Sarasota Bay Estuary Program Director's Note: https://sarasotabay.org/directors-note-permit-received-for-red-tide-study

Earlier today, I received a letter from the Florida Department of Environmental Protection's (FDEP’s) South District Office, that included a permit (FLOA00062) that was issued under Chapter 403, Florida Statutes. Representatives of Alarivean, Inc. in Scottsdale, Arizona, applied for this permit, with technical (but not financial) support from the SBEP.

The permit is for a project that we have referred to as the Magic Jet Ski - Director's Note: Red tide mitigation - potential involvement in field trial (sarasotabay.org). While the name is something we embrace as being self-deprecating, the science and engineering behind the proposed activity is solid and promising. The permit allows for the testing of a “…mobile system that injects nano oxygen and ozone bubble generation vessels into the water to…destroy harmful algal blooms…”

The permit will allow for the SBEP to work with the folks at Alarivean, Inc. to test a system that is intended to combine the science behind the mitigation of red tides with an engineering approach that could – hopefully – provide a benefit that is relevant at management scales. The background behind this approach goes back almost 50 years, when researchers from the National Marine Fisheries Service Laboratory in Milford Connecticut used ozone to treat seawater during a red tide in Tampa Bay (Blogoslowski et al. 1975). At that time, the red tide organism we now call Karenia brevis was called Gymnodinium breve. Extracts of the red tide toxin were derived from water samples from Tampa Bay during an ongoing red tide event with cell counts of around 275,000/L. Extracts for the control were made from the water, and then injected into laboratory mice, all of which died within 3 ½ minutes. In contrast, when water samples with the red tide organism were treated with ozone, and the extract was then injected into laboratory mice, all the mice lived. The researchers showed that treating a red tide-infected water mass with ozone deactivated the toxin that the red tide organism produces.

This was not a great surprise to the authors, as they noted that ozone had been used to sterilize seawater contaminated with human pathogens as far back as 1929 (Voille 1929) and that ozone was used in shellfish operations that needed to deal with various pathogens and/or toxins as far back as the early 1970s. In the early 1980s, researchers looked at ozone as a more environmentally friendly approach to reducing biofouling in pipes and other infrastructure for power plants, where the default approach had been to use chlorine or chlorinated compounds. Because of this decades-long interest in ozone as a sterilizing agent for marine waters, there is a wide variety of toxicity information available for us to work with, to put boundaries on what might be considered “too much” ozone for non-target species.

In the early 1990s, researchers at the University of Florida (Schneider and Rodrick 1992) verified that the toxins produced by the red tide organism could be reduced by over 99% after treatment with ozone. Importantly, these researchers found that ozone not only killed off the red tide organism, but the toxin itself. After all, what good would it be to kill off the organism only to have the dead cells dump their toxin into the water column? That’s not the case – both the organisms and their toxins are reduced by ozone. A follow-up study by researchers at the University of Florida and Mote Marina Laboratory (Schneider et al. 2003) verified that both the red tide organism and the toxins produced by the organism were substantially reduced by ozonated seawater.

So, what is ozone? It is an oxygen molecule (O2) with an extra oxygen atom (O3). When exposed to seawater, the extra oxygen atom dissociates from the other two oxygen atoms, and it acts as a strong oxidizing agent, seemingly capable of killing off both the red tide organism and its toxins – whether inside the cell or in the water column.

This begs the question – if the topic of ozone treatment of red tide is so well researched, why aren’t we using it already to treat red tides? Good question, and the answer seems to be related to how to make science on a laboratory scale work at a management-relevant scale. And that’s where the folks at Alarivean are important. We’ve known that ozone can work to mitigate the impacts of red tide for almost 50 years, but one of the things that makes this project exciting is the opportunity to find out if we can produce ozonated seawater at management-relevant scales.

The engineers and other staff at Alarivean contacted the SBEP about a year ago, with a proposed project that could potentially create ozonated seawater at rates of 1,000 to 2,000 gallons per minute (gpm) on a mobile platform. That’s a lot of ozonated seawater produced on a short timescale! And the mobile platform – it’s a modified jet ski. Actually, it’s a modified SeaDoo, because that brand of personal watercraft (PWC) has a closed cooling system, like the average car. Other types of PWCs might overheat if you drove them through a red tide, as the high viscosity of such “thick” water reduces heat transfer. Something I learned myself after running my boat through Tampa Bay during the Piney Point-induced red tide of 2021. Ozone would be created by using a tank of liquid oxygen and running the outflow across an electrical discharge. Then the ozonated seawater would be distributed into the water column via the PWC’s nozzle – the same flow of water that can push a PWC across the water at such high speeds (thanks to Newton’s Third Law of Motion). The next step is to discharge the generated ozone gas in the form of nanobubbles.

What’s a nanobubble? A very small bubble. Why is this important? Well, if you SCUBA dive, you know that the rule of thumb is to come up to the surface at a rate no faster than a dime-sized bubble. Large bubbles migrate upwards at faster rates, leaving you at risk of an embolism. Extremely small bubbles won’t migrate upwards – they will hang around in the water column – where they’re needed – and not come up to the atmosphere, where the ozone would be wasted. Also, it appears that nanobubbles can have negative charges, which will help them disperse into the water column better.

Will this technique, the “magic jet ski” work? Frankly, we don’t know. But, the science is solid, the engineering expertise impressed both ourselves and FDEP, and this project has cost the SBEP nothing to develop. That’s right – no funds were used from SBEP, or the state or the federal government to get this permit. The vessel itself was constructed by the folks at Alarivean on their own. Why would they do this for free? Well, if it works, and if agencies want to try it out in their own waterbody, Alarivean would not likely want to continue to run their operation for free, basically. That’s the business model, and it is not only transparent, it incentivizes creativity and engineering expertise.

However…SBEP is involved in the permit as a party that is charged with testing the technique’s efficacy. The permit calls for testing this out in the open waters of Sarasota Bay, with both a treatment and a control plot. This would not be an aquarium, or even a canal, but the open waters of the bay. The idea would be that when the next red tide event arises, both the “magic jet ski” and a regular, unmodified one would head out onto the bay and pilot those crafts across the water in a pattern similar to each other in areas that would then be sampled. Samples would be collected to test if there is a difference in the amount of red tide organisms, red tide toxins, and a suite of indicators to show if there are any adverse environmental impacts.

Currently, we have no red tides in our local waters, and frankly, I think we’d all prefer that this technique never gets tested, because we have to have an active red tide (Karenia brevis levels higher than 100,000 cells/L) to test this out. But the absence of red tides is unlikely to be the situation long-term, which is why we are happy that FDEP gave us a five-year window on this permit. To be clear, we don’t know if this will work, or not. The permit makes it clear that whatever the results are, the SBEP will inform FDEP, as well as our Policy and Management Boards, in a timely manner.

This may or may not work. But if it does, envision this scenario – satellite imagery suggests a red tide is forming offshore, and field samples verify it is in fact Karenia brevis. Then, the University of South Florida (USF) red tide forecasting center tells us that a mass of red tide organisms would be expected to enter Sarasota Bay via New Pass and Big Pass next Tuesday on incoming tides. If this technique works, it might be worthwhile sending a magic jet ski or two out to those passes during that red tide, going back and forth across those passes treating that incoming mass of water at a rate of 1,000 to perhaps 2,000 gpm.

This is not a remedy for dealing with the excessive nitrogen loads that we deliver to our nearshore waters that make red tides larger, more intense, and longer-lasting –Director's Note: Red tide duration and nitrogen loads (sarasotabay.org)

This is a band-aid, basically. But sometimes you need a band-aid.