Table Of ContentGulfResearchReports,Vol.9,No.3.205-210,1996 ManuscriptreceivedJuly24,1995;acceptedSeptember26,1995
DISTIUBimONOFLOX07HFMCt/SraX>iM/S(CIRKIPEDIA;RHIZOCEPHALA)
PARASITIZINGCRABS OFTHE GENUSCALLINECTES
INTHE SOUTHWESTERN GULF OF MEXICO
FernandoAlvarezandJorgeCalderdn
ColeccidndeCrustdceos,ImtitutodeBiologta,UniversidadNacionalAutdnomadeMexico,
ApartadoPostal70-153,Mdxico04510,D,F.,Mexico.
ABSTRACTApreliminarystudyontheinteractionbetweentheparasitichamac\(iLoxothylacustexanusandtwo
ofitshostspecies,thebluecrabCallinectessapidusandthedarkbluecrabC.rathbunae,intheGulfofMexico
ispresented.Datawereobtainedfrom923crabs,162C.sapidusand761C.rathbunae,dsiposit^intheColeccidn
dcCrusUccos,InstiuitodeBiologfa,UniversidadNacionalAut6nomadeMexico(UNAM),thatwerecollected
in14coastallagoonsandsites alongtheMexicancoastoftheGulfofMexico.ThedistributionofL.texanus
parasitizingeachoneofthehostspecies,meanhostsizevariation,distributionofnumberofparasiteexternae
perhost,andmorphologicalmodificationsoftheabdomenofthehostsareanalyzed.
Introduction fromthepopulationbecausetheydonotattainlegalsize,
andb)theparasitizedfraction,whichdoesnotreproduce,
Thecrabsofthegenus Callinectes,mainly theblue competeswithunparasitizedindividualsforfoodandspace.
crabC.sapidusRathbun,andthedarkbluecrabC.rathbunae Studies have been carried out on the distribution of
Contreras,supportoneofthemostimportantcommercial rhizocephalans(Hochbergetal.1992),hostsizedistribution
fisheries,bothin terms ofvolumeand value, within the (CTuistmas1969;Adkins1972;RaganandMatheme1974),
GulfofMexico (Anonymous 1994).Ofthebioticfactors changes in prevalence during outbreaks (Guistmas 1969;
thataffectbluecrabpopulationsnegativelyintheGulfof Park1969;WardleandTirpak199l),therelationshipbetween
Mexico,theparasitismbyihizocephalanbarnaclesmaybe parasite size (externasize) and host size (Reinhard 1950;
oneofthemostimportant,periodicallyreachingveryhigh WardleandTirpak1991),andthemorphologicalchangesthat
prevalences(WardleandTirpak1991;LorSnetal.1993). parasitizedcrabsundergo(Reinhard 1950; Hochbergetal.
Rhizocephalanbarnaclesparasitizesusceptibleshrimps 1992).In^iteofthegreateconomicimpomneeoftheblue
andcrabsthroughaplanktoniclarvalstagefromwhichan crabGsheryinMexico,onlytwostudieshaverecordeddata(Mi
endoparasiticphaseoriginates,aphasethatisnotevident theprevalenceofLoxothylacustexanusBoschma,itsseasonal
unless the host is examined histologically. During the variation,andhostsizevariation:Lordnetal.(1993),who
intemalphaseoftheparasite,thehosiextemalmorphology analyzedthecrabpopulationsofAlvaradolagcxinandL6zaro-
changes; the male abdomen becomes broader through a (Mvez etal. (in press), who studied parasitized crabs in
processthathasbeencalledfeminization(Reinhard1950). Tamiahualagoon.Theobjectiveofthisstudy istopresent
The emergence ofareproductive body called **extema” additicxialrecordsofparasitizedcrabsofthegenusCallinectes
follows the endoparasitic phase. The externa emerges within the Gulfof Mexico in order to update the known
throughtheinternalsurfaceoftheabdomenofthehostafter distributionofL.texanus,todeterminewhathostspeciesare
molting, while the host exoskeleton is still soft. Inhost being parasitized, to establish the host sizerange, and to
species parasitized by the rhizocephalan family presentfiguresofthemostcommontypeofmoiphological
Sacculinidae, hosts will not molt once the externa has variationsofparasitizedcrabs.
