1. Effects of rocky intertidal algal cover on invertebrate diversity at Green’s Point, NB
Marissa Hackman
Clay Steell
Hannah Kienzle
Jessica Browne
Alanna MacDonald

2. Pro Plant Cover Plant cover can provide protection from the tide
The presence of macroalgae can increase invertebrate colonization (Downes 2000)
Plant richness has been noted to increase invertebrate richness (Knops et al. 1989)
Some research has shown that canopy algae can host more invertebrate diversity (Bustamante et al ).

3. Con: Plant cover
Plant cover may increase invertebrate abundance rather than richness (Gunnill 1982)
In a study examining Fucus vesiculosis, a decrease in biomass affected abundance and biomass not richness (Wikstrom and Kautsky 2007)

4. Purpose and Hypothesis
To investigate the effect of plant cover on invertebrate richness
Hypothesis:
Increasing plant cover will increase overall invertebrate richness
Photo by David Fenwickh

5. The Algae A. nodosum dominant
F. vesiculosis distribution more variable (Thomas, 1994)
Fucus vesiculosis
Ascophyllum nodosum

6. Notable Invertebrates
Littorina spp.
Testudinalia Testudinalos
Balanus balanus
Semibalanus balanoides
Buccinum undatum
Gammarus oceanicus
Asterias forbesi
Carcinus maenas
Bryozoan spp.
Periwinkles, Common Tortoise Limpet, Common Whelk, amphipod, Forbes Sea star, Green Crab,

7. Sampling Area: Greens Point
Large, rocky substrate
Relatively high wave exposure

9. Methods - Sampling Two transects with 10 quadrats each
Surveyed elevation up beach
% cover and type of algae recorded
Organisms collected to identify later
Species identified next day to determine richness

10. Methods - Statistical Analysis
Multiple regression
Independent variables:
% cover Fucus
% cover Ascophyllum
Distance
Do these variables predict invertebrate diversity (species richness)?

11. Results
12 species
Primarily gastropods and crustaceans

12. Results Most likely model incorporates only Fucus
% cover has a significant effect on richness (R2=0.21, p=0.043)
Ascophyllum cover and distance from shore
Not significant predictors in models where they were included
Model
AIC
likelihood
Fucus
-9.31
Fucus + Distance
-7.57
Fucus + Ascophylum
-7.383
Null model
-6.965
Full model
-5.857

13. Results

14. Discussion Greater Fucus coverage may increase invertebrate richness
Ascophyllum coverage had no relationship with invertebrate richness
Reflects the variation found in the literature

15. Discussion
Research has shown that macroalgae coverage is associated with increased faunal diversity
In contrast, several studies have reported no relationship

16. Discussion
Plant coverage may provide protection from desiccation or temperature extremes
May be able to support more herbivores and hence attract predatory invertebrates
These factors may explain trends observed in Fucus

17. Discussion
This relationship may be affected by interaction with other physical factors (i.e. epiphytes, wind exposure) and other plant species
Potential influence of structural differences between Fucus and Ascophyllum
May explain differences

18. Discussion: Future Research
Measure abundance of each species
Using diversity indices rather than solely richness
Increased number of samples
Taken from various sites
will allow a more thorough analysis more accurate description of this relationship

19. Questions and Comments