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11 Hard Substrate

11 Hard Substrate. I. Physical Conditions A. High energy waves B. Temperature fluctuations 1. Rocks become hot 2. Freeze in winter C. Amount of water fluctuates 1. Submerged at high tide 2. Dry at low tide (no particles to retain moisture). II. Vertical Zonation

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11 Hard Substrate

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  1. 11 Hard Substrate

  2. I. Physical Conditions A. High energy waves B. Temperature fluctuations 1. Rocks become hot 2. Freeze in winter C. Amount of water fluctuates 1. Submerged at high tide 2. Dry at low tide (no particles to retain moisture)

  3. II. Vertical Zonation A. ZONATION: A distribution pattern in which organisms have a fairly distinct upper & lower range limits B. Rocky intertidal exhibits one of the sharpest gradients of physical factors in the world 1. Compete submergence in a liquid medium to dry land in a few meters 2. Environmental conditions are more extreme than those encountered by terrestrial species between shorelines and the tops of mountains 3. Opportunity for ecologists to investigate the important ecological question, “Why does a species occur in one place, but not in another?”

  4. Species Zonation on Pier Pilings http://www.flickr.com/photos/patrick-smith-photography/3453238514/sizes/o/in/photostream/

  5. II. Vertical Zonation (continued) C. Factors determining zonation 1. Physical (= exposure) a. Usually determine upper limits of organisms b. In areas with pronounced tidal change, a tidal height of a few feet can result in major differences in exposure

  6. Zonation in an Australian Rocky Intertidal Habitat http://www.google.com/imgres?imgurl=http://www.mesa.edu.au/friends/seashores/images/zonation.jpg&imgrefurl=http://www.care2.com/c2c/groups/disc.html%3Fgpp%3D11767%26pst%3D930340&h=200&w=300&sz=22&tbnid=J8IDIwqvVGt7JM:&tbnh=77&tbnw=116&prev=/images%3Fq%3Drocky%2Bintertidal%2Bzonation&usg=__I6qzVdwSSYa09zPh_TdYyGfB0Vo=&sa=X&ei=6HRNTJWPFMP6lwfS8N31DQ&ved=0CCsQ9QEwAw

  7. 1. Physical Factors (continued) c. Critical tide hypothesis (1) At certain tidal heights, organisms experience great differences in exposure time compared to organisms located slightly lower (2) These differences in exposure time determine whether or not a species can survive at that tidal height

  8. b. Tidal curve for a mixed semidiurnal tide 22 h 10 h 8 h Time of Day Modfied from Nybakken, 2001, p. 250

  9. Zonation in a Rhode Island Rocky Intertidal Habitat http://oceanexplorer.noaa.gov/explorations/03windows/background/chemosynthetic/media/fig2_589.jpg

  10. C. Factors determining zonation (continued) 2. Biological a. Generally determine lower limits b. Examples (1) Predation (2) Competition (3) Recruitment of larvae (a) Timing of (b) Number of larvae that settle

  11. 3. Classic study by Joe Connell on causes of zonation in rocky intertidal a. Studied the causes of zonation patterns (or limits species distribution) in a rocky intertidal habitat in Australia

  12. Small Barnacle Species #1 Big Barnacle Species #2

  13. 3. Classic study by Joe Connell (continued) b. Observed zonation pattern (1) High Intertidal dominated by adult Chthalamus a small barnacle (called here Species #1) (2) Middle Intertidal dominated by adult Semibalanus a large barnacle (= Species #2) (3) Barnacle larvae settlement (a) Species #1 settled from High to the Middle Intertidal (b) Species #2 settled from High through to the Low Intertidal

  14. MLW neap MLW spring Summary of Connell’s zonation experiments. Width of the bars indicates the relative effects of principal limiting factors; MHW, mean high water; MLW, mean low water. (Modified from Levinton, 2009, p. 364, after Connell, 1961.)

