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Chapter 11 PowerPoint Presentation

Chapter 11

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Chapter 11

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  1. Chapter 11 Between the Tides

  2. Location • Narrow fringe along the shoreline that lies between the highest high tide and the lowest low tide

  3. Easy to study

  4. A unique environment • Organisms are regularly exposed to air • Emersion – being out of water and exposed to air • Immersion – being submerged

  5. Bottom Type (Varies) • Sand, mud, rock • Substrate – material on or in which organisms live

  6. Types of Communities

  7. Rocky Shore Communities • Organisms are attached to rocks • Sessile – permanently attached • Epifauna – live on the surface of the substrate

  8. Challenges of the Environment • Exposure at low tide – can lead to desiccation (drying out), temperature changes, salinity change • Adaptations: clam up, run and hide (tide pool or crevice), tolerate it • High tide – wave shock, restrictions on feeding • Adaptations: flexible, low profile, strong anchors (muscular foot, holdfast, byssal threads), thick shell, compact shape

  9. Plentiful Resources • Plenty of nutrients, light and food • High tides bring plankton and detritus (decaying organic matter)

  10. The Battle for Space

  11. Limiting Resources • There is not enough space – all areas are occupied – competition for space

  12. Vertical Zonation

  13. The rocky intertidal community is usually divided into distinct bands or zones at characteristic heights in the intertidal • Vertical zonation - A given species is only found in a particular vertical range

  14. Zonation is Caused by: • Complex interaction of physical and biological factors • Upper limit determined by physical factors • Lower limit determined by biological factors

  15. Soft-Bottom Intertidal Communites

  16. Substrate: Sand or mud • Organisms are buried in the sand or mud (substrate) • Infauna – live in the sediment

  17. Challenges of the environment • Size of particles determines many physical characteristics of the habitat

  18. Problems for Sandy Bottoms • Sediments are constantly shifting – nowhere to attach • Water drains quickly • Can have a lot of water motion

  19. Problems for Muddy Bottoms • More organic matter to decay and use up oxygen • Flow of water that brings in new oxygen is reduced • Except for the upper few centimeters of mud the interstitial water (water between the grains) is deficient of oxygen

  20. Anoxic – sediments with absolutely no oxygen • Anaerobic bacteria can break down organic matter without oxygen – hydrogen sulfide is produced as a byproduct • H2S – smells like rotten eggs and turns things black