In episode 9, we’re sitting down with Dr. Dennis Hanisak and Kristen Davis from Florida Atlantic University’s Harbor Branch Oceanographic Institute. We cover IRLON, or Indian River Lagoon Observatory Network of Environmental Sensors, measuring the water quality and weather data of the lagoon, accessible data, community outreach and hope for the future.

To learn more about the IRL Council and our lagoon home, visit

Listen on Apple Podcasts

Listen on Spotify

Listen on Youtube

Listen on Google Podcasts

Listen on Amazon Podcasts

Listen on Buzzsprout

Share and Connect

If you enjoyed our new episode, please feel free to share with your friends and family. Questions? Contact us today or connect with us on Twitter, Tik Tok, Instagram, YouTube, and Facebook.

Interested in doing your part? Make a donation to the IRL, purchase lagoon merchandise on our site or buy an IRL license plate today.


[Audio transcription via]


Episode Speakers:

KJ Ayres, GIS/IT Data Scientist, Indian River Lagoon National Estuary Program

Dr. Dennis Hanisak, Florida Atlantic University’s Harbor Branch Oceanographic Institute

Kristen Davis, IRLON Manager, Florida Atlantic University’s Harbor Branch Oceanographic Institute

Duane DeFreese: Hi, I am Duane DeFreese, executive director of the IRL Council and the Indian River Lagoon National Estuary Program. Welcome to our One Lagoon, One Voice podcast. 

Each week, myself or one of my staff members will host leaders in the community, scientists along the lagoon, people who know a lot about the system, to talk about some of the problems, and most importantly, some of the solutions to solve the Indian River Lagoon’s health and make sure it’s great for future generations. 

If you enjoy hearing us talk about the Lagoon, like and subscribe to this podcast. So, let’s get the show started, and let’s talk a little lagoon.

KJ Ayres: Hello there. Welcome to One Lagoon, One Voice. My name is KJ Ayres, and I am the current GIS/IT Data Scientist for the Indian River Lagoon National Estuary Program. So today we’re here to talk to two of my favorite scientists on the Indian River Lagoon, Dr. Dennis Hanisak and his lab manager, Kristen Davis, from Florida Atlantic University’s Harbor Branch Oceanographic Institute.

Dennis Hanisak: Hey, how are you? Thanks for having us.

Kristen Davis: Hi, KJ. Thank you for having us today.

KJ Ayres: We’re going to dive into some of the work that the Hanisak Lab is doing regarding water quality monitoring for the Indian River Lagoon. So Dennis, Kristen, would you introduce yourself to our guests?

Kristen Davis: Hi, I’m Kristen Davis. I have been with Dr. Hanisak since 2005, and I’ve had a series of positions here, but my current day-to-day is IRLON manager.

KJ Ayres: For those listening, can you tell us what IRLON is?

Kristen Davis: Sure. IRLON stands for Indian River Lagoon Observatory Network of Environmental Sensors. My background, I’m from Pennsylvania originally and went to school at Millersville University, which is in the state university system there. And I really wanted to study in warm water, not in cold water. Most of my peers went to the Chesapeake. I made my way down south here, and it’s actually where I met Dennis for the first time.

One of our stops was Harbor Branch, and one of the Ocean Science Lecture Series was occurring during our time here. So I walked up to him and said, “I want to be an intern.” And he thought I meant just an intern in general, and I’m like, “No, no, no, your intern.” So luckily I was able to apply and, yeah, was an intern that summer with him.

KJ Ayres: I didn’t know that’s how you met Dennis.

Kristen Davis: Mm-hmm. Started in 2005. I was an intern in 2002.

KJ Ayres: So what led you to your lab manager position?

Kristen Davis: Well, he actually had a project starting and needed a technician on the project, so I interviewed and was able to move down to Florida here, from Pennsylvania, within a couple months or so.

KJ Ayres: Awesome. Well, Dennis, I’m going to shoot it back to you and ask you the same question. So kind of give us a little bit of your background, your education, and what you’re currently doing and talk a little bit about the IRLON network.

Dennis Hanisak: I also grew up in the Northeast. I grew up in New Jersey and I went to Rutgers. In my senior year, I started gravitating toward ecology, and that led to me deciding what kind of ecology, and I’ve always liked water. So very simplistically, I put those together and applied to some schools and I ended up going to University of Rhode Island and I got my master’s there in phytoplankton ecology and I got my PhD. I thought I’d end up somewhere else, but I was very surprised to come to Florida.

