Polar regions characteristically have marked seasonal variation in the availability of food due to great reduction or elimination of primary production during the winter. It is hypothesized that the evolution of large body size in high-latitude planktonic organisms is a response to this extreme seasonality of food supply and permits winter survival by increasing the store of body tissues and lipids available for metabolism. Yen proposes to further examine the ecology and lipid metabolism of Euchaeta antarctica, a predaceous copepod and the largest species in this worldwide genus, to test the above hypothesis. She will also examine the role of this species in the marine food web, and determine how its life history and physiological specializations adapt it for survival in a polar regime. Data from this project in combination with other information on Euchaeta antarctica will advance present understanding of why this species is a major component of Antarctic zooplankton and a dominant planktonic carnivore. This project will examine lipid content and composition of female Euchaeta antarctica, their eggs and their food. Rate of lipogenesis will be determined by carbon-14 labeling. The project also will examine changes in lipid metabolism with ontogeny and reproductive state, and as a function of environmental temperature. Field work will be done at Palmer Station, Antarctica.
