1. Lecture 9 – INTERTIDAL ZONATION BIOLOGICAL FACTORS

2. reproductive mode competitionlarval settlement predation survival grazing BIOLOGICAL FACTORS

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- Open2 - Fence3 - Roof4 - Cage Grazers excluded Grazers in Normal Shade Normal

6. 1- Open2 - Fence3 - Roof4 - Cage Grazers excluded Grazers in Normal Shade Normal 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

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

9. 2. Predation Pisaster ochraceous on Mytilus californianus

10. 2. Predation Pisaster ochraceous on Mytilus californianus Time (Years) 0246810 Height above chart datum 1.5 1.0 0.5 Pisaster removal begins Pisaster removal ends

11. 3. Competition ChthalamusSemibalanus

12. 3. Competition Millport, Isle of Cumbrae

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

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

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

16. 3. Competition Lifted SmotheredCrushed?? 100 50 0 Source of Mortality

17. 3. Competition MHWS MTL MHWN MLWN MLWS Larval settlementEffects of physical factorsCompetition Chthamamus Semibalanus

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

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

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

21. 100 50 100 50 Chthalamus Semibalanus Drip Dry Percent cover by each species Tidal Height MHWNMLWN Wethey 1983. Biol.Bull. 165:330 Distribution of Semibalanus and Chthalamus

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

23. Wethey 1983. Biol.Bull. 165:330 Tidal Height MHWNMLWN Vertical-North Vertical-West 10º Slope-South Chthalamus Semibalanus Settlement density ( no./cm 2 1.0 0.5 2.0 1.0 0.5 Distribution of Semibalanus and Chthalamus

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

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

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

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

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

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

30. 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

31. Summary Observed distribution and abundance temperature desiccationice wave exposure reproductive mode competition larval settlement predationsurvival grazing