Who’s Minding the Diatom Herbarium?

One in a new series “Who’s Minding the Collection?”

By Christine Sellers

They’re invisible to the naked eye and lie at the bottom of the food chain. But they are found in every body of water and can tell scientists a lot about that puddle, stream, river and ocean.

They are diatoms, single-celled organisms, or algae. Known for important yet subtle differences in structure, diatoms are valuable resources to scientists who assess water quality.

The Academy’s Diatom Herbarium, first organized in the 1940s and utilized for environmental assessments by Dr. Ruth Patrick, is a premier resource for researchers around the world. With nearly 250,000 slides, each containing tens of thousands of diatoms, the collection is the second largest and one of the oldest of its kind in the world. Diatomists maintain an online database which makes type-rich and geographically diverse data available to any researcher. (A type is a specimen on which the description of a new species is based.)

Eager to learn more about the collection, what makes diatoms stand out in a natural history museum, and how diatoms help solve real-world problems, I spoke with Collection Manager Alison Minerovic. Plus, I wanted to actually see one.

Alison Minerovic, the Academy’s newest collection manger, sorts through the historic slide collection of diatoms. Photo by Chelsea Smith/ANS

I first realized I was interested in science when… I was about 4 or 5 five years old. I grew up playing in the creek behind my house. I also used to play in the mud.

I decided to concentrate specifically on diatoms because… I got an internship with a consulting firm that specialized in water quality monitoring and that used diatoms as water quality indicators. Before that, I’d never even heard of them.

Diatoms are… a type of algae. What differentiates diatoms from other types of algae is that they are single-celled organisms contained in glass shells called frustules.

Diatoms are important to study because… they are the base of the food web for aquatic organisms, photosynthetic, can grow anywhere there’s a little bit of water, and serve as really good indicators of the health of a water body. In addition, algae, including diatoms produce 20 to 25 percent of the world’s oxygenmore than land plants!

I learned of the Academy’s Diatom Herbarium when… I was in graduate school studying how diatom flora found in sediment cores changes over time. My advisor had close ties to the Academy because he had deposited a lot of samples here.

Triceratium castillatum var. fasta Shulze is the Latin name for this diatom. It was identified by John A. Shulze, a member of the Academy’s Biological and Microscopical Section from 1812-1931. Shulze created 3,000 diatom slides by using a pig’s eyelash or other coarse hair to meticulously pick up a single diatom and place it just-so on a slide.

My job as collection manager consists of… acquiring new specimens, diatom slides, and diatom literature, loaning out specimens, keeping detailed records of the herbarium’s material, and digitizing the collection to disseminate information to fellow scientists worldwide.

Seeing diatoms is different than reading about them in a textbook because… you can’t really appreciate the 3-D structure of a diatom or understand what the scientific terminology means when you’re just reading about them. To fully appreciate the complex structure of diatoms, you need to examine them with an electron microscope.

Some of my favorite diatoms are… groups of Sellaphora and Eolimna that I’m studying for my dissertation. They’re small, morphologically poor, and difficult to distinguish due to similar features.

Diatoms come in an amazing variety of beautiful shapes. These are artificially colored and add to nature’s own artistry.

Besides the general collection… we have important slides of diatoms put together by pioneering Academy diatomists including Ruth Patrick, Charles S. Boyer, Charlie Reimer, Christian Febiger, and John A. Schulze, to name a few. The Diatom Herbarium would not exist today without their amazing contributions.

By putting images and data about each diatom online… we are making important information more accessible to taxonomists and researchers around the world who might not be able to come to Philadelphia to view the material in person.

As the Academy’s newest collection manager… I’m looking forward to working on longer, bigger projects, making information about the herbarium more readily available, and learning more about the other collections, as well as the history behind the Academy.

Minerovic first discovered diatoms when she interned at a consulting firm that specialized in water quality. Photo by Amanda Chan/ANS

The collection is useful in helping solve real-world problems… because it provides taxonomic descriptions of diatoms that can be used to make assumptions or hypotheses about water quality. Without these taxonomic descriptions, carrying out applied research would be impossible.

When I’m not working, I like to… be outside. I enjoy rock climbing, hiking, camping, and spending time with my pets.

For information about the Entomology Collection, visit our website. If you would like to support entomology research  and collections, please contact Monica Cawvey Gallagher, vice president of Institutional Advancement, at gallagher@ansp.org. Better yet, donate now by clicking the blue box.

To read previous posts in this series, visit:

Who’s Minding the Entomology Collection?

Who’s Minding the Malacology Collection?

Who’s Minding the Ornithology Collection?

Who’s Minding the Ichthyology Collection?

Who’s Minding the Botany Collection?