Scientists working for NASA and for the Universities Space Research Association used satellite data from 1998 to 2012, and a computer model, to assess populations of phytoplankton. They found that the density of diatoms had decreased by 1.22% per year globally, with much of the decline happening in the North Pacific. The researchers attributed the decrease to less mixing in the uppermost water, perhaps caused by a decrease in wind.
http://www.sciencedaily.com/releases/2015/09/150923134209.htm [sciencedaily.com]