Vessel Grounding Management at Lignumvitae Key Botanical State Park

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Vessel Grounding ManagementatLignumvitae Key
Botanical State Park

• Lignumvitae Key Submerged Land Management Area
  (LKMA)

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Vessel Damage

• Results in scars, blowholes and trenches on grass
  beds,
• directly removes seagrass and coral,
• increases erosion and turbidity causing more
  seagrass loss

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EROSION DEEPENS AND WIDENS A BLOWHOLE
LOSS OF ENTIRE FLAT
OVER 137 ACRES OF SEAGRASS DAMAGE WAS VISIBLE ON
1997 AERIAL PHOTOGRAPHY OF LIGNUMVITAE MANAGEMENT
AREA
EROSION, LOSS OF ADDITIONAL GRASS
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Four point management approach at Lignumvitae

• Education
• Channel Marking
• Enforcement
• Limited-Motoring Zones

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On-Site Restoration

• Attempts to repair the most severe sites,
• The following techniques are used
• fill for trenches and blow holes
• seagrass transplants
• temporary bird fertilization stakes to jump-start
  growth

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This site was originally a twin propeller
scar. It eventually eroded into a wide, deep
trench. It was filled to stop further erosion
and further loss of seagrass.
The ultimate long-term goal for this site is
recovery to seagrass habitat. Note the
no-motor sign posted along the channel adjacent
to this site to warn boaters.
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Recovery of seagrass within grid setting of bird
fertilization stakes on a heavily scarred
flat (dark rectangles in the circle).
Bird fertilization stakes in a newly restored
site.
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Costs of Restoration (2005)

• Filling
• About 250 per cubic yard
• Sites generally require 15 to 300 cubic yards of
  fill.
• Staking and Planting
• About 35 per single stake and plant unit
• Sites generally require from 25 to 200 units

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• SUCCESS OF RESTORATION
• GOAL OF ARRESTING EROSION HAS BEEN 100 ACHIEVED
  ON ALL SITES.
• GOAL OF RESTORING SEAGRASS HAS HAD MIXED SUCCESS
  DEPENDING ON THE SITE AND GENERALLY REQUIRES A
  LONG PERIOD OF TIME (OVER 2 YEARS).

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• When YOU Go Boating, Why Not
• Take a look at your chart for a minute before you
  leave,
• Dont be afraid to ask the locals for advice if
  youre unfamiliar with the area,
• If youre out and about and not sure about the
  markers, slow down for a minute and be sure.
  Whats the hurry?
• Save yourself, the environment, and the
  government some time and money by avoiding
  grounding when you can.
• THANK YOU AND HAPPY BOATING!