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Periphyton as Indicators
Periphyton and Algae Links
- Freshwater Algae Links (Bowling Green State University, Ohio)
- Diatom Home Page (Indiana University, Indiana)
- Eureka: Diatoms - a great general educational site
- Great Lakes Diatoms
- The Plankton Net - focusing on marine biology and a great general educational site (Ohio University)
- Algae and Periphyton (North Carolina DENRC's Ecosystems Unit)
- Algal Biology: Phytoplankton and Periphyton Community Analyses (Florida DEP)
- The Phycological Society of America
Periphyton are benthic (attached) algae that grow attached to surfaces such as rocks or larger plants. Periphyton are primary producers and sensitive indicators of environmental change in lotic waters. Because periphyton are attached to the substrate, this assemblage integrates physical and chemical disturbances to the stream reach. The periphyton assemblage serves as a good biological indicator due to:
- a naturally high number of species
- a rapid response time to both exposure and recovery
- identification to a species level by experienced biologists
- ease of sampling, requiring few people
- tolerance or sensitivity to specific changes in environmental condition are known for many species
For example, diatoms in particular are useful indicators of biological condition because they are ubiquitous and found in all lotic systems.
By using algal data in association with macroinvertebrate and fish data, the strength of biological assessments is optimized. The objectives of a rapid bioassessment protocol for periphyton could include, but would not be limited to, assessment of biomass (chlorophyl a or ash-free dry mass), species, composition and biological condition of periphyton assemblages.
Please keep track of the National Lakes Assessment, a study in which EPA is working with states, tribes and others to survey the quality of the nation's lakes, ponds and reservoirs. This includes phytoplankton and sediment diatoms and also provides field and laboratory guidelines.
For even more information on the use of periphyton, please see EPA's Rapid Bioassessment Protocols, and the US Geological Survey's NAWQA protocols.