In October 2024, Pyramid Lake experienced an unusual natural event that captured the attention of local communities and researchers alike. The lake, typically known for its serene and clear blue waters, transformed when a large bloom of cyanobacteria spread across its surface, turning the water into a dark green hue.

This phenomenon, driven by the growth of Nodularia spumigena, a type of blue-green algae, was not only a visually striking display but also raised concerns about potential environmental and health risks. In this article, we will explore the science behind this event, its causes, and the potential impact on the lake’s ecosystem.

The Mystery of Pyramid Lake’s Swirling Cyanobacteria

For several days in October, Pyramid Lake looked like a canvas painted with swirling green patterns. Visible even from space, the bloom was so large and vibrant that it caught the attention of locals and scientists alike. Satellite images captured by the Landsat 9 satellite on October 8, 2024, showed mesmerizing whirlpool-like currents across the lake, as the algae moved and danced in the water.

The Operational Land Imager-2 (OLI-2) onboard the satellite provided detailed natural-color images that showcased the extent of the bloom. This Nodularia spumigena bloom, often associated with warm, saline waters, was particularly active, leaving residents to marvel at the natural colors and shapes it formed.

This particular cyanobacterium thrives in environments with low nitrogen levels, using its unique ability to fix nitrogen from the atmosphere. This helps it outcompete other organisms, ensuring its survival in environments like Pyramid Lake. But while the swirling algae are visually stunning, they signal something deeper: a potential environmental shift.

According to the Pyramid Lake Paiute Tribe Water Quality Program, this bloom was one of the most active seen in recent times. Locals could not help but discuss the change, marking it as a unique event in the lake’s history.

The Dangers of Nodularia Spumigena and Its Toxic Effects

While the sight of the algae bloom is undeniably beautiful, it brings with it serious health concerns. Nodularia spumigena can produce a potent toxin known as nodularin. This toxin can be harmful to both animals and humans, with potential effects on the liver if ingested or if skin contact occurs.

The Pyramid Lake Paiute Tribe responded quickly, issuing safety warnings on October 15, 2024, advising people to avoid contact with the water until the bloom subsided. This proactive approach is crucial, as cyanobacterial blooms, like the one turning Pyramid Lake’s waters dark green, can pose serious health risks when not properly managed.

The health risks associated with this toxin highlight the complex relationship between humans and the natural world. Cyanobacteria are essential components of aquatic ecosystems, playing a key role in the oxygen cycle.

However, when environmental conditions are right—such as in warmer temperatures with elevated nutrient levels—these organisms can become harmful, turning from essential contributors to dangerous threats.

Earth, in its coverage of the bloom, highlighted that Nodularia spumigena‘s ability to fix nitrogen from the atmosphere ensures its resilience in Pyramid Lake’s unique conditions, allowing it to thrive in spite of challenges that would prevent other species from surviving.

Monitoring and Protecting Pyramid Lake’s Ecosystem

Pyramid Lake’s green waters are not just a visual wonder; they are a vital ecosystem with a rich history. A remnant of the ancient Lake Lahontan from the last ice age, it’s home to a number of unique species, including the endangered cui-ui fish (Chasmistes cuius), which is of cultural significance to the Pyramid Lake Paiute Tribe.

The lake also holds the distinction of being the site where a world-record Lahontan cutthroat trout was caught in 1925, weighing an astonishing 41 pounds.

Given the environmental importance of Pyramid Lake, scientists and environmental organizations closely monitor its water quality, especially during events like cyanobacteria blooms. Tools such as the San Francisco Estuary Institute’s water quality analysis system provided critical data showing increased chlorophyll-a levels between late September and mid-October 2024, which were linked to the onset of the bloom.

This surge in chlorophyll-a levels acted as an early warning signal, helping researchers track the bloom’s progress and potential impact on both aquatic life and human health.

NOTE – This article was originally published in Indian Defence Review and can be viewed here