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Wave Exposure and its Effects on the
Diversity of a Shoreline
Anne Haley, Lauren Jonah, Riki Krentz, Jessica Hingley & Caroline Méthé
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Introduction - diversity
• Health and survival of ecosystem
• 2 variables: richness & evenness
• Two diversity indices: Shannon-Wiener and Simpson’s
• Physical & biological stressors affect diversity - eg. wave exposure
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Wave Exposure• Strong influence on diversity
• Contradictory past research in animal species
• More agreement in botanical species− Greater diversity in wave-exposed
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Effects of wave exposure
• Research question: What is the optimal amount of wave exposure to yield the greatest diversity?
• Intermediate Disturbance Hypothesis
• Our hypothesis: greater diversity at moderate → high → low
• Three sites: low, moderate and high
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Methods
• Indian Point, Greens Point and Bar road
• 10 quadrants of 1x1m
• 100m transect line
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Methods
• Quadrant counts− Animal counts & estimates− % plant coverage
estimates
• Unknown species were taken back to the lab for further identification
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Results
• No significant difference between sites− Data was not normalized
• Diversity indices− Moderate → Low → High
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Results - Fauna
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Results - Fauna
• Species diversity: moderate → low → high
• Moderate wave exposure = highest alpha
• Overall low beta (changeover in species)
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Results - Flora
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Results - Flora
• Species diversity: high → moderate → low
• High and low wave exposure = highest alpha
• Overall high beta (changeover in species)
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Discussion
• Support for the intermediate disturbance hypothesis−Moderate wave exposure = greatest species
diversity• High wave exposure sites did not have greater
diversity than sites with low wave exposure
• These results were analyzed only on animal species, due to plant abundance was measured in percent coverage
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Discussion
Crashing of waves on intertidal substrate (disturbance): independent variable
Habitat disturbances: −Renew limiting resources:
oxygen, nutrients−Prevent dominating species
Excessive amounts = unsuitable habitat
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Discussion
High Wave ExposureGreater number of plants• Plants are colonizers after disturbance due
to succession
No barnacles recorded • Desiccation, duration of emergence• Whiplash effect (Grant, 1997)
− Fronds physically remove barnacles with wave motion
• Interaction with whelks?
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Discussion
Low Wave ExposureVery few plants were found• Soft, muddy substrate which does not
provide a surface for fauna to grow
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Areas for improvement• Samples collected from the immediate
surface• Some species gone unnoticed
• Brief sampling time (low tide)• Estimations• Varying counting methods• Normalize data• Inaccurate identification
• Little differences in barnacle and periwinkle species
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Conclusions
• Species diversity was highest in areas with moderate wave intensity
• Proven by the intermediate disturbance hypothesis− Balance of disturbances yields the greatest
amount of species richness and evenness → diversity
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Questions?