Well Said: Hurricanes and water quality transcript

Host: Hey everybody and welcome to Well Said, the University of North Carolina at Chapel Hill’s podcast where we talk with students, faculty and staff about what’s going on on campus and around the world. And today were talking about hurricanes and water quality with Hans Paerl, the Kenan Professor of Marine and Environmental Sciences at the UNC Institute of Marine Sciences.

Host: Whenever a hurricane hits, we hear a lot about how the storm has impacted people with flooding and storm surges. But we don’t usually talk about how the storm has effected the actual water. Your research has focused on water quality and how storms impact it. So, let’s start out today by talking about water quality and why is water quality so important?
Paerl: Well, water is one of the key resources we need to live. You know, we need to be able to drink it, use it in ways to enhance our lifestyles. Wash, shower, swim in it — recreational value of water. And let’s not forget that water has a lot of resources that we value very much, including fisheries, aquaculture, agriculture depends a lot on water, of course. And now, you know, agriculture depends on good water quality, particularly when you consider things like organic growing crops and stuff like that. So, there’s multiple reasons why water quality is important and why it’s important to maintain good water quality, but probably the more important (thing to) understand is changes in water quality, so we can start doing something about improving it.

Host: So, we talking a lot about water quality here, but what actually constitutes good water and bad water? How do we classify them?
Paerl: Yeah. Well, good water quality is water that you can use without having to remove anything or treat it in many ways to get rid of pollutants, for example. There are other issues with water quality that are really important that you might not think are very important. They’re sort of out of sight, out of mind issues. For example, algae blooms. You know, we all know that algae live in the water and some lakes and streams and estuaries are a little bit greener than others and we usually don’t worry about that very much. But we can get some bad players in there that can produce toxins, for example, that affect everything from the organisms that eat them to humans need to consume the water. That’s not very obvious, you know, when you look at a system many times. So, there needs to be a lot of good diagnostic capabilities, first for understanding what’s usable, acceptable, and fishable and drinkable and eatable. Water quality is probably one of the most important resources we have.

Host: How does poor water quality impact people and then how does it impact the ecosystem?
Paerl: Well, algae blooms affect people in various ways. First of all, let’s just define what a bloom is. A bloom is excessive growth of algae in the water that usually turns the water green or sometimes even red or yellow. So, there’s an aesthetic issue there. No one wants an algae bloom in front of their expensive home on the water, for example. And then we get into issues of ecosystem effects. If there’s too much algae growing in the water when those algae die and sink, they go to the bottom and all that algae the material consumes oxygen and can lead to iron depletion of oxygen in the bottom waters. That can lead to things like fish kills, for example, or bad odors, hydrogen sulfide, for example, and essentially making the water unusable for drinking water purposes. And even irrigation purposes, in some places. And then lastly, the organisms that form the blooms can produce toxic substances. They don’t mean to do that to kill people. Most of these toxic substances are metabolites that are produced by the algae for all sorts of reasons — their own competition with other algae and survival — it just happens that a lot of those metabolites can be toxic to people and domestic pets, for example, and even smaller animals, that consume the algae themselves. And that can lead to chronic diseases such as liver disease, neurological problems and even death.

