Geoscience Reference
In-Depth Information
strengthened.by.either.amorphous.or.crystalline.calcium.carbonate..Mollusk.shells.
have.crystals.of.calcium.carbonate.dispersed.in.an.organic.matrix.(Lowenstam.1981;.
Harper.2000)..These.calcium.carbonate.crystals.take.the.form.of.either.aragonite.or.
calcite,.there.being.considerable.variation.within.molluskan.families.in.crystal.type.
(Taylor.and.Reid.1990)..Because.aragonite.is.at.least.50%.more.soluble.in.acidic.sea-
water.than.calcite,.mollusks.with.aragonite.shells.may.be.particularly.susceptible.to.
acidiication.(Mucci.1983;.Feely.et.al..2004)..Because.the.shell.thickness.affects.the.
susceptibility.to.breakage.(Vermeij.1979),.mollusks.will.presumably.become.more.
vulnerable. to. predators. (e.g.,. ishes,. crabs,. and. shorebirds),. abrasion. from. storms,.
and.also.to.crushing.by.off-road.vehicles..It.is.thus.reasonable.to.assume.that.many.
beach.species.will.be.at.risk.if.their.calcium.metabolism.is.impaired.
An.elevated.level.of.CO
2
.can.have.other.marine.biological.effects..First,.it.may.
promote.photosynthesis.(Melillo.et.al..1993).and.thus.the.nutritional.supply.to.beach.
fauna..Second,.elevated.CO
2
.leads.to.the.acidosis.of.tissues.and.body.luids.with.neg-
ative.consequences.for.growth.and.reproduction,.especially.in.lower.marine.inver-
tebrates.because.they.have.a.weak.capacity.for.physiological.compensation.(Pörtner.
et.al..2004;.Pörtner.2008)..Third,.acidiication.can.reduce.the.development,.growth,.
and.survival.of.planktonic,.invertebrate.larvae.(Dupont.et.al..2008;.Kurihara.2008),.a.
situation.with.probable.consequences.for.beach-dwelling.adults..Finally,.the.possibil-
ity.of.long-term.negative.effects.is.suggested.by.the.role.of.oscillations.in.aquatic.CO
2.
in.the.Permian.Triassic.mass-extinction.events.(Bambach.et.al..2002;.Berner.2002).
Alternatively,. elevated.CO
2.
and.acidity.may.pose.few.problems.for.species.that.
can.acclimate.or.adapt,.that.have.a.specialized.tolerant.physiology,.or.that.are.pre-
adapted.to.environments.with.wide.natural.variations.in.CO
2
.(Pörtner.et.al..2004)..
Sandy.beaches.may.be.such.environments.because.interstitial.CO
2.
concentrations.are.
naturally.variable,.i.e.,.they.increase.during.high.tide.and.decrease.during.low.tide.
(Pearse.et.al..1942)..Species.living.interstitially,.especially.nematodes.and.harpacti-
coids,.can.be.tolerant.of.both.varying.pH.and.temperature.(Wieser.et.al..1974).
i
nTeraCTing
s
Tressors
More.complicated.are.the.effects.of.interactions.among.climate-change.factors.and.
with.other.anthropogenic.pressures..For.example,.if.the.shells.of.calcifying.species.
are.weakened.by.lowered.pH,.they.may.be.more.susceptible.to.vehicles.and.heavier.
storms..In.addition,.nonclimate.factors.such.as.pollution.may.act.to.lower.the.resil-
ience. of. assemblages. to. the. pressures. of. climate. change.. Also,. the. interaction. of.
increased.wave.energy.with.sea-level.rise.and.spring.tides.may.combine.to.exacer-
bate.the.erosion.of.beaches.and.dunes.with.probable.ecological.impacts..While.the.
intertidal.beach.invertebrates.may.recover.rapidly.from.storms.(Ansell.1983),.their.
effects. on. dunes. would. persist. longer. if. attached. dune. plants. and. their. dependent.
fauna.were.lost.(Brown.and.McLachlan.2002;.DLWC.2001)..Birds.such.as.the.Little.
Tern,. Pied. Oystercatcher,. Beach. Stone-Curlew,. Hooded. Plover,. and. Red-Capped.
Plover. nest. in. the. supralittoral. (Annette. Harrison,. pers.. comm.). as. do. the. Green.
Turtle.and.Leathery.Turtle..Consequently,.these.species.would.be.at.risk.and.most.
are.already.listed.as.threatened.
