Graduation Date

Fall 2023

Document Type



Master of Science degree with a major in Biology

Committee Chair Name

Erik Jules

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Emily Jones

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Cascade Sorte

Third Committee Member Affiliation

Community Member or Outside Professional

Fourth Committee Member Name

Paul Bourdeau

Fourth Committee Member Affiliation

HSU Faculty or Staff

Subject Categories



The effects of climate warming on the distribution of range-expanding species are well documented, but the interactive effects of climate warming and range-expanding species on recipient communities remain understudied. For example, with climate warming, range-expanding species may become a threat to local biodiversity due to their relatively stronger competitive or predatory effects on potentially weakened, or less well-adapted recipient communities. Acanthinucella spirata is a predatory marine gastropod that has expanded its distribution north along the California coast since the Pleistocene via a poleward geographical range shift, tracking climatic warming. To assess whether A. spirata has stronger predatory effects on the recipient community in their expanded range and is better suited to the warming conditions than a local predatory snail, I used a combination of field and laboratory studies to examine the feeding activity of A. spirata and a local predatory whelk (Nucella lamellosa) on shared prey on Cape Mendocino under ambient and elevated conditions. From a series of field surveys, I concluded that A. spirata is a potential competitive threat to N. lamellosa, due to its high local abundance, overlapping habitat, and shared prey on Cape Mendocino. In the laboratory experiment, I observed that A. spirata was a more efficient consumer of barnacles than N. lamellosa overall and ate significantly more barnacles than N. lamellosa under warmer conditions. As climate change continues, environmental conditions will become more stressful for all species; however, range-expanding A. spirata populations may be at a competitive advantage relative to N. lamellosa, as they exhibit greater abundances and a higher feeding rate at warmer temperatures than the local whelk.

Citation Style




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