2. Introduction
● Louisiana has lost over 1,800 square miles of land
● More and more land will be lossed in the future
● Loss of land= loss of shore lines= domino effect
● We focused on the Isles Dernières Barrier Island Wildlife
Refuge
2
3. Rationale
● The Islands in Terrebonne Bay are
extremely important
● The problem: Ecological and Economic
impacts
● Objectives
● Possible solutions
3
4. Approach
Restoration for Raccoon and Whiskey Islands
● Marsh elevation was built higher than recommended to
slow erosion on Raccoon Island
● More ecologically complex design that incorporated tidal
inflows with canals to encourage natural hydrologic
ecology on Whiskey Island
4
5. Approach
● Comparison of 2 salt marsh restoration sites
on 2 Louisiana Barrier Islands
○ Whiskey and Raccoon Islands
● 3 year study to evaluate success of
restoration
○ Success was defined as the sites ability to
support ecological processes
5
6. Methods
● Sand was excavated from
nearby sand bars to
increase elevation of the
islands
Dredging
● Isles Dernieres Barrier
Wildlife Refuge in
Terrebonne Bay, Louisiana
Study Site
● 129 ha on Whiskey
(0.8m) and 24 ha
on Raccoon (1.1 m)
Restoration
6
7. Methods ● Used to Evaluate species
presence with recording units
that were mounted on the
Islands
Acoustic Monitoring
Habitat Monitoring
● 1 meter squared plot was
analyzed on each Island over
the three year period and the
% ground cover per plant
species was determined
7
9. Funding
● National Coastal Wetlands
Conservation
● National Coastal Resilience Fund
● EPA through Clean Water Act
● Educating the public
9
10. Relevant Design Equations: Erosion
● Sediment Transport Equations and
Shields Diagram
○ Dimensionless Shear Stress
○ Actual Shear Stress
○ Shear Velocity Reynolds Number
○ Experimental Curve Value
If the actual shear stress is larger than the
dimensionless shear stress, sediment
transport can be expected.
10
11. Results and
Discussion
Figure 1: Comparison of treatment
types on Whiskey and Raccoon
islands in the Isles Dernieres Wildlife
Refuge, Terrebonne Bay, Louisiana,
2016–2018. A) Reference site,
Whiskey; B) Restoration site,
Whiskey; C) Reference site,
Raccoon; D) Restoration site,
Raccoon.
11
12. Table 1: Comparison of mean species richness and standard deviation for
acoustic monitoring via ARUs and point counts for each treatment type
(restoration [Res], reference [Ref], and mean [Av]) for Whiskey and Raccoon
islands
12
13. Table 2: Results from generalized linear models to evaluate effects of
habitat covariates on avian species richness derived from the passive
acoustic sampling of breeding birds in resorted and reference habitats on
Whiskey Island
13
14. Table 3: Results from generalized linear models to evaluate effects of
habitat covariates on avian species richness derived from point counts
of breeding birds in restored and reference habitats on both Whiskey
and Racoon Islands
14
15. Table 4: Results from intercept-only and highest ranked occupancy models
to evaluate effect of habitat covariates on the Ammospiza maritima and
Ixobrychus exilis occupancy on restoration and reference sites on Whiskey
Island from 2016-2018
15
16. Conclusion
● Restoration was successful
● Ideas to combat coastline erosion
○ Sand dunes
○ Pulsating waves
○ Vegetation control
● Sand dunes
○ Acts as a buffer to the coastline
● Pulsating Waves
○ Keeps the amount of erosion to a minimal
● Vegetation control
○ Longer roots tend to anchor the coastline better
16
17. Conclusion
● Principle of ecology;
○ Limit number of factors
○ All components are interconnected
● Limit number of factors
○ Only touch a limited amount of variables each time
● All components are interconnected
○ Everything in nature affects one another
17
18. Conclusion
● Self design
○ Team cannot keep up with all the variable
change affects
○ Naturally occurring
○ Helps maintain the balance in nature
○ Change one variable = nature integrates it and
maintain homeostasis
18
19. References
Barnes, Stephen, et al. "Economic evaluation of coastal land loss in Louisiana." (2015).
Barnes, S. R., and Stephanie Virgets. "Regional impacts of coastal land loss and Louisiana’s
opportunity for growth." LSU EJ Ourso College of Business Economics and Policy Research Group,
Environmental Defense Fund (2017).
Barbier, Edward B., et al. "The value of estuarine and coastal ecosystem services." Ecological
monographs 81.2 (2011): 169-193.
Byerly, Paige A., et al. "Effects of barrier island salt marsh restoration on marsh bird occurrence in
the northern Gulf of Mexico." Restoration Ecology 28.6 (2020): 1610-1620.
Cretini, Kari F., et al. "Development and use of a floristic quality index for coastal Louisiana
marshes." Environmental monitoring and assessment 184.4 (2012): 2389-2403.
Deegan, L. A., H. M. Kennedy, and R. Costanza. "Factors contributing to marsh land loss in
Louisiana's coastal zone." Developments in Environmental Modelling. Vol. 5. Elsevier, 1983. 915-
919.
