Positive effects of the introduced barnacle Balanus glandula on the native limpet Siphonaria lessonii in the high interidal of Argentina

GOTTLIEB, E.R.F.; JORGE LUIS CEFERINO GUTIERREZ; PALOMO, M.G.; BAGUR, M.; GONZALEZ, J. A.

Congreso; Western Society of Naturalists 101st Meeting; 2020

Limpetsusesubstrateroughnesselements(i.e.crevices,sessileorganisms)asrestingsitesduringinactivity.Introducedbarnacles,Balanusglandula,accountformuchoftheroughnessinhighrockyintertidalzonesofArgentina.Weevaluateifintroducedbarnacleshaveadirectpositiveeffectondensitiesofanativelimpet,Siphonarialessonii,andapositiveeffectonalgalgrowththerebyindirectlyaffectinglimpetdensities.Limpetdensitieswerepositivelyrelatedtobarnacledensitiesin11outof19sitessurveyedinBuenosAires,RioNegro,andChubutProvinces.Non-significantpositiverelationshipswerefoundatsiteswithrelativelylowlimpetdensitiesand/orroughbasalsubstrate.Ahighproportion(40.18%- 94.25%)oflimpetsateachsitewereadjacenttobarnacles.Limpetspositivelyrespondedtotheadditionofepoxybarnaclemimicsintobarnacle-freeareas.Barnacleremoval,withlimpetexclusion,ledtodecreasedalgalgrowth.Surveysandexperimentsin107TierradelFuegoProvincerevealedsimilarpatternsbetweentwospeciesofSiphonaria (S.lessoniiandS.lateralis)andanativebarnacle(Notochthamalusscabrosus).Barnaclesincreasesurfaceroughnessinthehighintertidal,providingrefugeforlimpets.Barnaclesmayconfershade,temperaturecontrol,andincreasedsurfacemoisture.Increasedsurfaceareafrombarnaclesincreasesalgalbiomass,indirectlydrivingthepositiverelationshipbetweenbarnacleandlimpetdensities- limpetsgrazeonalgae.Consequentincreaseoflimpetdensityinbarnacledenseareasdecreasesalgalbiomass.