Predation Impacts of Round Goby on Zebra Mussels in the Great Lakes

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Predation Impacts of Round Goby on Zebra Mussels
in the Great Lakes

• Megan Fencil

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Static vs. Dynamic modeling

• In fisheries ecology, GIS is mainly used for
  descriptive mapping.
• Increased need for visualization of ecological
  models
• - spatially and temporally dynamic factors
• - interaction of species when they meet
• Ill focus on predator-prey interaction of round
  gobies and zebra mussels
• Difficulties
• Large number of assumptions
• Too many interaction effects to model
• Lack of data

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Zebra mussel(Dreissena polymorpha)

• Native to Russia
• Introduced to U.S. in ballast water
• Negative impacts clog pipes, foul ships,
  litter beaches, sink buoys, colonize native
  animals
• 5 billion cost in 10 years (U.S. Fish and
  Wildlife Service)
• Positive impact improved water clarity from 6
  inches to 30 feet!

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Zebra mussels spread very rapidly!
1st U.S. appearance in 1988 Lake St. Clair years all Great Lakes, Mississippi, Tennessee,
Hudson, and Ohio River basins
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Round goby(Neogobius melanostomus)

• Native to Black Caspian Seas
• Introduced to U.S. in ballast water
• Negative impacts
• Aggressively eat eggs fry of native fishes
• Outcompete native species for nest sites
• Excellent sensory system gives an advantage
  (night)
• Very robust
• Spawn over long time period in summer
• Rapid population growth (20/m3 in Calumet Harbor
  20 fish in a bathtub)

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Round gobies competitively displace native species
Is there room for one more?
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The spread of round gobies

• 1990 St. Clair River (channel between Lake Huron
  and Lake St. Clair)
• 1994 well-established in Lake Erie
• 1995 Lake Superior and Lake Michigan

Ohio State University
Preventing the spread electric goby barrier
Map modified from USGS website,2001
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Interaction of gobies and zebra mussels

• Gobies eat up to 78 zebra mussels/day
• Gobies prefer small mussels near the substrate
• Mussels in goby-free waters are larger
• Gobies are main predators of mussels
• BUT, zebra mussels will not disappear due to
  gobies
• Negative effect of predation mussels filter-feed
  and bioaccumulate toxins
• Sport fish (bass, walleyes, perch, trout) may be
  affected

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Work in Progress Clarifying the problem with
ArcGIS

• Apply a population growth model to overlaid
  distribution maps of mussels and gobies
• - Where do they interact?
• - What will be the effect on mussel population
  size?
• Population growth for prey (zebra mussels)
  population (Lotka-Volterra)
• dH / dt r H - b1 H P
• H number of prey
• P number of predators
• r rate of growth for prey population
• b1 predation rate (coefficient expressing the
  efficiency of predation)

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Predicting the potential spread of invasives

• Hitchhikers are carried on/in recreational
  boats
• If they arrive at an new site, can they survive?
• Potential for invasion requires proper
  conditions
• Light
• Depth
• pH
• Temperature
• Food supply

Overlay of layers can predict invasion
success - Several currently uncolonized sites
will be studied - Can they support zebra mussels
and/or round gobies?