Soil Cores

What can we learn from soil cores?

Soils and sediment can tell us a lot about the health of a wetland, including nutrient concentrations, average productivity, and flooding patterns. There’s a rich history in every soil sample that scientists can piece together if they know what to look for.

Soil cores are a method of collecting soils that allow the observer to get a vertical profile within a layer of sediment or soil. [1] Depending on the desired characteristic, cores can be a foot of material from the surface or they can be over 6 feet tall starting 20 feet below the surface. Each study using a core sample can tell a diverse story. For example, cores in coastal wetlands can be used at CRMS sites to measure accretion on top of marker horizons in an RSET-MH apparatus , in swamps to gauge the oxidation potential of soils, or in marsh to quantify the living root mass that provides structural integrity to platforms. Sediment types, decomposition, and bulk density can also be measured.

Knowing the quality of soils that you’re working with is important in planning for success in the restoration field. Poor soil quality will have lower success in repopulating native flora, as we discussed in our Wetland Wednesday post here. Soil cores lead us to a better understanding of processes that we may not be able to see and to predict the future of ecosystems. Soil testing is a crucial part of conservation and will be a vital tool in the fight to protect our coast.


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National Honey Bee Day – August 18th

August 18th was National Honey Bee day in the USA, but what’s all the buzz about? Pollinators play vital roles in plant communities, including carrying pollen from plant to plant. How does that work? How do honey bees know which flowers need their help? How do they communicate with other bees? All of that and more to come on this special #WetlandWednesday!

There are many kinds of pollinators, from birds to bugs to bats! A mutualistic relationship between pollinators and flowering plants allows the pollinators to collect food and allows the plant to spread its pollen to other individuals. Different animals have different strategies of carrying pollen. Honey bees use some very complex methods of finding, harvesting, and spreading pollen within plant communities. There are almost 20,000 described species of bees; some live in colonies and some do not, some pollinate only one plant species and some pollinate multiple species. The most cultivated of the honey bees (genus: Apis), the Eastern Honey Bee (A. mellifera), is a colonial bee species that does not specialize on one plant. In flight, bees build up an electrostatic charge on their fine, branched hairs. When bees climb into flowers looking for sugary nectar, their charged hairs attract pollen even from a couple of millimeters away! The charge and the branches in their hairs help to keep the pollen attached when the bee leaves in search of its next bounty of sugar.

How do honey bees find flowers? Using a combination of visual, chemical, and communicated clues, bees are highly specialized to find the flowers that are just right for them. Compound eyes do not have the high definition visuals that human eyes have, but they can see ultraviolet light. Some flowers have ultraviolet patterns on their petals called “nectar guides”. [1] When in flight, bees will not always see color, but they can still see shapes and can recognize nectar guide shapes, as well as smell aromas from the flowers. Bees can also communicate instructions or coordinates for finding flowers through “waggle dancing”! [2]

Honey bees pollinate throughout wetlands across the world and have major positive impacts on ecosystem health. Native trees and shrubs of Louisiana that are dependent on pollinators like the European honey bee include Wax Myrtle (Morella cerifera), Southern Magnolia (Magnolia grandiflora, our Louisiana state flower), and Dwarf Palmetto (Sabal minor). Some smaller flowers that need bee pollinators include Wooly Rosemallow (Hibiscus lasiocarpus), Coneflower (Rudbeckia triloba), and Trumpet Creeper (Campsis radicans). [3] Honey bees are also vital in pollinating about 90% of agricultural crops nationwide! Without pollinators, our Louisiana wetlands would not be as productive and vibrant as they are, and we need the help of pollinators to #ProtectOurCoast!





