Date of Award

2026

Thesis Type

Open Access

Degree Name

Honors Bachelor of Arts

Department

Biology

Sponsor

Dr. Pamela M. Brannock

Committee Member

Dr. Brandaliz Santiago-Narvaez

Committee Member

Dr. Paul Stephenson

Abstract

Rising sea surface temperatures (SSTs) and increasingly frequent marine heat waves (MHWs) are reshaping intertidal communities worldwide. This study investigates potential shifts in the distribution of the two blue mussel species, the warm-affinity Mytilus galloprovincialis and the cold-affinity Mytilus trossulus, along the northern coast of Hokkaido, Japan, one of the most rapidly warming marine regions around the world. Sampling was conducted at four sites (Absahiri, Hamatonbetsu, Lake Notoro Inner, and Saruru) in May to June 2025 and compared to baseline data from Brannock and Hilbish (2010). Three nuclear markers (Glu-5’, ITS, MAL-I), analyzed via polymerase chain reaction and restriction enzyme digest where applicable, were used to assign individuals to one of four genotypic categories: homozygous M. trossulus, homozygous M. galloprovincialis, F1 hybrid, and other hybrids. Significant declines in M. trossulus and corresponding increases in M. galloprovincialis were detected at three of four sites over the 17-year period, while hybrid frequency did not increase. These findings are consistent with the hypothesis that rising SSTs may be contributing to the competitive displacement of the native M. trossulus by the invasive M. galloprovincialis, with broader implications for intertidal biodiversity and long term ecosystem resilience.

Rights Holder

Olivia Prelog

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