Airboats: A Tool for Restoration

Navigating wetlands can be difficult for traditional boats due to the changes in water depth and the amount of mud and muck, as well as the meandering of the waterways. Because of these complications, boats that travel both over land and water are needed to explore coastal wetlands. The creation of airboats and innovations in their design have allowed for greater exploration of wetlands and are vital to CWPPRA’s wetland restoration.

Airboats evolved since their introduction in 1905 by Alexander Graham Bell, who is also credited as the inventor of the telephone. His first model was named the “Ugly Duckling”, a crude test vehicle that incorporated an aircraft propeller mounted on the back of a simple pontoon boat. Over the next decade, further developments turned airboats into World War I reconnaissance vessels. Following the end of the war, commercialization led to a rise in popularity among civilians with companies designing taxis and recreation vessels alongside independent innovators creating their own airboat designs. One of the most revolutionary models was built in 1943 at Bear River Migratory Bird Refuge in Utah and dubbed the “Alligator I”. This design was the first known to use air rudders rather than traditional rudders, and most airboats today replicate the Alligator I’s flat bottom hull with air rudders. [1]

Thanks to the inventors at Bear River, Louisiana’s wetlands are more navigable than ever. Further developments have allowed airboats to pass over land, increased passenger capacity and engine horsepower, allowing those in pursuit of recreation, scientific research, and sport hunting/fishing to reach previously inaccessible parts of our wetlands. CWPPRA teams visit project sites using airboats to help get an idea of problems to be addressed through the duration of projects, ensuring the best quality of restoration for our coast. Restoration and preservation have been made easier with creative solutions like airboats, so we would like to recognize the innovators who worked a century ago to improve upon each other’s designs. Once again, the land loss crisis and need for wetland restoration in Louisiana is too large for us to do it alone. We need all the help we can get from innovators like those at Bear River Migratory Bird Refuge to help restore our coast.

 

[1] https://en.wikipedia.org/wiki/Airboat#First_prototypes

Featured image is from a CWPPRA site visit to our BA-34-2 project.

Marsh Madness

Buckle up sports fans, because things are heating up, and not just on the college basketball court. CWPPRA projects are putting their best foot forward to land a spot in the next round of competition. There are 22 contending players going into a free-for-all to win a spot on CWPPRA’s roster. This draft means a lot to the strength of our team, so it is important that all the potential projects are in peak condition.

The CWPPRA project selection process is all about fundamentals. Projects are evaluated on how strong they would be on the defense for the United States national team and ranked accordingly. Task Force “coaches” are looking for projects that can block opponents such as hurricanes, will continue to develop after they join the team, and will work well with with other projects. Today, our contenders are practicing and refining their fundamentals before they have a shoot-out on April 11th on the technical committee’s home court in Baton Rouge. Technical Committee members will select a subset of 10 player projects that they think will be well-rounded to benefit team Louisiana and all its fans. That list of 10 projects will go on to the final round of the competition, and up to 4 will make the cut.

If you are a fan of coastal restoration, feel free to send us your draft picks for the upcoming vote! All the current stats for the candidate list can be found on our March 11 newsflash at https://www.lacoast.gov/ocmc/MailContent.aspx?ID=10119. We look forward to signing some of these exciting new prospects and we wish the projects luck!

 

Featured Image from https://www.pinterest.es/pin/380413499743991365/?lp=true

 

First Day of Spring

Spring is in the air! That means a burst of life in our coastal wetlands. You may already see flowers blooming, new leaves on trees, and a variety of migratory birds returning to their nesting habitat. Today, on the first day of spring, let’s explore the annual rebirth of Louisiana’s coastal habitats.

As plants proliferate in the warmer temperatures, so too a riot of colors joins the landscape. Some coastal favorites are seaside goldenrod (Solidago sempervirens), buttonbush (Cephalanthus occidentalis), and salt marsh morning glory (Ipomoea sagittata) for good reason: they produce attractive flowers that saturate the wetlands with color. Other plants have less colorful flowering and fruiting structures but are more prevalent. Many sedges (Family Cyperaceae) are beginning to put out their iconic inflorescences, the branching flower clusters, as are several grasses (Family Poaceae). Other popular marsh plants including Juncus and Spartina species also begin their pollination cycle. The reliable reproduction of these graminoid (grass-like) plants is helpful in CWPPRA marsh creation projects because those species repopulate new land more quickly than woody plants. Once they move in and put down healthy roots, they demonstrate the effectiveness of CWPPRA projects and their success!

