Talitrid orientation as bioindicator of shoreline stability: protected headland-bays versus exposed extended beaches

(1)

ContentslistsavailableatScienceDirect

Ecological

Indicators

j ou rn a l h om ep a g e :w w w . e l s e v i e r . c o m / l o c a t e /e c o l i n d

Talitrid

orientation

as

bioindicator

of

shoreline

stability:

Protected

headland-bays

versus

exposed

extended

beaches

F. Scapini

a,∗

_,

_S.

_Gambineri

b

_,

_C.

_Rossano

c

_,

_M.

_ElGtari

d

_,

_L.

_Fanini

e

_,

_D.H.

_Nourisson

f

a_Department_of_Biology,_University_of_Florence,_via_Romana_17,_Firenze,_Italy b_Department_of_Biology,_University_of_Florence,_via_Romana_17,_Firenze,_Italy c_Department_of_Biology,_University_of_Florence,_via_Romana_17,_Firenze,_Italy

d_University_of_Tunis_El_Manar,_Faculty_of_Sciences,_Departement_of_Biology,_Research_Unit_Bio-Ecology_and_Evolutionary_Systematics,₂₀₉₂_Manar_II,_Tunisia e_Institute_for_Marine_Biology_{Biotechnology}_and_Aquaculture,_Hellenic_Centre_for_Marine_Research,_Heraklion,_Crete,_Greece

f_Department_of_Biology,_University_of_Florence,_via_Romana_17,_Firenze,_Italy

a

r

t

i

c

l

e

i

n

f

o

Articlehistory: Received4October2014 Receivedinrevisedform 24December2014 Accepted6January2015 Keywords: Sandybeaches Beachecosystem Bioindicators Talitrids Behaviouraladaptation Orientation

a

b

s

t

r

a

c

t

Thebehaviouroftalitrids,beingalocaladaptationtobeaches,isknowntoberelatedtoenvironmental stability.Theuseofbehaviouralresponsesofresidentpopulationsasbioindicatorofshorelinestability hasbeentestedundervariousconditions,includingaftersoftandhardengineeringactionstostabilise erodedbeaches.Portstructureslikelyhaveimpactonsedimentlongshoretransportationandshoreline stability.Thequestionwaswhethertalitridorientationbehaviourcouldbeproposedasbioindicatorof impactsalsoforsandybaysoflimitedextensionandhighlyusedforrecreation,suchasthoseinthe vicinityoftouristicportstructures.Orientationexperimentswerecarriedoutonasetofsandybeaches ofdifferentextensionandmorphology,eachoftheminthevicinityofatouristicport,acrossthe Mediter-raneancoasts.Theprotocolincludedfieldorientationtestsofpopulationsoftalitrids,thenanalysedin termsoforientationprecisionseawards(consideringsuncompassorientationasthemostlocallyadapted behaviouralmechanism)indifferentseasons(beforeandafterthetouristicseason)andtimesofday.The populationsfrommoreprotected(eithernaturallyorartificially)headland-baysshowedahigher preci-sionoforientationwithrespecttotheshorelinedirectionthanthosefromextendedbeaches,moresubject tochangesinlongshoresedimentarytransportasconsequenceofnaturalandhumanactivities.The dis-tancefromtheportandtouristicpressurehadnoinfluenceontalitridorientation.Animportantstabilising factorforthesandybeachecosystems,includingtalitridpopulationsandtheirbehaviouraladaptation, appearedtobethepresenceofseagrassbanquette.Thebehaviouraldatapointoutthatbioticinformation proceedingfromlocalanimalpopulationslinkedtobeachsedimentsmaycomplementsedimentology dataandallowscalingtheimpactsoccurringonadevelopedcoastline.Thisbecomesparticularlyrelevant whenconsideringinterdisciplinaryapproachestomonitoringstrategies.

1. Introduction

1.1. Talitrids:ﬁnetuningtoachangingenvironment

Sandybeacheshostabundantanddiversearthropod

communi-tiesintheintertidalandsupra-littoralzonesexploitingthewrack

deposited by tides and waves (Schlacher et al., 2014). Within

∗ Correspondingauthor.Tel.:+390552755149;+393397057222.

E-mailaddresses:felicita.scapini@unifi.it(F.Scapini),simone.gambineri@unifi.it (S.Gambineri),claudia.rossano@unifi.it(C.Rossano),elgtari.mohamed@gmail.com (M.ElGtari),alloctona@yahoo.it(L.Fanini),delphinehelene.nourisson@unifi.it (D.H.Nourisson).

the mobile arthropod fauna communities, talitrids (Crustacea,

Amphipoda,Talitridae)are keystonespeciesthat showpeculiar

behaviouraladaptationstunedtotheenvironmentalfeatures of

sandybeaches(Scapini,2006,2014;Walshetal.,2010).Talitrids

inhabitingsandybeachesarenight-active,butmayexpresssolar

orientationseawardsduringthedayincaseofdisplacementby

mechanicalfactors(e.g.,waves,predators)ortofacea

dehydra-tionriskwhileburiedinthesandinthesupra-littoralzone.This

isparticularlyevidentinMediterraneanmicrotidalbeaches,where

talitridsoccupyazoneveryclosetothewaterline(Scapinietal.,

1997;Colombinietal.,2002;Fallacietal.,2003).Differencesin

orientationcapability,withtheuseofalternativemechanismsand

cues,werefoundrelatedtothestabilityofbeaches(Scapini,2006).

OnItalianshores,sunorientationwasshowntobeadaptedtothe

http://dx.doi.org/10.1016/j.ecolind.2015.01.012

(2)

shorelinedirectionand inheritedonmorestablebeaches,while

onchangingshorelines ascatter towardvarious directionswas

observedinthesamples(Scapinietal.,1995).Theinterpretation

oftheseresults,supportedbypopulationgeneticsdata,wasthat

stablebeachesofferedalongertimeforbehaviouraladaptationto

beﬁxedbynaturalselectionand/orlearning.ThestudyofScapini

etal.(1995)wasintegratedbyrelatingbehaviouralandgenetic

adaptationwiththechangesofshorelinethroughtime(decades)as

reportedinthetopographicmapsofItaly(C.N.R.-M.U.R.S.T,1997).

