Approximately one-half of all small streams in North America contain freshwater red algae and many maintain several species of Rhodophyta. These organisms constitute a significant food source for riverine grazers, and they provide habitat for numerous prey and predator species. Despite the importance of freshwater red algae in stream ecosystems, few aquatic biologists are able readily to identify these organisms. To rectify this problem, Dr. Robert Sheath of the University of Rhode Island is working on a comprehensive inventory of all genera and species of red algae of North America, employing morphological and chromosomal data to construct reliable identification keys, supplemented with photographs and illustrations to highlight critical characters. In assessing variation among the species, Dr. Sheath employs computerized image processing to analyze structural features of the specimens. Geographic groupings of species will be related to ecological conditions, and trends will be analyzed in relation to past glacial periods, bedrock, water chemistry, stream flow regimes, and flyways of waterfowl (a major mechanism of dispersal of spores and fragments of red algae). A comprehensive taxonomic treatment of all the freshwater red algal species will provide the necessary foundation for further evolutionary and ecological studies.
