1. Estuaries

2. Introduction We’ve already seen what it’s like near the edge!We’ve already seen what it’s like near the edge! Ocean life is rough. Adaptation is the key to long term survival.Ocean life is rough. Adaptation is the key to long term survival. What about in environements which appear to be less disturbed? Does chaos still rule in a world of “living on the edge,” such as estuaries?What about in environements which appear to be less disturbed? Does chaos still rule in a world of “living on the edge,” such as estuaries? Let’s find ouch, shall we?Let’s find ouch, shall we?

3. Estuaries Estuaries are old structures.Estuaries are old structures. Invading seas to land masses form drowned river valleys or coastal plain estuaries.Invading seas to land masses form drowned river valleys or coastal plain estuaries. Others are known as bar-built estuaries, where sediment accumulation restricts sea/fresh water interaction.Others are known as bar-built estuaries, where sediment accumulation restricts sea/fresh water interaction. Glaciers can also create estuaries by cutting off sea water access to inland lakes (fjords).Glaciers can also create estuaries by cutting off sea water access to inland lakes (fjords).

4. Salty sources: Cape Hatteras is a perfect example of a man-made estuary. (High exchange, high productivity)

5. Milford Sound, NZ. Little exchange (low D.O.) Good example of a fjord system.

6. Salt wedges

7. Tidal Action: Animals in some estuaries are subjected to two cycles of varying salinity. Animals in these harsh environments enjoy benefits of highly productive grounds at the expense of difficult living conditions.

8. How well do you tolerate change?

9. Some animals are just better than others…

10. Plants play an important role in estuary “stability.” Cordgrass (Spartina) is an example of a grass which promotes bank stability while providing shelter for many small animals. Like mangroves, they excrete excess salt from their blades.

11. Other plants store water in succulent “leaves.” This form of water storage dilutes salts taken up by the plant during photosynthesis.

12. Mudflats and marsh creeks serve as spawning grounds for many species of fish. Catadromous: Sea to fresh Anadromous: Fresh to sea Anadromous: Fresh to sea

13. Primary productivity: very high in esturary mud flats. Especially for these horn snails Cerithidea californica which are excellent deposit feeders.

14. And the list goes on…

15. Birds have also evolved to take advantage of abundant food sources on mudflats.

16. Feast or famine? When the tide is in… food is scarce. When the tide drops… animals feast while they can…

17. Biofiltration: Estuary’s most important role? This salt marsh is dominated by grasses and benthic bacteria.

19. Figure 12.18

20. Figure 12.19

21. Figure 12.20

22. Figure 12.21

23. Figure 12.22