2. Coral/algal Reefs II What forces maintain reef diversity?

4. Planet Earth video

5. Ecological functional groups

6. A larger scale view: reef building process

7. Atoll structure

8. Habitat diversity within an atoll

13. Niche dimensions enhancing reef fish diversity Defensive tactics Defensive tactics Feeding Feeding –Food type –Food location –Timing of foraging Life-history and social structure Life-history and social structure

14. Physical defenses: Spines of Porcupine fish

15. Physical defenses: misdirection, Butterfly fish

16. Territoriality: Pomacentrus

17. Poisons: Purple trunk fish, lionfish

18. Feeding: >50% feed on other fish Variation by size, location, timing Variation by size, location, timing

19. Feeding: coral (Triggerfish)

20. Feeding: “inverts” by probing (file fish)

21. Feeding: marine worms (butterfly fish)

22. Feeding: plankton (purple queen)

23. Feeding: algae (surgeon fish)

24. Feeding: other fish/ cleaning symbiosis –Pacific Cleaner Wrasse –Moray Eel –Saber Tooth Blenny

26. External factors influencing diversity Proximity to mangrove nurseries Proximity to mangrove nurseries –Mumby et al. 2004, Nature 427:533 –Compare fish biomass from reefs near mangroves and where mangroves scarce Species Scarce mangrove Rich mangrove H. sciurus 1,20533,349 H. pumieri 5,17416,280 Haemulidae11,63667,370 L. apodus 7396,192

27. How can coral/algal reefs support so many species? “Bottom-up” hypotheses “Bottom-up” hypotheses –High degree of nutrient recycling (symbiotic mutualism) promotes corals –Coral diversity promotes associated species –“Biotic multiplier effect” “Top-down” hypotheses “Top-down” hypotheses –Predation rates/disturbance reduce competition –Patchy environments with variable colonization –Priority advantage (inhibition model)

28. Utilitarian justification for reef conservation Therapeutic compounds from marine species Therapeutic compounds from marine species –Anti-virals from sponges, seagrass –Anti-tumor compounds from tunicate, dogfish, bryozoan, sea hares, cyanobacteria, sponge –Compounds to promote bone grafts from stony corals Tourism Tourism Food Food Impact on global climate, carbon exchange Impact on global climate, carbon exchange Models for scientific study Models for scientific study

29. Processes important in reef dynamics – what maintains the reef structure? Symbiosis (and dissolution of associations) Symbiosis (and dissolution of associations) Competition Competition Predation and grazing Predation and grazing Disturbance & recovery Disturbance & recovery

30. Competitive dynamics Exploitation competition (for light) Exploitation competition (for light) –Upright, branching corals can shade massive corals –Encrusting algae can spread over corals Interference competition (for space) Interference competition (for space) –External digestion by some corals –“Sweeper” tentacles for some species Hierarchy of competitive dominance Hierarchy of competitive dominance –Algae easily overgrow most corals –Among corals Pocillopora is nastiest

31. Dynamics of predation on coral reef species Coral-feeding fish are present but usually not devastating Coral-feeding fish are present but usually not devastating –Territorial damselfish create safe zones (up to 60% of surface area) –Coral-feeders have their own predators Starfish, such as “Crown-of-Thorns” can be problematic Starfish, such as “Crown-of-Thorns” can be problematic –Population “outbreaks” can damage living corals

32. Dynamics of grazing on algal reef species Urchins are major consumers (e.g., Diadema antillarum) Urchins are major consumers (e.g., Diadema antillarum) Grazing by herbivorous fish can be specialized on algae (more impact than fish feeding on corals) Grazing by herbivorous fish can be specialized on algae (more impact than fish feeding on corals) Grazing can suppress competitively dominant algae Grazing can suppress competitively dominant algae Indirect effects can become important Indirect effects can become important