Duarte, Carlos M., et al. "The role of coastal plant communities for climate change mitigation and
adaptation." Nature Climate Change 3.11 (2013): 961-968. 19
20. References
Khalil, Syed M., et al. "Overview of coastal restoration in Louisiana." Shore & Beach 79.3 (2011): 4-
11.
Liu, Haoran, Kehui Xu, and Carol Wilson. "Sediment infilling and geomorphological change of a
mud-capped Raccoon Island dredge pit near Ship Shoal of Louisiana shelf." Estuarine, Coastal and
Shelf Science 245 (2020): 106979.89-2403.
Prabhakaran, Sudesh, Vikneswaran Nair, and Sridar Ramachandran. "Community participation in
mitigating marine waste to reduce climatic change in tourism destinations." Worldwide Hospitality
and Tourism Themes (2016).
Temmink, Ralph JM, et al. "Mimicry of emergent traits amplifies coastal restoration success."
Nature communications 11.1 (2020): 1-9.
Turner, R. Eugene, and Yu Mo. "Salt Marsh Elevation Limit Determined after Subsidence from
Hydrologic Change and Hydrocarbon Extraction." Remote Sensing 13.1 (2021): 49.
Sparks, Eric L., et al. "Cost-effectiveness of two small-scale salt marsh restoration designs."
Ecological Engineering 53 (2013): 250-256.
Wang, Faming, et al. "Plant biomass and rates of carbon dioxide uptake are enhanced by successful
restoration of tidal connectivity in salt marshes." Science of the Total Environment 750 (2021): 20
Engineering design in regards to erosion is necessary for a successful restoration
Shear velocity reynolds number and experimental curve value can be calculated to find dimensionless shear stress using the shields diagram, compare that to actual shear stress
Ds-particle diameter
Ys-particle specific weight
Y-water specific weight
Tc-critical shear stress
R-depth
S-bed slope
u*-shear velocity
V-kinematic viscosity
g-gravity
top two whiskey, bottom two raccoon
whiskey: the dominant cover type for the plant, water, and the bare ground did not differ significantly between treatment types, but the restored sites had significantly higher S. alterniflora and lower A. germinas percent cover than the reference sites
raccoon: the reference sites had a significantly greater percent plant cover and less bare ground than the restored sites
Ambient noise from breeding laughing gulls completely obscured recordings for the ARU measurements on Raccoon Island, and so point count was implemented on both islands to overcome this limitation
ARU data from Whiskey only
Akaike's Information Criterion, statistical analysis, used for model selection
K is the number of model parameters
W is the likelihood of a model so for ex 85% of the total explanation for index species presence can be found in the first model with ...
the index species presence was higher in restored sites than reference sites
Species presence decreased with percent plant cover, increased with plant height, and showed a weak positive response to standing water depth.
based on the point-count data for both islands
Detection of index species and species presence was constantly lower on Raccoon
For Whiskey, no model showed substantial support, with little difference in AICc values between the top model and all other models
For Raccoon, the top model indicated that index species presence was negatively associated with the restored site, however, there was not a significant difference between the best-supported model (delta = 0) and the null model.
shows the results for Least Bitterns and Seaside Sparrows bc they couldn’t reach a conclusion about habitat association for the other indicator species
Seaside Sparrows were found in 9 out of 16 sites over the 3 year period
top model for the sparrows in Table 4 indicates that occupancy was highest in restored sites, was positively associated with percent plant cover, and was negatively associated with plant height. However, detection was highest during the first year of the study
The Least Bitterns were detected in 12 of the 16 sites over the 3 year study. The top model showed that occupancy was higher in restored sites, negatively associated with percent plant cover, and positively associated with plant height.
Researchers concluded that mixed restoration success between the two islands when solely defined by avian species presence. However, in regards to habitat characteristics, restoration was successful in creating a functional habitat on Whiskey but was not as successful on Raccoon because the land created there could not be defined as an emergent salt marsh within the 3 yr study period. Low index species presence and lack of breeding marsh species was common for both treatment types though, which suggests that even the reference site can not be classified as an adequate salt marsh habitat for avian species.
All in all, the restoration was a success. Leading to the success, there are 3 ideas that mainly influenced the results.. These ideas are Sand dunes, pulsating waves, and vegetation control. Sand dunes acts like a buffer in between the water and the eroding islands. Pulsating waves keeps the amount of water crashing onto the shoreline to a minimal. The final idea is vegetation control. Vegetation may be used to anchor the sand around the land to keep the soil from eroding too fast.
Next is the ecological principles that the researchers kept in mind. The two main ones we looked at were limited faceted and that components are interconnected. Limiting the number of factors helps a lot as we can see the effects of a small variable change. The other principle is that all components in an ecosystem is all connected to each other and changing one variable may change something else.
The final ideal that the researchers kept in mind is self design. Nature has been around much longer than humanity so nature have full control over variable that humans may never keep up with. This is naturally occurring, so humans almost have no impact in self design. Self design is mainly there to maintain the natural homeostasis of an ecosystem after something has changed. In order for these Islands to remain long term, vegetation must remain to provide structural support against erosion. Without a healthy ecosystem where birds and plants prosper then the island will have to have more sediment added and costly dredging will be the main source of structure.
We actually went ahead and prepared a few questions with answers to give a little more insight into the project.