appearedandthemeansizeofparasitizedhostsisusually
significantlylessthanthatofunparasitizedhosts(Reinhard MaterialsandMethods
1956; O’Brien and VanWyk 1984), However, themost
important effect caused by this parasitism is that host Dataonparasitizedbluecrabsfromthesouthwestern
gonadsdonotmature(parasiticcastrationsensuO’Brien GulfofMexicowereobtainedthroughtheexaminationof
and Van Wyk 1984). The effects of the parasitisra by alltheC.sapidusandC.rathbunaefromtheGulfofMexico
rhizocephalansatthepopulation levelare:a)parasitized deposited in the Coleccidn de Crustdeeos, Instituto de
individuals are not removed by the commercial fishery Biologia,UniversidadNacionalAutdnoinadeM^xico(UNAM).
205
AlvarezAND Calder6n
Fourteen localities were represented in these samples, Loxothylacustexanusand thenumberofextemaepercrab
including coastal areas and coastal lagoons (Altamira, was recorded. The distribution of number of parasite
Chairel, Pueblo Viejo, Tamiahua, Casitas, La Mancha, exiemaeperhost was compared to a Poisson (random)
Mandinga, Alvarado, Soniecomapan, Coaizacoalcos, distributionwithachi-squaretest.Themostcommontypes
Machona,Atasta,T6rminos,andChampotdn)asdepicted of abdomens of parasitized male crabs were identified
inFigure1.Detaileddescriptionsofthesecoastallagoons (triangularandrounded)andparasitizedindividualswere
and sitescanbe found elsewhereinanumberofpapers classifiedaccordinglybyspecies.AG-testofindependence
(Contreras 1985; Y^ez-Arancibia and Day 1988;
Rosas 1989).Eachcrabwasidentifiedandexaminedfor wasusedona2x2contingencytable,totestiftriangular
the presence ofrhizocephalanexiemae. All crabs were abdomens were equally frequent in males of both host
sexed and the shape ofthe abdomen recorded; sex was species,andaStudent’st-testwasusedtocomparetheir
determinedthroughtheinspectionofgonopodsandgenital mean sizes. The two types ofabdomens forparasitized
pores.Inthiswayfeminizedcrabs(crabsthatareparasitized malesandtheextrabroadabdomenofparasitizedfemales
butwhichdonotyetshowtheparasiteexterna)werealso werefiguredtoaidintheiridentificationinthefield.Crab
found.Theinlemalsurfaceoftheabdomenofallcrabswas sizescorrespondtocarapacewidthinmillimeters(mm),
examined in search of small extemae or scars of andmeanvaluesarefollowed±onestandarderror.
206
2
DistributionofLoxothylacustexanusParasitizingCalunectesinSouthwesternGulfofMexico
TABLE1
SamplesofcrabsexaminedbyspeciesandlocalitywithintheGulfofMexico.Valuesrepresentnumberofparasitizedcrabs/
numberofunparasitizedcrabs,and meanhostsize/meansize ofunparasitizedcrabs,followed by ±onestandard error.
Asterisksrepresentsignificantdifferencesbetweenmeans. AllmaterialisdepositedintheInstitutodeBiologia,UNAM.
Callinectessapidus Callinectesrathbunae
*
Altamira,Tamaulipas 0/9
Chairel,Veracruz 0/21
PuebloViejo,Veracruz 5/1 87.8±10.4 0/90
Tamiahua,Veracruz 9/53 123.0±3.7/116.4±2.5 0/289
Casitas,Veracruz 1/4 101.4
LaMancha,Veracruz 0/13 0/5
Mandinga,Veracruz 0/5 6/123 120.2±7.2/109.9±1.5
Alvarado,Veracruz 0/4 0/112
Sontecomapan,Veracruz 24/32 91.6±1.9/111.2±3.0* 67/26 86.0±1.6/104±3.3*
Coatzacoalcos,Veracruz 0/2
Machona,Tabasco 1/0 94.3
Atasta,Campeche 1/0 IS.