But I came for a job, and the job was being a postdoc here at Harbor Branch. I worked with a most wonderful mentor and scientist, Dr. John Ryther, who was very distinguished in biologic oceanography who got into aquaculture and was interested actually in seaweed cultivation to solve the world’s energy crisis. So I was a postdoc here and I did a lot of that aquaculture type plant work, and there was an opportunity to do a more broader program in marine botany.

As time went on, I decided to really just kind of focus a little bit more on Indian River Lagoon. It’s right here on our doorsteps. I still remember the first time I saw it was with Dr. Ryther when I was here for an interview for the postdoc position, and we walked behind the Johnson House here on campus, for those who know that. Very obvious structure that one sees from the water. And he just said, “That’s the Indian River. It’s really interesting, but nobody knows anything about it.” That always kind of stuck in my brain.

So as time went on, I got more and more involved in Indian Lagoon work. Again, mostly from the marine plant angle, seaweeds, macroalgae, sludge, and then seagrasses. That led me to develop that project with… We focus mainly on water quality. I’ve always done water quality because to me, I need to know what the environment is like to understand the organisms in it, and that’s especially true for marine plants because they’re much more intimate with the environment than animals even. And then that led to us doing that work and then really expanding everything.

KJ Ayres: Can you discuss how IRLON came to be?

Dennis Hanisak: Yeah, so that really grew out of that project that I said, “Hey Kristen, if you’re going to come to Harbor Branch, you could work for me.” So that was kind of what got us into thinking about real-time water quality monitoring.

Those data saws were doing hourly measurements, but we’d have to go out once a week and download them and maybe the data was going to be there, maybe it wasn’t. So about 12 years ago, I started a program called IRLO, I-R-L-O, so that’s an acronym for Indian River Lagoon Observatory. So the first part of that IRLON acronym. And really, my goal was just to try to foster more collaboration and more of us talking and sharing and disseminating our data, with the idea, really, of being to better understand the lagoon’s ecological function. So that’s me, kind of the scientist, right?

But also, increasingly, it was obvious that everything we do has to tie to management. That’s true for probably all marine science more or less nowadays. I mean, there’s always an application. So our application is if we can understand Indian River Lagoon better, then we, we the global we, can also do a better job managing it.

There’s several parts to it, to IRLO, but IRLON is kind of like what most people know about, and that’s this network of advanced observing stations. We provide real-time, highly accurate, high resolution, biogeochemical, if you will. So we can say water quality.

Kristen Davis: Quality.

Dennis Hanisak: But again, I like to think a little broader because I think water quality sort of has a certain context to it and there’s more to it than just that. And also we do weather data. So we have meteorological sensors that are also at our water quality monitoring sensors. So we couple those two big things together, which I think was actually novel.

KJ Ayres: Dennis, I know you go into the field, but Kristen, what exactly are some of the water quality parameters that you measure so maybe people who aren’t as familiar with the Indian River Lagoon Observing Network can kind of expand on it and kind of know what you guys are monitoring for?

Kristen Davis: Sure. The biogeochemical instrument package, or BIP, as we call it, that measure anything from temperature, salinity, depth, biological parameters like dissolved oxygen. We’re looking at chlorophyll fluorescence, which serves as a proxy for phytoplankton so we can kind of get an idea of when blooms are occurring. But in addition to chlorophyll, we also measure turbidity and CDOM, which is colored dissolved organic matter, or watercolor.

KJ Ayres: Thank you for explaining that.

Kristen Davis: And we’re basically looking at those three as attenuators of light. Again, because we are really tied into the marine plants, so we want to know what’s going to impact the amount of light reaching the bottom of the water column. So overall, we measure 20 different water quality parameters and eight weather parameters at 13 sites on an hourly basis. And the first site was deployed in 2013. So we’re generating a lot of data.

KJ Ayres: Dennis and Kristen, could you explain a little more about why these water quality parameters are so important to monitor?