  15. Barnacle Zonation in the Intertidal Zone High Intertidal Middle Intertidal Low Intertidal Small Barnacle Sp #1 Big Barnacle Sp #2 Missing Small Barnacle Sp #1 Big Barnacle Sp #2 Missing Missing Larval Settlement Adult Distribution

  16. 3. Classic study by Joe Connell (continued) c. Transplant and cage experiments (1) Transplanted Species #1 from High Intertidal to Middle Intertidal (2) Transplanted Species #2 from Middle Intertidal to both the High and Low Intertidal (3) Covered some transplant cages to prevent predation (4) Removed the big Species #2 competitor from cages containing the small Species #1

  17. Connell Performed Transplant & Cage Experiments Transplants High Intertidal Middle Intertidal Low Intertidal Species #1 Species #2 Species #1 Species #2 Moved Sp #1 from high to middle intertidal Species #2 Species #2 Moved Sp #2 from middle to high and low intertidal

  18. Connell Performed Transplant and Cage Experiments Cage Experiments for Species #1 Open Covered Covered Exposed to Predators No Predation No Predation With Species #2 Removed Species #2

  19. 3. Classic study by Joe Connell (continued) d. Results (1) Small Species #1 could live in Middle Intertidal only if there were no predators AND no competitors

  20. Results of Transplant & Cage Experiments for Small Barnacle Species #1 High Intertidal Middle Intertidal Low Intertidal Uncovered Cages Small Barnacle Sp #1 Small Barnacle Sp #1 Missing Missing Missing Uncovered transplants did not survive. Eaten by predators

  21. Results of Transplant & Cage Experiments for Small Barnacle Species #1 Covered Cages Species #2 Not Removed High Intertidal Middle Intertidal Low Intertidal Small Barnacle Sp #1 Small Barnacle Sp #1 Missing Covered transplants did not survive. No predation, but overgrown by Sp #2 competitor

  22. Results of Transplant & Cage Experiments for Small Barnacle Species #1 Covered Cages Species #2 Removed High Intertidal Middle Intertidal Low Intertidal Small Barnacle Sp #1 Small Barnacle Sp #1 Missing Covered transplants survived if there were no predators and no competition from Species #2

  23. Species #2 Transplant and Cage Experiments High Intertidal Middle Intertidal Low Intertidal Big Barnacle Sp #2 Missing Big Barnacle Sp #2 Missing Larval Settlement Adult Distribution

  24. Species #2 Transplant and Cage Experiments Transplants Species #2 Species #2 Species #2 Species #2 Species #2 Species #2 Species #2 Species #2 Species #2 Moved Sp #2 from middle to high and low intertidal

  25. d. Results (continued) (2) Species #2 died of exposure (= desiccation) in High Intertidal

  26. Results of Transplant & Cage Experiments for Small Barnacle Species #2 High Intertidal Middle Intertidal Low Intertidal Missing Transplants of Species #2 died of exposure (= desiccation) in high intertidal Big Barnacle Sp #2 Big Barnacle Sp #2 Big Barnacle Sp #2 Big Barnacle Sp #2 Big Barnacle Sp #2 Big Barnacle Sp #2 Missing

  27. d. Results (continued) (3) Species #2 could survive in Low Intertidal if there were no predators

  28. Results of Transplant & Cage Experiments for Small Barnacle Species #2 High Intertidal Middle Intertidal Low Intertidal Species #2 could survive in low intertidal if there were no predators Big Barnacle Sp #2 Big Barnacle Sp #2 Missing

  29. 3. Classic study by Joe Connell (continued) e. Conclusions (1) Niches of small Species #1 (a) Fundamental Niche extended from High to Middle Intertidal (b) Realized Niche was High Intertidal

  30. Results of Transplant & Cage Experiments for Small Barnacle Species #1 High Intertidal Middle Intertidal Low Intertidal Small Barnacle Sp #1 Realized Niche Fundamental Niche Fundamental Niche Competitively Excluded Small barnacle could live in Middle Intertidal if there were no predators and no competitors