Host: So, it’s clearly very important that we’re paying attention and keeping an eye on the water quality because it impact’s people’s health and the environment. And you’ve personally created a program that helps people monitor water and have a better idea of what’s going on. So, what is that program and how does it work?
Paerl: We’re using vessels that are out there as ships of opportunity to actually collect water quality data for us and that data can then be recorded and transmitted from the bridge of the ferries, in the case of North Carolina ferry system, back to the lab and also shared with the management agencies. And the program that has been in place now in North Carolina since, well actually, since hurricane Floyd back in 1999. It’s called FerryMon. It stands for Ferry Operated Monitoring Systems. It’s an autonomous system. The ferries are just going back and forth, of course, on their routes. And below deck, we share the water that goes into the cooling system for the ferries. Part of that is shared by us. It goes through a couple of small tanks that have sensors in them and those sensors are reporting all the time the water that’s flowing through as the ferries are plying the waters of Pamlico Sound or the Neuse or other systems. FerryMon has been operational now for, well, almost 20 years and it has told us a lot about what the water quality conditions are, for example, in Pamlico Sound, which is not routinely monitored by any other program because it’s so big and it’s a difficult place to work because of weather changes, the distances are huge. So, the ferries are great. They’re the first thing on the water, the last thing to go off the water if we have a hurricane. So, they have been able to fill a lot of data gaps in terms of what the conditions are out there and then also when we get an event, whether it be a spill, an algae bloom, for example, out in the system, or in the case of hurricanes, the impacts of these large storm events that are now becoming much more frequent and some would argue more intense, too. And we’re, of course, at the doorstep of many of those storms that come and hit our coastal waters. So, we have a system in place now using the ferries as essentially ships of opportunity to do this automated water quality. The other thing that the ferry’s system contains is a carousel-type of collector. So, we measure the water quality conditions, and then just downstream from that tank that has the sensors in it is collection device — looks like a big box that has bottles in it. Those bottles can be filled with water at programmed times and then a technician will come out to the ferries and collect those bottles for very specific measurements, including toxins, for example, or contaminants, pathogenic bacteria that the seafood folks would be interested in, and for anything else that anyone wants because we can share that water with any other experts that have expertise, for example, in identifying industrial chemicals, agricultural chemicals, things like that.

Host: So, now that we know a little bit more about what water quality is and how it impacts people and the environment, how do hurricanes impact water quality?
Paerl: Well, their impacted can be anything from very little to huge. And that has to do with how much rainfall or storm dumps onto the watershed and the runoff that we get from that event coming into the system. In the case of Floyd, for example, which was really the kind of the first big hurricane that we did a lot of water quality monitoring on, and that occurred in September of 1999, and many listeners probably remember that it flooded most of the eastern part of North Carolina and towns and cities were isolated for up to six weeks. But FerryMon was out there, you know, collecting data all the time and what we found with Floyd, for example, was that the salinity changes that occur in the Pamlico Sound rapidly made the habitat for certain fish species and shellfish species, like crabs for example, uninhabitable. That information was very useful in terms of, you know, having the state fisheries management folks understand why there shouldn’t be fishing going on in some of those places because what was left there was very important in terms of providing larvae for the next seasons, for example, for settlement. And, also there were issues of fish disease from the rapid changes in salinity and also pollutants that came into the system. And so, there were are quite significant increases in things like sores on fish, fish diseases that were mainly a ramification of that storm event. And then lastly, the nutrients that came in with the huge bowls of fresh water came into the system, they didn’t just flush out of the system because Pamlico Sound is a lagoonal system. It’s essentially like a big bathtub out there that holds the water and that water exchanges with only a few narrow inlets to the coastal ocean. But what happened with Floyd was that the bathtub got filled, in fact it overflowed, but many of the pollutants and nutrients and sediments that came down with all that water stayed in the systems. The system was essentially a trap for those nutrients. And we saw algae blooms, for example, six to nine months after Floyd hit the system that were still largely due to the nutrients that came in from Floyd. Now, we’re actually looking at Matthew in a similar way because Matthew, like Floyd, was a very wet storm event. And there’s still recharge coming, for example, from groundwater and other sources coming into the system. So, Matthew, while it wasn’t as big of an event as Floyd, it did have this residual impact on the system that we’re still monitoring and we’re also really looking at other factors that may come into play in terms of long-term water quality issues like the organic matter that came down with all the farmland that was inundated and even flushing of swamps and places up stream that all essentially went into his giant bathtub system. And the bathtub is still working its way through all these nutrients. You know, they don’t just get chewed up and you get one algae bloom and it’s all over. There are long-term ramifications. So, the thing we’re really concerned about with storms now is not only the size of the storms, in terms of how much water, but the frequency. Because we can see now from Floyd and Matthew and even other storms that have impacted our coastal and estuarine systems, that the systems require a certain amount of recovery, they need to work their way through the pollutants and nutrients that come into the system and then get back to some kind of normal state that would be, you know, desirable habitat for fish species, shellfish, et cetera. And what we’re seeing now with this increased frequency, is the system is still recovering when it’s being hit by a new system. And this is what happened with Floyd and Dennis and Irene back in ’99. We had kind of a glimpse of it. But given the fact that there are projected increases now in not only intensity but frequency of the storm events, and we’ve certainly seen that in North Carolina. I mean there’s been a big upswing since the mid-90s. So, we’ve seen these events and what they can do and also the concern that we have now about this increased frequency of these major events. The other thing that hurricanes do that we’re just starting to learn about a bit more over the past five years or so, is how they affect the carbon cycling in the system. And, you know, carbon is not thought about is a nutrient like nitrogen and phosphorus, for example, in the system, but carbon plays a very important role in terms of our climate, for example. The amount of carbon dioxide that we’re putting into the atmosphere has an effect, the greenhouse effect, obviously. We’ve put equipment on the ferries now that can actually monitor the flux of carbon, carbon dioxide it’s coming into the system versus what’s going out. Because Pamlico Sound is like a big bank, you know, when you think of it in terms of carbon. There’s a lot of carbon stored up in there from what comes in from the watershed, what comes in from the marshes around the system, what’s being produced in the system. So from a larger scale climatic perspective, big systems like Pamlico Sound can influence the flux of CO2 in and out of the atmosphere. And we think it might play an important role in the ocean, too because, you know, hurricanes travel over the ocean so they’re also affecting the carbon dioxide equilibrium between the atmosphere and the ocean.

