Graduation Year


Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts



Reader 1

Sarah Gilman

Reader 2

Lars Schmitz


Thermal stress is one of the main abiotic stressors affecting the growth of intertidal species. Sessile species like barnacles are more impacted by this stress since they cannot move. Previous studies have suggested that Balanus glandula barnacles at the Friday Harbor site in Washington are better adapted to the cold water and air temperatures recorded in northern California rather than warmer temperatures. To test this, I compared growth rates at a Washington site (Friday Harbor) and a southern California site (Newport Beach), both of which have warm air temperatures for barnacles. The barnacles in Friday Harbor are more physiologically adapted to colder temperatures due to the cooler water temperatures, while the Newport Beach barnacles are more adjusted to the warmer temperatures overall. I hypothesized that the Newport Beach B. glandula barnacles will have higher growth rates since their physiology is better matched to their environment. Using temperature and barnacle growth data from both sites, I found that Newport Beach air temperatures were significantly warmer. None of the growth data was significant, however, there was an emerging pattern that showed that Friday Harbor had higher growth rates. Further experimental research is necessary to determine if this trend carries significance or if it is due to confounding variables. This data is crucial because learning about how these barnacles adapt to thermal stress can provide a basis for understanding how they will adapt in the future with increased rates of global warming. This can also provide insights into how global warming will affect intertidal ecosystems.

This thesis is restricted to the Claremont Colleges current faculty, students, and staff.