Dennis Hanisak: Well, we measure all kinds of things. So for example, some very basic things, temperature. How cold does it get? So in 2010 and 2011, for example, before we had IRLON in place, we had an incredible cold spell two years in a row in January. And we look back now at that and we think that there was a lot of things that happened as a result of that, including a lot of things that died, fishes and so on, that released a lot of nutrients, which was part perhaps of understanding why we started having harmful algal blooms at that point.

Now, this week, I’ve been getting multiple inquiries from the media about how hot is the lagoon, and is that impacting seagrasses, for example. So that’s just a really basic thing, and I think everybody out there can understand temperature.

Another one that I think everybody can understand that is incredibly important, relatively easy to measure is salinity. Salinity is how salty the water is. One of the biggest issues, if not the biggest management issue is that the watershed of the Indian River Lagoon was artificially expanded with all the canals that had to be built to drain what essentially was just wetlands. Without that, we couldn’t live in the houses we live in, we couldn’t grow the crops that we do in the watershed. So the watershed was greatly expanded. It’s designed to get water off of the land quickly. So not only back a hundred years ago when this got started, but every time it rains, people will have to worry about flooding because we’re so low.

So salinity is a very good indicator of how much fresh water is coming in. Too much fresh water can be extremely stressful. If there’s Lake Okeechobee discharges, and a lot of people are interested in that, if that water’s discharged, sometimes it also comes with toxic cyanobacteria or blue-green algae, which is another harmful algal bloom. So there’s those kinds of things.

Another one that I think everybody can understand is oxygen. All multicellular organisms, so most of what we think of as plants and animals, need oxygen. And if the oxygen is not there, unless the organism, such as a fish, can get out of the way and move to someplace that has oxygen, they’re going to die. And we’ve had a lot of fish kills. Most notably in 2016, massive fish kills, but we have them every single year.

So that’s just one parameter, but we also do things like nutrients. We do measure the pigments. So we do measure the phytoplankton, many of which can include the harmful algal blooms that people are most worried about. Those are just a few examples.

KJ Ayres: I feel like maybe the general public sometimes questions why we’re monitoring what we’re monitoring, and I feel like monitoring is super important. And I know you came up with the One Lagoon monitoring plan that Duane’s mentioned, and it’s really popular. Can you guys both tell me what the future plans are for IRLON and who’s using IRLON right now?

Kristen Davis: One of the upgrades we made to the network in 2020 was launching our new website. With that, we’re actually able to better track individual users of our network. The website’s available at Data are freely available to everyone.

Some of the different users that we’ve seen have ranged from commercial fishermen who are looking at the conditions for if the turbidity is good, go fishing near that site. We’ve had commercial crab fishermen are putting some of their cages near our site so they can get an idea of what the water quality is. We’ve had questions from different sailing schools about our wind data. They would like it every minute instead of every hour that we provide. So it’s a little bit outside of our scope at the moment, but it’s always good to know they’re using it.

And honestly, I think one of the most exciting things for me is the different students who are able to use our data as part of their projects. They’re able to use the same data set for the studies that they’re conducting, and it prevents them from having to measure the water quality themselves. So they’re able to do more maybe with the funds that they’re given.

KJ Ayres: That’s really cool. I didn’t even think about the educational, recreational, commercial side of it, because I feel like most of the time we just think about the scientific uses or maybe the management uses, but a lot of people within the community are benefiting from utilizing IRLON.

Dennis Hanisak: Yeah, and on the scientific side, I mean, there are modelers. And if you know anything about modelers, the more data they can get, the better.

KJ Ayres: The more accurate their models?

Dennis Hanisak: Yeah, or they can verify them. And again, a lot of the students, like Kristen mentioned, they can utilize our data. And a lot of people have published anything from microbiology of the Indian River Lagoon, you name it, up to marine mammals. And then they use a piece of our data depending on where they worked or maybe the questions they asked. So it does make the data available to the broader scientific community as well.

One of the big challenges, really, is we have different types of customers, if you will. We have to try to explain it to different people, the public a different way sometimes than the modeler, for example.

KJ Ayres: Yeah. I know IRLON is both of your babies, but I feel like it’s very important to get it out there so people are aware that there’s more sensors and there’s more monitoring out there than what people are actually aware of. I do know that you guys are talking about putting in coastal ocean acidification sensors as well. So could you maybe explain what coastal acidification is and why it’s kind of a breakthrough for your lab?

