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Macrophytes as Indicators
Utricularia (Bladderwort)
Photo courtesy of University of Florida’s Aquatic, Wetland, and
Invasive Plant Information Retrieval System
Macrophytes are aquatic plants, growing in or near water that are either emergent, submergent, or floating. Macrophytes are beneficial to lakes because they provide cover for fish and substrate for aquatic invertebrates. They also produce oxygen, which assists with overall lake functioning, and provide food for some fish and other wildlife. Crowder and Painter (1991) indicate that a lack of macrophytes in a system where they are expected to occur may suggest a reduced population of sport and forage fish and waterfowl. In addition, the absence of macrophytes may also indicate water quality problems as a result of excessive turbidity, herbicides, or salinization. However, an overabundance of macrophytes can result from high nutrient levels and may interfere with lake processing, recreational activities (e.g., swimming, fishing, and boating), and detract from the aesthetic appeal of the system.
Macrophytes are excellent indicators of watershed health because they:
- respond to nutrients, light, toxic contaminants, metals, herbicides, turbidity, water level change, and salt
- are easily sampled through the use of transects or aerial photography
- do not require laboratory analysis
- are easily used for calculating simple abundance metrics
- are integrators of environmental condition
For more information on macrophytes, please visit the following websites: 
- Non-Woody Vegetation and Woody Vegetation as Indicators of Wetland Health
- Aquatic Plant Monitoring in the State of Washington (Washington DOE)
- The Center for Aquatic and Invasive Plants
- Common Wetland Plants of North Carolina (North Carolina Department of Environment, Health and Natural Resources)
- Aquatic, Wetland and Invasive Plant Manuals, Field Guides and Textbooks (University of Florida)
- The Aquatic Plant Management Society
- Midwestern Wetland Flora (USDA - Soil Conservation Service)
- Washington Department of Ecology – Aquatic Plants and Lakes Home page
- Macrophyte and Periphyton lab (Florida International University's Southeast Environmental Research Center [SERC])
- SERC Macrophyte Links
- Diatom Image Archive
- The North American Lake Management Society Macrophyte links
- EPA Lake and Reservoir Bioassessment and Biocriteria Technical Guidance