Download The effects of substrate types on species diversity

The effects of substrate
types on species
diversity
Michelle Johnson, Amanda Jeanson,
Marshall Elsemore, & Aneri Garg
Outline
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Background
Hypothesis
Methods
Results
Discussion
Conclusion
Study Site
Physical and Biological Stress
● Wave exposure
● Competition
● * Tidal height *
● Predation
Substrate Cover
Substrate Type
Proportion on large islands and
mainland of Quoddy Region (%)
Bedrock
35.2
Coarse Sediment
55.1
Mud
9.2
Salt Marsh
0.5
Substrate Impact - Sand
● Sand/Mud:
o
Heavily modified by tides, wind, storm surges
o
Less vegetation
o
Low-medium diversity
o
Burrowing organisms
Substrate Impact - Cobbles
● Cobbles:
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Colliding rock and debris from wave action
o
Diversity dependent on local features & positioning
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Low species diversity
Substrate Impact - Rock
● Bedrock:
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Development of tide pools and crevices
o
Promote high diversity
o
Mediate thermal stress
Hypothesis
● Difference in diversity between all 3
substrate types
● Highest diversity on rocky substrate
H0 :There is no difference in diversity between
all 3 substrate types
Materials
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100m measuring tape
1m square quadrat
Ziploc bags for species collection
Camera
Methods
• 2 transects were set up at separate locations based on differences in:
• Vegetation cover
• Wave action
• Substrate size
• Ten quadrats were placed along each transect.
Methods Cont’d
• Each organism found was collected, while
taking note if the specimen found was
present on the surface of the substrate or
underneath the flora cover.
• G. oceanicus and B. balanus were
unable to be collected due to difficulties
in handling their large numbers.
Different Substrate Types
● Large Rocks
● Cobbles
● Sand
Analysis
● Species richness
● Species diversity
o
o
Shannon-Wiener Index
Simpson`s Index
● Cochran`s Q Test
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Nominal data
*Scuds and barnacles removed from the analysis
Results
Continued Results
Table 1: Species diversity for different substrate
Species Richness
Shannon-Weiner Index
Simpson`s Index
Boulders
Cobbles
Sand
8
2
1
0.657
0.276
0
3.5
1.8
1
Statistics
● Cochran`s Q Test
o
X2 = 0.503
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X2crit(.05, 8) = 14.067, and p < .05
o
Reject the null hypothesis

A difference in diversity between substrate
Accepting our Hypotheses
Results supported our hypotheses:
• Diversity on the three substrates differed and that with
the highest species diversity was indeed found on the
large rock substrate (aka boulders)
Implications with past Literature
High Diversity within Large Rocks
Bertness (2006)
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Muscle bed protection from physical factors
• Diversity: crabs, limpets
Seed (1996)
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Species evenness allows few abundant species
Leads to increased diversity
Peterson (1991)
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Availability of rock space controls diversity levels and not prey availability
• Our experiment suggests:
• Prey availability competition leads to lower levels of diversity than competition for
space
Implications with past Literature
Low Diversity within Sand/Rock
Donovan and Tyrell (2005)
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Ease in modification of this substrate from high winds, waves and storms lower diversity in this
substrate
Species that live in this substrate tend to be burrowing species.
• Burrow for protection
Limitations
• One sampling site: Physical factors skew data
• Equipment: Inability to count all species in Quadrats
• Tide Movement: Inconsistent tide levels in the two sampling sites.
Conclusion
• This experiment looked to:
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show a difference in diversity based on the type of substrate sampled.
• Our results showed:
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A difference in diversity between the three substrates investigated in this
experiment.
• Increased diversity on large rock substrates (boulders).
• **The results supported work found in past literature and supported
diversity theories mentioned.
• This Experiment Demonstrated:
• Substrate type seems to have an effect on species diversity (although many
other factors also play a role).