Rocky IIMARS 345024 October 2013Salinity Tolerance is important for determining the distribution of estuarine organismsOrganism Distribution“Oligohaline”Width of Shape = Number of SpeciesLotsFewSpecies RichnessOligohaline – minimum richness2-10 PSUMarine SpeciesFreshwater SpeciesBrackish Water SpeciesAll SpeciesSalinity, PSU (o/oo, g/L)Controls of organism distributionI. Physical factorsa. Tide – critical tide levelsb. Exposure – desiccation and temperaturec. Waves – mechanical stressII. Biological factorsa. Competition – space, food, lightIntertidal ZonationNybakken & BertnessStrong dominance by one organism -Why?Rock Barnacles(Semibalanus balanoides)www.hafro.is/images/ myndasafn/s-fjorukarl.jpgLittle Gray Barnacles(Chthamalus stellatus)www.marlin.ac.uk/species/ Chthamalusstellatus.htmDistributions tend NOT to overlap in natureConnell’s experiment: Why don’t their distributions overlap?c cc cb bb bc bb cc cc cb bb bc bb cc cc cb bb bc bb cXXXXXXXC = ChthamalusB=Balanus (actually Semibalanus)ElevationTreatment (settling plates)All C All B MixedAnswer: Combination of physical AND biological factors:Competition for spaceControls of organism distributionI. Physical factorsa. Tide – critical tide levelsb. Exposure – desiccation and temperaturec. Waves – mechanical stressII. Biological factorsa. Competition – space, food, lightb. Predation and herbivoryFood Webhttp://alpha2.bigelow.org/mitzi/images/mid%20zone/mussel_4.jpgCompetitive dominant = musselsHow do other organisms gain a foothold?**sea stardogwhelkmusselsbarnacleshttp://alpha2.bigelow.org/mitzi/images/mid%20zone/nuc_ind_2.jpgNucellahttp://alpha2.bigelow.org/mitzi/images/mid%20zone/nuc_feed_2.jpgSeastars Clumped at Edge of Mussel BedStarfish = “Keystone predator,” a concept first articulated by Robert Payne, UWAnswer: predation can create openings, patches that allows recruitment of other species.Physical disruption can do the same thingControls of organism distributionI. Physical factorsa. Tide – critical tide levelsb. Exposure – dessication and temperaturec. Waves – mechanical stressII. Biological factorsa. Competition – space, food, lightb. Predation and herbivoryuppermidlowersubtidalForces structuring rocky intertidal communities(here the example is algae) vary with tidal elevationControls of organism distributionI. Physical factorsa. Tide – critical tide levelsb. Exposure – desiccation and temperaturec. Waves – mechanical stressII. Biological factorsa. Competition – space, food, lightb. Predation and herbivoryc. Recruitment – larval settlementSupply Side EcologyRoughgarden et al. 1998sea starbarnaclebarnacleRoughgarden et al. 1998TemperatureRoughgarden et al. 199819821983El Nino1984Note the structure in what to us is a “featureless” environmentOffshore transportNo TransportChlorophyll ConcentrationRoughgarden et al. 19981982 1983El Nino1984Roughgarden et al. 1998El NinoBertnessIntertidal ZonationNybakken & BertnessWhat’s Wrong with this Picture?Controls of organism distributionI. Physical factorsa. Tide – critical tide levelsb. Exposure – desiccation and temperaturec. Waves – mechanical stressII. Biological factorsa. Competition – space, food, lightb. Predation and herbivoryc. Recruitment – larval settlementd. Succession – replacement of organisms through time1stspecies slows colonization1stspecies has no effect1stspecies enhances colonizationSucession in the Rocky Intertidalhttp://alpha2.bigelow.org/mitzi/images/mid%20zone/clado_2.jpgReference plotFarrell et al. 1991 Ecol. Monographs 61:95-113 A = AlgaeB = BalanusC = Chthamalushttp://alpha2.bigelow.org/mitzi/images/mid%20zone/clado_2.jpgFarrell et al. 1991 Ecol. Monographs 61:95-113 Cleared plot Succession:1st: C2nd: B3rd: AEarly dominant eventually losesFarrell et al. 1991 Ecol. Monographs 61:95-113 Effect of C on BToleranceSuccession1st: C2nd: B3rd: ARemoving Chthalamusdid not affect BalanusrecruitmentFarrell et al. 1991 Ecol. Monographs 61:95-113 Effect of B on AFacilitationSuccession1st: C2nd: B3rd: AHaving barnacles on the rock helped algae become establishedFacilitation due to live barnacles?Farrell et al. 1991 Ecol. Monographs 61:95-113 Barnacle tests are better than live barnacles!What do barnacles provide?• Rough surface to collect algal spores• Protection from desiccation• Protection from grazinghttp://alpha2.bigelow.org/mitzi/images/mid%20zone/limpet_dors_2.jpgProtection from grazing?Farrell et al. 1991 Ecol. Monographs 61:95-113 Algae does fine when limpets excludedGrazing vs. barnacle presenceFarrell et al. 1991 Ecol. Monographs 61:95-113 Algae does WORST when limpets are present and there are no barnaclesAnd BEST when limpets are excluded and barnacles are presentIntertidal ZonationNybakken &