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Monitoring Wetlands: Deciding What to Measure by Tom Danielson
There is a rich tradition of volunteers monitoring the quality of streams, rivers, and lakes. Now, a growing number of volunteer groups are turning their attention to monitoring the quality of wetlands or the success of restoration activities. I often enjoy seeing the look on stream monitors' faces when they take their first step into a wetlands The bright glint of excitement is suddenly replaced by a worried expression as they sink to their ankles (or knees) in mud. You're not in a nice cobble stream anymore! Obviously, monitoring wetlands comes with a new set of challenges. However, the benefits far outweigh the minor inconveniences. Wetlands include some of the most productive and diverse habitats in the world. The rich flora and fauna of wetlands can provide a lifetime's worth of beauty, exciting discoveries, and inspirational experiences. Besides, let's be honest, naturalists thrive on the "hardships" of becoming intimate with nature ... and monitoring wetlands will provide no shortage of entertaining tales to share with your compatriots. A variety of methods There is no one "right way" to monitor wetlands. The purpose of this article is not to say that one method is better than another, but to introduce several types of methods and their strengths and limitations. Wetland professionals use a variety of methods depending on the objectives of the monitoring programs. Some of these methods have been adapted by volunteer groups. In general, wetland monitoring methods can be clustered into four broad categories: (I) functional assessments, (2) habitat assessments, (3) wetland inventories and characterization, and (4) biological assessments. Functional assessments To lake and stream monitors, the idea of a "functional assessment" may seem new and unfamiliar. Instead of measuring water quality parameters or characterizing biological communities, functional assessments attempt to estimate the ability of a wetland to perform various "functions, such as storing surface water, filtering water, and maintaining plant and animal communities. Why is it that wetlands are sometimes evaluated in terms of function, while other water bodies usually are not? The reasons are complex; but a brief answer is that historically wetland policy has focused on protecting wetlands from being drained or filled. The main protection for wetlands has been under Section 404 of the Clean Water Act, which regulates dredging and filling and is administered by the Army Corps of Engineers. Since decisions on whether to issue dredge-and-fill permits take wetland function into account, methods were developed to assess functions. In contrast, protection for streams, lakes, and rivers historically focused on reducing the amount of chemicals discharged into them and maintaining their biological communities. The main protection for these water bodies has been state water quality standards. Only relatively recently have states started to develop bioassessment methods for wetlands and refine their water quality standards to better reflect conditions found in wetlands. One of the first functional assessment methods was the Wetland Evaluation Technique (WET). This method failed to work as well as planned because it treated all wetland types the same and did not account for regional differences in wetland functions and values. The hydrogeomorphic (HGM) approach is a recent effort that is currently being developed by the Army Corps of Engineers. HGM actually consists of two parts: a wetland classification system and a series of regional functional assessment guide books for different wetland classes. By recognizing that wetland types can be very different and there can be large regional differences in wetlands, HGM is attempting to address two of the shortcomings of earlier functional assessment approaches. In general, functional assessments tend to be "rapid" methods based on the "best professional judgment" of trained wetland professionals. Much of the information for the assessment can be obtained from maps and records. Only a single site visit is required and there is no need for exhaustive data collection in the field. The same features that make functional assessments attractive also limit their use. The reliance on "best professional judgment" tends to limit this method's usefulness for volunteers, as well as for local governments and other organizations that don't have ready access to wetland experts. Also, these methods are sometimes subjective and difficult to reproduce from one professional to another. However, volunteers in Maine are using a modified functional assessment to monitor tidal marshes. Habitat assessments Habitat assessment methods are based on the assumption that if the habitat is there, then the animals will be there. The classic model is the Habitat Evaluation Procedure (HEP), developed by the U.S. Fish and Wildlife Service to answer questions like "Would this be a good habitat for ducks?" (or any species of interest). For HEP, a team of biologists visits a wetland and judges the ability of the habitat to support the species in question. Like functional assessments, habitat assessment methods require a trained biologist or wetland professional. However, volunteers can be trained to collect at least some of the needed data (e.g., vegetation type, number of snags). Perhaps the most limiting aspect of habitat assessments is that they tend to focus on only a small number of species and do not provide assessments of overall wetland quality. But they may be well suited for volunteer projects interested in protecting a single species, such as King Rails. Wetland inventories and characterization This approach has been the most widely used among volunteer monitoring groups. Some projects inventory just one or a few types of plants or animals. Volunteers with the Bird Studies Canada/Long Point Bird Observatory Marsh Monitoring Program, for example, monitor birds and amphibians. Other projects in this category do extensive mapping and sampling of a variety of plant and animal communities, along with characterizing features like soils and hydrology. A manual used by volunteers in Washington State, Monitoring Wetlands: A Manual for Training Volunteers, explains protocols for monitoring birds, amphibians, vegetation, hydrology, wetland buffer condition, soil types, and topography. Volunteers at Jug Bay Wetlands Sanctuary in Maryland, one of the longest-running volunteer wetland monitoring programs in the country, survey fish, plants, birds, reptiles, and amphibians and study nutrient cycling. Citizen groups that follow such comprehensive approaches become intimately familiar with "their" wetlands and generate lots of useful data. However, these projects are often resource- and time-intensive, making them impractical for monitoring a large number of wetlands. Biological