Dennis Hanisak: I don’t even know how many people out there really understand ocean acidification. A lot of people don’t realize that a lot of that CO2, the carbon dioxide that is the result of all of our combustion of fossil fuels, it goes initially into the air, to the atmosphere, but about at least a third, maybe up to a half goes into the ocean. And there’s a chemical reaction that occurs with CO2 gas going into the ocean, and basically it results in a reduction of pH. pH is the units of acidity.

So we’ve known for about 20 years that this was happening in a serious way. We knew theoretically it was going on. And at that time, 20 years ago, most of us thought, “Well, it’s going to happen more in certain types of places like deeper water, colder water stuff. It’s not going to be something in a place like the Indian River Lagoon.” And it turns out that places like the Indian River Lagoon are just primed for this. That’s because there’s other stressors that can get added on top of what’s going on with the CO2 coming from the atmosphere.

These stressors are things like nutrients, which is a big issue in the Indian River Lagoon, and organic material. The tannins that we see, that dark colored water. Well, that’s a sign of organic material. So freshwater inputs in general.

And also another component is actually upwelling. So upwelling is a coastal phenomenon, and many of the listeners out there may know if they go to the beach. A lot of years, the water gets really cold at the beach in August, usually. July, August. That’s because we have these deep water upwellings that happens right off our coast, and that goes all the way up to the edge of the beaches and sometimes comes into the lagoon and you can actually feel it when you’re working out in the lagoon.

So all of those things add on to the problems with reductions on pH. I’ll just say that this was a big challenge for us. When I think, “What did I do in the pandemic? What did we do here at Harbor Branch?” because we worked all through it, and what we did is we did those upgrades and we added the coastal acidification, which is something I really am excited about. But Kristen can tell you the real details.

Kristen Davis: Perfect. Well, as Dennis mentioned, we do measure pH. It’s a pretty standard measurement for most monitoring groups. We’ve been monitoring that since the inception of IRLON in 2013. We use a SeaFET instrument that is manufactured by Sea-Bird Scientific. It’s a little bit different than most of the other pH sensors that are out there. It uses ISFET technology. Please don’t ask me to explain that acronym. I can give you the website if you want to look it up, but basically it’s a higher accuracy type of measurement. So it’s really allowing us to track those minute changes that are really important to monitor when you’re looking at both ocean and coastal acidification.

Part of our upgrades in 2020 was deploying a BCO2 sensor, which is measuring the partial pressure of carbon dioxide in the water column. The reason we were so excited to add this to our network is because with two parameters of the carbonate system, we’re able to calculate the rust of the parameters, including aragonite saturation.

KJ Ayres: So Kristen, can you explain what aragonite saturation is for those that are tuning in?

Kristen Davis: Aragonite saturation, or omega AR values, is commonly used to track acidification, because basically, it’s a measure of the carbonate ion concentration. So while different physical and biological factors can influence individual parameters within the carbonate system, such as pH or PCO2, aragonite saturation state is a better indicator of whether or not organisms are able to form shells, because most of the time, shells use aragonite. So if it is above one, it means that aragonite is more likely to precipitate for organisms to form shells. If it’s below one, it means that the carbonate and aragonite is dissolving, so it’s less likely to be available in the water for organisms to use.

KJ Ayres: Can you give examples of some of these organisms?

Dennis Hanisak: For example, in the lagoon, I think the biggest concern that people would have would be on shellfish. So for example, we have a small but not insignificant effort to grow clams. The last several years, some of the clam farmers have said, “Things aren’t quite right. Our little guys aren’t doing as well.” And I’m not saying that it is, but it could very well be that they are starting to experience some of the detrimental aspects of coastal acidification. Oysters would be in the same category.

So I think that’s something… And not to jump too far ahead, but we’re seeing huge variability throughout the lagoon, and it’s heavily influenced by, like last year, for example, it’s heavily influenced by when we had the two storms, big storms. It was freshwater inputs there. You could see the really fast impact that that has on those coastal acidification parameters that Kristen discussed.

So we think this is one of these emerging issues that really needs a lot more study, and we’re hoping to really work that up in the coming year for the year 2022, which is now complete, and just get it out there and let people know what’s going on. But it’s really, really variable, so therefore, it’s really interesting.

