Grateloupia turuturu is an invasive red algae, native to the western Pacific. Along with being the largest known red alga, it is widely considered to be a top threat for local marine habitats. Among the effects G. turuturu can have on a regional ecosystem are: disruption of shoreline ecology, sequestering of nutrients vital to local organisms, and the overall displacement of native organisms. G. turuturu was originally discovered in Boston Harbor by Mathieson et al. in 2007. The alga has also been present in Narragansett Bay, Rhode Island, for 14 years. Using molecular techniques, we sought to determine whether this introduction into Boston Harbor is in fact G. turuturu and not one of several closely related species. The RbcL gene has been shown to distinguish G. turuturu from similar species. To do this we tested and compared several published protocols for red alga DNA isolation, and sought to optimize the polymerase chain reaction for several sets of primers to amplify segments of the RbcL gene. We then will sequence these amplified segments. After sequencing we will compare the results of Boston Harbor with different locations including Narragansett Bay and herbarium samples from Europe that are confirmed to be G. turuturu. This will give us a better understanding of the source of G. turuturu in Boston Harbor.