T^rminos,Campeche 0/7 V5 81.9±3.3/113.5±3.8*
Champot6n,Campeche 0/1
*P<0.001
Results smaller than unparasitized crabs; while there were no
significantdifferencesintherestofthelocalities.
A total of 923 crabs, 162 C. sapidus and 761 C. ThenumberofparasiteextemaeinC.sapidusvaried
rathbunae,wasexamined; fromthistotal, 38C. sapidus fromonetothree;32crabshadoneexterna(84.2%),five
(23.5%) and 83 C. rathbunae (10.9%) wereparasitized had two(13.2%),andonehad three(2.6%). In turn,
(Table1).Parasitizedcrabswerefoundineightofthe 14 in C, rathbunae^thenumberofparasiteextemaeranged
coastal lagoons and sites that were examined (Pueblo fromonetofour;50crabshadoneparasiteexterna(60.2%).
Viejo, Tamiahua, C^sitas, Mandinga, Sontecomapan, 20hadtwo(24.7%), 11 hadthree(13.6%),andtwohad
Machona,Atasta,andT6nninos)asshowninTable 1. four(2.5%).Assumingthatthedistributionofparasitesis
Inoursamples,C. sapiduswasparasitizeilinPueblo theresultofsimilarprocessesinallthesitesstudiedand
Viejo,Tamiahua,andSontecomapanlagoons,Veracruz. sincethesedistributionsdepartconsiderablyfromnoimality,
ThemeansizeofparasitizedC.sapidusrangedfrom thedistributionofnumberofextemaeperhostwasanalyzed
87.8±10.4mminPuebloViejolagoonto123.0±3.7mm only by species and not by locality. In C. sapidus, the
inTamiahualagoon; therangeofsizesofparasitizedC. distributionofextemaecorrespondstoarandomdistribution
sapiduswasfrom70.0to134.6ram,bothfromTamiahua (Table2),whileinC.rathbunae,thedistributiondeparts
lagoon,Veracruz.C.rathbunaewasparasitizedinCasitas considerably from random and approachesacontagious
andthecoastallagoonsofMandingaandSontecomapan, one, with a larger proportion of hosts having multiple
Veracruz; Machona lagoon, Tabasco; and Atasta and extemae(Table3).
TC.6rrmaitnhobsulnaageoornasn,gCeadmfpreocmhe8.1T.h9e±me3,a3nmsimzeoifnpaTr6arsmitiinzoesd maleOsuatndo2f73(871p.a1r%as)iwtiezreedfCe.maslaepsi;dwuhsi,le11in(C2.8r.a9t%h)buwnearee,
lagoon,Campeche,to120.2±7.2mminMandingalagoon, therewere41parasitizedmalesand42parasitizedfemales.
Veracruz;therangeofsizesofparasitizedC. rathbunae InC.sapidus,threeof11 males(27.3%)hadatriangular
wentfrom45.3mminSontecomapanlagoon,Veracruz,to abdomen,whiletheremainingeighthadabroadabdomen.
144.1 mm in Mandinga lagoon, Veracruz. InTdrminos For C. rathbunae, nine out of 41 crabs (22%) had a
lagoon,parasitizedC.rathbunaeandparasitizedcrabsof triangularabdomen(Figure2).Thefrequencyof^jpearance
bothspeciesinSontecomapanlagoonweresignificantly oftriangularabdomenswasindependentofthehostspecies
207
AlvarezAND Calder6n
TABLE2 TABLE3
Distribution ofexternae ofLoxothylacus texanus on 162 Distribution ofexternae ofLoxothylacus texanus on 761
CaUinecfes sapidus* Observed ft’equencies are compared CaUinectesrathbunae.Observedfrequenciesarecompared
(Chi-square test) tothe expectedfrequenciesofaPoisson (Chi-squaretest)totheexpectedfrequenciesofaPoisson
(random)distribution. (random)distribution.