KJ Ayres: I’m going to switch gears a little bit. I really appreciate you guys talking, kind of explaining what your lab is doing and kind of a little bit more about the IRLON network. But a lot of people believe that the Indian River Lagoon is, quote, unquote, “dying” or not doing as well as it used to be. I know you and your lab are continuing to monitor the lagoon, and you’re even starting to replant some seagrasses. Can you tell me why you believe science matters, especially the science that you’re doing? And do you have hope for the recovery of the IRL?

Dennis Hanisak: Well, I think being a scientist, some people might say, “Of course he’s biased.” Science matters. I mean, all of the advancements that we have in our civilization, almost all of them have some kind of technological or science basis.

Specific to the Indian River Lagoon science, if we don’t understand how the Indian River Lagoon works, we can’t manage it. And I would argue that pretty much everybody who lives here would like to see better management of the Indian River Lagoon. They probably would like to see cleaner water. I know when I think of Duane De Freese, I always remember on one of his restoration targets… And I hope it’s okay to invoke you, Duane. I remember one time he said, “The day I can go out, walk in the lagoon, clear water, be able to get a good fish and get me some clams…” I don’t think he said, “Get me.” I think that’s my definition. “Get some clams-

KJ Ayres: Your paraphrase.

Dennis Hanisak: — then I’ll know we’re making progress.” I think that’s what the average person wants to see. But I think what the average person doesn’t get is we have a lot of work to do. And the reasons for that is it’s an estuary, and estuaries are constantly changing throughout the year from year to year, from place to place.

The Indian River Lagoon is a really long, skinny estuary. Very shallow. So it’s very different. And some of the issues in Brevard County are very different than the ones in Martin County, for example. And on top of that though, we have this climate change, which we didn’t think about until fairly recently, really. We don’t have a very good handle on it. Now we know that one of the biggest concerns always was going to be rising sea level. So it’s a very changing environment normally, if there is such a thing as normally.

KJ Ayres: And then you added more levels of complexity.

Dennis Hanisak: Yeah, exactly. So hope for the future. Yes, of course there’s hope for the future. The reason for that is first of all, I do believe that the Indian River Lagoon National Estuary Program has a really good plan. Anybody who wants to look at it, just go to the website and you can see what that plan is.

KJ Ayres: I’m going to put my little plug,

Dennis Hanisak: There you go. Take a look at it. It is a long-term plan, and it’s not going to get done all at one time. But progress is being made.

And the other thing that gives me good thoughts is that the generation of students now that are coming up, they don’t have to deal with the shock and awe of people like me saying, “Oh my God, things are changing way too fast. What happened to the coral reefs? Oh my goodness, the glaciers are melting. What’s going on in the Arctic? What’s going on in the Antarctic?” and all that kind of stuff. They kind of know that things are going badly. They’re mostly interested in things that didn’t exist 10 years ago or 15 years ago, like conservation biology, restoration ecology. I think they’re going to have wonderful careers, and they’re going to be the ones to really deal with this on a daily basis. I’m a big believer in education, and I’m a big believer that there are people out there who really want to target this.

The other cool thing is in recent years, unfortunately driven by the seagrass losses and the dying manatees, the State of Florida, the federal government, and also private groups are putting resources, i.e., money into looking at the Indian River Lagoon, looking at the seagrass losses and so on. So it’s going to be a long battle. Now, the really good news is… And-

KJ Ayres: Let’s leave on a good note.

Dennis Hanisak: For example, the seagrass decline, which was really enormous, it’s starting to turn around. Specifically, the seagrass has done some great recovery just in recent months in Mosquito Lagoon and up and down the estuary, including our local area. I was out for the last two weeks, six sites we have, and we’ve seen in Indian River County, for example, quite an increase in seagrass over last summer and over last winter. It is looking really much, much better.

Now, will that last for long? We don’t really know. But it’s not the end of the road. And we may be surprised, seagrass may be even more resilient than we thought about. That’s true for a lot of organisms. These organisms have been around for millions of years and they’ve been exposed to all kinds of things. The challenge is that right now they’re being hit so fast by so many different things, and the magnitude and the speed at which humans can change things is much different than what happened before humans were the big player.

So is there reasons to be optimistic? I think so. I think so.

