Download Interactions between Individual Substrate Type and Macrofauna

Hilary Hamilton, Samantha Scriber, Isla Murphy, Jenna Munden,
Katherine Fraser, Joe McSheffery
Interactions between Individual
Substrate Type and Macrofauna
Biodiversity in the Midlittoral Rocky
Intertidal
Overview
 Introduction
 Research Questions and Hypotheses
 Materials and Methods
 Results and Discussion
 Conclusions
Introduction
Background Information
 Sediment characteristics reflect the salinity, oxygen content,
pore-water content, temperature, food availability,
sedimentation rate, substrate consistency, turbidity, and
predation found in a particular environment
 sediment characteristics define what organisms can survive in
the environment
 Biodiversity: describes the sum total variation of life forms in a
specific environment.
Previous Studies
 community structure varies with the type, complexity and
heterogeneity of the substrate (Holland & Elmore, 2008).
 Previous studies have reported that substrate heterogeneity
enhances the diversity of macrobenthos species (Wang et al,
2009).
 preferable environment for settling, breeding, and preying, as
well as better shelter, and richer food sources in comparison
to other habitats
Rocky Intertidal Zone
 Interface between marine and terrestrial
habitats
 Substrates typically found in the rocky
intertidal zone include bedrock, boulder,
cobble, gravel, sand and algae
 The mixture of substrates changes based
on tidal location and other
environmental factors such as wave
exposure at a particular location.
Gap in Knowledge
 Details relating to substrate types are often overlooked
leading to an oversimplified experimental design
 Time consuming
 Complex intertidal conditions
Research Questions
 Goals - in depth analysis of substrate composition and
biodiversity
 Among heterogeneous substrates, which types of substrate
promote the highest level of biodiversity in the rocky shore
intertidal zone located off of the Passamaquoddy Bay?
Hypothesis
 Biodiversity will be highest at sites with algal cover.
 provides a buffer of external stressors such as heat, desiccation,
and wave stress for invertebrates
 in high densities algae may trap sediment and smother the
invertebrates or limit feeding but this effect will be reduced by
the high wave action characteristic of the rocky intertidal zone.
Materials and Methods
Materials
• 1 m2 quadrat
• 100m Transect
• Plastic bags to transport specimens
• Aquarium to store specimens at Hunts
• Species Identification guide
Methods
 Sampled at Indian Point, Bar Road, Left and Right of Road at
Green’s Point
 Mid-intertidal zone Parallel with shore. Limiting factors
between quadrats.
Methods
 Sampled 10m intervals.
 Each quadrat recorded substrate coverage
Substrates
 Sand/Mud/Silt= Any sediment smaller than a fingernail
 Algae= Ascophyllum nodosum,Vertebrata lanosa, Fucus vesiculosus
 Cobble= Stones smaller than your fist, larger than fingernail
<x<
 Rock= Larger than your fist, large enough to move easily
 Bedrock

Methods
 Members of group counted organisms and they were




recorded
Identified in the field
Given identifying characteristic and brought back to
Huntsman Marine Center
Identified at Huntsman Marine Center using identification
key, dissecting scope.
Recorded in excel
Results and Discussion
Diversity Indices
Shannon-Wiener
Simpson’s
 Weighted towards evenness
 Weighted towards
 Measures representation of
 Measures the probability of
 Diversity at a minimum at
 Diversity at a maximum at
a species throughout a
sample
0
abundance
two organisms being the
same species
0
Hard-Substrates: Cobble
Shannon-Wiener
Simpson’s
1.2
1.4
1
1
Simpson's Diversity
Shannon Weiner Diversity
1.2
0.8
y = -0.0021x + 0.8395
R² = 0.0147
0.6
y = 0.0031x + 0.4823
R² = 0.0922
0.8
0.6
0.4
0.4
0.2
0.2
0
0
0
20
P=0.6545
40
60
Percentage of Cobble Cover
80
100
0
20
P=0.2206
40
60
Percentage of Cobble Cover
80
100
Significance
Significance of trendline determined by linear regression analysis
Bedrock Significance
 Significant p-value of 0.0174 for linear analysis with
Shannon’s diversity
 Increasing bedrock cover relates to decreasing biodiversity
 Significant cover range 10% to 100%
 Intermediate Disturbance Hypothesis
Habitat Complexity and Biodiversity
1.6
1.4
Shannon Wiener Diversity
1.2
y = 0.1195x + 0.4252
R² = 0.2169
1
0.8
0.6
0.4
0.2
0
0
0.5
1
1.5
2
2.5
3
Number of Substrates per Quadrat
3.5
4
4.5
Wikstrom & Kautsky (2007)
 Increased biomass of understory
organisms in areas with Fucus
compared to areas without Fucus.
 Since no species were specific to
Fucus, this result can be assumed to
be due to the characteristic of Fucus
being an ecosystem engineer.
Chi2 Test for Biomass
Bar Road
Green’s Point: Right
Indian Point
Green’s Point: Left
Soft Substrates: Algae
Biomass
 Each transect showed significant difference in the number of
animals in each plot than what would be expected by chance.
Sampling Site
3 plots with highest
algal coverage
Observed % of
biomass
Expected % of
biomass
Green’s Point
Left
68
30
Green’s Point
Right
82
50
Indian Point
82
30
Bar Road
48
30
Species Distribution
Indian Point
1600
1420
Number of Individuals
1400
1200
1089
1000
892
800
538
600
400
200
0
163
34
1
3
5
10
2
9
1
Species
13
1
2
1
Species Distribution
Bar Road
500
474
450
400
Number of Individuals
400
337
350
300
250
200
150
117
100
50
16
1
0
Balanus balanus
Buccinum
undatum
Gammarus
oceanicus
23
19
Isopoda Littorina littorea Littorina obtusata Mytilus edulis
unknown
Species
Semibalanoides
Species Distribution
Green’s Point: Left
1000
909
900
Number of Individuals
800
700
600
553
500
400
353
316
300
194
200
100
0
29
160
3
30
1
Species
11
Species Distribution
Green’s Point: Right
No Barnacles
600
515
Number of Individuals
500
400
306
300
220
200
113
100
51
6
0
6
1
12
Species
10
13
20
1
Jenkins, Norton & Hawkins, 1999
 Negative interaction between algae and cyprid.
 Positive interaction between algae and adult.
Soft Substrates: Algae
Algae and Barnacle interactions
Sampling Site
Number of
Barnacles
% of total Algae coverage
Green’s Point
Left
0
87
Green’s Point
Right
11
63.5
Indian Point
1294
1.3
Bar Road
811
2.53
Soft Substrates: Algae
Vertebrata lanosa and Ascophyllum nodosum
Conclusions
 Although we observed some interactions between substrates
and biodiversity
 Significant findings:
 Bedrock = significant negative interaction
 Chi-squared test for heterogeneity of substrate and biomass
 Simplistic substrate definitions
 Greater sample sizes could lead to more concrete conclusions
Questions?