Lynbya blooms found in shallow waters at Keauhou Bay

The “Red Sea Moss” Lyngbya came to the Kona Coast this month. It was the first noted in Keauhou Bay by Na Maka o Ke Kai Waterkeeperʻs Dennis Mihalka. This so-called moss or algae is neither. It is Cyanobacteria. The bacterial cells string together to make long filaments. The filaments give rise to the appearance of an algae. This bacteria is found in the tropical Pacific shore from time to time. It is unique as it can fix nitrogen from the atmosphere and needs a phosphorus source to thrive, unlike typical marine algae or phytoplankton.

Blooms of Lyngbya occur on the Kona Coast. A Lyngbya bloom in the late summer of 2015 occurred at Kohanaiki. Children playing in the shallows developed a skin rash. Some parents were concerned when children developed skin lesions under the waistband of the swimming suits. When the filaments break off and lodge under swimwear, modest toxins from the Lyngbya can cause pronounced skin irritations.

Treatments include washing the skin well and adding soothing ointments like calamine and cortisone creams. If Lyngbya exposure is to the eyes, rinse well with drinking water, and seek medical assistance. Wash and dry the swimsuits to avoid reexposure. The best treatment is prevention. Learn to recognize Lyngbya and avoid the tidal area where the red seagrass is present.

Seasonal episodic blooms of Lyngbya are known in Hawaii and elsewhere. The bacteria may be responding to warmer water temperature and the presence of phosphates. Phosphates are known to contaminate groundwater that flows into the sea. Control over excessive phosphate in groundwater and the sea will come as sewage leaks and cesspool usage are resolved.

This is yet another sign of untoward human influence of the near coastal waters. Help support the mission of the Kona Coast Waterkeepers at

For further information contact Dr. Rick Bennett Much appreciation to Dennis Mihalka for photos and this announcement.