KJ Ayres: I don’t think I’ve ever asked you that question in the few years that we’ve known each other, so I’m very happy that you were able to explain it so well. And I don’t know, it makes me very excited for the future, that we still have generations interested and the next generation to come of scientists, if that makes sense. If you could say one thing to everybody that lives on the Indian River Lagoon, what would you say just to kind of end off this podcast? I’m going to ask both of you. Kristen, you want to go first?

Kristen Davis: I think the one thing I would say to people is that one person can make a difference. So to do that, you really need to be knowledgeable about what’s going on in your local area, especially. And I think there’s so much good information that’s provided by a lot of the groups in our area, like the National Estuary Program and IRLON, that I think becoming aware of what’s going on and potentially some causes behind the troubles that we’re having is the best step forward because then you can —

KJ Ayres: Address those problems.

Kristen Davis: — help to contribute to the resolution of the issues, yeah.

Dennis Hanisak: In terms of my thoughts too, I would say for people out there listening, if you really care about the lagoon, get involved with it. There’s so many groups up and down the lagoon. And again, you can get all this information through the Indian River Lagoon National Estuary Program website, which is…

KJ Ayres:

Dennis Hanisak: There you go. And I would say you’ll learn a lot. If you don’t go out in the lagoon very often, you should go out in the lagoon. There’s lots of opportunities to do that. Best one is you have a friend who has a boat, right? But also there’s a number of opportunities up and down the Lagoon, including one here at Harbor Branch that we take kind of a scientific approach of what’s going on in the lagoon, but it’s also a really nice boat ride. And you will learn so much about this body of water that’s right at our doorsteps.

And our economy is heavily based on the Indian River Lagoon. And why we are where we are historically is because of that lagoon. Well, you probably wouldn’t be out there listening to these podcasts if you didn’t really care. But if you don’t care about the lagoon, then you should start caring, because it’s going to impact us a lot.

And besides just the scientific reasons and the idea that we should have a lot of diversity, a lot of different kinds of organisms, it also does impact our economy and waterfront. Obviously, the property values go a lot higher and lower depending if there’s harmful algal blooms floating by. So I think really, just try to get involved, get more people involved, go out and have a good time on the lagoon.

And you know what? The lagoon is still a really cool place. The lagoon is not dead. It’s changing and will never be what it was like a hundred years ago, but it’s up to the people now to decide what they want it to be for the next hundred years.

KJ Ayres: That was wonderful. So I just wanted to thank you both, Dennis and Kristen, for spending this half hour with me to discuss the work that you’re doing and kind of just your outlook on what’s going on in the Indian River Lagoon. If you’re interested more about the Hanisak Lab or the work that they’re doing, again, I’m going to reiterate, you can go to to get the information.

Kristen Davis: KJ, thank you, and to the Indian River Lagoon National Estuary Program for having myself, and I’m going to preemptively include Dennis here, on this podcast, allowing us to share the work that we’re conducting here at Harbor Branch and with IRLON. And also, I’d like to take the opportunity to thank the entire team behind us who they’re out working hard today. They’re out right now in the field in this heat. So thank you for having us, and thank you for allowing us to share all of our work with you and the public.

Dennis Hanisak: Well said. And I enjoyed it a lot too, KJ, and we’re happy to update you on this and anything else we do in the future.

KJ Ayres: So I just wanted to thank everybody for tuning in. If you enjoyed the discussions about the Indian River Lagoon, please like and subscribe to this podcast to learn more about the Indian River Lagoon National Estuary Program. You can get involved in volunteer opportunities, tips for living lagoon friendly, or just to support the lagoon restoration. You can purchase One Lagoon merchandise at

Another way to support the Lagoon restoration efforts is to purchase a newly redesigned Indian River Lagoon license plate. The license plate has helped raise about $8 million for lagoon restoration projects since its inception. To stay informed about lagoon news and upcoming events, follow us all on Facebook, Twitter, Instagram, all at One Lagoon. Thank you.

Share and Connect

If you enjoyed our new episode, please feel free to share with your friends and family. Questions? Contact us today or connect with us on Twitter, Tik Tok, Instagram, YouTube, and Facebook.

Interested in doing your part? Make a donation to the IRL, purchase lagoon merchandise on our site or buy an IRL license plate today.