Outstanding in the Field Episode 7 - Science in the Swamp
In this episode of Outstanding in the Field, we take you to the swamps and coastal wetlands of Louisiana, the land of bayous and beignets and a state with one of the most dynamic coastlines in the United States. The wetlands that make up the Louisiana coast are vast and help protect important cultural and natural resources. Here we learn about how USGS plays a key role in monitoring coastal wetlands through the Coastwide Reference Monitoring System or CRMS.
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Narrator: Welcome, and thanks for listening to another episode of Outstanding in the Field, the U.S. Geological Survey’s podcast series produced by the Ecosystems Mission Area. This series highlights our fun, fascinating, and sometimes hot and buggy fieldwork studying ecosystems across the country. I’m Marisa Lubeck.
Narrator: Today, we head to Louisiana, the land of bayous and beignets and a state with one of the most dynamic coastlines in the United States. The wetlands that make up the Louisiana coast are vast and help protect important cultural and natural resources. Wetlands are habitat and a nursery for important fish and wildlife species and protect coastlines from erosion and storm surge. They also filter contaminants from water and are a backdrop to the coastal fishing communities that have resided there for generations. Louisiana’s coastal wetlands support more than 30 percent of the United States’ commercial fisheries, protect five important shipping ports, and an estimated 20 percent of the nation’s oil and gas is pumped from or transported through these important ecosystems.
However, Louisiana has experienced the greatest coastal wetland loss of any other state in the continental United States. About one-quarter of the state’s coastal wetlands – an area approximately the size of Delaware – have been lost since the 1930s. The Mississippi River carries sediment downstream on its way to the Gulf of Mexico feeding the wetlands, but alterations to the river, coupled with sea level rise, subsidence, and increasing storm intensity and frequency are resulting in the disappearance of Louisiana’s wetlands. Though the land change rate ebbs and flows over time, USGS scientists recently estimated that Louisiana has lost one football field worth of wetlands every 100 minutes – sometimes those losses have been as much as a football field worth every 34 minutes.
To help combat the loss of these important habitats, Federal and state-funded restoration projects aimed at restoring hydrological conditions and rebuilding wetlands have been implemented. The Coastal Wetlands Planning, Protection, and Restoration Act, also known as CWPPRA, was implemented in 1990. In addition to funding projects to restore wetlands across the coast, money was designated to develop a system to monitor the long-term success of these projects. The USGS plays a key role in this monitoring program, known as the Coastwide Reference Monitoring System or CRMS.
Sarai: Over the years it became evident that we needed a more standardized approach for monitoring all types of restoration and the ecological condition of our wetlands in Louisiana. And so that’s how CRMS was developed, as a standardized way to monitor across the coast.
Narrator: That’s Sarai Piazza, an ecologist at the Wetland and Aquatic Research Center and program manager for CRMS.
Sarai: CRMS is a partnership between the state of Louisiana and the federal government. The, the state agency that implements is the Coastal Protection and Restoration Authority and US Geological Survey is the federal partner for CRMS. So jointly USGS and CPRA implement the project.
Narrator: CRMS is considered the world’s largest coastal monitoring program with publicly available data. Nearly 400 field sites ranging from freshwater marshes to saltwater marshes to swamps are scattered across the Louisiana coastal landscape.
The USGS is responsible for collecting data at a subset of 45 of the CRMS sites. Using standard procedures across all sites, USGS biologists like Rachel Villani visit CRMS sites all year round to collect hydrology, soil, vegetation, and land change data.
Rachel: I get to go to places that a lot of people don’t get to go to, and I get to go to them fairly regularly. And I really like that, just getting to know the coast and getting to know a whole different side of Louisiana that most people don’t get to see.
Narrator: Rachel and other USGS scientists venture into the swamps to collect data essential to coastal Louisiana restoration efforts. Having consistent long-term data means that restoration planners are comparing apples to apples across the state, which ensures they are making informed decisions about the future of coastal Louisiana.
Narrator: Some CRMS sites are almost an hour from the nearest boat launch, so an early morning departure with the airboat means Rachel and her colleagues can collect site data before the Louisiana heat sets in. Once at a site, the data collection usually begins with vegetation plot surveys and soil measurements.
Rachel: We set our poles out, take a picture, and we’ll go through what we think the percent cover is of that plot. What species are in the plot, what the percent cover is of each species, we’ll measure the dominant species, we’ll measure the water depth if there’s any water on the marsh, we’ll take pore water at each vegetation plot 10 cm depth and 30 cm depth.
Narrator: Pore water is where you measure the water from within the pores of the soil.
Rachel: And you can use this thing called a sipper. You can stick the sipper into the two different depths and pull the water up and then you get the salinity and temperature and conductivity of water within the soil.
Narrator: To track land change, Rachel and the team measure micro elevations of the marsh using a tool called a Rod Surface Elevation Table rod, or RSET.