  31. e. Conclusions (continued) (2) Niches of big Species #2 (a) Fundamental Niche extended from High to Low Intertidal (b) Realized Niche was Middle Intertidal

  32. Results of Transplant & Cage Experiments for Small Barnacle Species #2 High Intertidal Middle Intertidal Low Intertidal Realized Niche Big Barnacle Sp #2 Fundamental Niche

  33. e. Conclusions (continued) (3) For sessile species in the intertidal… (a) Upper limits were determined by physical factors such as desiccation during low tide (b) Lower limits were determined by biological factors i Competition ii Predation

  34. MLW neap MLW spring Summary of Connell’s zonation experiments. Width of the bars indicates the relative effects of principal limiting factors; MHW, mean high water; MLW, mean low water. (Modified from Levinton, 2009, p. 364, after Connell, 1961.)

  35. Two intertidal boulders in Washington. Boulders are 10 m apart with the same orientation yet they have completely different cover (barnacles at left, seaweed at right). It is often not clear why such great differences in dominance are found http://life.bio.sunysb.edu/marinebio/rockyshore.html

  36. C. Factors determining zonation (continued) 4. Disturbances that clear patches a. Examples (1) Winter ice scouring (2) Logs bashing rocks in storms b. Timing relative to recruitment c. Size of patch cleared

  37. III. Zones A. Upper Intertidal (= Splash zone) 1. Physical conditions a. Seldom submerged (dry) b. Hot 2. Organisms are sparse a. Encrusting algae b. Periwinkles (Littorina) c. Some limpets d. Small acorn barnacles e. Most predators are terrestrial (1) Birds (2) Raccoons

  38. Acorn barnacles and periwinkles in an upper intertidal habitat in Central California Photo; Jack O’Brien July, 2013

  39. III. Zones (continued) B. Middle Intertidal 1. Physical conditions a. Submerged & exposed at regular intervals b. High energy waves

  40. B. Middle Intertidal (continued) 2. Organisms adapted for attachment a. Sea weeds have strong holdfasts b. Barnacles use cement c. Mussels use byssus threads (1) Can only feed when submerged, thus upper limit is determined by available food or feeding time (2) Crowd out competitors

  41. Brown and red algae on rocks in middle intertidal zone in the Central California Coast Photo: Jack O’Brien, July, 2013

  42. B. Middle Intertidal (continued) 3. Filter-feeders common a. Barnacles b. Mussels 4. Predators a. Dog whelks prey upon barnacles b. Sea stars prey upon mussels (1) Cannot withstand exposure (2) Determine lower limit of mussels

  43. The sea star Pisaster ochraceus is a top predator on eastern Pacific rocky shores. This sea star was turned over while attacking a mussel, Mytilus califomianus.(From Levinton, 2009, p. 365;photo by Jeffrey Levinton.)

  44. Mussel bed near Barnfield, British Columbia, showing abundant purple and orange sea stars Pisaster ochraceus below a Mytilus califomianus mussel bed. (From Levinton, 2009, p. 366;photo by Jeffrey Levinton.)

  45. Aggregation of sea stars, Pisaster ochraceus, at the periphery of a mussel bed dominated by Mytilus californianus. (From Levinton, 2009, p. 368;courtesy of T. H. Suchanek.)

  46. C. Lower Intertidal 1. Submerged most of the time 2. Organisms a. Lots of predators b. Large seaweeds dominate (a) Red and brown algae (b) Exposure often determine upper limit

  47. Brown algae forming kelp bed in the lower intertidal zone in the Central California Coast Photo: Jack O’Brien, July, 2013

  48. 2. Organisms in Lower Intertidal (continued) c. Fish d. Grazers such as sea urchins e. Few filter-feeders f. Sea anemones

  49. Sea Anemones in California Rocky Intertidal Habitat http://life.bio.sunysb.edu/marinebio/rockyshore.html

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