Morphological Variation in Codium Fragile in the Northwest Atlantic

摘要

Codium fragile (Suringar) Hariot, an invasive Asiatic green alga, has colonized areas of the NW Atlantic within the past fifty years. The plant has a dichotomously branched cylindrical thallus made of tangled filaments surrounded by a dense covering of swollen filament tips, or utricles, terminating in pointed mucrons. This study's goal was to investigate morphological differences in NW Atlantic C. fragile populations to determine which subspecies are present. In the summer of 2008, surveyed 24 sites from the Canadian Maritimes to Long Island Sound and evaluated size variation in utricles. Morphological investigations revealed a two-fold difference in utricle and mucron lengths between populations. Utricle and mucron size variation could be due to genetic or habitat differences. Mucron variability may indicate that this is not the ideal diagnostic feature for subspecies identification. Results suggest that only C. fragile subsp. fragile may be present in the NW Atlantic.