Graduation Year


Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts



Reader 1

Professor Sarah Gilman

Reader 2

Professor Melissa Coleman

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2020 Elena C Kovachevich


There are many factors affecting the vertical distribution of sessile invertebrates that cannot be avoided. While it may prove difficult to test the significance of these factors out in the field, the effects they create can be visualized through physiological differences within intertidal environments. Previous research has shown that intertidal zonation of invertebrates is determined either by biotic or abiotic stimuli depending on the elevation. However, there are still some subtle nuances that need to be further explored to examine discrepancies within an individual intertidal species. The intent of this experiment was to compare Balanus glandula sizes at different elevations to determine which elevation supported the largest size for this species. I hypothesized that the middle elevation would contain the largest mean size due to significant factors affecting lower and upper level zonation. Using data collected from Friday Harbor, Washington, my hypothesis was supported in two out of three of my time periods. However, the data collected also secondarily showed that the frequency of barnacles at upper elevations were almost triple the amount found at lower elevations, even though they were smaller. These results may suggest that, while upper elevations may be a more stressful environment, Balanus prefers to allocate more energy while young in an area that allows for more recruitment.

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