Diatoms of North AmericaHave you ever wanted to sit on your couch and explore diatoms without a microscope? It is now possible!
Several thousand virtual slides from the ANSP Diatom Herbarium team are now available, based on support from the National Science Foundation and the team at Drexel University.
We have been scanning diatom slides using a customized system based on an Olympus BX53 microscope with a motorized stage, a Lumenera digital camera, and image processing software by Objective Imaging, LTD. The system supports scanning at various magnifications and light settings, including brightfield and differential interference contrast. To balance the goal of digitizing as many slides as possible with the need to keep file sizes manageable, we have primarily used 400x magnification. Our initial efforts focused on slides from federal surveys (US EPA, USGS) of rivers and lakes. The study sites are accompanied by detailed water chemistry and habitat data, so they are invaluable for investigating diatom ecology and biogeography.
Drexel undergraduate students Austin John, Khang Duong, and Rohan Chandraghatgi (supervised by Dr. Mark Zarella) developed a pipeline for image processing and a web-based virtual microscopy application adapted that simulates the use of a real microscope. Most of the slide scanning was carried out by Drexel students Naomi Friedman, Caroline Gallen, Micaela Kersey, Cassidy Joyce, Abigail King, Diana Markarian, Hannah Dominguez, Sylvia Leppik, Cecilia Papadakis, and Paulina Restrepo. The NSF support enabled students to experience diatom research and, as a result, several students have further contributed taxon pages to the Diatoms of North America project (diatoms.org).
Sylvia and Hannah scanned Dr. Mark Edlund’s slides from Lake St. Croix sediment cores, using this project as an example of how diatoms are used in paleolimnological studies.
