WH A T W E H A V E L E A R N E D
Nutrient availability varies widely year-to-year, influencing the base of the food web Marine productivity depends on nutrients, particularly the availability of nitrate. In the Chukchi Sea, ocean currents bring the nitrate northwards from the Bering Sea. The amount of nitrate can vary from year to year by as much as 50%. The nitrate in turn determines how much phytoplankton can grow. Phytoplankton are the base of the food web, supporting all the other species that live in the Chukchi Sea. Recent warming alters phytoplankton community structure, distribution and growth Arctic ocean warming and shorter periods of sea ice cover have altered the timing, distribution, composi- tion and nutritional quality of phytoplankton, which form the base of the food web. Multi-year periods of warmer-than-average conditions alter the seasonal phytoplankton succession pattern from diatoms in spring to smaller phytoplankton in late summer/fall. Such changes in phytoplankton communities influ- ence the diet quality and quantity for zooplankton and benthic invertebrates, including availability of omega-3 fatty acids that are higher in spring than late summer. This new information will be used to better understand potential changes in energy and nutrition transfer to other organisms in the food web in the northern Bering and Chukchi Seas.
3
Made with FlippingBook Ebook Creator