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INTERTIDAL ZONATION BIOLOGICAL FACTORS
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1. Grazing -growth of Laminaria - zone ends abruptly Why?
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1. Grazing Experiment done in New South Wales, Australia
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Underwood (1980 Oecologia 46:201) Used exclusion cages 1- Open2 - Fence3 - Roof4 - Cage Grazers excluded Grazers in Normal Shade Normal
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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
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2. Predation Pisaster ochraceous on Mytilus californianus
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2. Predation Pisaster ochraceous on Mytilus californianus
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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
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3. Competition ChthalamusSemibalanus
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3. Competition EHWS MTL ELWS Chthalamus zone Semibalanus zone
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3. Competition EHWS MTL ELWS Chthalamus zone Semibalanus zone Remove Semibalanus
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3. Competition EHWS MTL ELWS Chthalamus zone Semibalanus zone Remove Chthalamus
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3. Competition Lifted SmotheredCrushed?? 100 50 0 Source of Mortality
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3. Competition MHWS MTL MHWN MLWN MLWS Larval settlementEffects of physical factorsCompetition Chthamamus Semibalanus
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4. Larval Settlement Generalized life cycle for marine invertebrates Dispersing larva (planktonic) settle juvenile adult egg
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4. Larval Settlement Larval settlementFinal distribution pattern
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4. Larval Settlement Larval settlementFinal distribution pattern happens because of 1. Indiscriminate settlement and high mortality
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4. Larval Settlement Larval settlementFinal distribution pattern happens because of 1. Indiscriminate settlement and high mortality 2. Discriminate settlement and low mortality
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4. Larval Settlement Flustrellidra lives on Ascophyllum Hurlbut ‘91 - Distribution of Bryozoans
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4. Larval Settlement Hurlbut ‘91 - Distribution of Bryozoans Alcyonidium Chondrus Fucus Rock Geukensia
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4. Larval Settlement Hurlbut ‘91 - Distribution of Bryozoans Flustrellidra Ascophyllum
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4. Larval Settlement
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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
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Summary Observed distribution and abundance temperature desiccationice wave exposure reproductive mode competition larval settlement predationsurvival grazing
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