Blooming Seas Around the Chatham Islands

At about 800 kilometers (500 miles) east of New Zealand’s South Island, the sparsely populated Chatham Islands are rugged, remote, and often inconspicuous. In January 2026, however, a ring of bright green and blue swirls in the ocean put a natural spotlight on the far-flung specks of land.

A bloom of phytoplankton—tiny photosynthetic organisms that become visible to satellites when their numbers explode—encircled the Chatham Islands in austral summer. Surface currents and eddies carried the floating organisms into intricate wisps and swirls. The VIIRS (Visible Infrared Imaging Radiometer Suite) on the NOAA-20 satellite captured this image of the display on January 10, 2026.

The Chatham Islands sit on the Chatham Rise, an underwater plateau that extends eastward from the South Island of New Zealand. The top of the rise is relatively shallow and separates areas of deeper water to the north and south. These seafloor contours make blooms common along the Chatham Rise, where cold, nutrient-rich currents from the Antarctic and warm, nutrient-poor water from the subtropics converge. The well-mixed water, coupled with long daylight hours, can boost phytoplankton populations.

With phytoplankton at the base of the food web, the waters around the Chatham Islands support productive fisheries, with valuable species such as pāua, rock lobster, and blue cod. The region is also home to an array of marine mammals, including five seal species and 25 whale and dolphin species. Amid this abundance, however, the islands are a hotspot for whale and dolphin strandings, in which hundreds of animals are sometimes beached.

NASA Earth Observatory image by Lauren Dauphin, using VIIRS data from NASA EOSDIS LANCE, GIBS/Worldview, and the Joint Polar Satellite System (JPSS). Story by Lindsey Doermann.

References & Resources

• Murphy, R. J., et al. (2001) Phytoplankton distributions around New Zealand derived from SeaWiFS remotely‐sensed ocean colour data. New Zealand Journal of Marine and Freshwater Research, 35(2), 343–362.
• NASA Earth Observatory (2009, December 28) Phytoplankton Bloom Over Chatham Rise, South Pacific. Accessed January 15, 2026.
• NASA Earthdata Ocean Color. Accessed January 15, 2026.
• New Zealand Department of Conservation Chatham Islands marine mammals. Accessed January 15, 2026.
• Pinkerton, M.H. (2011) A balanced trophic model of the Chatham Rise, New Zealand. Unpublished NIWA report.

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January 10, 2026

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