Study Questions: Final (Update, 1 pm, 6 Dec 2004)

The following questions cover the material from lecture and readings since Midterm II. Recall that the final is cumulative, and you will want to study from previous lectures, readings, labs, and exams. (Final exam questions on previous material will emphasize topics already covered on the midterm exams.)

1. What five major ecological processes influence diversity of a community?
2. Define disturbance and succession. What are some typical disturbance mechanisms in marine communities?
3. Explain "dominance control." How does competition affect species diversity? Why is habitat structure related to diversity?
4. How might predation, parasites, and herbivores decrease diversity? How can they increase diversity? Why are sea otters called Keystone predators? How do they increase diversity?
5. What is the Intermediate Disturbance Hypothesis? Why is diversity highest in the middle stage of succession? Why is diversity highest across the landscape when disturbance rates are intermediate? Explain examples of this hypothesis from corals and from rocky intertidal communities.
6. In what three ways do marine plant communities play important ecological roles (what is their contribution to the community)?
7. What are the distinctive characteristics of green, red and brown algae? What are some general differences in their life styles and habitats? Which alga is most likely found in deep water? In the tropics? In northern lattitudes? In kelp beds?
8. Where are Kelp forests and beds found (geographically, depth, substrate, ocean conditions)? How does urchin behavior and abundance affect kelp beds? Why are kelp forests so diverse? Describe the natural and manipulative removal experiments, and what they show about the role of urchins and otters.
9. Define a trophic cascade. Explain the role of killer whales and urchins and the trophic cascade found in kelp communities. Draw an interaction web.
10. What are the two common species of sea grasses in the US, and where do they occur? What three roles do sea grass beds play in the ecosystem? How do sea grasses affect atlantic bay scallops? What is causing declines in sea grass beds?
11. What are two marine communities that are dominated by amphibious marine angiosperms? What problems do angiosperms face? What limits the distribution of mangroves? What adaptations do mangroves have for marine living? What ecological role do mangroves play on the shoreline? What is the chief threat to mangroves?
12. Hermatypic corals are the primary 'builders' of coral reefs. Describe how these animals build massive reef structures over time. What is the distribution of reef building corals, both geographically and with depth? Why are they rare in the eastern Pacific and Atlantic in the Southern Hemisphere? Describe atolls, and barrier and fringing coastal reefs. How are atolls formed? In which ocean are they most abundant and why?
13. Why are coral reefs so productive, despite living in nutrient-poor tropical waters (at least 3 reasons)? Identify two costs and two benefits for each of the following: the coral, the zooxanthellae.
14. What is coral bleaching? What conditions lead to coral bleaching?
15. Give two examples of founder control (larval access) in determining community diversity. Describe habitat, species, and circumstances that lead to founder control.
16. Why are coral reefs so diverse? Describe the mechanisms explaining diversity in cryptic communities, reef fish, and in the corals themselves (e.g., non-transitive competition, larval access and the lottery hypothesis, and disturbance). Which coral communities are "dominance controlled" and which is "founder controlled."
17. What three physical major factors affect intertidal communities? What stresses does the tide alone cause? Which part of tide range is the most physically stressful? Which is most biologically stressful? How does predation pressure change along a depth gradient? Why?
18. Where are soft-sediment and rocky intertidal habitats mostly located, and why?
19. What causes zonation in rocky intertidal communities? What usually sets the upper limits of an organism's distribution? The lower limits? Use the Balanus-Chthamalus example to explain.
20. Why is the rocky intertidal musel zone a "dominance controlled" community? What processes maintain zonation versus diversity in the mussel zone? How does the fugitive species Postelsia coexist with mussels?
21. Define keystone species. Why are corals or kelps not considered to be keystone species? Show the interaction web for the keystone interaction between seastars and the mussel zone community. Why is this an "indirect" effect?
22. What are the major foraging types of animals in soft sediment habitats? What are some of the predators, deposit feeders, suspension feeders found on soft-sediments?
23. How does the ecological role of salt marshes differ from and resemble seagrasses, kelps, and mangroves? Why is faciliation well-known only from salt marshes? How does facilitation lead to species coexistance in salt marshes, and how does it work?
24. Why are there so many exotic species in coastal marine habitats? What steps can be taken to minimize the spread of exotic species?
25. How do exotic species affect native biological communities of marine organisms? Name and describe two damaging exotic species found in our region (where they live, what they have impacted). What are the ecological processes and mechanisms? Illustrate competition, predation, and habitat alteration with examples.
26. How do overexploitative fishing activities alter biodiversity? Describe two specific mechanisms by which overexploitative fishing can alter communities and ecosystems.
27. Name three types of marine protected areas. Which is the most protective? What are the main potential advantages of marine reserves? Have they been demonstrated?