Stock Photo - Plankton plume, North Island, New Zealand is featured in this image photographed by an Expedition 12 crewmember on the international space station. According to NASA scientists, plankton blooms are beginning to appear with increasing spring solar illumination of the Pacific coast of New Zealand's North Island. They point out that the center of this slightly enhanced image a plume can be seen extending from the coastline (near Castlepoint in the southern part of North Island), where it starts rotating in an eddy. Another broader swath of less intensely colored plankton appears in the lower part of the picture. Both plankton masses are being swept offshore (eastward) by waters of the Antarctic Circumpolar Current. Large areas of plankton production are generated along the convergence zone-known as the Subtropical Front, at about 40 degrees south latitude-between the Antarctic Circumpolar current and subtropical waters. The convergence zone provides the mixing mechanism for nutrients, with plankton blooms appearing when spring lighting becomes strong enough. Scientists note that the convergence zone extends generally east-west at about the latitude of Cook Strait that divides New Zealand's North and South Islands (not visible). Satellite imagery shows that the plankton blooms in this image extended fully 8 degrees of longitude eastward, past the Chatham Islands. Smaller, brightly colored eddies along the coastline are sediment plumes generated by wave action and supplied by rivers. The coastal sediment patterns reveal the precise location of the convergence zone. Castlepoint marks a change in coastline orientation but also a change in near-shore current direction: south of Castlepoint sediment is moved by the major north-flowing Antarctic Circumpolar Current. But north of Castlepoint, near-shore sediment is transported southwards by currents in the subtropical waters, before being entrained in the Antarctic Circumpolar Current.