Host: If we’re going to be getting these hurricanes more frequently, and that means less time for the system to flush this all out, is there anything we can actually do to help the situation?
Paerl: Well, two major things. One is, given the fact that we’re in a more stormy world, so to speak, you know, we need to deal with this in the watershed because that’s really where the nutrients and lot of pollutants are coming from. So, better management of our lands is an obvious step that would help. For example, applying fertilizers at times when we know we don’t have these large-scale events and applying them sparingly so that we know if you apply extra fertilizer, for example, in August and September, well, there’s a good chance that a lot of that is going to wash into our waters. Better fertilizer management certainly should be a big priority. Things like a no-till agriculture to reduce the loss of settlements. Impervious surfaces play a huge role. Storm water runoff, for example, in cities in urban areas. And having appropriate retention ponds to catch that water so that it doesn’t immediately flow into our waterways. That can help a lot in terms of retaining the nutrients on land, processing them on land and not allowing them to immediately fertilize our waters, which are already over fertilized. Constructing artificial wetlands and making sure that we protect our swamps and natural habitats where water flows through and can be processed to remove some of those nutrients are also really important steps. We’ve done a good job in the new space and with riparian buffers. These our strips of land around agricultural and even urban areas that are vegetated so that the plants on the land actually take up a large amount of these nutrients as opposed to the water just flowing off the lands into the receiving waters. So, those are all really good strategies that are going to play a bigger role as we are into stormier world. Taking the other end of it, you know, the receiving end, the estuaries and coastal systems, we need to manage our fisheries to be responsive to these events. For example, we know that fish are more susceptible to disease, for example, when we have these large-scale events. We know that the more stressed in terms of the habitat that they have to live in, particularly shellfish. So, probably protecting some of those species at times, or all the time, to be able to have them reproduce adequately under stressful conditions, for example, is really important. So, there are going to be periods where, you know, we may not be able to fish our favorite fish species because they’ve been stressed and need to be protected. Or we may need to focus more on aquaculture forest restoration projects and also restore oysters and other shellfish in areas that are not going to be as impacted as we’ve seen in some of our estuaries, for example, out in the coastal water, which maintain their salinity much longer. So, there are lots of management steps that can and should be taken in terms of protecting our natural resources out there, too.