Diatom Herbarium

The Academy's Diatom Herbarium, one of the two largest in the world, is a primary source of taxonomic and ecological information. It includes approximately 220,000 slides (curated and non-curated), of which about 5,000 are types. Materials include both fossil and recent diatoms collected from fresh, brackish, and marine habitats. In addition to its world coverage and its inclusion of fossil diatoms, the herbarium has an extensive record of materials collected as part of freshwater environmental surveys from throughout the United States. These surveys were the work of the former Department of Limnology, and its successor, the Phycology Section of the Patrick Center for Environmental Research. Often extending over decades, these surveys offer a unique resource for the study of long-term changes in diatom populations and ecology.