intertidal ecology

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Intertidal Ecology. Rocky Shores Sandy Shores: sandy beaches Muddy Shores: mud flat. Divisions of Ocean environment. Where? Who? What are they doing there?. Why did these students have to stand in water to do the work?. Mixed, semidiurnal, and diurnal tide curves. Intertidal Ecology. - PowerPoint PPT Presentation


  • Intertidal EcologyRocky ShoresSandy Shores: sandy beachesMuddy Shores: mud flat

  • Divisions of Ocean environment

  • Where? Who? What are they doing there?

  • Why did these students have to stand in water to do the work?

  • Mixed, semidiurnal, and diurnal tide curves.

  • Highest tideLowest tideIntertidalFlatSubtidal zoneThe intertidal zone is the zone between the highest and lowest tides

  • Flood and ebb tidesWater-air alternative exposureRhythmicRich diversity and density within a small areaCharacteristics of the intertidal zones

  • Length of maximum submergence (hours)

  • Rocky Shore EcologyZonationFactors affecting zonationPhysical Environmental ConditionsBiological Interactions

  • Typical Rocky intertidal zonation patterns(Pacific)Zonation: Predictable distinctive distribution pattern of marine organisms through intertidal zone

  • Typical Rocky intertidal zonation patterns(Atlantic)

  • Zonation of major species on rocky shores. The figure is a general scheme of common animals and algae found in eastern North America. Details will differ for specific locations.

  • Classification of zones in all habitat type (Ricketts et al., 1985) Zone 1: uppermost horizon: Highest reach of spray and storm waves -- the mean of all high tides: the splash, spray, supralittoral, or Littorina zone Zone 2: high intertidal: Mean high water -- a bit below mean sea level: the home of barnacles and other animals tolerating more air than waterZone 3: Middle intertidal: about mean higher low water -- mean low waterZone 4: Low intertidal: normally uncovered by minus tides only. This zone can be examined during only a few hours in each month

  • Factors modifying zonation of Rocky shoreAbioticWave action and tidal rangeDesiccationHeat stressSalinityreduced feeding timeDO and gas exchange

    BioticLarval settlementIntra- and interspecific competitionPredation and grazingPhysiological tolerance and adaptationbehavioral pattern, mobility

  • Exposure-shelter diagram for Hong Kong shores. The range of the six litterine species are superimposed. 1. Nodilittorina pyramidalis; 2. Nodilitorina millegrana; Peasiella sp.; 4. Littorina brevicula; 5. Littorina scabra; 6. Littorina melanostoma.

  • Physical conditions of rocky intertidal areasTides-Periodical change the organisms' living environmentsTemperature-desiccation (could be fatal), particular in tropic region Wave action--exerts the most influence on organisms and communities

  • Physical conditions of rocky intertidal areas (cont)Wave action (cont)mechanical effect--smash and tear away objects;acts to extend the limits of the intertidal zone by throwing water higher on the shore (splashing allows the marine organisms to live higher in exposed wave-swept areas than in sheltered areas within the same tidal rangechange the topography of intertidal area by move substratum aroundmix atmospheric gases into the water--increasing the oxygen content

  • Physical Conditions of Rocky intertidal areas (cont)Salinity-the intertidal may be exposed at low tide and subsequently flooded by heavy rains or runoff from heavy rains --- either would sense severe problemsSubstratum topography - grain size would changepH and nutrients (not very important)

  • General distribution patternsRandom distribution: distribution of organisms can be explained by random chance Even distribution: organisms occur in an even mannerPatchiness: Organisms occur in isolated groups within a larger contiguous suitable habitat

  • AdaptationAdaptation to desiccation (water loss) Move to moist place or under the moist cover (crabs & snails)Tolerate high % water loss (Fucus, Porphyra, Enteromorpha, up to 60-90%)Reduce water loss by close shells (snails, barnacles, limpets home scar)Build shield to cover up (sea anemone or sea urchin covered with shell fragments)

  • Changes in the extent of vertical zonation with change in exposure to wave action.

  • Diagrammatic representation of the adaptations to water loss in intertidal organisms.

  • Many snails of the genus Littorina live high in the intertidal zone. When exposed, the snail protects itself from desiccation by pulling back into the shell and covering the opening with the operculum. First it secretes a mucous thread that attaches the shell to the rock.

  • AdaptationAdaptation to high temperature (heat)Temperature shock canaffect, metabolic and biochemical processes, such as enzyme function and oxygen demands.retard cellular activities, such as ciliary motion.inhibit behavioural activities, such as feeding & protection against predators.inhibit reproductive behaviour, such as egg laying and copulation.

