RENSEL, M.A.*; ELLIOTT, J.K.; WIMBERGER, P.; University of Puget Sound; University of Puget Sound; University of Puget Sound: Will the introduced mussel Mytilus galloprovincialis outcompete the native mussel M. trossulus in Puget Sound? A study of relative frequencies, growth and survival among different habitats

The European blue mussel (Mytilus galloprovincialis = Mg) has become established in a variety of areas throughout Puget Sound, and Mg is hybridizing with the native mussel M. trossulus (Mt). To examine the frequencies of each mussel species and hybrids (Mgt) among different habitat types, we conducted field surveys of docks, pilings, and intertidal areas at several sites in Puget Sound. We found that Mg and Mgt were most abundant on floating docks, and that large Mg and Mgt mussels also occur at low tide levels on concrete walls and pilings. A variety of factors (e.g., growth/survival rates, predation, larval recruitment) may be causing these observed distribution patterns. In this study we performed a field experiment to examine the relative growth and survival rates of Mg and Mt on docks and pilings. Small mussels of each species were reared in cages placed on the sides of docks and at high/low tide levels on pilings. Individuals of Mg had higher survival and growth than Mt in all areas except the high intertidal. These results indicate that the introduced Mg has superior growth and survival to the native Mt, and Mg has the potential to outcompete Mt under certain environmental conditions.