MEPS 360:179-187 (2008)  -  DOI: https://doi.org/10.3354/meps07314

ABSTRACT: Complex 3D biological-physical models are becoming widely used in marine and freshwater ecology. These models are highly valued synthesizing tools because they provide insights into complex dynamics that are difficult to understand using purely empirical methods or theoretical analytical models. Of particular interest has been the incorporation of concentration-based copepod population dynamics into 3D physical transport models. These physical models typically have large numbers of grid points and therefore require a simplified biological model. However, concentration-based copepod models have used a fine resolution age-stage structure to prevent artificially short generation times, known as numerical ‘diffusion.’ This increased resolution has precluded use of age-stage structured copepod models in 3D physical models due to computational constraints. In this paper, we describe a new method, which tracks the mean age of each life stage instead of using age classes within each stage. We then compare this model to previous age-stage structured models. A probability model is developed with the molting rate derived from the mean age of the population and the probability density function (PDF) of molting. The effects of temperature and mortality on copepod population dynamics are also discussed. The mean-age method effectively removes the numerical diffusion problem and reproduces observed median development times (MDTs) without the need for a high-resolution age-stage structure. Thus, it is well-suited for finding solutions of concentration-based zooplankton models in complex biological-physical models.

KEY WORDS: Plankton · Copepods · Modeling · Marine ecology · Oceanography · Limnology · Methodology · Mean age