Diatoms

High magnification view of a diatom's cell wall
The hard cell wall, or "frustule", of a diatom

© St. Croix Watershed Research Station / Mark Edlund

Diatoms are a type of algae that have cell walls made of silica. When they die, portions of the cell walls called frustules settle into the bottom sediments and are preserved like tiny bits of glass. Different species of diatoms can be identified by the unique patterns of their frustules.

In life, diatoms are sensitive to environmental changes, and the composition of diatom communities (presence and abundance of different species) will shift in response to such changes. In death, then, the layers of frustules contained in bottom sediments provide a history of water quality going back hundreds of years.

Long-term Monitoring

We work with the St. Croix Watershed Research Station to collect and identify diatom frustules from the same places where we monitor water quality. We collect diatom samples from each lake on a 3- to 5-year rotation.

Our partner:

St. Croix Watershed Research Station

Learn More

Briefs provide a one- or two-page overview of the latest findings and what they mean. Monitoring reports are in-depth technical reports that include data analyses and possibly management recommendations.

Briefs

Source: Data Store Saved Search 388. To search for additional information, visit the Data Store.

Monitoring Reports

Source: Data Store Saved Search 408. To search for additional information, visit the Data Store.

Monitoring Protocol

Protocol documents detail precisely how monitoring is carried out.

Ramstack JM and Others. 2008. Diatom Monitoring Protocol Version 1.0: Great Lakes Inventory and Monitoring Network. Natural Resource Report. NPS/GLKN/NRR—2008/068. National Park Service. Fort Collins, Colorado

Last updated: April 9, 2018