No.externae Observed Expected No.externae Observed Expected
perhost frequencies frequencies {O-EflE perhost frequencies frequencies (0-E)2/E
0 124 122.72 0.013 0 678 640.57 2.18
1 32 34,11 0.130 1 50 110.17 32.86
2 5 4.74 0.014 2 20 9.47 11.70
3 1 0.44 0.712 3 11 0.54 202.61
4 2 0.02 169.93
Total 162 162.01 X^.869.P>0.05 Total 761 760.77 X^19.30,P<0.0001
(x^[1]=1.83,P>0.05);motherwords,triangularabdomens isgreaterthanthatforC.sapidus(70,0to134.6mm),and
are equally frequent in both hostspecies. Meanhost nodefinedpatternofhostsizevariationalongageographic
sizesformaleswithtriangularabdomenwere83.76±8.29 gradientisevidentwiththeavailabledata.
mm(range67.2to92.7mm)forC.sapidusand82.25±6.53 ThenumberofL. texanusexiemaeappearing inthe
Iran(range45.3to115.8mm)forC.rathbunae\msignificant twohostspecies differedstatistically.InC. sapidus, the
differenceswerefoundbetweenthetwomeanvalues(t-test, occurrenceofexternaewasnotsignificantlydifferentfrom
t[10]=0.121,P>0.05). a random distribution, indicating that the chances of
becoming parasitized are the same for all individuals.
Discussion However,inC.rathbunae,thenumberofexternaeperhost
approachedacontagiousdistribution,suggestingthatthis
TwospeciesofthegenusCallinectes,C.sapidusand speciesmayoccurnaturallyinamoreaggregatedpattern
C. rathbunae,areparasitizedbyLoxothylacustexanusin thatmayfavormultipleinfections(Hoeg 1982).
thesouthwestern(julfofMexico.C.sapidusisparasitized, The recognition ofparasitized crabs in the field is
as indicated by the records presented here and basedonthepresenceofexternaeoftheparasiteandonthe
complementedwiththeinformationprovidedbyLor^^net identificationofaberrantforms ofthe abdomen. In this
al. (1993), throughoutthecoastoftheStateofVeracruz study,twotypesofabdomenswererecognizedforparasitized
from Tamiahua lagoon south to Alvarado and males:rounded,similartoamaturefemaleabdomen,and
Sontecomapanlagoons.Noclearpatternofvariationof triangular, such as those of immature females. The
host size can be discerned in C. sapidus along the recognitionofthetwo typesofabdomensforparasitized
Mexican coast, contrary to what Hochberg et al. maleswasfirstmadebyReinhard(1950)withbluecrabs
(1992)foundforthenorthernandeasternGulfofMexico. from Galveston Bay, Texas. Parasitized males with
Whileinonepreviousreport(Lor^etal.,1993) triangularabdomensmaynotoccurinallpopulations,as
C.rathbunaewasfoundtobeasecondhostforL.texanus, the existence of two morphologies for abdomens of
no information on the extent ofthe distribution of this parasitizedmaleswasnotdiscussedinaninvestigationof
associationwasavailablepriortothisreport.C.rathbunae parasitized blue crabs from the west coast of Florida
isanendemicoftheGulfofMexico,occurringsouthfrom (Hochbergetal. 1992). The frequencyofappearanceof
the United States-Mexico border to probably T^rminos both forms in males and mean size of crabs bearing a
lagoon, Campeche (Williams 1974); however, it is triangularabdomendid not differ significantlybetween
parasitized only southwards from Casitas, Veracruz, to hostspecies.Theoriginofthetriangularabdomenmaybe
Campeche.Itisrelevanttonotethatalthoughverylarge related to the number of times an infected host molts
samplesofC.rathbunaehavebeenobtainedfromTamiahua betweenthetimeofinfectionandthetimeofemergenceof
lagoon (Ldzaro-CMvez etal. inpress), this species has theexterna(Alvarez 1993),sotheextentoffeminization
neverbeenfoundparasitizedinthatarea,confirmingthat wouldberelatedtothedurationoftheinternalphaseofthe
itisparasitizedonlyinthesouthernportionofitsrange. parasite.Consequently,theappearanceofthetwotypesof
ThesizerangeofparasitizedC.rathbunae(45.3to144.1mm) abdomenscouldvaryseasonallyandgeographically.
