1. INTERTIDAL ZONATION BIOLOGICAL FACTORS

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

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

4. Underwood (1980 Oecologia 46:201) Used exclusion cages 1- Open2 - Fence3 - Roof4 - Cage Grazers excluded Grazers in Normal Shade Normal

5. 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 grazers

6. 2. Predation Pisaster ochraceous on Mytilus californianus

7. 2. Predation Pisaster ochraceous on Mytilus californianus

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

9. 3. Competition ChthalamusSemibalanus

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

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

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

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

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

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

16. 4. Larval Settlement Larval settlementFinal distribution pattern

17. 4. Larval Settlement Larval settlementFinal distribution pattern happens because of 1. Indiscriminate settlement and high mortality

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

19. 4. Larval Settlement Flustrellidra lives on Ascophyllum Hurlbut ‘91 - Distribution of Bryozoans

20. 4. Larval Settlement Hurlbut ‘91 - Distribution of Bryozoans Alcyonidium Chondrus Fucus Rock Geukensia

21. 4. Larval Settlement Hurlbut ‘91 - Distribution of Bryozoans Flustrellidra Ascophyllum

22. 4. Larval Settlement

23. 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

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