Thesehypothesesremainedindeedtobetestedinawidercontext,

toavoidbiasduetodifferencesincoastlinemorphology,suchas

unevenpresenceofheadlands,rivermouthsandrockyshores(see

e.g.Barsantietal.,2011,regardingItaliancoasts).Laterstudiesled

howevertosimilarconclusions:differencesinorientationprecision

towardtheshorelinewereshownbypopulationsfromdifferent

pointsalongthesamecontinuousbeachontheTyrrheniancoasts

ofItaly,subjecttodifferenterosion/accretiondynamics(Scapini

etal., 2005;Ketmaieret al.,2010).AlsoBouslamaet al.(2011)

foundalinkbetweentalitridbehaviourandenvironmental

stabil-ityontwobeachesoftheTunisiancoastscomparingbehavioural

traits(orientationandlocomotoractivityrhythms).OntheAtlantic

coastofUruguay,Faninietal.(2009)comparedtheorientationof

talitridsfrombeachesdifferinginmorphodynamicsandobserved

amorepreciseorientationonareﬂectivebeachthanona

dissipa-tiveone,duetotheprotectedpositionoftalitridpopulationsacross

thebeach,wherethewaveenergyisreﬂectedbythebeachslope

(HabitatSafetyHypothesis,DefeoandGómez,2005).OnthePaciﬁc

coasts,inChile,onoceanicmacrotidalintermediatebeaches,a

bet-teradaptedseawardorientationwasobservedonaprotectedbeach

thanonanexposedone(ScapiniandDugan,2008).Althoughthe

relationoftalitridbehaviouraladaptation/plasticitywithrespect

to stable/changingshoreline wasnot clearly stated among the

hypothesestobetested,therelationshipbetweenpopulation

fea-tures andsandybeachecology andmorphology appearedclear

fromliterature(Soaresetal.,1999;McLachlanandBrown,2006;

Defeoetal.,2009).In summary,thereisa consistentindication

acrossgeographicalmacro-areas, oftalitrid adaptation(allowed

bya highbehaviouralplasticity)tothestabilityoftheshoreline

inhabitedbythepopulations.Whilethedebateaboutthemeaning

of“shorelinestability”is still open(depending onthe

perspec-tiveofeachdiscipline),theinformationprovidedbylocaltalitrid

populationscanprovideanintegrationofthosefeatures,whichare

relevanttothespecies-environmentperspective.

1.2. Behaviouroftalitridsandman-madestructures:open

questions

TheMAPMED project(ENPICBC-MED programme)aimedat

characterizingport areasintheMediterranean,todevelop

suit-ablemonitoringtoolsthatcansustainPortAuthoritiesinmanaging

theseareas.Withintheprojectframework,asuiteofpossible

sta-bilizing/destabilizingfactorsweretakenintoaccountthatmayact

onashoreline.Portstructuresmayimpactonsedimentlongshore

transport andsandybeachstability (Poulosand Chronis,2001).

Thesedynamics,generatedbyman-madehardstructures,mayact

withfastertimethanthenaturalonesandseverelyimpactbeach

ecosystem (Dugan etal., 2008; 2013).Behavioural experiments

(etho-assays)wereplannedonbeachesatdifferentdistances

up-driftordown-driftfromtheportstructurestoassesstheeffects

oftheportimpactsonmobilemacrofaunaadaptation.Threeport

areas were selected across the Mediterranean, in the western

MediterraneanBasin(Italy,Sardinia,PortofCagliari),intheeastern

one(Greece,Crete,PortofHeraklion)andonthesoutherncoasts

(Tunisia,eastern coast,Portof ElKantaoui) (Fig. 1a).The three

localitieswerecharacterisedbythepresence oftouristic

infras-tructures and similar seasonality of tourism (peaks in summer

months);thedirectimpactofhumantramplingandother

mana-gementswereconsequentlysupposedtobesimilar.Toeachofthe

selectedbeachesanindexofbeachuse(Recreationand

Conserva-tion,integratinginaﬁnalscorebothnaturalandhumanfeatures

ofthebeach-dunesystem)wasassigned(McLachlanetal.,2013).

Theapproachofthisstudywasbasedoncurrentmodels

devel-opedincoastalengineeringregardingtheconceptof“staticbay

beach”(Hsuetal.,2010;Barsantietal.,2011).Accordingtothis

concept,apocketbeachwouldbestable,whileanextendedbeach

wouldbesubjecttolongshoresedimenttransportdependingonthe

dominantwinds,currentsandwaves,andthustochangesasa

con-sequenceofhumanactionsandman-madeinterruptions(Barsanti

etal.,2011).

1.3. Hypothesesforbehaviouraltestsonchangingcoastlines

Arthropodcommunityfeaturesandorientationoftalitridstothe

shorelinehadbeenusedinsimilarcontextstomonitorthe

stabil-ityofthebeachecosystemwithrespecttochangedsedimentary

dynamicscausedbysoftandhard engineeringmeasuresto

sta-bilisebeachesagainsterosion(Faninietal.,2007;Bessaetal.,2013;

Nourissonetal.,2014).Measurablechangesintalitridorientation

parameters, suchas theprecisionwithrespecttotheshoreline

direction,wouldprovideatoolforamonitoringprogrammeofthe

impactofman-madestructuresonthebeachecosystem(Scapini,

2014).Inacomplexsystemsuchasthetouristicareasunder

anal-ysis, it is relevant, ﬁrst of all, to know to which of theabove

mentionedfactors(directtourismimpactoreffectsofhumanmade

structuresonthesedimentarytransport) willrespondthelocal

talitridpopulation.

Inthisstudycurrentparadigmswereconsidered,which

summa-rizethestabilityconditionofasandybeachundertheperspective

ofdifferentdisciplines,andweretestedviathebehaviouroflocal

talitridpopulations.Itwasassumedthatonmorestablebeaches

(inthepresentcaseonpocketbeaches,eventuallystabilisedbythe

presenceofwrack,Duganetal.,2003,2013)talitridswouldshow

anorientationpreciselyadaptedtothe(stable)shoreline,whileon

beachesmoreexposedtowinds,currentsandwaves,andstressed

bychangesin sedimentarylongshoretransport, talitrid

orienta-tionwouldbemorescattered.Theinterferenceofportstructures

withlongshoresedimentarydriftswasexpectedtohavea

conse-quenceonresidentpopulations,likelydetectableinbehavioural

adaptation.

Alternativenotmutuallyexclusivehypothesesthathavebeen

consideredbythisstudywere:

(1).Theintensityofrecreationactivities(expressedbythe

Recre-ation index,McLachlan et al.,2013)wouldhave anegative

impactonthemobilemacrofauna.

(2).Thevicinityoftheportstructure(distancefromtheport)would

haveanegativeimpactonthetalitridpopulationsandtheir

behaviouraladaptation.

(3).Theextensionofthebeach(pocketbeachvs.extendedbeach)

wouldaffectthetalitridbehaviouraladaptationtothe

shore-linedirection.

(4).The presence of dunes and wrack (Conservation index,

McLachlanetal.,2013,orlocalecologicalstabilisation)would

positivelyimpactonthebehaviouraladaptation.

2. Materialandmethods

2.1. Studysiteschoiceandcharacterisation

Orientationtestsontalitridswerecarriedoutin2012intwo

(3)

Fig.1. (a)LocationoftheselectedbeachesacrosstheMediterraneancoasts,neartouristicports:Cagliari(39◦₁₂_N,₉◦₀₇_E;_Sardinia,_Italy);_El_Kantaoui₍₃₅◦₅₄_N,₁₀◦₃₆_E;

Tunisia);Heraklion(35◦₂₅_N,₂₅◦₀₈_E;_Crete,_Greece)._(b)_Calamosca_beach₍₃₉◦₁₁₁₂_N,₉◦₀₉₀₇_E)_at₃₅₀₀_m_from_the_Cagliari_port;_(c)_Chat_Mariem_beach₍₃₅◦₅₅₅₈_N,

10◦₃₃₅₆_E)_at₅₂₀₀_m_from_El_Kantaoui_port,_and_Hannibal_beach₍₃₅◦₅₃₂₉_N,₁₀◦₃₆₀₁_E)_at₁₀₀_m_from_the_El_Kantaoui_port;_(d)_Tombrouk_beach₍₃₅◦₁₉₅₅_N,₂₅◦₁₂₀₇_E)

at5000mfromtheHeraklionport,andArinabeach(35◦₁₉₄₉_N,₂₅◦₁₄₁₀_E)_at₈₀₀₀_m_from_the_Heraklion_port._North_is_up._Anchor_symbols_indicate_the_port_position.

andone attheend of it(September) onbeachesneartheport

ofCagliari(Italy,Sardinia;31May,22September),theportofEl

Kantaoui(Tunisia; 7–8June,26–27 September)andtheport of

Heraklion(Greece,Crete;16–18May,12–13September)(Fig.1a).

