Loss of marine phytoplankton

Phytoplankton are the oceans major consumer of carbon dioxide, a primary producer of atmospheric oxygen, and the base to any marine food web. A loss of marine phytoplankton not only would affect the marine ecosystem, but also the general health of our planet. A significant portion of the earth's oxygen (anywhere from 20-50%) is produced by these microscopic organisms, so without them life on earth would certainly be threatened.