Invasive Aquatic Species

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Invasive Aquatic Species In The Atchafalaya
Basin Glenn Thomas Rachel Walley
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Acknowledgements Jody David LDWF Inland
Fisheries Dist. VI Jill Jenkins USGS/LSU
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• Asian Carps
• Common (German) carp Cyprinus carpio
• Grass carp Ctenopharyngodon idella
• Silver carp Hypophthalmichthys molotrix
• Bighead carp H. nobilis
• Black carp Mylopharyngodon piceus

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• Ecological Impacts
• Primary Feeding Strategies
• Consumption (depletion)
• Competition (displacement)

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Fishery-Independent Captures Atchafalaya
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Commercial Landings Statewide
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Reduced condition factor of two native fish
species coincident with invasion of non-native
Asian carps in the Illinois River, U.S.A. Is this
evidence for competition and reduced fitness?
IRONS, SASS, MCCLELLAND, AND STAFFORD Journal of
Fish Biology (2007)
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Gizzard Shad
Bigmouth Buffalo
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Gizzard Shad
Bigmouth Buffalo
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Continuing Research
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Ploidy Determinations
Is fish diploid or triploid? Detection of 2N or
3N status can assist with tracking occurrence and
potential source type (e.g. escapements from
captivity, intentional introduction, or breeding
populations)
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Ploidy Determinations
Nile tilapia 2.2 pg diploid black carp 2.1,
triploid black carp 3.2 pg.
(ALL BLACK CARP HAVE BEEN NORMAL DIPLOIDS)
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Channeled Apple Snail Pomacea canaliculata

• South America Amazon Basin
• Asia
• Throughout Tropics aquarium trade, food
• 1 rice pest Philippines
• Established, Jefferson parish
• Identified, Iberia parish

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Aquatic Plant Communities

• Invasive species are in high abundance
• Native plant species are in peril
• Competition for resources

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Troublesome Species

• Common Salvinia
• 1980, South and Central America
• Water Hyacinth
• 1880s, South America
• Hydrilla
• 1970s, Southeast Asia
• Giant Salvinia
• 2006, Brazil

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Paragrass Brachiaria mutica

• Africa to Florida, pasture grass cattle forage
• Hollow floating stems, 6 meters across slow
  moving water
• Fresh or brackish
• Considered one of the worst weeds in the world

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Invasive Submersed Versus Native

• Hydrilla branches at the waters surface to forms
  dense canopies

Coontail Ceratophyllum demersum Fanwort Cabomba
caroliniana
Hydrilla H. verticillata
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Invasive Floating Versus Native

• Form dense mats
• Shade-out native submersed
• Inhibits algal photosynthesis

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Study Area
Randomly selected sample sites that represent the
different habitat types characteristic of the ARB
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Methods

• Low water stage
• Survey of percent coverage at each site
• Water and soil samples collected

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Percent Coverage Across Habitat Types


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Plant Community Interactions

• MANOVA
• Total percent coverage
• Inverse relationship between the percent coverage
  of native and invasive plants
• Reduced model

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Plant Community Interactions
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Conclusion

• Dominated by a few invasive species that
  overwhelm the many, but less aggressive, native
  species
• Recommendations
• Improve control methods for management
• Herbicides
• Biological control
• Prevention
• Education to increase public awareness

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Acknowledgements

• Committee members
• Drs. William E. Kelso, D. Allen Rutherford, Megan
  La Peyre
• Dr. Michael D. Kaller, Debra Kelly, Dr. Robert
  Gambrell, Adam Piehler, Brian Heiman, Jerry Lang,
  Lauren Hart, Robyn Sellers, Jenny Bodin, Jonathan
  Fisher, Thorpe Halloran, Jesse Bahm, Jonathan
  West.