The document summarizes key concepts about intertidal zone ecology: 1) Organisms in the intertidal zone face extreme temperature and salinity changes and have adapted in various ways to survive, such as sealing their shells, clustering in wet spots, or being able to dry out and recover. 2) Intertidal organisms also cope with powerful waves through physical adaptations like holdfasts, byssal threads, or streamlined bodies, as well as behavioral adaptations like living in dense colonies. 3) Distinct vertical zones of organisms are formed based on physical factors like exposure to sun and heat as well as biological factors like competition and predation.

1. Chapter 11 Between the Tides Intertidal Zone = Littoral Zone

2. Rocky Shore Communities Rocky shores occur on steep coasts without much sediment. Formed by uplift or when waves and currents carry sediments away leaving the rocks. Common on West Coast and on the East Coast north of Cape Cod, MA

3. EXPOSURE AT LOW TIDE These periwinkles get through low tide by clustering in a moist, shady crevice. They also seal against the rock to retain moisture.

4. The ocean stays in small tide pools at low tide. Life is tough in tide pools because of drastic changes in salinity, oxygen, and temperature.

5. Mussels form dense clumps that retain moisture. This can help protect the mussels themselves and provides habitat for a variety of smaller organisms.

6. Seaweeds grow only on moist rocks, not on ones that dry out.

7. The shell ridges on this tropical snail help it stay cool by radiating heat. The white color also reflects sunlight.

8. Intertidal areas have extreme temperatures and salinity more than any other marine environment. How do they survive this hostile place?

11. Incoming waves refract or bend from the shelf Power of the Sea

12. Wave impact is stronger at headlands and less in bays

14. WAVE SHOCK: Shock to animal from the waves The giant green sea anemone lives low in the intertidal zone. a) In sheltered locations it grows tall b) In heavy wave action they are shorter to reduce drag

15. Organisms like this brown alga (kelp) withstand waves by being flexible. They are streamlined to reduce water resistance.

16. Intertidal animals get some protection from wave shock by growing in dense groups. Waves slide over much of them forming eddies. This also traps plankton near them.

17. A general food web on a rocky shore.

19. Vertical Zonation

20. Patterns of zonation on temperate shores

22. Intertidal organisms live attached to the rocks. Space gets used up.

23. The sea palm uses waves to compete for space. Adults “drip” spores on competitors and get pulled from rocks. This clears the way for new sporelings.

24. Intertidal organisms form distinct bands or zones.

26. Keystone Species A key predators whose effects on their communities are greater than their abundance Example: Sea Otter Otters eat sea urchins and other invertebrate kelp grazers. No otters = no kelp forest = few animals that live there. Kelp protects shoreline from wave erosion.

27. Sediments are classified by the size of particles. Sand is relatively coarse. Clay is fine. Silt and Clay together are mud.

28. Fine Sediments are found in calm areas such as bays and lagoons. Coarser sediments are found in areas affected by waves and currents.

29. Interstitial Water Water between the grains of sand. New water between grains brings oxygen. Only the top few centimeters of mud has oxygen. Anoxic – No oxygen Hydrogen Sulfide – “rotten egg” noxious gas produced by anaerobic bacteria w/o oxygen.

30. Figure 11.28a

31. Figure 11.28b

32. Figure 11.28c

33. Burrowing of a clam The foot does all the work. Foot gets pushed down and expands to anchor the clam. Clam gets pulled by the foot. Is this infauna or epifauna? Epifauna – Lives on the Sediment Infauna – Lives in the Sediment

34. Transplantation, Removal and Caging Experiments

35. Caging Experiment: Mussels grow in cage because lobsters could not get in to eat them. Mussels out-compete the sea weed.

38. Ecological Succession

42. Biological Interactions determine the type of seaweed that predominates

43. Green Sea Anemone catches small prey with tentacles but also gets nutrition from zooxanthellae, a symbiotic algae in its tissues

44. Getting Around Clams use their foot – Sea Cucumbers use an inchworm style. They digest organic material and leave the rest behind.

45. Food Web on Sandy Beach

46. Zonation pattern on Sandy Beaches