Rachel: It’s a metal rod that’s driven into the ground until refusal, which is usually like 80 or 90 feet. And all of that is surveyed in, so we know the exact elevation of that, and we use an arm, it’s called the table, to measure micro elevations, in four directions, usually 90 degrees apart. And that is done twice a year, in the spring and in the fall. And using that information you can see how the marsh is changing over time, like the elevation has changed on a very micro scale.
Narrator: They also measure land accretion, which is a natural process where soil is added to the surface over time. They do this by periodically laying white clay over the soil. Months later, they return to the site to collect a soil core, which provides a vertical profile of the sediment. The core is collected by inserting a copper tube into the ground and using liquid nitrogen to freeze the soil around the outside of the tube, in a process called cryo-coring. Using the profile of the accretion cryo-core, they can measure how much soil has been added above the white clay layer over time. Finally, every site has equipment which automatically collects hydrology data.
Rachel: Every hour it measures salinity, temperature, depth, and conductivity. Every hour year-round, it’s an unfathomable amount of data for hydrology for every site because every site has one of those.
Narrator: It’s not all fun and games, though. Rachel and the data collection team need to keep an eye out for hazards during their day. They regularly encounter alligators and snakes, have to be ready for a sinking airboat or a flat tire, and also have to have a game plan if the weather turns bad.
Rachel: We looked up and the sky was just a weird grey purple color. The weather had gone bad real quick. We were just 45 minutes from the boat launch, we didn’t have any cell phone service, couldn’t check the radar. So we made the decision to run north, sort of closer to the storm but there was a houseboat there that we knew was only a few minutes from where we were.
[Thunder and Lightning]
We were there for probably an hour and a half. You really don’t want to stay out longer than you need to or get caught in a second wave or something, so we made a run for it and we made it back to the boat launch, the boat didn’t sink, nobody got struck by lightning, everything ended up fine, but that was probably the worst storm I’ve been caught in.
Narrator: While Rachel and the USGS field crew are on the water collecting the data, Sarai handles many of the behind-the-scenes details of the statewide program. Part of Sarai’s role in the Baton Rouge office is to work with USGS computer scientists and researchers who manage the extensive database, analyze the dataset for trends, and make the data for every CRMS field site accessible on the public-facing website.
Sarai: Because its publicly available, it’s used for a variety of purposes. Landowners use it to know when it might be a good time to go hunting, academic researchers use it to support very specific applied research projects, different state and federal agencies use it as a source of information when they are establishing projects across the coast.
Narrator: The intended purpose is to be able to plan and implement large scale restoration across the Louisiana coast effectively and be able to evaluate how a restoration project is working based on the data that is being collected at a CRMS site.
Sarai: When you’re trying to plan a restoration project whether it be a marsh creation project where we’re pumping in sediment from a different part of the coast to actually build the platform for a marsh to establish or a hydrologic restoration project where we might be managing the inflow and outflow of water to specific marsh, knowing a lot about the hydrology in that specific location helps to plan a restoration project.
Narrator: CRMS has been collecting data for nearly 15 years. USGS scientists like Sarai and Rachel who have been a part of the program since almost the beginning have personally observed changes in the wetland habitats they study.
Sarai: What was marsh in 2007 perhaps when the boardwalk was built is now open water and so we have lost some sites throughout the years, but one of the important things about CRMS is that we continue to monitor throughout the evolution of a site being washed away. And so, we have data from when the site was functioning as a wetland all the way until when all of the land is gone and then it is now functioning as a water body.
Narrator: They’ve also observed water bodies that are now wetlands. In 2000, dredged materials from nearby Lake Pontchartrain were used to create a marsh at one of the CRMS field sites.
Rachel: And so now it’s been there 20 years and that probably one of the most, it’s like probably one of the most healthy and beautiful marshes I think I’ve ever seen.
Narrator: CRMS is Louisiana-based, but the program provides a framework that other regions and countries can use as they set up their own long-term landscape-scale environmental monitoring programs. And what happens in coastal Louisiana concerns everyone in the United States, not just Louisianans.
Sarai: The funds that support CRMS and the larger CWPPRA program come from a sport fish restoration and boating trust fund. So, when people in Minnesota buy fuel for their motorboat or buy a fishing license or fishing equipment or buy a motor for their boat, a small portion of that goes into a fund, which in turn funds CWPPRA and therefore CRMS. And so, people all over the United States are contributing to the CRMS program because they buy motor boat fuel and fishing equipment and fishing licenses.
And I think that’s fitting because the wetlands we have in Louisiana that are disappearing quickly are important to the rest of the United States in terms of navigation and providing habitat for fish and wildlife and in general the Mississippi River watershed is the top five largest in the world and so it doesn’t matter if you’re in Kansas, you are still linked to the wetlands in coastal Louisiana.
[Walking through Wetlands]
Narrator: For more information about USGS involvement in the CRMS program, please visit www dot lacoast dot gov forward slash crms.
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This podcast is a product of the U.S. Geological Survey, Department of the Interior. A special thanks goes out to Rachel Villani and Sarai Piazza from the USGS Wetland and Aquatic Research Center and the Outstanding in the Field podcast team. You can follow us in Instagram at USGS_Wild. I’m Marisa Lubeck. Thanks for listening.
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