Amphibians as
Ecological Indicators
Herpetoculture
Pensacola Jr College
Background
w Amphibian declines over past
25 years
w Species or communities
w Some declines have known
human cause, some dont
w Long term field studies
needed to evaluate significance of declines
Relation to
Physiology
w Amphibians have no skin
protection
w Amphibian skin is most
permeable of any animal group
w During rehydration, absorb
toxic organic residues
Results =
Ecological Indicator Species
w Amphibians are the most
sensitive animals to:
Environmental contamination (toxins, diseases, etc)
UV radiation
w When amphibian numbers
decline in an area, provides early warning signal
Reasons for
Declines
w Habitat destruction (esp.
breeding sites)
w Direct killing / removal
w Introduction of non-native
predators / competitors
w Exposure to increased UV-B
w Introduction or increase in parasites
/ diseases
Reasons for
Declines (contd)
w
Global environment change:
Higher temperatures
Acid rain
Rainfall pattern changes
w Absorption through skin:
Pollutants, pesticides, toxins
w
Natural population cycling
Case Study 1
Minnesota Frogs
w 1995: high school students
in Minnesota find deformed frogs
w Continued study due to fears
re: human water supply
w Controversies: is it
widespread, cause, etc.
Leopard frog
deformed legs
Leopard frog
poor metamorphosis
Leopard frog
missing leg
Toad extra leg
Frog- extra set of
hind legs from stomach
Leopard Frog
missing eye
Case Study 2
Slender Salamander Monitoring
w Plethodontidae: breath
through skin only
w Why use them to monitor?
Found in very high numbers
Near bottom of food chain,
critical to food web
They indicate health of
habitat
Garden Slender
Salamander
Amphibian
Conservation
w Conservation organizations:
less than 3% of budgets to herps (mostly birds and mammals)
w Amphibians do not always
have needs met by mammal/ bird reserves
w What happens if we continue
to ignore them?