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Bayou Cane Marsh Creation (PO-181)


In 2005, the marshes in the North Shore Mapping Unit sustained severe damage due to Hurricane Katrina. Hundreds of acres of emergent marsh within this mapping unit were lost, resulting in hundreds of acres of shallow open water and scour ponds averaging about 2 ft deep. USGS calculated a 1984 to 2016 area loss rate of -0.91 % per year. Currently there is one area along the shoreline that looks as if a breach is forming. This area also has a small pond immediately behind the critical shoreline. If there were a breach in this area it would allow direct connection between the fresher interior marshes and higher salinity waters of Lake Pontchartrain.
Restoration Strategy:
The overall goal of this project is to restore marshes that were lost and/or damaged due to the effects of Hurricane Katrina. Restoring the marshes should reduce salinity effects on interior emergent marshes.
The proposed features of this project consist of filling approximately 384 acres of shallow open water and nourishing an additional 65 acres of fragmented and/or low marsh with material hydraulically dredged from Lake Pontchartrain. Target settled marsh elevation would be +1.2 NAVD 88, but will ultimately correspond to surrounding healthy marsh.
Progress to Date:
This project was approved for Phase I Engineering and Design on February 9th, 2018.
This project is on Priority Project List (PPL) 27.

Louisiana’s Defense Systems: Wetlands and the Case of the Great Wall of Louisiana

In 2013 the US Army Corps of Engineers (USACE) completed construction of the “Inner Harbor Navigation Canal Lake Borgne Surge Barrier”. The project is funded through the Hurricane and Storm Damage Risk Reduction System (HSDRRS) for southeast Louisiana and considered to be the largest civil works project in corps history. The barrier was built to combat storm surge heights like those observed during Hurricane Katrina in 2005. More commonly known as the Great Wall of Louisiana, engineering innovations like a 1000 foot trestle allowed the project to be completed in about 3 years’ time instead of an estimated 20. The barrier wall is 1.8 miles in distance, 26 feet tall, and at an estimated construction cost of $1.1 billion federally funded dollars.

Louisiana contains 40 percent of the continental United States’ wetland acreage. Coastal wetlands can protect against storm surge energy and flooding by marsh grasses, trees, and soil working as as system. However Louisiana continues to lose wetlands due to problems like subsidence, sea-level rise, sediment deprivation, oil and gas development, and climate change. With an extreme need of wetland preservation, coastal agencies like CWPPRA and USACE are strategizing to combat these issues.

USACE is one of the five managing agencies of the Coastal Wetlands Planning, Protection, and Restoration Act. CWPPRA’s mission is to fund, plan, design, and construct restoration projects in coastal Louisiana at a large and fast pace scale. CWPPRA projects are synergistically funded through partner programs, such as the Inner Harbor Navigation Canal Borgne Surge Barrier to protect, preserve, and restore Louisiana’s coast.


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Measuring Water Quality

Many wetlands of Louisiana receive their freshwater input from the Mississippi river, whose watershed drains approximately 40% of the United States’ waterways. [] Pollutants get into the river from nonpoint sources, which are things like agricultural runoff, urban runoff from roads and sewage, or precipitation of atmospheric compounds, and thus they are spread into Louisiana’s wetlands.[3] Excessive pollutants deteriorate wetlands because they kill vital plants and animals in the ecosystem, which has feedback onto other species. Before interfering with anything in an ecosystem, we need to understand how the ecosystem functions.

Water quality plays a huge role in keeping wetlands healthy. The term “water quality” refers to several characteristics of a body of water, including salinity, nutrient concentration, turbidity, and dissolved oxygen [1]. These factors contribute to how well individuals can live and grow in the ecosystem associated with that body of water. For example, some plants and animals have a strong preference for either high or low salinity (See Salinity Stress Tolerance article), some prefer higher water levels (see Flooding and Hypoxia article), and some can live in many combinations of conditions.