ConsistentlytotheoverallgoalsoftheMAPMEDProject,itwas

plannedtostudybeachesonbothsidesoftheportstohighlight

eventualeffectsofportstructures.Howeverthenaturalvariability

ofthecoastlinesandtheirfeaturesdidnotallowforageometric

placementofthestudysites.Thedataanalysischosen(seebelow)

wasconsequentlythoughttoberobusttovariability.NearCagliari,

theetho-assayscouldbeperformedonlyonanaturallyprotected

sandybay ontheleft side ofthe port,Calamosca(39◦1112N,

9◦0907E,Fig.1b)becauseontheothersideoftheportnotalitrids

werefound(FSandCR,personalobservations).Thosebeacheshad

beennourishedwithnewsedimentstofavourrecreationactivities,

whileatCalamoscathepocketbeachwasstabilisedbykeepingthe

seagrassbanquetteonsite.NearElKantaouiasandybeachwas

chosennexttotheport(100m)onitsrightside,protectedbythe

portstructures,Hannibalbeach(35◦5329N,10◦3601E,Fig.1c),

andanextendedbeachwaschosenontheleftsideat5200mof

theport,ChatMariembeach(35◦5558N,10◦3356E,Fig.1c).On

thissidenearertotheport,itwasnotpossibletoﬁndestablished

talitridpopulations(SG,MEandCR,personalobservations).Near

Herakliontwobeacheswereselectedontherightsideoftheport,

Tombroukbeach(35◦1955N,25◦1207E;5000m,Fig.1d),which

wasprotectedbyanaturalheadland,andArinabeach(35◦1949N,

25◦1410E;8000m, Fig.1d),a naturalbaythatdidnotpresent

prominentstructures.Ontheleftsideoftheportnotalitridswere

found(LF,CRandDN,personalobservations);theHeraklion

air-portislocatedimmediatelyaftertheport,sothatthebeachesareon

therightsideofboththeman-madeinfrastructures.Ateach

exper-imentalsessionaproﬁleofthebeachwasdrawnfromthewaterline

tothebaseofthedune,usingstandardtopographicmethodology

(measuresofbeachwidth,slope,andshorelinedirection).

Recre-ationandConservationindices(RIandCI;McLachlanetal.,2013)

wereestimatedforeachbeachthroughaconsultationamongthe

authors,whohadvisitedthebeaches.Thisconsultationwas

per-formedindependentlyoftheanalysesoforientation.

2.2. Orientationexperiments

Theorientationexperiments(etho-assays)wereperformedon

thebeaches,usingaPlexiglasarenawitha40cmdiameter,

hav-ing72pitfalltrapsof5◦eachatitsrim;atransparentcylindrical

screencoveredtheentiredevice.Awhitecardboardwasplaced

aroundthearenacircumferencetoscreenoffthelandscape,sothat

sunorientationwasobserved,tobecomparedamongthevarious

localities.Thearenawaspositionedhorizontallyonasmalltable

at1mabovethebeachsurface;pitfalltrap72wasorientedtothe

North.Thetalitridsamplesfortheetho-assayswerecollected

ran-domlyfromthewaterlinetothebaseofthedune.Groupsofabout

tenindividualswereplacedinthecentreofthearenabymeansofa

transparenttubeverticallyinsertedthroughthecoverofthearena;

afteroneminutethetubewasremovedandtheanimalswerefree

tohoporruninthepreferreddirection.Experimentalseriesof4–6

groupswererepeatedtwice,inthemorningandintheafternoon,

usingnewindividualseachtime.Thisprocedurewasappliedasthe

orientationofindividualstestedinsmallgroupscanbeconsidered

independent(Scapinietal.,1981).Morethanfoursampleswere

testedwhentwosympatric talitridspecieswerepresentonthe

beach;thespecieswerecheckedlaterinthelaboratory,sothatthe

individualstestedwerenotdisturbedbeforetheetho-assay.Ateach

releasethefollowingimmediatevariableswereregistered:timeof

(4)

airhumidity(%;electronicthermo–hygrometer),andsky

cloudi-ness(0–8;visualappreciation),sunvision(visible,veiled,shape,

notvisible;visualappreciation).Allindividualstestedwerekept

inseparatetubeswith75%alcoholforthemeasurementof

intrin-sicvariables:morphometricmeasures(numberofsegmentsofthe

secondantennaeandcephaliclength,proxyofageandsize,

respec-tively,ofthetestedindividuals;Williams,1987;Marquesetal.,

2003),speciesandsex.Thesamplesarepreservedatthe

Depart-mentofBiology,UniversityofFlorence,Italy.

2.3. Orientationdataanalysis

Toestimatetheprecisionoforientationtowardtheshoreline,

thesummary statisticsforcirculardistributionswerecalculated

(Fisher,1993;S-Plus6Insightfulwithalibrarydevelopedadhoc;

MarchettiandScapini,2003).For eachangledistribution,itwas

calculated:themeanangle,themeanvectorlength(r)andthe

cir-cularconﬁdenceintervalaroundthemeanangle;theRayleightest

foruniformitywasapplied,toassessthenullhypothesisof

ran-domorientation.Probabilitydensityfunctionswerecalculatedand

smoothedviathekernel method,andweredouble plottedin a

Cartesiangraphtovisualiseallthepeaksofthecircular

distribu-tions(Fisher,1993).

In tests carried out under natural conditions severalfactors

mayinﬂuenceorientationsimultaneouslyandmustbetakeninto

consideration. A multiple regression analysis is recommended

whenthedataareobtainedundernatural(changing)conditions

(UnderwoodandChapman,1985),suchasthesetofetho-assaysat

thestudysitestobecompared.Multipleregressionmodelswere

developedadaptedtoangulardata(SPLM,SphericalProjected

Lin-earModels;Scapinietal.,2002;MarchettiandScapini,2003)to

pointoutthesourcesofvariation;thesigniﬁcanceoftherecorded

variablesandfactorstotheorientationangleswasestimated.First,

additivebaselinemodelsweredevelopedconsideringallthe

vari-ablesandfactors;furthermodelsweredevelopedconsideringthe

possibleinteractionsoffactors.Variousmodelswerecompared,

andthebestmodelwaschosenusingtheAkaikeInformation

Cri-terion(AIC),i.e.themaximumlikelihoodwiththeleastnumberof

parameters.Fromthebestmodel,theeffectsofsinglevariableson

theorientationangleswereestimatedusingtheLikelihoodRatio

Test(LRT),bycomparingthebestmodelwithnestedmodelsnot

containingthevariabletested.

