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Drought Conditions Turn Kealia Pond Pink

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A pink pond doesn’t sound natural… but it is! … especially if that pond is salty… very salty.  A whole group of salt “loving” organisms (aka halophiles) ranging from bacteria and archaea to algae to shrimp to fish and birds have adapted to life in water that most other organisms would say “No thank you!” to living in. The recent pink makeover at Kealia Pond is an example of where water got too salty for some of the typical inhabitants and the halophiles got happy and took over.

 

Pink water at Kealia Pond in November 2023.

The water turned pink at Kealia Pond in November 2023. Early analysis suggests it could be due to Halobacterium salinarum or one of its close relatives. PC: John Starmer

 

Why did the Kealia Pond turn pink?

So what is turning the water pink at Kealia?  While a definitive ID is still not available, a good suspect is Halobacterium salinarum or one of its close relatives.  The red-to-pink color of Halobacterium comes from bacteriorhodopsin, which helps capture light energy for photosynthesis. This protein is unique to archaea and one of the things that separates them from true bacteria.

Halobacterium, despite the name, is a type of halophilic (salt-loving) archaea, not a bacterium. The archaea were only split out from bacteria about 50 years ago and now are recognized to comprise one of the three domains of life, alongside true bacteria and eukaryotes (everything from single-celled algae to sea turtles). Archaea were first discovered in ‘extreme environments’ like salt ponds and thermal hot springs. They are now recognized as abundant and common in most environments from seawater to soil to animal skin and digestive tracts.  Interestingly, none of the species found to date are considered to cause disease.

Is this natural?

Kealia Pond is a dynamic landscape that floods and dries as the seasons change and water becomes more or less abundant. The name Kealia means salt-encrusted place and reflects that during the dry season, patches of white salt remain behind as water evaporates from large areas of this shallow wetland.  The only surface drainage for the pond that remains connected to the sea passes under the National Wildlife Refuge boardwalk. This drainage channel gets scoured out when high water breaks through the sand plug that usually closes off the channel from the ocean in Ma’alaea Bay. Because the channel is deeper, it still holds water even as the shallower parts of the pond and nearby mudflats earn their name and show off white patches of salt crystals scattered across the surface.

The conditions that led to the Halobacterium bloom are considered a natural, though unexpected, result of a long dry summer evaporating the pond and raising its salinity – about twice that of seawater at the moment. Pink salt ponds are a common occurrence around the world thanks to Halobacterium and other halophilic organisms can turn these ponds a range of colors. A small pond along Hana Highway in Kahului has exhibited the same sorts of color changes over the years, but its less striking color changes and small size have kept it from getting much attention.

Is this a Red Tide? / Is this Dangerous?

Is there any need to be concerned about what’s going on at Kealia Pond? Red tides or harmful algal blooms (HABS) are known to affect wildlife and humans by producing toxins. HABS, however, are caused by different organisms – often dinoflagellates or cyanobacteria – and are frequently associated with high nutrient levels in the water. These organisms cannot survive in the high salinity in the pond and have been discounted as the source of the color change. Interestingly, the archaea as a whole, including Halobacterium, are not known to cause any human disease, despite being among the most common organisms on earth.

Vertical image of Pink water at Kealia Pond in November 2023.Will the pond stay pink forever?

The Halobacterium are thriving right now thanks to the current high salinity at in the pond. Because conditions are optimal for the growth of these halophiles, rather than typical green algae, the pond will likely stay pink as long as the salinity remains high. When rains come and drop the salinity, the pond will certainly return to a more sedate and typical color as algae take over as the dominant plankton in the pond.

 

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Public Invited to Free June 12 Presentation on South Maui Ocean Water Quality Monitoring Results

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How clean is the ocean water at your favorite South Maui beach?

Get answers at a free presentation about ocean water quality along the coast of South Maui from ‘Āhihi-Kīnau (Makena) to Haycraft Park (Mā‘alaea) on Wednesday, June 12 at 6 pm. The talk will feature data collected at 20 South Maui sites by the community-based ocean water quality monitoring program Hui O Ka Wai Ola (Association of Living Waters). The presentation will take place at the Hawaiian Islands Humpback Whale National Marine Sanctuary at 726 South Kīhei Road in Kīhei. Admission is free and the public is invited.

“Sharing what we have observed in our first full year of data gathering in South Maui is a big milestone for our unique community-based program,” says James Strickland III, Project Manager. “We’ve learned some surprising things about our coastal water quality in South Maui, which we are looking forward to sharing with everyone at our presentation.”

The free presentation will also include information about why clean ocean water is so important to the future of Maui’s coral reefs.

The Hui O Ka Wai Ola program is co-managed by Maui Nui Marine Resource Council, The Nature Conservancy and West Maui Ridge to Reef Initiative, working in cooperation with the State of Hawai‘i Department of Health Clean Water Division. More than 40 Maui residents volunteer with Hui O Ka Wai Ola, covering 39 locations along Maui’s leeward shoreline.

“Clean ocean water is important for healthy coral reefs and for all ocean recreation,” says Tova Callender, Watershed Coordinator of West Maui Ridge to Reef Initiative. “To work towards clean ocean water along our shorelines, we need to understand where the water is impaired and what pollutants are to blame.”

“The Hui O Ka Wai Ola program follows a strict Department of Health approved Quality Assurance Project Plan (QAPP),” says Callender. “This allows the Hui to provide data the Department of Health can readily incorporate into its reports and databases, which are shared with County, State and Federal agencies, scientists, community groups and the public.”

Every three weeks the Hui team measures sediments, nutrients, and other pollutants from land-based sources that might be having a negative impact on water quality. They collect data for ocean salinity, pH, temperature, organic nutrients (nitrogen and phosphorous compounds), dissolved oxygen (DO), and turbidity). Nutrients, including nitrogen and phosphorus, can indicate agricultural runoff and sewage pollution. Sediments, which block sunlight and smother corals, can be carried from the land to the ocean by streams, flooding, and storm water runoff.

“We’ll be discussing all that we’ve found, the implications for the reef and marine wildlife, and the clues the data provides about the sources of any pollutants,” says Robin Newbold, Chair and co-founder of Maui Nui Marine Resource Council. “Ultimately, our goal is to use our data to bring about clean ocean water for Maui’s coastal areas, for all to enjoy.”

The Hui O Ka Wai Ola program is supported by Maui County Office of Economic Development (OED), Hawai‘i Tourism Aloha ‘Āina Program, North Beach West Maui Benefit Fund, Napili Bay and Beach Foundation, National Fish and Wildlife Foundation, Lush Cosmetics, The Makana Aloha Foundation, Honua Kai West Maui Community Fund, as well as individuals, families and local businesses. To learn more or to donate, please visit www.huiokawaiola.com or at www.mauireefs.org.