Ch. 11 Between the Tides

1. Ch. 11 Between the Tides

2. Basics • Intertidal zone • Between tides • Littoral zone • Best studied areas • Emersion vs. Immersion • Few marine places open to air • Must give up advantages • Habitat • The tides/community rely on type of bottom

3. http://www.youtube.com/watch?v=qfhNjpu_IU4

4. Basics cont. • Habitat • Community-all the different pop. in an area • Bottom-the material which organisms live on • Substrate/substratum • Different bottoms define habitat

5. Low Tide Exposure • Problems • Harsher environment • Higher up more time out of water • The highest is never submerged • Water Loss • Desiccation • Must tolerate, or prevent it • Two main ways, hiding or “clamming up”

6. Low Tide Exposure • Water Loss • Hiding • Go run and hide to somewhere wet • Tide pools • Sessile organisms only spawn in wet areas • “Clam up” • Some protective covering • Holds water, and they go in to their covering • Some clamp themselves to rocks

7. http://www.youtube.com/watch?v=FeUilWF-MoI

8. Rocky Bottom Communities • Basics • Formed by • Active coasts uplifting • Ice scraping and weighing • Waves carry away/erode • Organisms • Most are epifaunal • Many are sessile • Both cause stress

9. Low Tide Exposure • Water Loss • “Clam up” • Some close off their operculum • Not caring • Chitons and rockweeds just don’t care • Temperature and Salinity • Heat capacity allows for moderate water temp

10. Low Tide Exposure • Temperature and Salinity • Air temp. is more extreme • Most are eurythermal • Some hide in the shade • Some colors are lighter • Salinity also affects organisms • Some clam up • Some burrow (more common in soft)

11. Low Tide Exposure • Restriction of feeding • Deposit uncommon (rocky) • Filter common among sessile • Only underwater • Others eat detritus or seaweed • Predatory problems at low tide • Not being able to eat at higher up in the habitat • Slower development

12. The Power of the Sea • Waves • The distribution of wave action is varied • Refraction not perfect • Bays less action, headlands more • Wave impact intensity (wave shock) is varied • Coping with Wave Shock • Some only live sheltered • Deal with sediment more

13. The Power of the Sea • Coping with Wave Shock • Some anchor themselves to rocks • Seaweed-holdfasts • Mussels-byssal threads • Move slowly • Suction cups • No swim bladder • Anchoring can disadvantageous • Thicker shells • This causes greater diversity among locations

14. http://www.youtube.com/watch?v=r1KfBg56UVc

15. The Battle for Space • Space limitation • Plenty of food • Limiting resource is mainly open space • Ways to compete • First one there • Quick dispersal • Forcing out others • Growing over others

16. Vertical Zonation of Rocky Shores • Basics • Community divided into bands • One organism won’t exist throughout • Vertical zonation • General rule • Upper limit physical • Lower limit biological • Not perfect • Fuzzy • Split into • Upper, middle, lower • Not universal

17. Vertical Zonation of Rocky Shores • Upper intertidal • Highly exposed to air • Above high tide line • Affected by splash • “splash zone” • Farther on exposed coasts • Organisms • Lichens • Cyanobacteria • Algae • Periwinkles • Littorina zone • Limpets

18. Vertical Zonation of Rocky Shores • Middle intertidal • Parts are submerged more than others • Causes greater diversity • Top almost always has barnacles • Due to larva, predation, and desiccation tolerance • Bottom limit from predation/competition • Have to stop from drying out • Other parts are determined by the specific site

19. Vertical Zonation of Rocky Shores • Middle intertidal • The middle of the middle is dominated by • Mussels, barnacles, and brown seaweeds • Seaweed forms algal turf • Mussels killed by sea stars, or spiny lobsters • Keystone predator • Ecological succession • Final climax community • Not always typical • Diversity increases with competitive exclusion

20. Vertical Zonation of Rocky Shores • Lower intertidal • Immersed mostly • Many predators • Many seaweeds • Light and space limited • Self sustaining tide pools

21. http://www.youtube.com/watch?v=g7Rlh5sA8WE

22. Soft Bottom Intertidal Communities • Basics • Any bottom composed of sediment • Can be confusing • For book is burrowable • Dominate east Cape Cod and the Gulf • The shifting sediments • Unstable ground • Less seaweed, more seagrass

23. Soft Bottom Intertidal Communities • The shifting sediments • Most organisms are infaunal • Protection from physical and predators • Most sediment is a mix • Calmer=finer • Rougher=larger • Living in the sediment • Oxygen availability • Detritus main source of food • Deposit feeders

24. Soft Bottom Intertidal Communities • Living in the sediment • Oxygen availability • Oxygen and detritus is dependent on sediment size • Coarser=more • This is due to the porosity of the sediment • In muddy bottoms, the organic matter uses the little bit of oxygen • Interstitial water • Anoxic bacteria thrive • Others bioturbate • Others have special hemoglobin • And others are lazy

25. Soft Bottom Intertidal Communities • Living in the sediment • Getting around • To move around • Clams use muscular foot • Worms open a path with their pharynx • Crustacean dig • Some eat while moving through the sediment • Meiofauna live in between the grains and are worm-shaped

26. http://www.youtube.com/watch?v=vNqEQjGaDVk

27. Soft Bottom Intertidal Communities • Living in the sediment • Feeding • Plankton and diatoms are major primary producers • Suspension feeders lay out a net to catch detritus • Zonation • Not as obvious • Burrowing • Higher up the sand is drier • Crustaceans • Really hard to tell on mud flats where the tide line is fuzzy due to low slope