1. Figure 10.22

3. Subtidal Zone The part of the continental shelf that is always covered by water –from the low tide mark to the shelf break (150m or 490 ft)

4. Subtidal Zone Temperature varies from place to place due to its shallowness Bottom still affected by waves, tides and currents Very productive areas – nutrients & light

5. Subtidal Zone Soft Bottom Communites –Seagrass Beds Hard Bottom Communites –Kelp Forests

6. Seagrass Beds Develop in sheltered shallow water Most species prefer warm waters –Turtle Grass Some are found in colder areas –Eelgrass (Zostera marina) our local species

7. Figure 13.17

10. Ecological Targets Hard Clams Seagrass Meadows

11. Seagrass Beds Slow down currents Increase the depositing of sediments Have roots - can absorb nutrients from the sediment

12. Seagrass Beds Important nursery for juvenile animals –Bay scallop on Long Island

15. Figure 13.16 Generalized food web in a seagrass community

16. Hard-Bottom Subtidal Communities Less common than soft-bottom Submerged extension of rocky intertidal, hard parts of organisms (oyster shells, calcareous algae) Sometimes called “reefs” – not coral

17. Kelp Kelp = large brown seaweed Large holdfast to hold onto the rocky bottom Long stipes Fronds… 20-30m (65-100ft) Go through two stages in their life cycle

19. Laminaria Alaria (edible)

20. Geographic Kelp Distribution

21. Kelp Communities Arranged in distinct layers Giant kelp forms in deeper waters –reduced wave action –Forms a canopy

26. Figure 13.23 Kelp: Baja, CA

27. Figure 13.25

28. Kelp Communities Many organisms Sea Urchins = most important grazers or herbivores

30. Fig. nft

31. Sea Urchins What leads to population explosions? –Absence of their predators –Overfishing, less seals & sea lions, killer whales eat sea otters, more urchins

35. Figure 13.26