Hamline University Graduate School St' Paul, Minnesota

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Hamline University Graduate SchoolSt. Paul,
Minnesota
Frogs as Bio-indicators Joan Chadde, MI
Technological University Tony P. Murphy, Hamline
University Kristin Schuster, Houghton Middle
School
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Hamline University Graduate SchoolSt. Paul,
Minnesota
What are we being told by Amphibian (frog and
toad) malformities Amphibian populations locally
and globally But first

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Vs.
Frogs have
Toads have

• cold blood cold blood
• smooth or slimy skin warty and dry
  skin
• strong, long legs and stubby bodies
  with short webbed hind feet
  hind legs
• two bulging eyes parotid glands
  behind eyes
• lay eggs in clusters lay eggs in
  long chains
• a group of frogs is called a group of
  toads is called
• an ARMY of frogs a KNOT
  of toads

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Anuran Diversity
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Frogs and Toads

• 14 species in MN,
• 13 species in
• MI

92 species in USA
3,300 species in the world
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MN Frogs and Toads
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Why We Care

• Anurans are a part of the planets bio-diversity.

2. Anurans interact in interesting ways with each
other and the environment, i.e. both prey and
predators
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Why We Care
3. Anurans provide benefits to humans
i.e. Gastric Brooding Frog of Australia might
have provided answers for people suffering from
gastric ulcers
(Case of the Vanishing Frogs, T. Halliday and W.
R. Heyer).
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4. Frogs As Bio-indicators

• 1) double life--amphibious
• 2) permeable skin
• 3) absorb and concentrate toxins--biomagnification

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4. Frogs As Bio-indicators

• Biomagnification a process in which retained
  substances become more concentrated with each
  link in the food chain

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Malformed Amphibians
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External Malformations

• extra or missing limbs
• branching limbs
• spikes or protuberances
• missing eyes
• abnormal webbing

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Internal Malformations

• reproductive
• digestive
• urinary

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Malformed Frog Pictures
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Dr. David Hoppe, University of Minnesota-Morris
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Dr. David Hoppe, University of Minnesota-Morris
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Dr. David Hoppe, University of Minnesota-Morris
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Dr. David Hoppe, University of Minnesota-Morris
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Causes of Malformations

• genetic origins
• parasite disruption of limb formation
• chemical contamination
• viruses
• ultraviolet radiation
• physical trauma (predation,
• people)

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Trematode (flatworm) cysts have been demonstrated
to cause problems in limb bud development in
tadpoles
Dr. Stanley K. Sessions, Hartwick College
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Dr. Stanley K. Sessions, Hartwick College
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Possible Chemical Contaminants

• agrochemicals
• heavy metals
• acid rain
• chlorofluorocarbons (CFCs)

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Types of Agrochemicals

• herbicides
• Maneb-fungicide
• pesticides
• propylthiourea
• fertilizers

Dr. Stanley K. Sessions, Hartwick College
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Types of Agrochemicals

• applications of the herbicide atrazine have led
  to egg mortality and tadpole deformities
  (Hazelwood 1970)

Dr. Stanley K. Sessions, Hartwick College
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Where have all the frogs gone? Global Anuran
Decline

• a concern during the past decade
• frog declines widespread and well-documented
• possible causes include habitat destruction,
  increased UV radiation, and chemical
  contamination

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Global Population Declines

• Loss of habitat
• from filling in wetlands to create more
  farmland for crops, and to build more houses and
  roads

(Case of the Vanishing Frogs, T. Halliday and W.
R. Heyer).
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Global Population Declines

• Increasing ultraviolet radiation
• Pollution by chemicals
• Acid rain
• Pathogens
• Parasites
• Introduction of non-native species