Date of Completion
4-6-2026
Degree Type
Honors Thesis
Discipline
Biology (BIOL)
First Advisor
Maria Christina Vasquez
Abstract
Salinity is a key environmental factor that influences the physiology and distribution of intertidal mussels. Climate change is predicted to increase freshwater runoff and intensify hyposaline stress in coastal habitats. Previous research has established the mussel Mytilus trossulus as more hyposaline tolerant compared to its competitive congener M. galloprovincialis, however the physiological responses underlying this tolerance have not been studied. Thus, this study examined how reduced salinity affects clearance rate, a measure of feeding performance, in the invasive mussel M. galloprovincialis from Marina del Rey, CA and the native mussel M. trossulus from Coos Bay, OR. I hypothesized that clearance rate would decline under hyposaline conditions in both species but that M. trossulus would maintain higher clearance rates at lower salinities compared to M. galloprovincialis. Mussels were acclimated under control conditions (35 ppt, 17°C) for two weeks, exposed to salinity treatments ranging from 5-40 ppt for 7 days, and clearance rate was measured after the mussel filter fed for 30 minutes using a fluorometer. Clearance rate declined with decreasing salinity in both species. In M. galloprovincialis, clearance rate decreased by approximately 50% at 5 ppt relative to the control (35 ppt), although this trend was not statistically significant. In M. trossulus, clearance rate declined significantly from 3.45 L min-1g-1 at 35 ppt to 1.49 L min-1g-1 at 10 ppt and 1.60 L min-1g-1 at 5 ppt. Despite this decline, M. trossulus maintained consistently higher clearance rates than the invasive species across all treatments, suggesting greater tolerance to hyposaline stress. These findings indicate that native mussels may be better suited to persist under increasingly variable estuarine salinity environments driven by climate change.
Recommended Citation
Irribarren, Lainee and Vasquez, M. Christina, "Comparing the effect of hyposalinity on the clearance rate of the invasive mussel Mytilus galloprovincialis from Marina Del Rey and the native mussel Mytilus trossulus from Coos Bay, OR" (2026). Honors Thesis. 608.
https://digitalcommons.lmu.edu/honors-thesis/608
