Geoscience Reference
In-Depth Information
climate.change.is.already.affecting.both.terrestrial.and.marine.ecosystems.in.many.
ways.(Kennedy.et.al..2002;.Hughes.2003;.Schiel.et.al..2004;.Lovejoy.and.Hannah.
2005;.Harley.et.al..2006;.Vezina.and.Hoegh-Guldberg.2008;.Brierley.and.Kingsford.
2009;.Belant.et.al..2010;.Najjar.et.al..2010)..The.actual.biological.processes.involved.
are.dificult.to.identify.but.include.growth,.distribution,.reproduction,.activity.rates,.
recruitment,.and.mortality.(Drinkwater.et.al..2010)..Moreover,.some.forecasts.and.
speculations.have.been.made.about.the.consequences.of.climate-driven.biodiversity.
changes.on.the.functioning.of.rocky-shore.ecosystems.(Hawkins.et.al..2009),.on.the.
structure.of.calcifying.assemblages.(Kurihara.2008),.on.the.development.of.marine.
invertebrate.larvae.(Dupont.et.al..2008),.and.on.the.biomass.of.intertidal,.estuarine.
invertebrates.(Fujii.and.Raffaelli.2008).
An. important. question. involves. the. ability. of. species. to. acclimate. or. adapt. to.
climate.change,.given.that.climate-related.extinctions.have.already.occurred.in.some.
habitats.(Walther.et.al..2002;.Hughes.2003)..Species.able.to.migrate.poleward.may.
evade.temperature.stress.but.not.other.stresses.(e.g.,.increased.storminess.and.acid-
ity).. Furthermore,. surviving. species. are. likely. to. live. in. assemblages. whose. com-
position.has.been.altered.by.climate.change—another.evolutionary.pressure..Taken.
together,. these. evolutionary. pressures. may. well. have. profound. ecological. effects..
Although. there. is. little. climate-related. research. on. sandy-beach. species. directly.
(Jones.et.al..2007),.some.broad.ecological.effects.of.climate.change.on.beaches.can.
be.suggested.from.general.principles.and.relevant.research.from.other.habitats.
T
emperaTure
By. 2070,.annual.average.air. temperatures. are.projected.to.rise.by.1.0-6.0°C.rela-
tive.to.1990,.and.changes.in.extreme.temperatures.are.also.expected.(IPCC.2007)..
Presumably,.rises.in.water.temperature.would.be.less.than.those.for.the.air,.and.the.
extremes. would.be.less.severe.. Nevertheless,. because.temperature. is.an.important.
ecological.factor.(Krebs.1978).and.some.species.are.stenothermal.(Kennedy.et.al..
2002),. even. small. temperature. changes. may. have. severe. ecological. consequences..
For.example,.Leemans.and.van.Vliet.(2005).judged.that,.to.be.ecologically.accept-
able,.temperature.rises.should.not.exceed.1.5°C,.and.the.rate.of.change.should.be.less.
than.0.5°C.per.decade.
In. terms. of. biogeography,. warming. is. likely. to. cause. a. poleward. shift. in. inter-
tidal.species'.distributional.boundaries.with.the.replacement.of.coldwater.species.by.
those.from.warmer.waters.(Kennett.and.Stott.1991)..In.addition,.along-shore.distri-
butions.may.be.altered.by.a.“squeeze”.effect.(Harley.et.al..2006)..Here,.abiotic.stress.
may.alter.across-shore.zonation.patterns.such.that.a.given.species.may.be.displaced.
(squeezed).by.another.species.moving.into.its.zone..These.processes.would.change.
the.assemblage.composition.on.any.shore,.although.this.is.not.necessarily.a.cause.for.
concern.because.variation.in.the.composition.of.biotic.assemblages.is.normal.and.
assemblage.diversity.and.function.may.change.little.
The. species. most. affected. would. be. those. now. living. close. to. their. upper. ther-
mal.limit.and.unable.to.acclimate.or.adapt..They.would.become.locally.extinct,.and.
their.persistence.would.depend.on.migration.to.cooler.areas..This.may.be.dificult.
for.intertidal.species.(IPCC.2001),.especially.those.lacking.dispersive.larval.stages,.