Plant enthusiasts aren’t the only ones excited for springtime; wildlife watchers, especially birders, see an infusion of new plant growth and wildlife offspring. Many birds return from their wintering grounds in South America to the warm nesting grounds along the Mississippi Flyway. Songbirds like the beloved prothonotary warbler (Protonotaria citrea) fly across the Caribbean, the Gulf of Mexico, and our coastal waters to take advantage of the new plant life and insect population booms. South American migrants use the flyway to get further north alongside other species that use our coastal zone as a wintering habitat. Whether they are just stopping over or will be staying for the summer, Louisiana’s spring is one of the most exciting times to birdwatch. [1] Ultimately, birdwatching success diminishes at the same rate as our disappearing coastal wetlands. Habitat loss has major implications for population declines of bird species. Because birds have “favorite” wintering and nesting habitats, they are especially susceptible. Both their wintering and nesting habitats face the threat of deterioration and require protection. This part of the year is great for exploring all the natural areas that Louisiana has to offer, we suggest that you find a day that works in your schedule and visit a wetland near you; you’re bound to find something interesting. [2] We wish you all a happy spring and encourage environmental stewardship each and every day!

 

[1] https://www.birdwatchersdigest.com/bwdsite/explore/regions/southeast/louisiana/louisiana-birding-season-spring.php

[2] https://www.crt.state.la.us/louisiana-state-parks/maps/index

 

 

Raccoon Island Shoreline Protection/ Marsh Creation (TE-48)

wordpress fact sheet banner TE-48-01

The Isles Dernieres barrier island chain is experiencing some of the highest erosion rates of any coastal region in the world. Raccoon Island is experiencing shoreline retreat both gulfward and bayward, threatening one of the most productive wading bird nesting areas and shorebird habitats along the gulf coast.

An existing demonstration project on the eastern end of the island, Raccoon Island Breakwaters Demonstration project (TE-29), has proven that segmented breakwaters can significantly reduce, and perhaps even reverse, shoreline erosion rates. The primary goal of this project is to protect the Raccoon Island rookery and seabird colonies from the encroaching shoreline by: 1) reducing the rate of shoreline erosion along the western, gulfward side and 2) extending the longevity of northern backbay areas by creating 60 acres of intertidal wetlands that will serve as bird habitat. This project has been separated into two construction phases, Phase A and Phase B. Phase A includes the construction of eight additional segmented breakwaters gulfward of the island and immediately west of the existing breakwaters demonstration project and an eastern groin that will connect existing Breakwater No. 0 to the island. Phase B involves the construction of a retention dike along the northern shore to create a back bay enclosure that will be filled with sediments dredged from the bay and/or gulf, followed by vegetative plantings.

map.jpg

The project is located in the Terrebonne Basin on the western-most island of the Isles Dernieres barrier island chain in Terrebonne Parish, Louisiana.

This project was selected for engineering and design funding at the January 2002 Breaux Act Task Force meeting. Construction funding for Phase A was approved in October 2004. Request for Phase B construction funding is anticipated to occur in January 2008.

This project is on Priority Project List 11.

The Sponsors include:

Federal Sponsor: NRCS

Local Sponsor: CPRA

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. [1] 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.[2] 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 [3]. 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. [4] 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 https://www.fondriest.com/environmental-measurements/equipment/measuring-water-quality/.

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.

 

[1] https://www.nps.gov/miss/riverfacts.htm

[2] https://www.epa.gov/nps/basic-information-about-nonpoint-source-nps-pollution

[3] https://www.fondriest.com/environmental-measurements/parameters/water-quality/

[4] https://www.ysi.com/parameters/dissolved-oxygen

Featured image from https://phys.org/news/2017-01-technique-quickly-salt-marsh-vulnerability.html

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!

