The Pacific oyster, Magallana gigas, intentionally introduced for aquaculture purposes, often becomes invasive, resulting in significant alterations to coastal ecosystems [28]. In Argentina, Magallana gigas was illegally introduced in Anegada Bay (39º 50´ S to 40º 40´S and 62º 10´w) [29,30] around 1982 as part of an oyster culture project [31]. Since its introduction, the first