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Lecture 9 – INTERTIDAL ZONATION BIOLOGICAL FACTORS

Lecture 9 – INTERTIDAL ZONATION BIOLOGICAL FACTORS. BIOLOGICAL FACTORS. grazing. competition. larval settlement. survival. reproductive mode. predation. 1. Grazing. -growth of Laminaria - zone ends abruptly. Why?. 1. Grazing. Experiment done in New South Wales, Australia.

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Lecture 9 – INTERTIDAL ZONATION BIOLOGICAL FACTORS

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  1. Lecture 9 – INTERTIDAL ZONATION BIOLOGICAL FACTORS

  2. BIOLOGICAL FACTORS grazing competition larval settlement survival reproductive mode predation

  3. 1. Grazing -growth of Laminaria - zone ends abruptly Why?

  4. 1. Grazing Experiment done in New South Wales, Australia

  5. Underwood (1980 Oecologia 46:201) Used exclusion cages 1- Open 2 - Fence 3 - Roof 4 - Cage Grazers excluded Grazers in Grazers excluded Grazers in Shade Normal Normal Shade

  6. 1- Open 2 - Fence 3 - Roof 4 - Cage Grazers excluded Grazers in Grazers excluded Grazers in Shade Normal Normal Shade No growth or recruitment Recruitment but poor growth No growth or recruitment Recruitment and growth to nearly adult size Therefore - upper limit dictated by exposure + grazers

  7. 2. Predation Pisaster ochraceous on Mytilus californianus R. Paine

  8. 2. Predation Pisaster ochraceous on Mytilus californianus

  9. 2. Predation Pisaster ochraceous on Mytilus californianus Pisaster removal begins Pisaster removal ends 1.5 Height above chart datum 1.0 0.5 0 2 4 6 8 10 Time (Years)

  10. 3. Competition Chthalamus Semibalanus

  11. 3. Competition Millport, Isle of Cumbrae

  12. 3. Competition EHWS Chthalamus zone MTL Semibalanus zone ELWS

  13. 3. Competition Remove Semibalanus EHWS Chthalamus zone MTL Semibalanus zone ELWS

  14. 3. Competition Remove Chthalamus EHWS Chthalamus zone MTL Semibalanus zone ELWS

  15. 3. Competition 100 50 0 Lifted Smothered Crushed ?? Source of Mortality

  16. Chthamamus 3. Competition Semibalanus MHWS MHWN MTL MLWN MLWS Larval settlement Effects of physical factors Competition

  17. Distribution of Semibalanus and Chthalamus Semibalanus Chthalamus Wethey 1983. Biol.Bull. 165:330

  18. Distribution of Semibalanus and Chthalamus Nahant, Mass. No Chthalamus Guilford & Horse Island, Conn. Semibalanus & Chthalamus coexist Wethey 1983. Biol.Bull. 165:330

  19. Distribution of Semibalanus and Chthalamus 100 50 Vertical-North 100 50 Vertical-West Percent cover by each species 100 50 10º Slope-South Chthalamus Semibalanus MHWN MLWN Tidal Height Wethey 1983. Biol.Bull. 165:330

  20. Distribution of Semibalanus and Chthalamus 100 50 Drip Percent cover by each species 100 50 Dry Chthalamus Semibalanus MHWN MLWN Tidal Height Wethey 1983. Biol.Bull. 165:330

  21. Distribution of Semibalanus and Chthalamus Increasing sun exposure Percent cover by each species Chthalamus Semibalanus MHWN MLWN Tidal Height Wethey 1983. Biol.Bull. 165:330

  22. Distribution of Semibalanus and Chthalamus 1.0 0.5 Vertical-North 2.0 1.0 Vertical-West Settlement density ( no./cm2 1.0 0.5 10º Slope-South Chthalamus Semibalanus MHWN MLWN Tidal Height Wethey 1983. Biol.Bull. 165:330

  23. 4. Larval Settlement Generalized life cycle for marine invertebrates Dispersing larva (planktonic) egg settle juvenile adult

  24. 4. Larval Settlement Larval settlement Final distribution pattern happens because of 1. Indiscriminate settlement and high mortality 2. Discriminate settlement and low mortality

  25. 4. Larval Settlement Distribution of Bryozoans Flustrellidra lives on Ascophyllum Hurlbut 1991. J.Exp. Mar. Biol. Ecol. 147:103

  26. 4. Larval Settlement Hurlbut ‘91 - Distribution of Bryozoans Chondrus Geukensia Alcyonidium Rock Fucus Hurlbut 1991. J.Exp. Mar. Biol. Ecol. 147:103

  27. 4. Larval Settlement Hurlbut 1991. J.Exp. Mar. Biol. Ecol. 147:103

  28. 4. Larval Settlement Hurlbut ‘91 - Distribution of Bryozoans Flustrellidra Ascophyllum Hurlbut 1991. J.Exp. Mar. Biol. Ecol. 147:103

  29. 4. Larval Settlement Results Flustrellidra • larvae selectively settle on Ascophyllum • greater survivorship on Ascophyllum Alcyonidium • larvae show preferential settlement on Fucus and Chondrus • most adult colonies occur on rock Hurlbut 1991. J.Exp. Mar. Biol. Ecol. 147:103

  30. Summary desiccation ice temperature wave exposure reproductive mode grazing competition larval settlement survival predation Observed distribution and abundance

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