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

Introduction Intertidal austerity Overcoming austerity

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

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

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

Introduction GAP IN KNOWLEDGE Very exciting!

Materials and Methods Two sites Pagan’s Point Indian Point

Materials and Methods Group 1 Group 2

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

Materials and Methods Lab work Data collected: Height Width Species

Results Determination of elevations Indian Point Pagan’s Point

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

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

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

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

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

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

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.

Discussion At 0m Density-dependent mortality

Discussion Below 0m Decreased settlement High flow, low density

Discussion Predation Thermal Low settlement Desiccation Thermal Density Past Recruitment

Discussion Large barnacles uncommon Seasonal Ice scour Temperature

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

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

Discussion Further research Aging Density

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