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  • 1. The Effects of Road Salt (NaCl) on the Survivorship of Two Vernal Pool-Breeding Amphibians:
    The Wood Frog (Rana sylvatica) and Spotted Salamander (Ambystoma maculatum)
    Denise M. Roth
    Baldwin-Wallace College
    Department of Biology
    May 1, 2009
  • 2. “Why should we care if they all die? They are gross anyway!”
    -BW student
  • 3. Well… Good Question
  • 4. Algae
  • 5. So… What is going on?
    E.O. Wilson says:
    Habitat destruction
    Invasive species
  • 6. What is a Vernal Pool??
    Form from melting snow and spring rains
    Dry mid to late summer
    Naturally occurring
    Shallow (4ft > deep)
    Impermeable substrate on bottom
    Free of predatory fish
  • 7. Vernal Pool (cont.)
    Contain one or more of four indicator species
    Blue-spotted Salamanders (Ambystoma laterale)
    Fairy Shrimp (Anostraca)
    Wood Frog (Rana sylvatica)
    Spotted Salamander (Ambystoma maculatum)
  • 8. Wood Frog
    (Rana sylvatica)
  • 9. Wood Frog: Reproduction
  • 10. Spotted Salamander (Ambystoma maculatum)
  • 11. Spotted Salamander: Reproduction
  • 12. Egg Masses
  • 13. Salts as De-Icing Agents
    NaCl most common
    5 million tons/yr in Canada
    10-15 million tons/yr in US
    (Environment Canada Website)
    Lower freezing point of water!
    melts at lower temperatures
    Above ~ 15˚F
  • 14. Effects of road de-icing salt (NaCl) on larval wood frogs (Rana sylvatica)
    DomenicoSanzo, Stephen J. Hecnar 2003
    Environmental pollution
  • 15. Objective
    Determine the effect of road salts, if any, on amphibians at environmentally relevant field concentrations
    Road salts have a negative effect on amphibians.
  • 16. Study Location
    Thunder Bay, Canada
    Lakehead University Environmental Laboratories
  • 17. Field Concentrations
    Water analysis of 59 wetlands
    2 water samples from opposite ends of each
    Analyzed in university lab
    Expected to see:
    Salt concentrations negatively correlated with increasing distance of a wetland from the nearest road
    Negative correlation between salt concentrations and species richness
  • 18. Results: Field Concentration
    Range in NaCl from 0.39 to 1030.00 mg/l
    Seawater ~ 3.5% NaCl ( 19,400 mg/l)
    NaCl decreased with increasing distance from nearest road
    Species richness negatively correlated with NaCl and
    positively correlated with increasing distance to nearest road
  • 19. Materials and Methods:Acute Toxicity
    Experiment time 96 hours
  • 20. Methods cont.
    Death defined: “… no response to continued prodding with a glass rod.”
  • 21. Results: Acute Toxicity
  • 22. Results: Acute Toxicity (cont.)
  • 23. Methods:Chronic Toxicity
    30 tadpoles to each tank
  • 24. Methods (cont.)
  • 25. Results: Chronic Toxicity
  • 26. Mean time to Morph vs. Chronic Treatment concentrations
  • 27. Discussion
  • 28. Conclusions
    Road salts have a negative impact
    Chloride in roadside pools much higher than woodlands
    Supports hypothesis
    Species richness negatively correlated with NaCl concentrations
    Fewer tadpoles metamorphose with higher concentrations
    Does this relate to other amphibians? and is the evidence conclusive?
  • 29. Sara J. Collins, Ronald W. Russell 2006
    Environmental pollution
    Toxicity of road salt to Nova Scotia amphibians
  • 30. Objective
    “…examine how chloride concentrations in ponds, due to application of road salt, influence amphibian community structure and richness in roadside wetlands of Nova Scotia.”
    Elevated Chloride concentrations affect amphibian populations
  • 31. Nova Scotia
    April-Sept. 2006
    26 ponds
  • 32. Field Methods
    Water samples collected for lab analysis
  • 33. Chloride Concentrations
  • 34. Results: Species Richness
  • 35. Methods:Acute Toxicity
    Larvae of 5 amphibian species:
    Spotted Salamander
    Spring Peeper
    Wood Frog
    Green Frog
    American Toad
  • 36. Methods (cont.)
  • 37. Species Abundance vs. Chloride Concentrations
  • 38. Results: Acute Toxicity Tests
  • 39. Conclusions
    Spotted Salamanders and Wood Frogs were most sensitive to NaCl
    Road salt concentrations affected community structure
    Sensitive species were absent from high chloride concentrated ponds
    Acute toxicity results supported field observations
    Behavioral changes could result in reduction of species fitness
  • 40. Interpretation
    Exposure to road salts can affect amphibian community structure and species richness by excluding salt-sensitive species from high chloride environments
  • 41. Overall Conclusions
    At environmentally realistic concentrations, road salt caused physiological issues and decreased survivorship in amphibians.
    Acute toxicity results of both studies showed high rates of mortality
    Chronic exposure caused physiological differences
  • 42. This is not new information!
    In 1859 Charles Darwin noted that “nearly all amphibians and their spawn were killed by sea water”
    (Origin of Species)
  • 43. http://kornorstone.com/db3/00225/kornorstone.com/_uimages/BubbleBoy1.jpg
  • 44. Alternatives
    Potassium Acetate -76˚F $700-800/ton Less toxic; less corrosive; can cause %50 solution irritation if inhaled
  • 45. Future Studies
    Why do higher salt concentrations cause tadpoles to metamorphose faster?
    Why was there a spike in survival from 7500-9000 mg/l?
    Possible mutagenic effects of developing tadpoles
    Effects of other road salts on these two species
    Reasons for salt tolerance seen in the American Toad
    Long term effects on community structure
    How chemical runoff affects people
  • 46. “We now face an extinction episode on this planet comparable to that which marked the end of the dinosaurs about 65 million years ago”(Planet Earth Episode 1)
  • 47. Thank You!!
    BW Faculty:
    Friends… all of you!
  • 51. Questions?
  • 52. Function of Chloride
    Chloride: membrane function and water absorption
    In the body reacts with potassium
    Helps maintain osmotic equilibrium by creating concentration gradient
    through ATP either goes in to the cell or leaves the cell ~ based on solute concentration in the water vs. solute in the cell
    Moves from high to low concentrations
    Helps maintain pH
    Kidney function: co-transport proteins
    Na+, K+, Cl -