Ecological Landscape: Aquatic Communities

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Today, all of the aquatic communities in Vermont are fresh water. These include rivers, streams, lakes and ponds. Bogs, fens, marshes and swamps are wetland communities that are shaped by both aquatic and terrestrial processes. One or more of the following processes will affect all aquatic and wetland communities to some degree: nutrient availability, water currents, freeze-thaw cycles, average water depth, water table fluctuations and flooding. Depending on how each of these processes shapes the community, different plants and animals will thrive in different aquatic

Beaver: architects of aquatic and wetland communities

environments. For example, emergent plants grow in calm, shallow water where there is adequate access to sunlight and protection from strong uprooting currents.

Many of Vermont's water bodies are remnant features of the last glaciation. Lakes and ponds were left behind in depressions carved out by the glacier and some were formed by melted ice water. River valleys are widened or shaped first by glacial ice and later by glacial melt water.

One important aspect of all water bodies in Vermont is that they are continually changing their shape and depth. Sedimentation and shifting hydrologic patterns result in lakes shrinking, rivers shifting, and marshes drying up. Because aquatic communities are so dynamic, they require large, specially protected areas to thrive over long periods of time. Many nutrients and pollutants are soluble in water, and are easily transported throughout the community. Aquatic communities are especially sensitive to changes in pH, and contamination by limiting plant nutrients such as nitrogen. The result is that the many plant and animal species that depend on Vermont's aquatic and wetland communities for part or all of their lives are continually threatened by the loss and contamination and aquatic habitats. For example, the Restrictive Arm (the northeastern portion) of Lake Champlain regularly receives large quantities of agricultural run off. The fertilizers and pesticides that work to make Vermont's farms productive on land, act as deadly pollutants in the water. The result is an overgrowth of algae and bacteria, and the death of many aquatic plants and animals. In general, aquatic communities are more sensitive to, and take longer to recover from pollution than do terrestrial environments.

A good way to explore the aquatic communities in your area is to first look for surface water features on a topographic map. If you have a body of water near by, look for vegetation around the edges and

Riverine-floodplain community

in the water. Technically, a pond is shallow enough to support plant growth, and a lake is too deep to support plant growth (generally over six or seven feet deep). Check the banks for muskrat holes, and muddy shores for the footprints of any other wildlife. Look at the larger landscape context of the area. Are there large fields, forests, roads, farms, or developments near by? Is the water body man-made (as in surface water treatment ponds) or can you a distinct inlet and outlet. Be sure to look at a watershed map of your area to see where your body of water fits in. If you live on a major river it will be helpful to know about any dams or sources of pollution up stream. And finally, there are dozens of non-profit groups in Vermont that are based solely on the protection of specific water bodies or watersheds. These groups will be a great source of information to you as you put together the story of your landscape, and contemplate the protection of your community's aquatic resources.