3. Results

3.1. Localstability,exposureandhumanuse

The beaches differed for several features that may

inﬂu-encetheirstability:exposure, extension, slopeand presence of

wrackorseagrassbanquette(Posidonia,Table1).Atallsites,the

beachproﬁlesdifferedbetweenseasonsandappearedmoreﬂat

in September, after thetouristic season (Fig. 2). Regardingthe

exposuretodominantwinds,Calamoscawasprotectedfromthe

dominant WNWwinds, but was exposed to theSwinds, Chat

MariemandHannibalwereexposedtothedominantNNEandE

winds,ArinaandTombroukwereexposedtothedominantNNW

winds (Table 1; windﬁnder,2014). Regardingthe Conservation

andRecreationindices(Table2),theselectedbeachesfellwithin

thesamecategory(“C”,i.e.balancedusebetweenrecreationand

conservation), exceptfor Hannibal that washighly usedfor its

proximitytotheportandthehotels(assignedtocategory“B”,i.e.

intensiverecreation).

3.2. Talitridpopulations

Thesmallestbays,HannibalandCalamosca,presenteda

Posi-doniabanquette,inwhichtwosympatrictalitridspeciesOrchestia

stephenseni and Orchestia montagui were found. In the other

beachesonlyonetalitridspecies,Talitrussaltator,wasfound.The

samples presented high percentages of juveniles at Arina and

TombroukinMay(Table3).Inboththesebeaches,aswellasat

TombroukinSeptemberandHannibalinJune,thesexratioofthe

sampleswasmale biased,whilethesexratiowasconsiderably

femalebiasedatChatMariem(Table3).

3.3. Orientationoftalitrids

Theorientationoftalitridsresultedwelladaptedtothe

shore-line directionfor all populations in both seasons and times of

day,exceptforT.saltatoratChatMariembeach.Inthissolecase,

werecordedascatteredorientationtowardseveraldirectionsnot

linkedtotheshorelinedirection,asshownbythedensity

distribu-tionsforthispopulation(Fig.3)andthesmallvalue,closeto0,ofthe

meanresultantlength(r)obtainedinMay–June(Table3).No

appar-entseasonaldifferenceswereobservedinthemeandirections,but

theorientationafterthetouristicseasonwasslightlylessprecise

onallbeaches,withsmallermeanresultantlengths(comparethe

rvaluesinTable3),withagainthedifferentcaserepresentedby

ChatMariem.Onthisbeach,theprecisionimprovedfromJuneto

September,reachingthesigniﬁcancetoRayleightest,butwitha

meanangleoforientationdeviatingofabout80◦fromtheshoreline

direction(Fig.3;Table3).

Fromthemultipleregressionanalysisasigniﬁcantinteraction

wasfoundofthefactorbeachwithanintrinsicvariable(the

num-berofantennaearticles),themonth(beforeandafterthetouristic

season)andskyconditions(cloudinessandtimeoftheday)(M1,

Table4).Species,sex,airhumidityandtemperaturewerenot

sig-niﬁcantfactorsinthis model.Inconsiderationofthesigniﬁcant

interactionofthefactorbeach,wethencalculatedregression

mod-elsforeachbeachseparately.Thebestmodelwiththeleastnumber

ofparameterswasthatobtainedforArinabeach,inwhichonlythe

cephaliclengthwasretainedassigniﬁcantfactor(M5,Table4).In

factthesmallest(cephaliclength<0.5mm,N=50)andmediumsize

(1mm>cephaliclength>0.5;N=103)individualsweremore

con-centrated(r=0.7563andr=0.7436,respectively)thanthebiggest

ones (cephalic length>1mm, N=52; r=0.2453). The model for

Calamoscabeachhadenvironmentalfactors(skyconditions,sun

azimuthandtimeofday)assigniﬁcantfactors(M2,Table4);the

modelforHannibalbeachretainedalsothemonthassigniﬁcant

fac-tor(M4,Table4).Thehighestnumberoffactorswasretainedinthe

modelsofChatMariembeach(M3,Table4)andTombroukbeach

(M6,Table4),reﬂectingthescattershownbythedistributions,at

ChatMarieminbothseasonsandatTombroukinSeptember(Fig.3;

Table3).

4. Discussion

4.1. Talitridbehaviouraladaptationtobeachesinrelationto

humanuses

Thebeachesconsideredinthisstudyrepresentedasetof

differ-entdistancesfromtouristicportsandofecologicalconditions,with

theexceptionoftheestimatedConservationandRecreationindices

(CIandRI)whichdidnotdiffermuchamongsites.Theonlybeach

assignedtoadifferentcategorywasHannibalbeach,locatedvery

closetohotelstructures.Regardingtheotherbeaches,the

pres-enceofdevelopeddunesatChatMariem,Tombroukand,inlower

measure,Arinasuggeststhatthesebeachesarealsosuitablefor

pro-tection,howeverunlikelyinthelongterm,duetotheproximityof

touristicfacilities.Theyallwereassignedtoamixedusecategory.

Fromthisstudyitcanthereforenotbetestedtheeffectof

(5)

Table1

Beachfeaturesandmeteorologicalfactorsduringtheorientationexperiments.

Italy Tunisia Greece

Calamosca ChatMariem Hannibal Arina Tombrouk

May–June Sept. May–June Sept. May–June Sept. May–June Sept. May–June Sept.

Annualdominantwinds* _WNW,_ESE,_S _NNE,_E,_NNW _NNW,_SSW

Distancefromport(m) 3500(left) 5200(left) 100(right) 8000(right) 5000(right)

Extension(m) 150 11,000 450 800 2000

Wrack Posidonia Posidonia Posidonia No No

Seawarddirection(◦₎ ₁₉₀ ₁₈₁ ₅₈ ₆₀ ₆₉ ₉₉ ₂ ₃₅₁ ₃₄₈ ₃₄₉

Beachwidth(m) 22 20 22 21 24 20 20 29 20 26

Meanbeachslope(◦₎ _1.1 _2.0 _2.5 _1.9 _2.3 _0.8 _3.0 _0.8 _3.4 _3.4

Slopeconﬁdenceinterval(◦₎ _±3.1 _±2.0 _±5.0 _±3.7 _±2.2 _±2.4 _±1.8 _±3.8 _±1.7 _±4.6

Temperaturerange(◦C) 26–33 26–31 27–29 29–34 27–32 31–34 24–30 27–32 20–28 28–33 Airhumidityrange(%) 28–54 48–66 60–66 55–72 57–68 53–63 34–46 40–63 38–60 37–48

Cloudiness(0–8) 1–4 0-8 2–3 2–7 0 2–6 2–3 1–4 4–7 0–1

* _Calamosca_data_from_Cagliari_port,_Tunisia_data_from_Sousse,_Greece_data_from_Heraklion_port;_winds_in_order_of_prevalence.

