RUI: Changes in Mytilus edulis complex distribution as it correlates to increasing sea surface temperatures in the intertidal

Climate change can significantly alter the distribution of species worldwide, with dramatic ecological and economic impacts. This study investigates how rising ocean temperatures affect blue mussels, which are vital to marine ecosystems and global aquaculture. Blue mussels are being collected around Hokkaido, Japan, where ocean warming is occurring at a high level and varies around the island.

This, combined with differences in temperature tolerance between the two blue mussel species in Hokkaido, is being used to determine how ocean temperatures are influencing community composition. By combining genetic tools, temperature data, and reproductive studies, this project explores how climate change is affecting mussels and what that could mean for ocean ecosystems.

Undergraduate student training is a key aspect of the project, which will provide international fieldwork experience and on-campus research assistantships. Research activities are being incorporated into course-based undergraduate research experiences (CUREs), and datasets serve as case studies in upper-level undergraduate biology courses.

The goal of this study is to explore the effects of rising sea surface temperatures (SST) on the distribution, reproductive dynamics, and hybridization of the Mytilus edulis species complex in Hokkaido, Japan, where unprecedented decadal SST increases have been observed. Focusing on M. trossulus and M. galloprovincialis, it aims to (1) re-examine species distributions after 17-years, (2) evaluate changes in reproductive stages, and (3) investigate genetic structures of hybrid populations.

The project integrates traditional genotyping with double-digest restriction-site associated DNA sequencing (ddRAD-seq) to assess shifts in population structure. SST trends are being analyzed using long-term remote sensing data, while histological techniques will measure reproductive responses. This research leverages Hokkaido's hybrid zones as natural experiments to understand differential species responses to climate warming, providing insights into the mechanisms driving biogeographic shifts, reproductive adaptations, and genetic variability in hybrid systems.

The findings enhance knowledge of climate-related pressures on marine biodiversity and intertidal ecosystem dynamics.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.