 

[1] https://www.epa.gov/wetlands/wetlands-monitoring-and-assessment

[2] https://www.researchgate.net/figure/Rod-surface-elevation-table-marker-horizon-RSET-MH-in-both-shallow-and-deep_fig2_281113921

[3] https://www.pwrc.usgs.gov/set/

Featured Image from https://oceanservice.noaa.gov/sentinelsites/chesapeake-bay/welcome.html

Salt Water Intrusion

When it comes to Louisiana, there is no one reason for coastal land loss. Causes are both natural and man-made, but when those forces combine, they are detrimental to Louisiana’s coast. One example contributing to these synergistic forces is known as salt water intrusion.

Facts about Salt Water Intrusion: [4]

  • May occur in freshwater systems like aquifers or coastal marshes.
  • Is the movement of saltwater into interior areas or underground sources such as aquifers of freshwater marsh.
  • Most common in coastal regions, where freshwater is displaced by the inland movement of saltwater from the ocean.
  • Can also occur inland, far away from an ocean, as freshwater is pumped out from underground reservoirs and the salt-laden water from surrounding salty layers of the earth flow in.
  • Most common cause of saltwater intrusion is the pumping of freshwater from wells near coasts.
  • Climate change can increase saltwater encroachment along coastal regions as sea level rises.
  • Increased salinity of coastal freshwater can threaten the plant life and wildlife of coastal areas, destroy habitats such as marshes, and force the abandonment of drinking-water supplies.

swi_22

Coastal Louisiana is currently experiencing higher than expected salinity in traditionally freshwater marshes, waterways, and reservoirs [1]. It is possible for wildlife to adapt to locally saline conditions, but that is a process that requires time. A study by two professors at the University of Louisiana at Lafayette concluded:

  • Resident marsh fishes have genetic adaptations for localized salinity conditions [1].
  • Continued adaptation will be most successful if salinity increases gradually [1].
  • The existence of adaptation to salinity tolerance will be most important in aiding survival during surges of high salinity, such as those associated with hurricanes [1].

At the same time that sea level is rising, man-made actions are intensifying salt water intrusion through [4]:

  • Canal dredging, including oil and gas access canals
  • Channelization or straightening of natural waterways
  • Construction of levees for flood control
  • General development activities in the coastal zone

CWPPRA hydrologic restoration projects help reduce the inland march of salt water. Culverts and pumps restore the flow of freshwater into marshes, while locks and weirs create “one-way” channels out of the marsh that salt water can’t access.

Sources:

[1] Leberg, P. and Klerks, P. 2004. Final Report: Saltwater Intrusion On The Gulf Coast: An Assessment Of The Interactions Of Salinity Stress, Genetic Diversity And Population Characteristics Of Fish Inhabiting Coastal Marshes. University of Louisiana at Lafayette (ULL). Available: https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/5385 [May 22, 2018].

[2] Spatafora, James. 2008. Saltwater Intrusion of Coastal Aquifers in the U.S. Available: http://kanat.jsc.vsc.edu/student/spatafora/default.htm#homepage  [May 22, 2018].

[3] Encyclopedia.com. 2018. Available: https://www.encyclopedia.com/environment/energy-government-and-defense-magazines/saltwater-intrusion [May 22, 2018].

[4] Southern Regional Water Program. 2018. Louisiana Environmental Restoration. Available: http://srwqis.tamu.edu/louisiana/program-information/louisiana-target-themes/watershed-restoration/ [May 22, 2018].

[5] Fowler, Kristen. “Saltwater Intrusion – EnvS 546 Univ of Idaho”. ” 23 April 2016. Online video clip. YouTube. Accessed on 24 May 2018. <http://www.youtube.com/watch?v=puSkP3uym5k>

[6] PBS Newshour. “Testing the limits of saltwater intrusion”. 17 September 2015. Online video clip. Youtube. Accessed on 24 May 2018. https://www.youtube.com/watch?v=75CoHNQVbY8

[7] LSU AgCenter Video Archive. “Saltwater intrusion threatens rice acres”. 8 Jan 2016. Online video clip. Youtube. Accessed on 24 May 2018. https://www.youtube.com/watch?v=Z4TGPtq4bD0

[8] Stanford Alumni. Rosemary Knight, “Sentinel Geophysics: Imaging Saltwater Intrusion from Monterey to Santa Cruz”. 2 April 2014. Online video clip. Youtube. Accessed on 24 May 2018. https://www.youtube.com/watch?v=k4XcBx7OT3Y