Some Effects of the Little Vermilion Bay Sediment Trapping Project or: Whats the Deal with Terracing

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Some Effects of the Little Vermilion Bay Sediment
Trapping Project orWhats the Deal with
Terracing ?
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Questions

• Do terraces help to spur Submerged Aquatic
  Vegetation (SAV) growth?
• How much do terraces sink?
• Do terraces increase sedimentation?
• Fate of borrow ditches?
• Will emergent marsh vegetation colonize the
  terraces?

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Project and Reference Areas
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1999
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1999
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Project created 56 acres
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June 2000 - 1 year post-construction
August 2001 2 years post-construction
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Methods

• Aerial photography and land / water analysis
• Elevation survey
• Emergent vegetation sampling
• SAV sampling

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Methods

• Aerial photography and land / water analysis
• Elevation survey
• Emergent vegetation sampling
• SAV sampling

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Methods

• Aerial photography and land / water analysis
• Elevation survey
• Emergent vegetation sampling
• SAV sampling

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July 2002
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Methods

• Aerial photography and land / water analysis
• Elevation survey
• Emergent vegetation sampling
• SAV sampling

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Results

• Sediment depostion and elevation
• Emergent vegetation
• SAV

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April 2003
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Emergent Vegetation

• 42 species documented only S. alterniflora was
  planted
• In 2002, 98 of samples contained desirable
  wetland species
• In 2004, 97 of samples contained desirable
  wetland species

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Typical Terrace
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SAV
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Summary

• Do terraces help to spur Submerged Aquatic
  Vegetation (SAV) growth? Unproven
• How much do terraces sink? Not much
• Do terraces increase sedimentation? Yes
• Fate of borrow ditches? Most fill in
• Will emergent marsh vegetation colonize the
  terraces? Yes

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Acknowledgements

• NMFS, project sponsor
• USGS
• Troy Barrilleaux, LADNR
• Christine Thibodeaux, LADNR
• Dona Weifenbach, LADNR