Glass Algae Reveal Condition of Great Lakes Coast
Ann Arbor, MI — Microscopic algae are excellent indicators of water quality. They respond rapidly to changing water conditions because they have short life cycles and there are thousands of species, each with their own preferred environmental condition. For example, some species will tolerate pollution, while others thrive only in pristine water.
Algae were used to investigate Great Lakes watershed stressors and habitats as part of the Great Lakes Environmental Indicators (GLEI) project (glei.nrri.umn.edu). They found that algae not only reflected coastal habitat quality, but they were reliable indicators of human disturbance in the surrounding watershed.
The scope of the project was vast. Nearly 200 sediment samples from the U.S. coastline of the five Great Lakes were collected during the summers of 2002-2003 by researchers from the University of Minnesota Duluth Natural Resources Research Institute, John Carroll University, and the Environmental Protection Agency-Mid Continent Ecology Division. The coast hosts a wide variety of shallow habitats including unprotected shorelines, bays, and wetlands (riverine, protected, and coastal). A deeper, offshore coastal area was included as a fifth habitat type.
Changes in algae populations revealed how human disturbances around the lakes -like, agriculture and urban development-affect water quality. Golden-brown algae, known as diatoms, were used to develop mathematical models to calculate phosphorus for the lakes and habitats. Phosphorus is an important nutrient for algae. The researchers used actual water quality measurements (such as chemistry and water clarity), groups of diatom species, and phosphorus calculated from mathematical models to determine similarities and differences among the lakes and habitats and to learn more about them.
"Diatoms help us learn more about complicated ecosystems like the Great Lakes and how to better study them," says researcher Amy Kireta, one of the authors of the report. "They are often better indicators of water quality than chemical measures, which can fluctuate unpredictably."
Diatom algae are ideal choices for studying water quality because their cell walls are made of biogenic glass (glass produced by a living organism) that remains in the lake bottom after they die. The top of a sediment sample generally contains the diatom remains from the last several months and so, based on the species present, the predominant environmental condition over the past year can be calculated.
Diatom inference models can also be used to calculate environmental conditions dating back hundreds of years. Because environmental measurements have mainly been collected by humans in the last few decades, diatom remains in deeper sediments (deposited hundreds of years ago) provide important historical data that would otherwise be unavailable.
This set of diatom-based tools is now available for researchers to study coastal areas throughout the Great Lakes.
Original Publication Information
Results of this study "Coastal Geomorphic and Lake Variability in the Laurentian Great Lakes: Implications for a Diatom-based Monitoring Tool," are reported by Amy R. Kireta, Euan D. Reavie, Nicholas P. Danz, Richard P. Axler, Gerald V. Sgro, John C. Kingston, Terry N. Brown and Tom Hollenhorst in the latest issue (Volume 33, SI3, pp. 136-153) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2007.
Contacts
For more information about the study, contact Amy Kireta, University of Minnesota Duluth Natural Resources Research Institute; akireta@nrri.umn.edu, (218) 235-2185.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.