Meeting Abstract
One predicted biological consequence of rising temperatures due to global climate change are shifts in species’ ranges and latitudinal distributions. Cold-adapted species may suffer range contractions, while warm-adapted species may experience range expansions. Washington State mussel growers farm the warm-adapted Mytilus galloprovincialis and cold-adapted M. trossulus. The persistence of these congener species on aquaculture lines is closely tied to their attachment strength. It is not known how warming waters might affect attachment of these species. We compared attachment strength of Mytilus trossulus and M. galloprovincialis exposed to temperatures ranging from 10 to 25˚C. We found these species are equally strong at temperatures between 10 and 18˚C. Above 18˚C, they showed opposite responses to rising temperature: M. trossulus attachment weakened by 89% while M. galloprovincialis attachment increased by 62%. As water temperatures vary seasonally in Washington’s coastal bays, we predict attachment strength of M. trossulus will peak in the cooler winter months while that of M. galloprovincialis will peak in the warmer summer months. We tested these predictions by measuring attachment strength monthly on mussels growing in suspension culture in Penn Cove (M. trossulus), Quilcene Bay and Totten Inlet (M. galloprovincialis). Our field observations reflect the findings of our lab studies: seasonally weak attachment strength in M. trossulus coincided with periods of high temperature. Mytilus galloprovincialis attachment did not vary seasonally, and thus showed no correlation with temperature. Warming oceans could increase the competitive advantage of M. galloprovincialis in more northern latitudes, with detrimental effects on native M. trossulus populations.
