Award: OPP-1543328

Antarctica's coastal waters are home to some of the most exciting and vital aquatic animals on Earth. As winter transitions to summer and the sea-ice melts away, penguins, seals, and whales migrate into the area. They are there to feed on the abundant plankton in the water, and to fatten up before winter when the plankton disappear. Animals need fat because it is rich in calories. They eat fat-rich food to survive the winter, for reproduction, and to give them fuel for migration. But where does this fat come from? Our research is provided new information about fat in plankton, which is helping to answer that question. Microscopic organisms in the ocean, called phytoplankton, are significant producers of fat. They store these fats in droplets inside their cells. Phytoplankton are similar to plants. They need sunlight and nutrients and grow in the spring and summer. There are so many phytoplankton in the ocean off Antarctica that we thought fats might play a significant role in the food-web. Phytoplankton are at the base of the food web. Krill, which are shrimp-like animals, eat phytoplankton, and they get fatter. Krill, in turn, are eaten by penguins and whales. Thus, the energy contained in fats made by phytoplankton ultimately makes its way up to the larger animals that make Antarctica such an important place. We took samples of phytoplankton and other organisms in the ocean. We brought them to the laboratory to examine how much fat they contained. We also determined how quickly phytoplankton made fats. We discovered that phytoplankton get fatter as winter gives way to summer. It appears that the more light they get, the more fat they make. This means that the phytoplankton in the surface are fatter than those even just 50 feet below the surface. This might be one reason why krill feed so intensely near the surface: that is where their food is fattest and contains the most calories! Our research is relevant because the ocean near Antarctica is changing rapidly. The amount of sea-ice is gradually going down as the Earth continues to warm. Sea-ice blocks the sunlight that phytoplankton need. If there is less ice and more sunlight, phytoplankton may contain more fat. Whether this will help animals or not requires further research. We hope to that our work convinces scientists that fats are essential and that they will continue to examine fats in the future. Last Modified: 06/29/2020 Submitted by: Benjamin Van Mooy