File:Phytoplankton bloom off New Zealand (MODIS 2017-12-06).jpg

English: Between New Zealand’s South Island and the Chatham Islands, the ocean floor forms a long plateau which helps create a very productive region for marine life. The water north of the current is very deep, warm, and nutrient-poor but iron-rich. In contrast, the water to the south of the plateau is cold, nutrient-rich but iron-poor from the Antarctic. As the waters roll into the edges of the relatively shallow plateau, they rise and mix together, creating nutrient-rich, iron-rich, oxygen-rich waters.

Known as the Chatham Rise, this area of mixing water creates a perfect place for abundant blooms of phytoplankton – microscopic plant-like organisms. Such organisms live in the waters year-round in small numbers and when the currents are strongest (spring and fall) they start to reproduce explosively, creating massive blooms that can be seen easily from space. Phytoplankton and other microscopic organisms that thrive in these waters form the base of the marine food web, helping create an area rich in biodiversity.

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite acquired a true-color image of the spring bloom on December 2, 2017.