Algae Reduction

Algae growing in the heat produced by cave lights

NPS PHOTO

 

Lehman Caves as seen with incandescent bulbs

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As you take a tour of Lehman Caves, you might notice some green looking areas along the trail. Most people see this and immediately think they have discovered copper, but what you are seeing is in fact an unnatural algae growth that plagues show caves, including Lehman Caves.

The natural state of any cave is complete and total darkness. No light should exist deep within a cave system. Adding artificial lights to a cave upsets the delicate cave ecosystem, but are necessary to allow for people to safely enjoy these natural wonders. Since the first electric cave lights were installed in Lehman Caves in 1941, incandescent bulbs have been the lighting fixture of choice. Incandescent bulbs last an average of 200 hours, are fragile, operate at high temperatures and consume an average of 11,200 watts of power in the cave. They also give off yellow tinted light that hides the true color of cave formations and encourages algae growth.

 

Lehman Caves viewed with LED lights

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Algae is problematic for cave ecosystems. Algae deposits introduce an invasive food source into the cave ecosystem, and greatly affect the natural balance of cave life. Algae growth can also harm the cave, as algae can permanently change the color of the cave, and even waterproof formations and prevent them from ever growing again.

During 2006, park staff have replaced the incandescent bulbs with Light Emitting
Diodes (LEDs). LEDs last an average of 50,000 hours, are resistant to shock, operate at low temperatures, and consume one third the amount of electricity. The truer color rendition of LED’s show off the caves wide range of colors and should reduce algae growth.

 

Cleaning algae growths

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Even with LED lights, algae continues to grow. LED light emit enough heat which allows algae to grow, although at a slower rate. LED lights are still the right wavelength which allows these growths to continue. To control its growth, several methods can be adopted, including physical, chemical, and biological means. At this time, there is no ideal solution to this problem.

At Great Basin National Park and Lehman Caves, an active study is being completed within the cave system to determine which type of bulb, wattage, and wavelength of light best reduces algae growth , while still allowing for public enjoyment of this world class cave system. The current LED system has helped reduce the algae growth, but the problem still persists.

Until a more ideal lighting system is found, crews must regularly enter the cave to clean and remove the algae growths. Using nothing more than a spray bottle filled with a very diluted bleach solution, cave managers and volunteers meticulously wipe up these unnatural growths before they permanently damage the cave system.