(windﬁnder,2014). 0 0 3 5 2 0 2 5 1 0 1 5 0 Chat Mariem Hannibal Calamosca Arina Tombrouk 0 0 0 0 1 1 1 1 1 2

Fig.2.Proﬁlesoftheﬁvebeaches(Calamosca,Sardinia,Italy;ChatMariemandHannibal,ElKantaoui,Tunisia;ArinaandTombrouk,Crete,Greece)atthetimesofthe orientationexperiments(May–June2012:boldlines;September2012:dashedlines).Onthehorizontalaxisdistances(metres)fromthebasisoftheforedune(0)tothe shorelineareshown;ontheverticalaxistheheights(metres)abovesealevel(0)areshown.

hypothesis1,seeIntroduction).However,theindirectindication

canbetakenthatbeachesinthevicinityoftouristicinfrastructures

areunlikelytobedesignatedtoprotectionsensustricto.

Despitethedifferencesamongbeaches,alllocaltalitrid

popu-lationswerefoundcapableofsuncompassorientation,exceptfor

ChatMariempopulation.Theuseofsuncompassasorientation

mechanismcanbeinferredbythefactthattheorientationtendency

seawardswasthesameatdifferenttimesoftheday(morningand

afternoon)compensatingtheazimuthaldisplacement.

Theproximitytoaportwasfoundnottohaveanegativeimpact

ontheprecisionofseawardsorientation,withbeachescloserto

ports(likeHannibalbeach)hostingpreciselyorientedpopulations.

Asaconsequence,thehypothesisoftalitridorientationbeing

neg-ativelyaffectedbytheproximityofaport(alternativehypothesis

Table2

Beachcharacteristics:Conservation(CI)andRecreation(RI)indices(McLachlanetal.,2013),asestimatedbytheauthorsindependentlyfromtheorientationanalysis.

Heraklion Cagliari ElKantaoui

Arina Tombrouk Calamosca Hannibal ChatMariem

Type C(Multipleuse) C(Multipleuse) C(Multipleuse) B(Intensiverecreation) C(Multipleuse)

CI 2(1dunes,1

macrobenthos)

2(2dunes,0 macrobenthos)

1(0dunes,0 endangeredandiconic species,1intermediate macrobenthos)

1/2(0dune,0 endangeredandiconic species,1/2benthos)

3/4(2dunes,0 endangeredandiconic species,1/2

macrobenthos)

RI 5(2infrastructures,2 safetyandhealth,1 carryingcapacity)

5(2infrastructures,2 safetyandhealth,1 carryingcapacity)

4/5(2infrastructures, 2/3safetyandhealth,0 carryingcapacity)

(6)

Table3

Populationtraitsandsummarystatisticsoftalitridsunorientation.

Italy Tunisia Greece

Calamosca ChatMariem Hannibal Arina Tombrouk

May–June Sept. May–June Sept. May–June Sept. May–June Sept. May–June Sept. Species Orchestiaspp. Talitrussaltator Orchestiaspp. Talitrussaltator Talitrussaltator

Sexratio 0.733 0.909 0.349 0.574 1.423 0.886 3.400 0.723 1.400 1.857

Percentageofjuveniles(%) 7.1 0.0 1.2 1.2 0.0 0.0 63.3 4.7 25.0 4.8

Meancephaliclength(mm) 0.9 1.1 1.1 1.1 1.2 1.1 0.7 0.9 0.9 1.1

Conﬁdenceinterval ±0.2 ±0.1 ±0.1 ±0.1 ±0.2 ±0.2 ±0.3 ±0.2 ±0.3 ±0.3

Meann.ofantennaearticles 16.1 18.8 20.9 22.8 18.5 18.5 13 19.1 17.6 21.8

Conﬁdenceinterval ±2.9 ±1.7 ±2.8 ±4.3 ±2.2 ±1.9 ±6.7 ±4.1 ±5.2 ±5.5

N 84 84 86 86 126 84 120 85 96 63

Orientationmeanangle(◦₎ _159.8 _209.1 _88.5 _345.4 _80.9 _122.1 _341.4 _351.8 _336.5 _350.0

Or.conﬁdenceinterval(◦) ±14.2 ±19.8 NA ±22.3 ±9.0 ±15.0 ±8.0 ±12.6 ±14.3 ±25.0

Deviationfromseawarddir.(◦) −30.2 +28.1 +30.5 −74.6 +11.9 +23.1 −20.6 +0.8 −11.5 +1.0 Meanresultantlength(r) 0.5602 0.4329 0.080 0.3757 0.6688 0.5301 0.6548 0.5759 0.4911 0.3664 Rayleightest(p) <0.001 <0.001 n.s. <0.001 <0.001 <0.001 <0.001 <0.001 <0.001 <0.001

Table4

Multipleregressionmodels(SPLM)developedfromthetotaldataset(M0,M1)andeachbeach(M2-M6).AIC,AkaikeInformationCriterion;LikelihoodRatioTestforthe factors:*p<0.05,**p<0.01,***p<0.001.

M0

Startingadditivemodel

angle∼month+beach+posidonia+morning/afternoon+azimuth+air temperature+airhumidity+sun+sky

cloudiness+sex+cephaliclength+numberofarticlesof secondantennae Likelihood=2737.6287 AIC=2809.6287 Numberofparameters=36 Degreesoffreedom=878 M1

Totaldataset–Bestmodel

angle∼beach***_×_(number_of_articles_of_second antennae***₊_sky

cloudiness***₊_month***₊_{morning/afternoon}***₎

Likelihood=2638.0302 AIC=2738.0302

Numberofparameters=50 Degreesoffreedom=864 M2

BestmodelforCalamosca

angle∼sky

cloudiness***₊_azimuth***₊_{morning/afternoon}**

Likelihood=484.3845 AIC=500.3845

BestmodelforChatMariem

angle∼morning/afternoon***₊_azimuth***₊_number_of articlesofsecondantennae**₊_air_temperature₊_month

BestmodelforHannibal

angle∼morning/afternoon***₊_month***₊_sky_cloudiness** _Likelihood₌_571.1465 AIC=587.1465

BestmodelforArina

angle∼cephaliclength*** _Likelihood₌_541.6541 AIC=549.6541

BestmodelforTombrouk

angle∼cephaliclength***₊_{morning/afternoon}***₊_air humidity*₊_sky_cloudiness*₊_air_temperature*₊_month

Numberofparameters=14 Degreesoffreedom=145 LikelihoodRatioTestforthefactors:

*_p_<_0.05. **_p_<_0.01. ***_p_<_0.001.

2,seeIntroduction)wasnotsupportedbytheresultsofthe

etho-assays.

4.2. Talitridorientationwithrelationtosedimentarydynamics

andbeachextension

Theremaininghypotheses(3:extensionofabeachand4:local

ecologicalstability,seeIntroduction)suggestthattalitridscancope

withanthropogenicimpacts (portstructuresandtouristic

pres-sure)whenthelocalsedimentarydynamicsallowsforshoreline

stability.

Regardingthealternativehypothesisrelatedtobeachextension

(hypothesis3)itwasfoundthattheextensionofthebeach

nega-tivelyaffectedorientation.Thepopulationsfrommoreextended

beaches(ChatMariemandTombrouk)weremorescattered,while

thosefromsmallbay-beachesweremorepreciselyorientedtothe

shoreline(Arina,CalamoscaandHannibal).Itisworthnotingthat

talitridpopulationsfromsmallbays,protectedbynaturalor

arti-ﬁcialheadlandspresentedasunorientationwelladaptedtothe

shorelinedirectionofthebay,despitethespatialvariationofthe

generalcoast.Thebestbehaviouraladaptationoftalitrids(T.

salta-tor)wasobserved ontheArinabeachin Crete. AlsoCalamosca

inSardinia(apocketbeachprotectedbynaturalheadlands)and

HannibalinTunisia(protectedbyartiﬁcialgroynes)hadwell

ori-entedtalitridpopulations(O.montaguiandO.stephenseni).Onthe

otherhand,themostextendedbeaches,ChatMariem(11,000mof

extension)hadtalitrids(T.saltator)withamorescattered

orienta-tion(measuredbythemeanresultantlength,Table3).Tombrouk

(2000mofextension)presentedanintermediatesituation.

