An eddy is a water current that runs contrary to the main current. Years with heavy El Ni o winds appear to produce particularly large eddies that can last for several years and replenish nutrient-starved regions of the ocean. Observations of the Haida Eddy by the Canadian research vessel J.P. Tully show that the eddies move fresh water, iron and nitrates from land to sea. They observed unusually high Sitka and Haida eddies in the ocean during the severe El Ni o of 1998.
Phytoplankton is the minute plant life found in bodies of water.
With the subsidence of the Haida Eddy over the next year, we began to observe in the eddy a steady depletion of nutrients that are important to the food chain. The eddies usually drift westward and disappear within two years in deep waters off the Gulf of Alaska. These rotating masses of water can average up to a few hundred kilometers in diameter, forming along the coast within the northbound coastal current, Crawford said, and a large eddy can contain up to 5,000 cubic kilometers of water, which is about the volume of Lake Michigan. J.P. Tully have indicated that the subsurface water is fresher and warmer in this region than surrounding waters. Plans are under way to augment that data and to combine topographic measurements from space with new data on nutrient levels and fish abundance from ships to help fisheries predict annual food production.