Modeling population dynamics of scyphozoan jellyfish (Aurelia spp.) in the Gulf of Mexico

To gain understanding and predict how jellyfish populations will respond to anthropogenic changes, we first need to understand the factors that influence the distribution and abundance of current and historical populations. Hence, we have developed the first bioenergeticsbased population model for the ubiquitous jellyfish Aurelia spp. that incorporates both benthic and pelagic life history stages. This model tracks cohorts of both life stages with temperatureand/ or consumption-driven relationships for growth, reproduction and mortality. We present an initial model application to test hypotheses for the environmental factors that control the initiation of strobilation and inter-Annual variability in bloom timing and magnitude in Gulf of Mexico jellyfish populations between 1982 and 2007. To recreate the autumnal blooms of Aurelia spp. in the Gulf of Mexico, strobilation must commence while zooplankton biomass is increasing after the annual minimum. Under this scenario, the model simulated seasonal and inter-Annual variability of Aurelia spp. biomass that corresponded well with observations. Markedly larger blooms in anomalously warm, high zooplankton years resulted from enhanced ephyrae production compounded by enhanced medusa growth under these conditions. This model confirms the importance of the polyp-To-ephyrae transition in regulating jellyfish bloom magnitude and provides a mechanistic model framework which can examine how future jellyfish populations might respond to climate change.