 Phytoplankton concentrations have increased over the last century in coastal waters, and more recently have declined in the open ocean.Increases in nutrient runoff from land may explain the increases in coastal phytoplankton, while warming surface temperatures in the open ocean may have strengthened stratification in the water column, reducing the flow of nutrients from the deep that open ocean phytoplankton find useful.Estimates suggest something like 9 million tonnes of plastic is added to the ocean every year.