Hydrilla Hydrilla verticillata Management at SJRWMD

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Hydrilla(Hydrilla verticillata) Management at
SJRWMD
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District Goal for Management of Invasive Aquatic
Species

• To maintain control of nuisance aquatic
  vegetation, to protect the integrity of all
  structures, improve flood protection, navigation,
  recreation, and water quality.

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Methods used to control Hydrilla

• Herbicides Two types
• Contact - Aquathol-K
• Systemic - Sonar (Fluridone)
• Mechanical-- Harvesters
• Biological ---- Chinese grass carp

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Herbicide- ContactsAquathol-K (ENDOTHALL)

• Advantages
• Short residence time issues
• Little or no translocation through water
• Disadvantages
• With contact herbicide control can be temporary
  (like mowing lawn)
• Non-target plants sprayed with herbicide can be
  affected.
• Dissolved Oxygen levels can become low.
• Cost 750/acre

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Herbicide SystemicSonar (Fluridone)

• Advantages
• Can kill roots and shoots.
• Long lasting effect.
• Variety of emergent and submersed aquatic plants
  are susceptible
• Fluridone should not affect human health,
  zooplankton, benthic invertebrates, fish, and
  wildlife.
• Disadvantages
• It is slow acting - may take up to several months
  to reach full effect.
• Requires long residence time
• Some hydrilla has developed resistance.
• Cost 250/acre

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Mechanical Harvesters

• Advantages
• Can reduce sediment accumulation and DO problems
  by removing organic matter that normally decays
• Disadvantages
• Heavy wet material must be transferred to boat
  ramp and hauled off.
• Not species specific
• Can be detrimental to juvenile fish which are
  removed indiscriminately by the process.
• Only viable for large open areas with few surface
  obstructions.
• Cost 1000-5000/acre depending on location of
  disposal site

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BiologicalChinese grass carp (Ctenopharyngodon
idella)

• Advantages
• Most effective biological control agents.
• This voracious herbivore prefers hydrilla and
  2-25 fish can completely control one acre of
  hydrilla.
• Disadvantages
• Not selective, will devour most submersed as well
  as immersed.
• Can only be used in water bodies where they can
  be contained.

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Costs Assuming 1000 acre lake 8 foot deep

• Maintenance control treat it whenever
  discovered 45,000 annually
• (20 acres treated 3 xs annually at 750/acre)
• Manage at 30 coverage 450,000 annually
• (300 acres treated 2 xs annually at 750/acre)
• 30 gets out of hand and requires whole lake
  treatment 250,000
• (1000 acres at 250/acre with Fluridone)

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DEP History With The District

• Up until 1999 the District managed as many as 40
  DEP waterbodies.
• Since 1999 the district has returned all but 8 of
  those waterbodies back to DEP for management.
• This action was taken so the District staff could
  more effectively address control of upland exotic
  plant species that were being identified on
  District properties.

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DEP WaterbodiesManaged By S.J.R.W.M.D. as of 1999

• Lake Apopka
• Lake Blue Cypress
• St. Johns River
• Lake Helln Blazes
• Little Lake Sawgrass
• Lake Sawgrass
• Lake Washington
• Econlockhatchee

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Reasons for Hydrilla Control

• Hydrilla has the potential to hinder the growth
  of beneficial aquatic plants.
• It interferes with flood control, irrigation and
  navigation.
• It can adversely affect the public welfare (water
  supply, bridges, etc.)
• To prevent dissolved oxygen problems (fish
  kills).

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• What happens if we dont control
• Hydrilla?

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The Hwy 192 Bridge Crossing Over The St Johns
River 7/7/92
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Walking Across The St.Johns River Along The
Bridge At Hwy 192
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7/4/92 In River looking North at Camp Holly and
the Bridge
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Camp Holly Boat Ramp July 1992 Before/After
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1992 Lake Saw Grass Before/After
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Clearing River Channel North End Of Lake Helln
Blazes August 1992
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Stick Marsh Summer 2000
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Herbicide Application History Of The 6500 Acre
S.J.W.M.A. / Stick Marsh Since1999

• 1998-1999 229 Acres/Sonar liquid
• 1999-2000 100 Acres/Aquathol-K Liquid
• 2000-2001 234 Acres/Aquathol -K Liquid
  granules
• 2001-2003 No Applications, Hydrilla is at 80
  coverage.
• 2004---Hurricanes have removed all submersed
  vegetation and hydrilla has not been able to
  rebound.
• 2004-2007- No Applications, Hydrilla has not
  recovered.

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Any Questions?
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What are the blogs saying about the Stick Marsh
Now 2007!!
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blog.myspace.com/stickmarshbaittackle March 15
2007 Five bass over ten pounds each another
four over eight pounds each a total of more than
thirty and close to forty bass top five bass
weighted 56.25 lbs. Top 10 bass bass weighted
over 113 pounds three men fishing about seven
hours in the stick on march 15, 2007. All men in
the same boat. Pretty good day? It does not get
much better than that!! The FWC biologists
have said there is more bass than ever before in
the Stick Marsh and Farm 13. The biologists have
said the bass are larger than ever before.
Todays fishing by Mark Gross, Stanley Gross and
guest Ross with Hugh Crumpler as guide is just a
small proof the biologist know what they are
talking about.