Glowing rings of plankton surrounding New Zealand islands are linked to dangerous underwater plateaus — Earth seen from space

This dazzling satellite image shows a glowing ring of plankton surrounding the remote islands of New Zealand. The illuminated land area is a hotspot for fatal whale strandings and is tied to the same underwater structure that produced this spectacular bloom.

A glowing ring surrounds the Chatham Islands. The Chatham Islands are a group of 10 islands in the Pacific Ocean approximately 520 miles (840 kilometers) west of Christchurch on the east coast of New Zealand’s South Island. The largest of these islands, Chatham Island and Pitt Island, are approximately 36 miles (58 km) and 9 miles (15 km) in diameter, respectively. (Other land masses are much smaller and are not clearly visible in the image.)

The Chatham Islands are surrounded by the Chatham Rise, a shallow underwater plateau that extends up to 900 miles (1,450 km) from the east coast of the South Island. This hidden structure acts like a giant ramp that funnels cool, nutrient-rich water to the ocean surface. In summer, warm-season streams mix with this nutrient-rich water, providing perfect conditions for algae to thrive.

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The circular flower pictured was one of the largest in recent decades. Most of it is made up of coccolithophytes, a group of photosynthetic plankton, or “phytoplankton,” which convert sunlight into energy and surround themselves with a complex calcium carbonate armor.

The satellite images were taken using a special near-infrared filter, which likely accentuated the bright colors of the algae. But NASA’s Earth Observatory says the blooming microorganisms would have been clearly visible to the naked eye from space.

Phytoplankton are the basis of pelagic (open ocean) food webs, similar to the role of plants in terrestrial environments. As a result, the Chatham Islands are a hotspot for marine biodiversity, home to commercially important cod and lobster populations as well as a variety of animals including penguins, albatrosses, seals, and sea lions.

At least 25 species of whales and dolphins, or cetaceans, including killer whales (Orcinus orca), sperm whales (Physeter Macrocephalus) and pilot whales (Globicephala), are also drawn to the island for food, according to the New Zealand Department of Conservation (DOC). However, this is not necessarily a good thing for visitors.

Large schools of cetaceans often become disoriented in shallow waters and can accidentally get too close to shore and become trapped when the tide goes out, an injury that is often fatal without human intervention.

According to the DOC report, Chatham Island has experienced multiple strandings over the past few years, including an incident in October 2022 in which nearly 500 pilot whales stranded on Chatham Island over a period of about four days and were euthanized. In 1918, more than 1,000 pilot whales are thought to have died on shore, making it the deadliest whale stranding in recorded history. (Pilot whales are particularly prone to strandings because they are highly social, so one injured or disoriented individual can put the entire pod in danger.)

Whales aren’t the only species to meet an untimely end in the Chatham Islands. The archipelago was once home to at least eight endemic bird species, including the Chatham penguin (Eudyptes warhami), which have since become extinct. Most of these species became extinct 150 to 200 years ago, when the first human settlers arrived on the islands from Polynesia in the 15th century.