Curious by Nature: What’s bubbling in front of Jon Reiswig’s home?

For a few decades now, retired surgeon Jon Reiswig has lived with a perplexing oddity: the water in front of his North Douglas home constantly bubbles.


He’s puzzled over it himself, and even has had had visiting academics look at it to solve the mystery. But after years of theorizing — could it be a terrestrial gas leak? A murmuring mollusk? — with no definitive answer, he did what any sensible Juneauite would do: he called the newspaper.

In his initial email to the Empire, Reiswig wrote:

“We live on North Douglas. There are several areas or patches in the water in front of our home that have the appearance of H2O boiling. Of course it is not, but it is quite vigorous, particularly as you kayak or canoe over it and hear it. The patches are large enough so that we can make them our from a distance such as the second floor of our house. There is no odor. This is present no matter the season and has been present for 40 + yrs. Fifteen or 20 yrs ago we had a guest staying who got very interested and attempted to capture the gas to figure out what it is. We had a B&B at the time and as I recall he was up from University of Ohio doing research at the university here. He was unable to determine the composition of the gas. I assume this is coming from organic material buried deeply, or possibly living organisms. However, it is continuous so something of fairly large volume is causing it. I did call NOAA locally but they were not aware of cause.”

Photographer Michael Penn and I took a trip in January to Reiswig’s home near Fish Creek. There, a narrow, grassy beach gives way to an intertidal flat, where groups of dime-sized bubbles softly break the surface in a constant stream. Reiswig is right, you can hear them.

The bubbles have too many sources to count from the surface, a short trip canoe trip revealed, and occur in circular patches about two yards in diameter. There are at least 10 of these patches, spaced apart by varying distances, about 50 feet out from shore at a high tide on a band of water about 200 feet long.

Whatever gas is being released doesn’t smell, which might be key to finding out exactly what’s going on here.

Reiswig and the Empire discussed a few initial theories. The bubbles all occur in an area that becomes uncovered during low tide. When uncovered, maybe the ground acts as a sponge somehow, soaking up air at low tide and releasing air when the pressure of high tide forces it out.

Another idea: It could be a group of clams or other mollusks, some of which release gases when underwater.

The first step to testing either of these theories is to email as many scientists as you can. We reached out to a couple dozen University of Alaska professors, who had some interesting ideas as to what’s happening at Reiswig’s home. We included photos, a map and descriptions of Reiswig’s bubbling beach in our inquiries.

Michael Stekoll, a professor of chemistry and biochemistry, was one of the first people to respond.

“Here is a possibility. His waste water from a septic tank is emptying in the near shore. This is good nutrients for green and blue-green algae (or any algae for that matter). In the daytime, the algae are producing oxygen and thus the bubbles,” Stekoll responded.

Septic tanks, which many houses use on North Douglas, can overflow. The “drain field,” for the Reiswig’s septic tank, Stekoll said, would be in the intertidal zone. This happens to a lot of old homes, Stekoll added.

He suggested we look up our old friend the cyanobacteria, the culprit in another Curious by Nature column, where we investigated a pink pond near Herbert Glacier Trail last fall. Cyanobacteria is a plant-like alga that uses photosynthesis and can give off gases. It’s present in the area.

But it’s hard to imagine Reiswig has had a septic tank overflow constantly for that long without him or septic tank operators noticing. Cyanobacteria also fluctuate with temperature, which doesn’t fit well with Reiswig’s testimony that his bubbles have been going constantly for more than 40 years.

University of Alaska Southeast marine biologist Carolyn A. Bergstrom confirmed that Reiswig’s place isn’t the only local occurrence of odd bubbling. Bergstrom has experience studying sculpin and other animals in the Fish Creek area, which we’ve written about before.

Still, she couldn’t narrow down the answer for us.

“I’ve seen this many times in a number of places and have wondered about it myself. I don’t know what causes it but have thought it could be due to bivalves/bivalve burrows releasing gas, sediments releasing gas that seeped in during low tide, or algae/bacterial gas production from photosynthesis or respiration. Could be all of the above,” Bergstrom wrote.

Still three possible answers on the board.

So the Empire decided to try and eliminate at least one of these possible explanations by emailing as many mollusk experts as we could.

Sherry Tamone, who studies mollusks as part of her work with the University of Alaska Southeast, wrote that she is leaning away from cyanobacteria as an explanation. She followed her nose in this educated guess.

“I also have noticed this phenomenon off the Mendenhall Peninsula. I too put my nose to the water at the bubble release site and smelled nothing,” she said.

To her, that’s an indication that bacteria might not be causing Reiswig’s bubbles.

“Methane does not smell but sulfides do and if there were anaerobic bacteria responsible for the gas, I think it would smell. There are a lot of bivalves = clams (molluscs) and segmented worms (Annelids) living in the mud flats and when the tide goes out their burrows which were once full of water will drain into the mud. The animals are able to continue energy production and some will produce Carbon Dioxide. Most of the animals can reduce their metabolic rate and effectively hold their breath, but when the water comes back into the mudflat, air is released from the drained burrows,” she wrote.

Amanda Kelley, an assistant professor with the University of Alaska Fairbanks College of Fisheries and Ocean Sciences, seconded the idea that some kind of “marine methane or CO2 seep” could be the source.

“I’m guessing this is a methane or CO2 seep — it would be interesting to see if there is a localized reduction in seawater pH that is sometimes associated with such vents. I have seen methane seeps in the Santa Barbara Channel in California, and they have no smell associated with them. Very cool!,” Kelley wrote.

In summary, there are at least three possible explanations, here, according to the scientists we contacted: A seep of gases from the mud flats in front of Reiswig’s home, a group of mollusks releasing gases or possibly a group of smaller organisms, possibly cyanobacteria, causing the bubbles.

Without lab studies, it would be hard to find out which one of these answers, or a combination thereof, is correct, but from our research, a marine seep or a gathering of mollusks seem the most plausible explanations.



• Contact reporter Kevin Gullufsen at, 523-2228 or on Twitter @KevinGullufsen.



Curious by Nature answers reader-submitted questions about Mother Nature in Juneau and Southeast Alaska. Ever wonder why Juneau’s water gets so much murkier in the summer? Just how fast the Mendenhall Glacier melting? If the Fukushima disaster is hurting Juneau’s salmon stocks? Why your dog loves the smell of bear poop? Submit your question to and we will scour mountains, rivers, labs and university hallways trying to find the answer.


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