Relative Abundance of Mytilus edulis (invasive) and Mytilus trossulus (native) in Differing CO2 Concentrations of Vancouver Coastal Waters

Abstract

The relative abundance of the invasive blue mussel species, Mytilus edulis, to the native species, Mytilus trossulus, was recorded at Acadia Beach and Sunset Beach Park on Vancouver’s coast. Carbon dioxide measurements of the water at each location were also compared. M. edulis is of interest as it can potentially outcompete the native mussel species, affecting British Columbia’s marine ecosystem. Nineteen mussel samples were taken at both locations, as well as ten water samples, which were used to measure CO₂ concentration. DNA was isolated from the mantle tissue of the mussel, and used for polymerase chain reaction (PCR) and gel electrophoresis analysis to identify the phenotypically-identical species. A t-test was performed on the mean water CO₂ measurements, resulting in a statistically significant difference between the two locations (p-value < 0.001). The relative abundance of M. trossulus to M. edulis (n=19) at the site of lower CO2 concentration (Acadia Beach, 3.27 ppm) was 15.8%, while at the site of higher CO₂ concentration (Sunset Beach Park, 6.74 ppm) the relative abundance (n=15) was 20.0%. A Fisher’s test resulted in a statistically insignificant difference (p = 1.000) between the relative abundance of the two mussel species at the two sites. Findings suggest that the relative abundance of M. trossulus and M. edulis is unaffected by water CO₂ concentration of the observed range. Consequently, native and invasive blue mussel species’ relative distributions are likely to remain unaffected by a predicted increase in carbon dioxide level.