1. Variance in body size of S. balanoides and B
Variance in body size of S. balanoides and B. balanus along the intertidal
Cassy Muldoon-Gorchynski, Jenna Hinds, Jillian Hunt, Keegan Smith and Sarah Seaborn

2. Introduction
Intertidal austerity
Overcoming austerity

3. Introduction Barnacles are special! The skinny on barnacles
Physical description
Habitat
Distribution

4. Introduction Barnacle Species Similarities Distinguishing features
S. balanoides aka Acorn Barnacle
B. balanus aka Northern Rock Barnacle
Similarities
Distinguishing features

5. Introduction Factors Affecting Distribution Competition Predation
Desiccation
Water flow speed
Location of settlement
Food accessibility
Facilitation
Environmental austerity

6. Introduction
GAP IN KNOWLEDGE
Very exciting!

7. Materials and Methods
Two sites
Pagan’s Point
Indian Point

8. Materials and Methods
Group 1
Group 2

9. Materials and Methods Group 1 Stadia rod – tide height
Collect 50 barnacles
Within 1m radius
10m (Pagan’s Point)
20 sites
50m (Indian Point)
12 sites

10. Materials and Methods
Lab work
Data collected:
Height
Width
Species

11. Results
Determination of elevations
Indian Point
Pagan’s Point

12. Results – Volume vs. Elevation
Indian Point
Pagan Point
S. balanoides ?
B. balanus

13. Results 3 distinct elevation groups can be seen
Immediately around 0 (small sizes)
Above 0 (larger)
Below 0 (larger)
This was found to be true by Mann-Whitney U testing between groups
Overall trend is weaker at Pagan point transect
Sizes for the high and low groups are similar
In general, S. balanoides is smaller than B. balanus on both transects

14. Results S. balanoides versus B. balanoides based on elevation profiles
Indian Point Pagan`s Point
S. balanoides
B. balanus

15. Results – Volumes and Elevations
S. balanoides
Pagan Point
B. balanus at Pagan’s Point
S. balanoides at Pagan’s Point
Fit is less obvious, and weaker statistically-speaking
B. balanus
The results found at pagans point,
You can see how the barnacle size changes with distance in elevation

16. Results B. balanus at Indian Point S. balanoides at Indian Point
Volumes fit to elevations fairly well
B. balanus at IP is the “poster child” of our trend
S. balanoides
As you can see in each of these diagrams, the volumes of both balanus balanus and semibalanus balanoides at Pagan’s point fits well to the evelations. B. Balanus had the best fit in trend out of the two species at each location
Red line
To make trend, it is subtracted from zero, all values away from zero are distances away from zero point
B. balanus

17. Discussion Both species are smaller at 0m than above/below tide height
Roughly V-shaped distribution
Both species of barnacles are small at the Om level (telescope) than above or below the tide height
Each species at each location demonstrated a v-shaped distribution.
s. Balanoides at indian point?
Each point is the average size at that point on the transect
Smaller barnacles found within the barnacle band, and increase in size away from barnacle band in both directions

18. Causes for V distribution
Above 0m
Thermal Regulation (water flow rate)
Carcinus maenus
Predation
Decreases density
Green crabs invaded the area in the 1990s
They feed primarily on barnacles found on the higher intertidal region
End of my section.
Thermal regulation
High flow, supports solitary barnacles
Tend to be larger, Better thermoregulate
Low flow rate typically results in aggregated small barnacles.

19. Discussion
At 0m
Density-dependent mortality

20. Discussion
Below 0m
Decreased settlement
High flow, low density

21. Discussion Predation Thermal Low settlement Desiccation Thermal
Density
Past Recruitment

22. Discussion
Large barnacles uncommon
Seasonal
Ice scour
Temperature

23. Discussion Inter-specific interaction S. balanoides < B. balanus
Further research

24. Discussion Other factors affecting size Larval settlement distribution
Growth rate
Predation
Competition
Density-dependent mortality
Fecundity
Thermoregulation

25. Discussion
Further research
Aging
Density

26. Thank you very much for your time and attention!
Do you have any questions?