How does water quality affect toad populations?
Finn Amster, Hari Kumar, and Matt Halper
Introduction:● Toads are in decline
● Humans have a massive impact on toad habitats
○ Both terrestrial and aquatic
● California toad (Anaxyrus boreas halophilus):○ Lay eggs at high elevations
○ Need open water for breeding
○ Stripe down the middle of the back
Hypotheses:
Toad populations will be higher if
● The temperature is higher● Nutrient concentration is high● pH is neutral
Procedure:
● Pick 4 test sites● Test water quality ● Measure area and depth of body of water● Catch toads over 15 minutes● Count, measure, and release
Research Site 1:
● Eutrophic● Low alkalinity● Soft
Site 1
Research Site 2:
● Eutrophic● Low alkalinity● Soft
Site 2
Research Site 3:
● Oligotrophic● Low alkalinity● Very soft
Site 3
Research Site 4:
● Oligotrophic● Low alkalinity● Very soft Site 4
Research Sites:
Site 3 and 4
Site 3 and 4
Site 2
Site 1
Site 1 and 2
Site 1 Site 3Site 2
Num
ber o
f Toa
ds
Site Number
Toad size and population by site:● T-test, size: site 1 and 2 p = 0.0886
Site
Num
ber o
f toa
ds a
nd T
oad
Size
*
Total Dissolved Solids (ppm)
Num
ber o
f toa
ds
TDS:● Positive correlation
pH:
pH
● Strong positive correlation● Unexpected but probably due to natural geographical water pH● Water tends to be around 8
Number of toads
Hardness:● Strong positive correlation
Hardness (ppm)
Num
ber o
f toa
ds
Number of toads
Size
of p
ond
(cub
ic m
eter
s)
Size of pond:- Positive correlation- Number of toads per cubic meter are somewhat proportional
Discussion:
Main trends
● pH● Pool size● Hardness● TDS
Hypotheses: Revisited
Toad populations will be higher if
● The temperature is higher● Nutrient concentration is high● pH is neutral
How do Humans Relate to Toads and their Survival?
● Human waste greatly affects water sources○ Runoff from sewage, fertilizers, industrial manufacturing, etc.
● Small changes in ponds have big impact on toad populations
Going Forward:Improvements and Sources of Error:
● More data points
● Test temperature throughout the day
Further Questions:
● Cause of elevated pH in Tahoe
● Specific human activity impacting toads
Questions?
Water Temp (°C): 9.7 12.8 16 14.5
Air Temp (°C): 24.2 24.2 24.2 24.2
pH: 8.4 8 7.7 7.6
TDS (ppm): 182 183 29 30
Turbidity (cm): 122 122 122 72
Nitrite (ppm): 0.5 0.5 0 0
Size of Pond (m3): 123.5 19.8 15.8 1.6
Alkalinity (ppm): 1.5 2 7 4.8
Hardness (ppm): 100 50 0 0
Depth (m): 65.2 17.6 39.3 16.5
Number of Toads: 17 7 1 0
Avg. Size (cm): 2.1 1.8 11.5 0
Site 1 Site 2 Site 3 Site 4