Intertidal Communities

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Intertidal Communities. Rocky Shore Communities. The Intertidal. The intertidal zone is the area between the highest high and the lowest low tide Organisms that live in this area undergo the greatest variations in environmental conditions. Tidal Forces. - PowerPoint PPT Presentation

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<ul><li><p>Intertidal CommunitiesRocky Shore Communities</p><p>Rocky Shore</p></li><li><p>The IntertidalThe intertidal zone is the area between the highest high and the lowest low tideOrganisms that live in this area undergo the greatest variations in environmental conditions</p><p>Rocky Shore</p></li><li><p>Tidal ForcesGravitational pull on the earth by the sun and moon combined with centrifugal force generated by the earth-moon-systemSemidiurnal tidesDiurnal tides</p><p>Rocky Shore</p></li><li><p>Spring and Neap Tides</p><p>Rocky Shore</p></li><li><p>Rocky Intertidal CommunityRocky coasts usually occur on steep coasts that lack sediment</p><p>Fort Fisher is one of the only naturally occurring rocky outcrops in the S.E. U.S.EpifaunaSessile </p><p>Rocky Shore</p></li><li><p>Rocky Shore</p></li><li><p>Abiotic Factors</p><p>DesiccationExtreme changes in temperatureChanges in salinityTurbulence</p><p>Rocky Shore</p></li><li><p>Water LossFor survival the duration of exposure to air is criticalSessile animals have structural adaptations </p><p>Rocky Shore</p></li><li><p>DessicationAlgae - can withstand 70 - 90% of water loss in tissues and surviveLittorina sp. (Periwinkle) reduce area in contact with the substrate and have a light colored shell to deal with extreme heatsAlgae mat at low tide</p><p>Rocky Shore</p></li><li><p>Changes in TemperatureDue to its high heat capacity water shows a minimum change in temperature when compared with the airIf extreme temperature does not kill an organism it may severely weaken it and cause it to die of secondary causesExtreme temperatures may hasten desiccationAdaptations</p><p>Rocky Shore</p></li><li><p>Drastic Fluctuations in SalinitySalinity may change due to severe rainfall If severe enough at low tide the entire community may experience high mortality</p><p>Rocky Shore</p></li><li><p>Wave ActionWaves act to smash and tear organisms from the substrateSessile animals use cement (barnacles), holdfasts (seaweeds) and, byssal threads (mussels)Mobile animals have appendages for clinging and snails have an enlarged foot used for attachmentWave action also effects the intertidal by disturbing the substrate</p><p>Rocky Shore</p></li><li><p>Rocky Shore</p></li><li><p>Modes of FeedingDue to the lack of sediment there are no deposit feeders!</p><p>Almost all of the sessile animals are filter or suspension feeders</p><p>Heavy wave action also effects feeding</p><p>SuspensionFeedingBarnacles</p><p>Rocky Shore</p></li><li><p>Vertical ZonationSpecies settle in specific vertical bands based on their ability to withstand exposure to airThe rocky intertidal provides many microhabitats (Numerous niches)High species diversityDistinct banding which progress from the low tide line to the high tide lineZonation occurs due to a both physical and biological interactions</p><p>Rocky Shore</p></li><li><p>Rocky Shore ZonationOrganisms are found in a given area by their ability to compete and deal with physical factors. Most animals in the intertidal live near the upper end of their lethal limitsLower distribution is determined by competition and predation</p><p>Rocky Shore</p></li><li><p>Rocky Shore</p></li><li><p>Biotic FactorsCompetitionDue to the limited amount of area, competition for space is acute</p><p>Succession natural progression of communitiesThe creation of open spaces results in quick colonization by opportunistic species.Soon replaced by slower growing competitively dominant spp.</p><p>Rocky Shore</p></li><li><p>Rocky Shore</p></li><li><p>Keystone PredatorsKeystone species: a single species, which has a controlling effect on the community in which it lives</p><p>Rocky Shore</p></li><li><p>Tide pools Animals have the same physical factors to contend with</p><p>Closed Tide Pools </p><p>Open Tide pools </p><p>Rocky Shore</p></li></ul>