Currents play a vital role in the nutritional needs of the ocean's inhabitants. Currents create a process called upwelling that carries organic matter from deep waters and the sea floor to the surface. The nitrogen and phosphate help to fuel blooms of algae and other plants which are eaten by creatures such as krill. Krill and other small ocean inhabitants serve to feed larger surface ocean life. Upwelling then causes downwelling which carries oxygen-rich surface water below, without which the deep sea life would not survive the toxic waters.