Satellite Captures Seasonal Phytoplankton Bloom Around Chatham Islands

On January 10, 2026, the VIIRS instrument aboard the NOAA-20 satellite documented a phytoplankton bloom forming a ring-like pattern around New Zealand's Chatham Islands. The event is part of a regular seasonal occurrence in the region, which is known for its high marine productivity and biodiversity.

The bloom was visible due to chlorophyll in the phytoplankton reflecting sunlight. Data for the image was processed by NASA and sourced from the Joint Polar Satellite System (JPSS) and NASA EOSDIS LANCE.

Oceanographic Conditions

The bloom occurs annually during the austral summer. It is facilitated by the Chatham Rise, a broad underwater plateau that extends eastward from New Zealand.

This area acts as a convergence zone for colder waters from the Antarctic and warmer subtropical waters. The topography of the rise traps nutrient-rich waters, bringing them to the surface—a process known as upwelling—which supports phytoplankton growth.

Ecological Significance and Marine Life

Phytoplankton forms the base of the marine food web. The high productivity of the Chatham Rise supports a diverse ecosystem and commercially important fisheries for species such as pāua, rock lobster, and blue cod.

The area is a biodiversity hotspot, home to various species including penguins, albatrosses, and at least five species of seals. At least 25 species of whales and dolphins, including orcas, sperm whales, and pilot whales, frequent the region.

Historical Context of Marine Mammal Strandings

The region is also known for mass strandings of marine mammals. According to New Zealand's Department of Conservation, cetaceans in the area sometimes become stranded on the islands' shores.

The department documented a stranding event in October 2022 where nearly 500 pilot whales were euthanized on Chatham Island. A historical stranding in 1918 is believed to have resulted in the deaths of over 1,000 pilot whales.

Researchers are investigating potential links between these strandings and the area's oceanographic features.

Additional Background on the Chatham Islands

The archipelago was previously home to at least eight endemic bird species that are now extinct, including the Chatham penguin. Most of these extinctions occurred between 150 and 200 years ago following human settlement.