Turbidity is a measure of how much suspended sediment is in the water column. Higher turbidity causes less light to penetrate to the deeper layers, so highly turbid waters often have less submerged aquatic vegetation. Turbidity can be measured with a Secchi disk or Secchi tube. Dissolved oxygen is important to aquatic plants because they still need to exchange oxygen to carry out their metabolic processes. Dissolved oxygen is measured by either luminescence sensors or electrode oxidation. [2] Many of the instruments that measure different aspects of water quality are combined into a Multiparameter Water Quality Sonde to get multiple measurements from the same sample of water. More information on specific procedures and equipment for measuring water quality can be found at

Measuring water quality as a way of determining wetland health is important to many CWPPRA project locations. Measurements allow ecologists to determine any potential risks or threats from developing a project to the integrity of site’s established ecosystem. Fragile ecosystems can be drastically affected by constructing a project because the projects are likely to alter hydrology, salinity, and may introduce conditions that residents cannot survive. Forming a profile of water quality helps to predict the project’s positive and negative outcomes, and to predict the success and longevity of the project.





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Measuring Elevation Change

To provide the best possible care, doctors first must know what is going on with their patients. The same goes for ecologists and engineers with wetlands. Just like doctors can measure your growth and deduce what could help you get over a sickness, ecologists measure the “health” of ecosystems to try to keep them healthy.

Wetland habitats have many moving parts which makes them difficult to fully understand, but we can get a pretty good idea of whether they are growing or deteriorating and sometimes why. All CWPPRA projects require significant amounts of research to estimate the benefit of the project and minimize any damage that could come from disturbing already established wetlands. CWPPRA funds the Coastwide Reference Monitoring System (CRMS) program, which provides reliable coastal elevation data to scientists. Completed projects are monitored for wetland health factors including land accretion, productivity, and water quality to determine whether they are making a positive impact on coastal systems.

Elevation studies are necessary across our coast since we experience such high levels of sediment subsidence. Elevation can be measured in a variety of ways, such as geodetic leveling, Interferometric Synthetic Aperture Radar (inSAR), or satellite imaging. [1] Because of the lower precision, satellite imaging is not great for measuring elevation change for a specific point but is relatively reliable for larger changes over longer periods of time. Another common technique for measuring elevation change in wetland ecology is Rod Surface Elevation Tables with Marker Horizons (RSET-MH), which is implemented at all CRMS sites.


. Rod surface elevation table - marker horizon (RSET-MH) in both shallow and deep configurations. All installations associated with the current work will be deep. 
RSET-MH diagram with deep benchmark, shallow benchmark, marker horizon [2]
An RSET is attached to a deep benchmark that will resist erosion and accretion, somewhere between 20 and 25 meters below the surface of the marsh, where the hard-packed sediments lie. With a benchmark, scientists can measure the relative surface elevation . To measure the rate of sediment accretion between two time periods researchers deposit a layer of white clay on the soil’s surface, called a marker horizon. At a later date, researchers return to the site, collect a core sample, and measure the amount of sediment above the white clay to calculate an accretion rate. [3] RSET-MH is great for measuring one specific site for small and precise elevation changes, but is limited in area coverage. Luckily, through the Coastwide Reference Monitoring System, we are able to monitor elevation change and accretion rates at over 390 sites across the coast!

Measuring wetland health has many factors, not only elevation change. Check in next week for our next installment on wetland monitoring!





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Capitol Park Museum Outreach event

On July 7th, 2018, the CWPPRA Public Outreach team spent the day at the Capitol Park Museum in Baton Rouge, LA, talking to museum visitors. We were the special exhibit for the museum’s ‘First Saturday Family Program’ series. As the special exhibit, we were set up near the entrance, and we caught the eyes of all who entered the building. Visitors competed in Wetland Jeopardy, took silly pictures in our photo booth, and matched beanbag animals to their wetland homes! We also had Protect Our Coast posters, recent issues of WaterMarks, activity books, and other publications available.


The Museum hosts many special exhibits, which can be found on their calendar here.

We were fortunate to have this time in a great museum full of Louisiana history. The regular exhibits included Plessy v. Ferguson, sport hunting and fishing, the civil war, the Mississippi steamboats, and native tribal history. There were several exhibits on large local industries like farming, oil, and fisheries as well. Coastal wetlands are an important resource that all Louisianans share, contributing to storm protection, the economy, and recreational opportunities, and visitors to the museum had the opportunity to connect CWPPRA’s restoration work with the colorful history and culture of Louisiana.