Signiﬁcant differences werenot observed in theorientation

among species, conﬁrming the ﬁnding by Fanini et al. (2012)

on talitrids from Moroccan Atlantic beaches, and in line with

the paradigmthat biota onsandy beaches is physicallydriven

(7)

Fig.3. Talitridorientationontheﬁveselectedbeachesinthetwoseasons(May–JuneandSeptember2012,atthebeginningandendofthetouristicseason,respectively). Smalltrianglesinsidethecircles,individualdirections;arrowsinsidethecircles,meanvectors;arrowsoutsidethecircles,seadirectionatthetestsites;thesmoothlines outsidethecirclesrepresentkerneldensityestimates;thekerneldensityestimatesaredoubleplottedintheCartesiangraphsontherighttohighlightallthepeaks.Summary statisticsareshowninTable3.

orientationobserved in the etho-assays (with the exception of

ChatMariem in June) and thefactors retainedby themultiple

regressionmodelsdevelopedfromtheangulardistributionsfurther

explainsuchﬁnepopulation-ecosystemrelationship.TheArina

tal-itridswere theleast dependentonenvironmentalfactors(best

modelwiththeleastnumberofparameters,four),whilethe

mod-elsforTombrouk and ChatMariem had14 and 12 parameters,

respectively(Table4).Themultipleregression modelsbasedon

behaviouraldataconﬁrmthatthescattereddistributionsobserved

atTombroukandparticularlyatChatMariemwereinﬂuencedby

variousenvironmentalfactors,whilethemodelforthebest

ori-entedpopulations(Arina)retainedonlyoneintrinsicfactor,related

tothesizeoftheanimalstested.ThismeansthattheArina

popu-lationmainlyreliesonthesuncompasstoorienttoanadaptive

direction(theshoreline),coherentlyacrossallthereplicates

(sea-sonsandtimesofday).Thefactorsspeciesorsexdidnotaffect

orientation,whilesizeoragewasretainedbythemodelsforChat

(8)

juvenilerateinthesamples,beingjuvenilesmorelikelystressedby

dryairconditionsandconsequentlyorientingseawardsinamore

preciseway(ScapiniandDugan,2008).

A well-adapted seaward orientation of talitrids is expected

whentheshorelineisstablethroughoutthetime,asthisbehaviour

maybeinheritedorlearnedwithexperienceonthenatural

envi-ronment(Scapini,2014).Theconceptof“shorelinestability”has

beendebatedinsandybeachecologyandmanagement,as“littoral

driftisnotaconstantphenomenonatanygivensite”(McLachlan

and Brown, 2006,p. 319). Talitrids dwelling theintertidal and

supratidalzonesmaybeimpactedbylongshorelittoralsediment

driftand,incaseofchangesofshorelinedirectionorhumaninduced

interruptionsonthesandybeach,theresidentmacrofauna

popu-lationsmaynotﬁndtheconditionsforbehaviouraladaptationto

beﬁxed(DuganandHubbard,2010;Duganetal.,2013).

Barsantietal.(2011)havedescribed thelongshoretransport

alongtheItaliancoastsandproposedaconceptualmodelforthe

deﬁnitionofcoastalunitsoflittoraltransport. Accordingtothis

model, the Italian beach Calamoscais a pocketbeach with no

apparentlittoraltransport.Thisfactmayexplainthebehavioural

adaptationoftalitridsobservedatCalamosca.Thetwobeachesin

Crete(ArinaandTombrouk)differedforextensionandexposure,

withTombroukmorethantwiceextendedthanArinaandmore

exposedtotheprevailingNNWwinds.Accordingtothe

biolog-icalmodelproposedbyScapini etal.(1995)for Italianbeaches

thatpopulationsfrommore stableshorelineshaveabetter

ori-entationthanpopulationsfromchangingshorelines,thetalitrids

atArinawerebetterorientedseawardsthanthesamespeciesat

Tombrouk(Fig.3).ThetwoTunisianbeachesatthetwosidesof

theartiﬁcialportofElKantaouiofferedmoreextremeconditions:

Hannibalbeachisanartiﬁcialpocketbeach,whileChatMariemis

anextendedbeachbackedbynaturaldunes.Ontheformerbeach

thetalitridswerewellorientedseawards,whereasonthelatter

theywerescattered,likelyasaconsequenceofsandmovements,

bothnatural(duetowindsandcurrents) andinducedbyworks

occurringonthatbeach(ME,personalobservations).

4.3. Talitridadaptationandlocalecologicalstability

Regardingthelocalecologicalstabilitymaintainedbydunesand

vegetation(Nordstrom,2000),andPosidoniabanquette(hypothesis

4,seeIntroduction),dunesandbanquetteappearednottohavethe

sameecologicaleffectontalitridadaptation.Inthisstudythe

pres-enceofduneswasnotrelevantfororientation,whilethebanquette

hadapositiveimpactontheorientationoftalitridpopulationsboth

atCalamoscaandHannibalbeaches.AtCalamosca,thecleaningof

thisnaturalbeachwasregulatedsothatthePosidoniabanquette

wouldbekeptonplacetopreventsanderosionbythesea(FS

andCR,personalcommunicationbythebar-keeperonthebeach).

TheHannibalbeachwasperiodicallycleanedfromwrack,

how-everforashortseason(ME,personalobservation),butthisaction

apparentlyhadnonegativeimpactontalitridorientation.Onthe

contrary,duneswerepresentinthemoreextendedbeaches(Chat

Mariem,ArinaandTombrouk),favouringthepresenceoftalitrid

populations,butnotaconsistentbehaviouraladaptation.

Additionalinformation maybefoundin thesample

compo-sition:theﬁtnessofthetalitridpopulationsmaybeinferredby

thepopulationstructure andpossiblybyabalanced/unbalanced

sex-ratio. In a populationdynamics studycarried out

through-outtheyearonT.saltatorfromMediterranean(ItalyandTunisia)

andAtlantic(Portugal) coastsavaryingsex-ratiowasobserved,

with prevalenceof males prior or during the recruitment and

female-biasedunderstressfulconditionsinthewarmestand

col-destmonths(Marquesetal.,2003).Inthesamplesofthepresent

study,thesex-ratiowasstronglyfemale-biasedatChatMariem,

wherealsotheworstorientationwasobserved(Table3).Onthe

otherhand,atArinathelargestnumberofjuvenileswasfound,

showingahighrecruitmentrateinthispopulation,thusaﬁtnessof

thepopulationinlinewiththeresultsoftheetho-assays(Table3).

