Date of Award

Fall 2008

Project Type


Program or Major

Plant Biology

Degree Name

Master of Science


Invasive species pose a threat to the balance of intertidal ecosystems. Recently, two forms of the non-native species, Porphyra yezoensis Ueda, were found at multiple sites between New York and Downcast Maine. A 2007 New England survey confirmed the presence of P. yezoensis f. yezoensis at nine sites, including two beyond its reported distribution. Porphyra yezoensis f narawaensis A. Miura was found at four sites in Long Island Sound. To assess the ecological impact of f. yezoensis and f. narawaensis on Northwest Atlantic macroalgal communities, monthly density and biomass data were gathered in 2008 from seven southern New England sites along 20 m transect lines. P. yezoensis f. yezoensis was not detected at two historic sites. The f. narawaensis has expanded to Cape Cod. Fucoid algae epiphytized by P. yezoensis demonstrated no stature reduction. A Porphyra species of cryptic origins, P. spp. 'stamfordensis,' may be competing with P. yezoensis.