energy Budget (DEB) theory and in particular how it relates to photosynthetic organisms. I am using a DEB model to predict individual blade kelp growth through tracking the movement of mass from assimilation to use in maintenance, building new structure, or excretion.

We have had the basic structure and equations of the kelp DEB model since this past summer. The main modeling task I am working on currently is gathering data from the literature on parameters for the model. Parameters are fixed values in the equations such as maximum assimilation rate of nitrogen. This has proved to be quite a challenging process, because even though many papers have been published on sugar kelp, it is very infrequent that data is collected in the exact format needed for a particular parameter. Many parameters within the DEB model are too DEB specific to be directly related to literature values, so these will be fit to our field data within a logical range in comparison with an existing DEB model for phytoplankton (Lorena et al, 2010). I have spent a particularly large chunk of time trying to get an Arrhenius temperature, a marker of how temperature impacts metabolic rate, by compiling various metabolic rate data and converting it into a usable form. WebPlotDigitizer by Ankit Rohatgi has been a very valuable tool for gathering data from graphs in publications. In this process of thinking deeply about each parameter, guidance from our collaborator Dr. Romain Lavaud has been crucial. Romain has been able to re-direct me when I end up going down a particular parameter rabbit hole and clarify whether or not sources of data are reasonable references for this project.

Once I have as many parameters estimated with literature values as I can, we will start running the model in comparison to our field data to see how the DEB-specific parameters can be fit to provide a good fit of the model to the field data. Stay tuned!

Written by: Celeste Venolia