  • AdaptationAdaptation to high temperature (heat)Reduce heat gain from the environment.Have a relatively large body size (less surface area relative to volume and less area for gaining heat, taking longer to heat up). (Littorina spp larger at high tidal zone)Reduce the area of body tissue in contact with the sbustrate (difficult to achieve swept off by waves)Increase heat loss from the bodyElaborated shell ridges & sculptures acting as heat radiators (snails)Light-colored body (gain and lost heat slowly) Water evaporation (holding extra water in mantle cavity of barnacles, limpets exceeds the amount the animal needs to survive desiccation)

  • Differences in heat absorption between smooth, dark shells and sculptured, light shells.

  • AdaptationAdaptation to wave action (smashing and tearing effects) Limitation of size and shape (relatively small, squat bodies with streamlined shapes to minimize the exposure to the lift and drag of wave forces)Flexible and bending (seaweed)Firm attachment by holdfast (algae), cemented shellTemprary attachments by byssal threads (which can be borken and remade)Thick shells, no delicate sculpturingLarge foot to clamps to the substrataSeek shelters (crabs)

  • The distribution of barnacles from shelter to exposure (from Tain Tam to Cape DAguilar). 1. Balanus tintinnabulum volcano; 2. Tetraclita squamosa; 3. Pollicipes mitella; 4. Balanus variegatus variegatus; 5. Balanus amphitrite amphitrite; 6. Balanus albicostatus albicostatus; 7. Euraphia withersi. A detail of the numbers and fusion of the valves of the principal genera are also given.

  • Algal formation of exposed vs. sheltered coasts

  • AdaptationRespiration (gills highly susceptible to desiccation in air) Enclose in a protective cavity to prevent them from drying (molluscs)Reduction of the gill and formation of a vascularized mantle cavityMantel tissue act as lung for aerial respiration (barnacles)Close up (operculum) or clamp down (chitons and Limpets) to reduce gaseous exchangeRemain quiescent druing low tide to conserve oxygen and water

  • AdaptationSalinity (flood by fresh water or expose to extremely high salinity) Osmoconformers: organisms without mechanisms to control the salt content of their body fluids using same adaptation as to prevent desiccation.Osmoregulators: organisms with physiological mechanisms to control the salt content of their internal fluids

  • Causes of patchiness in algae on rocky shores. (A) Sweeping action of algal fronds. (B) Irregular spatial and temporal distribution of grazers. (C) Fluctuations in recruitment. (D) Refuge from grazing provided by pits and cracks in rock. (E) Escape of spoelings from grazers.

  • Biological factors controlling rocky intertidal zonationCompetition (barnacles as examples)Predation (starfish, mussels, and barnacles)Grazing (sea urchin on seaweed)Larval settlementInteraction among the controlling factors community ecology

  • Biological factors controlling rocky intertidal zonationCompetition (barnacles as examples)Predation (starfish, mussels, and barnacles)Grazing (sea urchin on seaweed)Larval settlementInteraction among the controlling factors community ecology

  • Intertidal zonation as a result of the interaction of physical and biological factors.The larvae of two barnacles, Chthamalus stellatus and Balanus balanoides, settle out over a broad area. Physical factors, mainly desiccation, then act to limit survival of B. balanoides above mean high water of neap tides. Competition between B. balanoides and C. stellatus in the zone between mean tide and mean high water of neap tides then eliminates C. stellatus.

  • Effect of desiccation and competition on two species of intertidal barnacles

  • Controlling factorsHigh tidal zoneChthamalus stelatus settled hereSemibalanus balanoides have no sufficient tolerance to drying and high temperatures.Mid tidal zoneChthamalus stelatus settled here but was overgrew, uplifted or crushed by Semibalanus balanoides

  • The main groups of algal grazers at different intertidal zones in temperate and tropical systems.

  • Effect of sea urchin removal on kelp growth on the Isle of Man, Great Britain.

  • Interaction of predation and physical factors in establishing the zonation of the dominant intertidal organisms on the rocky shores

  • Interactions among mussels (Mytilus), barnacles, and their predators on the northwester Pacific coast of North America, which allow barnacles to persist in the intertidal zone.

  • Succession in a northwest Pacific coast intertidal mussel bed in the absence of Pisaster.

  • Flow chart of Rocky intertidal Succession

  • Rocky intertidal food web.

  • Sandy and Muddy Shores1. Shape up of beachesSediment sizeWave actionSlope2. SurroundingsExposed vs protectedOceanic vs semi-enclosed waters, estuaries or wetlandsSeasonal vs n