4.4. Behaviouraladaptationasabioindicatorofshoreline

stability

To sum up, this study showed the link of the behavioural

adaptationoftalitridswithbeachgeomorphologyand

sedimen-tology,through etho-assays.The resultsappear consistentwith

longtermstability ofshoreline innaturallyand artiﬁcially

pro-tected headland-bay beaches, as from modelling of landforms

over both Oceanic (Thomas et al., 2010; Hsu et al., 2010) and

Mediterranean (Barsanti et al., 2011) coasts. The link between

thebehaviouraladaptationoflocalpopulationsstrictlyinhabiting

sandybeaches,suchastalitrids,andshorelinestabilityprovidedby

naturaland/orartiﬁcialheadlandsrepresentusefulinformationfor

integrate(bioticandsedimentary)monitoringofcoastalprocesses,

andfortheinterpretationofspeciesadaptationtochanging

envi-ronments.Otherstudieshaveproposedetho-assays(orientation

tests)asindicatorsof environmentalimpacts,tomonitor

artiﬁ-cialcoastline stabilisationboth intheshort- andmedium-term

(Faninietal.,2007;Bessaetal.,2013;Nourissonetal.,2014)oras

biomarkerofmetalpollution(UnghereseandUgolini,2009).The

interestinusinganimalbehaviourasecologicaladaptationliesin

thefactthatbehaviourintegratesseveraldrivingforcesatthelevel

ofindividuals(thatexpressthebehaviour)andpopulations.Thisis

shownbytheresultsofthemultipleregressionanalysis:the

num-berofparametersinthemodelsisleastinthosepopulationsthat

arewelladaptedtotheshoreline,reﬂectingtheconsistencyofthe

behaviourthroughouttheday,seasonsandwithvarying

meteoro-logicalconditions,aswellasamongindividualsofdifferentsexand

age.Alsothestatisticsofangulardistributionsoffervalidindices

thatmaybeproposedasbioindicatorsofchange:theprecisionof

theseawardorientation(expressedbythedeviationfromthe

sea-warddirection)andconsistencyofbehaviouramongindividuals

(expressedbythelengthrofthemeanvectorthatvariesfrom0–

noorientation–to1–perfectorientationofthesample).Inthis

studybeachesacrosstheMediterraneanwerecompared,subject

tosimilarimpacts,heavytourismpressureandthevicinityofport

structures.Despitethegeographicdistanceandgeomorphologic

differencesofthecomparedbeaches,thesedimentarydynamics

resultedtobethemainfactorofdisturbancefortalitridorientation.

Conversely,talitridorientationmaybeproposedasbioindicatoror

etho-assayfortheimpactofsedimentarychangingdynamicson

thesandybeachnaturalecosystem.

Acknowledgements

Theproject“MAnagementofPortareasintheMEDiterranean

Sea Basin (MAPMED, contract n. 6/2019)” has been funded by

ENPICBCMED(EuropeanNeighbourhoodandPartnership

Instru-ment for Cross-BorderCooperation in theMediterranean). This

publication hasbeen produced with theﬁnancial assistance of

theEuropeanUnionundertheENPICBCMediterraneanSeaBasin

Programme.Thecontentsofthisdocumentarethesole

responsi-bilityofUNIFI,HCMRandFSTandcanundernocircumstancesbe

regardedasreﬂectingthepositionoftheEuropeanUnionorofthe

Programme’smanagementstructures.

AppendixA. Supplementarydata

Supplementary data associated with this article can be

found,intheonlineversion,athttp://dx.doi.org/10.1016/j.ecolind.

(9)

References

Barsanti,M.,Calda,N.,Valloni,R.,2011.TheItalianCoasts:anaturallaboratoryfor thequalityevaluationofbeachreplenishments.J.Coast.Res.61,1–7(Special Issue).

Bessa,F.,Rossano,C.,Nourisson,D.,Gambineri,S.,Marques,J.C.,Scapini,F.,2013. BehaviourofTalitrussaltator(Crustacea:Amphipoda)onarehabilitatedsandy beachontheEuropeanAtlanticcoast(Portugal).Estuar.Coast.ShelfSci.117, 168–177.

Bouslama,M.F.,Charﬁ-Cheikhrouha,F.,ElGtari,M.,Nasri-Ammar,K.,Oueslati,A., Scapini,F.,2011.Relationshipsbetweenbiologicalcharacteristicsofthe crus-taceanamphipodTalitrussaltator,includingbehaviouralresponses,andlocal environmentalfeatures,CasestudiesofZouaraandKorba(Tunisia).In:Bayed, A.(Ed.),Sandybeachesandcoastalzonemanagement.ProceedingsoftheFifth InternationalSymposiumonSandyBeaches.19th–23rdOctober2009.Travaux del’InstitutScientiﬁque,Rabat,sériegénérale,Morocco,pp.17–23(n6). C.N.R.-M.U.R.S.T.,1997.Atlantedellespiaggeitaliane:Dinamismo–Tendenza

evo-lutiva–Opereumane.G.FierroEd.S.EL.CA.Firenze,Sheetsscales1:100,000,108 pp.

Colombini,I.,Aloia,A.,Bouslama,M.,ElGtari,M.,Fallaci,M.,Ronconi,L.,Scapini,F., Chelazzi,L.,2002.Small-scalespatialandseasonaldifferencesinthedistribution ofbeacharthropodsonthenorth-westernTunisiancoasts.Arespeciesevenly distributedalongtheshore?Mar.Biol.140,1001–1012.

Defeo,O.,Gómez,J.,2005.Morphodynamicsandhabitatsafetyinsandybeaches: life-historyadaptationsinasupralittoralamphipod.Mar.Ecol.Prog.Ser.293, 143–153.

Defeo,O.,McLachlan,A.,Schoeman,D.,Schlacher,T.,Dugan,J.,Jones,A.,Lastra,M., Scapini,F.,2009.Threatstosandybeachecosystems:areview.Estuar.Coast. ShelfSci.81,1–12.

Dugan,J.E.,Hubbard,D.M.,2010.LossofcoastalstrandhabitatinSouthernCalifornia: theroleofbeachgrooming.Estuar.Coasts33,67–77.

Dugan,J.E.,Hubbard,D.M.,McCrary,M.D.,Pierson,M.O.,2003.Theresponseof macrofaunalcommunitiesandshorebirdstomacrophytewracksubsidieson exposedsandybeachesofsouthernCalifornia.Estuar.Coast.ShelfSci.58S, 25–40.

Dugan,J.E.,Hubbard,D.M.,Quigley,B.J.,2013.Beyondbeachwidth:stepstoward identifyingandintegratingecologicalenvelopeswithgeomorphicfeaturesand datumsforsandybeachecosystems.Geomorphology199,95–105.

Dugan,J.E.,Hubbard,D.M.,Rodil,I.F.,Revell,D.L.,Schroeter,S.,2008.Ecological effectsofcoastalarmoringonsandybeaches.Mar.Ecol.29(S1),160–170. Fallaci,M.,Colombini,I.,Lagar,M.,Scapini,F.,Chelazzi,L.,2003.Distributionpatterns

ofdifferentageclassesandsexesinaTyrrhenianpopulationofTalitrussaltator (Montagu).Mar.Biol.142,101–110.

