Epiphytes on Cladophora glomerata in the Great Lakes and St. Lawrence Seaway with particular reference to the red alga Chroodactylon ramosum (=Asterocytis smargdina) [North America]

The range of C. glomerata along the east and north shorelines of the Great Lakes and St. Lawrence Seaway extends from just east of montreal to Thunder Bay on Lake Superior. The dominant epiphytes on Cladophora throughout this range are the blue-green algae, particularly Lyngbya diguetii, L. epiphytica and Chamaesiphon incrustans , which account for 53 to 90% of the cell density. The diatoms Cocconeis pediculus and Rhoicosphenia curvata contribute to much of the remaining density. The red alga Chroodactylon ramosum is a minor component of Cladophora epiphyton but is widespread in Lakes Ontario, Erie and Huron. Filament morphology, cell diameters and lengths of Chroodactylon are quite similar to those of marine forms. Chroodactylon has been found in 30 water sites from the Great Lakes or its drainage basin. Therefore, it appears possible that Chroodactylon , like Bangia atropurpurea , has originated in the Great Lakes by a migration from the Atlantic Ocean.