assessments In a biological assessment, investigators evaluate the condition of one or more biological "assemblages" (examples of assemblages are macroinvertebrates, plants, or fish). Since plant and animal assemblages reflect the cumulative effects of chemical, physical, and biological disturbances to a habitat, scientists can use them much the same way as a doctor would use a thermometer, blood pressure gauge, and other instruments in a physical exam. Using biological communities as indicators is different from simply inventorying the biota, as described in the previous section. By evaluating the composition, diversity, and condition of a plant or animal assemblage, wetland scientists can determine the overall "health" of a wetland. Bioassessments are designed to be a more rapid alternative to comprehensive inventories--that is, you save time because you don't have to monitor everything. The tradeoff is that the bioassessment methods must be developed, tested, and validated by scientists before they can be used as a screening tool. In addition, the indicator organisms must be identified accurately, at least to family level, for the bioassessment to yield useful results. So for volunteers, there is a big investment up-front in training. Many volunteer monitors are familiar with stream bioassessments using macroinvertebrates as indicators of stream quality. In this technique, rnacroinvertebrates from a stream sample are counted and identified (usually to family level). The data are then compiled into different "metrics," which are attributes that predictably change in value across a gradient from pristine sites to degraded sites. Common metrics include the number of mayfly, stonefly, and caddisfly families in a sample (EPT index) and the total number of families in a sample (taxa richness). Metric scores from the stream under study are compared to the metric scores in minimally impaired, or reference, sites. Through years of testing, stream scientists have chosen to use particular metrics because they have been found to reflect human disturbances to stream ecosystems. While protocols and metrics for stream bioassessment are well established, wetland bioassessment lags at least 15 years behind. (Nevertheless, some volunteers are already using bioassessments in wetlands.) The challenge now for wetlands is to figure out what assemblages to monitor, what metrics to measure, and what sampling methods to use. To work on these problems, the USEPA is coordinating an interagency "think tank" called the Biological Assessment of Wetlands Workgroup (BAWWG), which we fondly refer to as "bog." BAWWG has five focus groups, each investigating a different assemblage: algae, amphibians, birds, macroinvertebrates, and vascular plants. Each of these assemblages has strengths and weaknesses as a potential indicator of wetland health. For example, plants are good indicators because they are immobile (so they can't escape disturbances) and they are present in all wetlands. However, one drawback is that they often take a while before showing a response to a stressor. Birds are a perennial favorite because so many people care about them; but since they are highly mobile they are more reflective of conditions across a whole landscape rather than in a specific wetland. Amphibians are excellent sentinels of environmental condition, but their populations can naturally fluctuate from year to year. The boxes at the end of the article summarize some of the pros and cons for several assemblages. The value of monitoring living things As stated earlier, there is no single "right" way to monitor wetlands. But, as we've seen, volunteer groups who monitor wetlands most often focus on living things, whether through inventories or biological assessments-and there is a good reason for this. "Critters are uniquely interesting to humans," notes Jon Kusler, director of the Association of State Wetland Managers. If a citizen group wants to raise community awareness of wetlands, they'll do better to talk about songbirds and frogs than about groundwater recharge and water storage capacity. As Kusler says, "People relate to things they can see, smell, taste, and hear; things they can count and list." Judy Helgen, a wetland ecologist at Minnesota Pollution Control Agency and my colleague in the BAWWG workgroup, favors biological assessment because it focuses on the quality of the wetland itself, rather than on, utilitarian functions or services that the wetland can provide to society. "We have no problem thinking about protecting lakes and streams for the sake of protecting the species that live there," she says, "but people don't always buy into the idea of protecting the ecological integrity of wetlands. Instead, people tend to look at wetlands as the ecosystem that cleans up human pollution before it gets to lakes and streams." While wetlands do provide many values to society and are extremely important for protecting the health of streams, rivers and lakes, they also support unique communities of plants and animals that should receive the same protection. I encourage each of you to contact your state or local governments, nonprofit organizations, and schools to find out if you can help an existing wetland monitoring program. If they don't have one, ask why and offer your support in starting one. It is time to reawaken our childhood curiosities of searching for frogs among the lily pads and watching dragonflies whiz past our heads in a flash of color. Wetlands are beautiful and fascinating ecosystems and there is no better way to team about them than to monitor them.
Potential indicators: Pros and cons
Strengths and weaknesses of different assemblages that can be used as bioindicators for wetlands (based on Adamus and Brandt’s 1990 report): BIRDS + present in all wetlands
MACROINVERTEBRATES
VASCULAR PLANTS + present in all wetlands
AMPHIBIANS + some recognition by society of their ecological importance
ALGAE + measurable in wetlands that lack surface water
Resources EPA Wetlands Division Website : http://www.epa.gov/owow/wetlands. Adamus, Paul, and Karla Brandt. 1990. Impacts on Quality of Inland Wetlands of the United States: A Survey of Indicators, Techniques, and Applications of Community Level Biomonitoring Data. USEPA, Office of Research and Development, Washington, DC (EPA/600/3-90/073). Currently out of print but available at www.epa.gov/owow/wetlands/wqual.introweb.html. Danielson, Thomas J. 1998. Wetland Biological Assessment Fact Sheets. USEPA, Office of Wetlands, Oceans, and Watersheds, Washington, DC (EPA/843/F/98/001). Tom Danielson is the National Coordinator for the Biological Assessment of Wetlands Workgroup (BAWWG) and an Ecologist with the U.S. Environmental Protection Agency, Wetlands Division, 401 M Street, SW (4502F), Washington, DC, 20460; 20212605299; danielson.tom@epamail.epa.gov. (Article reprinted from "The Volunteer Monitor", Volume 10, No. 1, Spring, 1998) |
