Rocky Intertidal HabitatsMARS 345022 October 2013Rocky Intertidal Environments• Mud: – salt marshes – mangroves– mud flats• Sand: – beach• Rock: – rocky intertidalwww.uri.edu/cels/bio/rishores/rocky.htmIntertidal Zonation= terrestrial= subtidalmidupper intertidallower intertidalsplash zone= the vertical segregation of organisms along an intertidal gradientIntertidal Zonationhttp://www.asnailsodyssey.comhttp://www.picstopin.comhttp://alpha2.bigelow.org/mitzi/images/lower%20zone/gen_zone_2.jpgwww.picstopin.comNybakken & BertnessWhat’s wrong with this picture?http://alpha2.bigelow.org/mitzi/images/upper%20zone/upper_5_lg.jpgPeriwinkleshttp://alpha2.bigelow.org/mitzi/spray_2.htmlLichenshttp://www.johnharveyphoto.com/BotanicalBeach/Shield Limpets (Lottia pelta) & Ribbed Limpets (Lottia digitalis) + BarnaclesIntertidal Zonationhttp://alpha2.bigelow.org/mitzi/mid_3.htmlhttp://alpha2.bigelow.org/mitzi/images/mid%20zone/mussel_2.jpgLineage (full): root; cellular organisms; Eukaryota; Opisthokonta; Metazoa; Eumetazoa; Bilateria; Protostomia; Ecdysozoa; Panarthropoda; Arthropoda; Mandibulata; Pancrustacea; Crustacea; Maxillopoda; Thecostraca; Cirripedia; Thoracica; Sessilia; Balanidae; BalanusLineage (full): root; cellular organisms; Eukaryota; Opisthokonta; Metazoa; Eumetazoa; Bilateria; Protostomia; Lophotrochozoa; Mollusca; Bivalvia; Pteriomorphia; Mytiloida; Mytiloidea; Mytilidae; Mytilinae; Mytilus edulishttp://alpha2.bigelow.org/mitzi/mid_10.htmlBarnaclesMusselsIntertidal Zonationhttp://alpha2.bigelow.org/mitzi/images/lower%20zone/gen_zone_2.jpghttp://alpha2.bigelow.org/mitzi/images/lower%20zone/algae_forest_2.jpgIntertidal ZonationNybakken & BertnessWhat’s Wrong with this Picture?Species DiversityhighlowSpecies richness greatest in low intertidal/subtidal zonesControls of organism distributionI. Physical factorsa. Tide1 daySemidiurnalMixed SemidiurnalDiurnalMixed SemidiurnalMixed SemidiurnalNote Rangesdiurnalsemi-diurnalMixed semidiurnal tidesSemi-diurnal:2 HT/2 LT per day~ equal1 HT/1 LT 2 HT/2 LTunequal Diurnal: Mixed semi-diurnal1 dayTidal range (distance between high and low tides) also variesLHWHLWHHWLLWWhat do you use for “chart datum”?Depends on the location and the purpose (law). Two most common “Chart Datums”: Mean Low Water (MLW) or Mean Lower Low Water (MLLW)Other factors also affect water level - windNarrow tide range – wind effect relatively greaterOther factors also affect water level Basin-scale circulationSea Level ChangesTectonicsMajor El Nino eventsTectonic Trend: 19.3 cm/centuryGeorgia Coastal tidesTides for Old Tower, Sapelo Island November 8 - 12, 2012.Day DateHigh Tide Height Sunrise Moon Time % Moon/Low Time Feet SunsetTh8 High 2:38 6.6 6:47 AM Rise 1:03 418 Low 8:58 1.2 17:31 PM Set 13:518 High 14:57 7.18 Low 21:24 0.9F9 High 3:33 7 6:48 AM Rise 2:03 319 Low 10:01 0.9 17:30 PM Set 14:279 High 15:52 7.29 Low 22:21 0.5Sa10 High 4:29 7.5 6:49 AM Rise 3:05 2110 Low 11:00 0.5 17:29 PM Set 15:0510 High 16:48 7.410 Low 23:15 0Su11 High 5:24 8 6:50 AM Rise 4:10 1311 Low 11:57 0.1 17:29 PM Set 15:4511 High 17:43 7.6M12 Low 12:08 -0.4 6:51 AM Rise 5:18 612 High 6:19 8.5 17:28 PM Set 16:3012 Low 12:52 -0.312 High 18:37 7.8What kind of tide is this?Controls of organism distributionI. Physical factorsa. Tide – critical tide levelsb. Exposure – desiccation and temperatureAdaptations for Exposure:1. Avoid exposure • move away• burrow•cover up2. Decrease exposure• impermeable shell• mucus shield3. Tolerate exposureMay – LOW tides in the morningIntertidal exposed to sun all dayDecember – HIGH tides in the AMIntertidal under water all dayDaylight hours =Tolerate exposureCastro & HuberPeriwinkle SnailsAvoid Exposure - Move awaywww.usc.eduWhy are these barnacles distributed like this?http://www.johnharveyphoto.com/BotanicalBeach/Shield Limpets (Lottia pelta) & Ribbed Limpets (Lottia digitalis) + BarnaclesDecrease Exposure - Impermeable BarriersBarriers do not solve the heat problemControls of organism distributionI. Physical factorsa. Tide – critical tide levelsb. Exposure – desiccation and temperaturec. Waves – mechanical stressincreasing wave actionOpen coast Wave-sheltered bayControls 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 overlapc cc cb bb bc bb cc cc cb bb bc bb cc cc cb bb bc bb cXXXXXXXC = ChthamalusB=Balanus (actually Semibalanus)ElevationTreatmentAll 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 BedKeystone predator = starfishAnswer: 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 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. 1998El Nino eventTemperatureRoughgarden et al.