Processes controlling seasonality and spatial distribution of Centropages typicus: a modeling study in the Gulf of Maine/Georges Bank region
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Copepod populations in the Gulf of Maine/Georges Bank region are dominated by warm water species in late summer/autumn, which are specifically adapted to lower food conditions and higher temperatures and metabolic costs. Better knowledge of their physiological processes and behavior is needed to estimate the impact of changes in environmental conditions on their seasonality and spatial distribution. We investigated the population dynamics of the warm water species Centropages typicus in this region using a copepod population model coupled with a three-dimensional ecosystem model. Although growth and development of copepods are well-investigated processes and well represented in population models, the importance of other life-history traits (e. g. cannibalism, feeding and migration strategies) and their impact on seasonal dynamics and spatial distributions are recognized but difficult to quantify. In this study, species-specific life-history traits were included to investigate their influence on the spatio-temporal patterns. The results confirmed our assumption that cannibalism is a possible constraint controlling the abundances on Georges Bank. Omnivorous feeding by C. typicus on both phytoplankton and microzooplankton is important for maintaining the population in the deeper basins, while vertical aggregation in zones of high-food concentration is a secondary mechanism sustaining the population in low-food seasons. Finally, advective influx from the upstream region on the Scotian Shelf is critical in sustaining the Gulf of Maine population.