208
AlvarezAND Calder6n
LiteratureCited
Adkins,G.1972.Notesontheoccurrenceanddistributionofthe O’Brien,J.andP.VanWyk.1984.Effectsofcrustaceanparasitic
rhizoccphaianparasite{LoxothylacustexanusBoschma)of castrators(cpicarideanisopodsandrhizocephalanbarnacles)
blue crabs {Callinectes sapidus Rathbun) in Louisiana on growth of crustacean hosts. In: A. M. Wenner (ed.).
estuaries.LAWildlifeandFisheriesComm,TechBull2,13p. CrustaceanIssues3.A.ABalkema,Rotterdam,p191-218.
Alvarez,F. 1993.Theinteractionbetweenaparasiticbarnacle, Park,J. R. 1969.PreliminarystudyofBiscayneBay.QJFla
Loxothylactispanopaei (Cirripedia, Rhizocephala), and AcadSci32:12-20, '
threeofitscrabhostspecies(Brachyura,Xanthidae)along Ragan,J.G.andB.A.Matheme,1974.StudiesonLoxothylacus
thecastcoastofNorthAmerica,Ph.D.Dissertation, Univ. texanus.In:R.L.Amborski,M.A.Hood,andR.R.Miller
Maryland,CollegePark,MD,188p. (eds.),ProcGulfCoastRegSympDiseasedAquatAnim.
Anonymous.1994,AtlasPesquerodeMexico.InstitutoNacional LSU-SG-74-05.BatonRouge,LA.p185-203.
dePesca,SecretaifadePcsca,234p. Reinhard,E.G.1950.Ananalysisoftheeffectsofasacculinid
Christmas,J.Y.1969.ParasiticbarnaclesinMississippiestuaries parasiteontheexternalmorphologyofCallinectessapidus.
withspecialreferencetoLoxothylacustexanusBoschmain BiolBuU98:277-288.
thebluecrab{Callinectessapidus).ProcAnnConference Reinhard. E. G. 1956, Parasitic castration ofCrustacea. Exp
SEAssnGomeandFishComm22:272-275. Parasit5:79-107.
Contreras,F, 1985.Laslagunascosterasmexicanas.Secretaiia Rosas,C.1989.Aspectosecofisiol6gicosdelaajaihasCallinectes
dePesca,263p, sapiduSyCallinectesrathbunaeyCallinectessimilisdela
Hochberg,R.J.,T,M.Bert,P-Steele,andS.D.Brown. 1992. zonasurdelaLagunadeTamiahua,Veracruz(Crustacea:
Parasitization of Loxothylacus texanus on Callinectes Decapoda: Portunidae). Tdsis Doctoral, Facultad de
sapidus:aspectsofpopulationbiologyandeffectsonhost Ciencias,UNAM,Mexico,215p.
morphology.BullMarSci50:117-132. Wardle, W, J. and A. I- Tirpak. 1991. Occurrence and
Hoeg, J. T. 1982. The anatomy and development of the distributionofanoutbreakofinfectionofLoxothylacus
rhizocephalanbarnacleClistosaccuspagwriLilljeborgand texanus (Rhizocephala) in blue crabs in Galveston
relationtoitshostPagurusbemhardus(L.).JExpMarBiol Bay, Texas, with special reference to size and
Ecol58:87425. coloration of the parasite’s external reproductive
Uizaro-Chfivez,E.,F.Alvarez,andC.Rosas.Inpress.Records structures. JCrustBiol 11:553-560,
of Loxothylacus texanus (Crustacea: Rhizocephala) WiUiams, A. B. 1974. The swimming crabs of the genus
parasitizingthebluecrab,Callinectessqpidus,inTamiahua Callinectes{Doc&podsi:Portunidae).FishBull72:685-798.
Lagoon,Mexico.JCrustBiol. Yfihez-Arancibia, A, & J. W. Day. 1988. Ecologfa de los
Loran, R. M., A. J. Valdez and F, Escudero. 1993. Algunos EcosistemasCosterosenelSurdelGolfodeMexico: La
aspectos poblacionalesde lasjaibas Callinectes spp. en Regi6ndelaLagunadeT6rmin(>.s.UNAM-Organizaci6nde
lagunasdeAlvarado,Veracruz.CiencPesquera10:15-32. EstadosAmericanos,5l8p.
210
