Geoscience Reference
In-Depth Information
relatively. undisturbed. by. humans,. such. as. national. parks,. conservation. sites,. and.
rural.areas.some.distance.from.urban.centers.
There. appears. to. be. no. single. cause. for. amphibian. population. declines.. Like.
other. animals,. amphibians. are. affected. by. numerous. environmental. stresses. that.
often.act.in.complex.ways.(Blaustein.et.al..2011)..The.causes.for.the.decline.of.a.
given. species. may. be. different. from. region. to. region. and. even. in. different. popu-
lations. of. the. same. species.. Synergistic. interactions. between. more. than. one. fac-
tor.may.be.involved..There.may.be.interspeciic.differences.and.even.differences.
between. life. stages. in. how. amphibians. react. to. environmental. changes. and. other.
stresses.
Some. of. the. concern. about. amphibian. population. declines. is. due. in. part. to. the.
fact.that.amphibians.are.considered.by.many.biologists.to.be.excellent.“indicators”.of.
environmental.change.and.contamination.(Blaustein.1994;.Blaustein.and.Wake.1995)..
They.have.permeable,.exposed.skin.(not.covered.by.scales,.hair,.or.feathers).and.eggs.
(not. covered. by. shells). that. may. readily. absorb. substances. from. the. environment..
The.complex.life.cycles.of.many.species.potentially.expose.them.to.both.aquatic.and.
terrestrial.environmental.changes..These.attributes.and.the.fact.that.amphibians.are.
ectotherms.make.them.especially.sensitive.to.changes.in.temperature,.precipitation,.
and.other.environmental.changes.such.as.increases.in.ultraviolet.radiation.
KEY ISSUES
In.this.chapter.we.address.several.key.questions.concerning.the.effects.of.contempo-
rary.climate.change.on.amphibians..Are.amphibian.populations.affected.by.global.
climate.changes?.What.are.the.major.climate.changes.affecting.amphibian.popula-
tions?.How.are.amphibian.populations.affected?.In.addressing.these.questions,.we.
summarize.how.amphibian.populations.may.be.affected.by.global.climate.changes,.
and. we. identify. some. of. the. main. agents. contributing. to. climate. change.. We. also.
attempt.to.incorporate.several.key.methods/paradigms.that.biologists.use.to.assess.
how.populations.may.be.affected.by.climate.change.
PERSPECTIVE ON GLOBAL CLIMATE CHANGE
In.the.1970s,.environmental.biologists.and.atmospheric.scientists.predicted.that.two.
signiicant.human-induced.environmental.changes.(global.warming.and.ozone.deple-
tion).could.potentially.affect.the.biology.of.a.wide.array.of.plants,.animals,.and.micro-
organisms.(Andrady.et.al..2009)..Increased.emissions.of.“greenhouse”.gases.resulting.
from.burning.fossil.fuels.and.land.conversion.were.projected.to.cause.a.signiicant.rise.
in.global.temperatures.in.the.coming.decades..Moreover,.it.was.shown.that.chloroluo-
rocarbons.(CFCs).and.other.commonly.used.industrial.gases.were.depleting.the.earth's.
protective.ozone.layer,.increasing.the.amount.of.cell-damaging.ultraviolet-B.(UV-B;.
280-315. nm). radiation. that. reaches. the. Earth's. surface. (van. der. Leun. et. al.. 1998)..
Scientists. projected. that. species. might. respond. to. these. global. changes. by. altering.
their.behavior.and.shifting.ranges..However,.if.they.are.unable.to.adapt.to.these.envi-
ronmental.changes,.they.may.experience.increased.mortality.and.signiicant.sublethal.
effects..Additionally,.a.number.of.scientists.suggested.that.global.warming.and.ozone.