Fanini,L.,Defeo,O.,DoSantos,C.,Scapini,F.,2009.TestingtheHabitatSafety Hypothesis with behavioural ﬁeld experiments: amphipod orientation on sandybeacheswithcontrastingmorphodynamics.Mar.Ecol.Prog.Ser.392, 133–141.

Fanini,L.,Gecchele,L.,Gambineri,S.,Bayed,A.,Coleman,C.O.,Scapini,F.,2012. Behaviouralsimilaritiesindifferentspeciesofsandhoppersinhabitingtransient environments.J.Exp.Mar.Biol.Ecol.420-421,8–15.

Fanini,L.,Marchetti,G.M.,Scapini,F.,Defeo,O.,2007.Abundanceandorientation responsesofthesandhopperTalitrussaltatortobeachnourishmentandgroynes buildingatSanRossorenaturalpark,Tuscany,Italy.Mar.Biol.152,1169–1179. Fisher,N.I.,1993.StatisticalAnalysisofCircularData.CambridgeUniversityPress,

Cambridge,277pp.

Hsu,J.R.-C.,Yu,M.-J.,Lee,F.-C.,Benedet,L.,2010.Staticbaybeachconceptfor scien-tistsandengineers:areview.Coast.Eng.57,76–91.

Ketmaier,V.,DeMatthaeis,E.,Fanini,L.,Rossano,C.,Scapini,F.,2010.Variation ofgeneticandbehaviouraltraitsinthesandhopperTalitrussaltator(Crustacea Amphipoda)alongadynamicsandbeach.Ethol.Ecol.Evol.22,17–35. Marchetti,G.M.,Scapini,F.,2003.Useofmultipleregressionmodelsinthestudyof

sandhopperorientationundernaturalconditions.Estuar.Coast.ShelfSci.58S, 207–215.

Marques,J.C.,Gonc¸alves,S.,Pardal,M.,Chelazzi,L.,Colombini,I.,Fallaci,M., Bous-lama,M.,ElGtari,M.,Charﬁ-Cheikhrouha,F.,Scapini,F.,2003.Comparisonof Talitrussaltator(AmphipodaTalitridae)biology,dynamics,andsecondary pro-ductioninAtlantic(Portugal)andMediterranean(ItalyandTunisia)populations. Estuar.Coast.ShelfSci.58S,127–148.

McLachlan,A.,Brown,A.,2006.TheEcologyofSandyShores,2nd_edition._Academic Press,London,pp.373.

McLachlan,A.,Defeo,O.,Jaramillo,E.,Short,A.D.,2013.Sandybeachconservation andrecreation:guidelinesforoptimisingmanagementstrategiesfor multi-purposeuse.OceanCoast.Manag.71,256–268.

Nordstrom,K.F.,2000.BeachesandDunesonDevelopedCoasts.Cambridge Univer-sityPress,Cambridge,pp.338.

Nourisson,D.H.,Bessa,F.,Scapini,F.,Marques,J.C.,2014.Macrofaunalcommunity abundanceanddiversityandtalitridorientationaspotentialindicatorsof eco-logicallong-termeffectsofasand-dunerecoveryintervention.Ecol.Indic.36, 356–366.

Poulos,S.,Chronis,G.,2001.Coastlinechangesinrelationtolongshoresediment transportandhumanimpact,alongtheshorelineofKatoAchaia(NW Pelopon-nese,Greece).Mediterr.Mar.Sci.2(1),5–13.

Scapini,F.,2006.Keynotepapersonsandhopperorientationandnavigation.Mar. Freshw.Behav.Physiol.39,73–85.

Scapini,F.,2014.Behaviourofmobilemacrofaunaisakeyfactorinbeachecologyas responsetorapidenvironmentalchanges.Estuar.Coast.ShelfSci.150,36–44. Scapini,F.,Audoglio,M.,Chelazzi,L.,Colombini,I.,Fallaci,M.,1997.

Astronomi-cal,landscapeandclimaticfactorsinﬂuencingorientedmovementsofTalitrus saltatorinnature.Mar.Biol.128,63–72.

Scapini,F.,Buiatti,M.,DeMatthaeis,E.,Mattoccia,M.,1995.Orientationbehaviour andheterozygosityofsandhopperpopulationsinrelationtostabilityofbeach environments.J.Evolut.Biol.8,43–52.

Scapini,F.,Aloia,A.,Bouslama,M.,Chelazzi,L.,Colombini,I.,ElGtari,M.,Fallaci,M., Marchetti,G.,2002.Multipleregressionanalysisofthesourcesofvariationin orientationoftwosympatricsandhoppers,TalitrussaltatorandTalorchestiabrito, fromanexposedMediterraneanbeach.Behav.Ecol.Sociobiol.51,403–414. Scapini,F.,Chelazzi,L.,Colombini,I.,Fallaci,M.,Fanini,L.,2005.Orientationof

sand-hoppersatdifferentpointsalongadynamicshorelineinsouthernTuscany.Mar. Biol.147,919–926.

Scapini,F.,Dugan,J.,2008.Sunandlandscapeorientationinadultandjuvenile sand-hoppersOrchestoideatuberculata(Amphipoda,Talitridae)fromtwobeachesin southcentralChile.Mar.Ecol.–Evolut.Perspect.29,19–27.

Scapini,F.,Ugolini,A.,Pardi,L.,1981.Analysisofastronomicalorientationinlittoral amphipodsusingindividualandgrouptests(CrustaceaAmphipoda).Monit.Zool. Ital.(N.S.)15,77–86.

Schlacher,T.A.,Jones,A.R.,Dugan,J.E.,Weston,M.A.,Harris,L.,Schoeman,D.S., Hub-bard,D.M.,Scapini,F.,Nel,R.,Lastra,M.,McLachlan,A.,Peterson,C.H.,2014. Open-coastsandybeachesandcoastaldunes.In:Maslo,B.,Lockwood,J.L.(Eds.), CoastalConservation.CambridgeUniversityPress,NewYork,pp.37–94. Soares,A.,Scapini,F.,Brown,A.,McLachlan,A.,1999.Phenotypicplasticity,genetic

similarityandevolutionaryinertiainchangingenvironments.J.MolluscanStud. 65,136–139.

Thomas,T.,Phillips,M.R.,Williams,A.T.,2010.Mesoscaleevolutionofaheadland bay:beachrotationprocesses.Geomorphology123,129–141.

Underwood,A.J.,Chapman,M.G.,1985.Multifactorialanalysisofdirectionsof move-mentofanimals.J.Exp.Mar.Biol.Ecol.91,17–43.

Ungherese,G.,Ugolini,A.,2009.Sandhoppersolarorientationasabehavioural biomarkeroftracemetalscontamination.Environ.Pollut.157,1360–1364. Walsh,M.E.,Bourla,M.H.,Sabella,C.M.,ForwardJr.,C.M.,R.B.,2010.Y-axis

orienta-tioninthesupratidalamphipodTalorchestialongicornis(Say):hierarchyofsun, beachslopeandlandmarksasorientationcues.Mar.Freshw.Behav.Physiol.43, 203–220.

Williams,J.A.,1987.Therelationshipbetweenantennalsegmentnumberand moult-inginTalitrussaltator(Montagu,1808)(Amphipoda,Talitridae).Crustaceana53, 243–252.