Connecticut Water Trails Program

Wetlands

What Happens When A Wetland Disappears

Flooded basements in the spring. Entire downtowns inundated. Millions of pounds of soil washed downstream, destroying farmland, fisheries, and food for wildlife.

Whether it's localized flooding or catastrophes such as the Midwest floods of 1993, the entire United States is at risk from increased flooding due to our destruction of wetlands.

The Army Corps of Engineers has studied the causes of flooding, and advocates wetlands protection as the most cost efficient way to prevent flooding. For example, Florida and Louisiana were both hit directly by Hurricane Andrew in 1992. Florida suffered ten times the destruction. The difference? Louisiana had retained more of its coastal wetlands.

Small-scale wetlands destruction can also have far-reaching effects. As they disappear, so to do their abilities to recharge groundwater, collect sediment, and trap pollutants. In addition, isolated wetlands often serve as crucial habitat for small populations of rare birds, insects, and amphibians. For example, only a few whooping cranes nest at local wildlife refuge. But if irrigation drew down the water table enough to dry up even portions of this wetland, the crane's nesting success could be threatened by predator access or other problems associated with the diminished wetland.

Agriculture and urbanization have devastated the wetlands of California's Central Valley. In previous centuries, this huge valley's wetlands supported 40 million waterfowl. Today, it supports only 8 million waterfowl, with simultaneous reductions in recreation, hunting, and fishing associated with this habitat.

The impact of wetland destruction occurs far beyond what we can see. Aquatic invertebrates are primary consumers in many aquatic ecosystems: they consume algae and other organic matter, and subsequently become food for other types of invertebrates and vertebrates throughout the food web. Some species are found only in a few springs or streams; their loss could ripple out far beyond their isolated wetlands.

The loss of small, seemingly insignificant wetlands accumulates problems no matter where they are. For example, in urban areas, many construction crews ignore or are unaware of seasonal stream channels and ponds. They fill the depression in the ground without considering the cumulative impact of this landscape alteration. But the subsequent home or business owners will have to deal with the flash floods, wet basements, and inundated parking lots.

Downstream water quality begins to suffer, too, and affects life from the microscopic to the megafauna.

So what are we to do? Learn to live with more floods, less water, fewer fish?  Will our children be able to spend quiet fall mornings hidden among the tall grasses of wetlands, watching one of the wonders of the natural world-the autumn migration of ducks and other waterfowl?

Why Care About Wetlands?

A wetland provides important services to our environment; and when it disappears, so do those services. We lose vital flood protection, water cleansing, and food. All of the animals and plants that live in that habitat for all or part of their lives often have nowhere else to go. Frogs have no place to mate and lay eggs; pintail ducks lose a watering and feeding stop on their long migrations; aquatic insects die and all the animals that eat them must find food elsewhere.

Wetlands and the Environment

Wetlands cover less than ten percent of the earth's surface, but are the source of almost one-quarter of the world's productivity. For example, saltwater wetlands provide nursery habitat for most of the fish and shellfish that we eat. As these habitats are destroyed, the ability of fish populations to replenish themselves is also destroyed. What effect do you think this could have on our food supply in the future? Wetlands are so productive because of the amount of vegetation they contain. Abundant plants constantly photosynthesize, converting carbon dioxide to oxygen and producing energy and food. Nutrients produced by the plants are distributed widely through floods, storms, and tides. And the dead and dying plants (detritus) form the base of food webs: Protozoa, bacteria, fungi, and larvae consume the detritus; fish, worms, birds, and insects consume the detritus-consumers; and so on.

The dense vegetation of wetlands create a natural water treatment system that surpasses anything that humans have created. As water enters a wetland, it slows. Sediment settles out and is trapped by the wetland plants and their roots. The plants also absorb almost two-thirds of the nitrate and phosphorous commonly carried in stormwater runoff and floods, especially from water that has come from agricultural areas and their heavy loads of fertilizer.

Bacteria in the water and soil also can neutralize wastes, including the body wastes of animals and humans. The slowed, cleansed water of a wetland may pass into another waterway, but much of it percolates into the ground and recharges groundwater supplies. Such supplies provide a majority of the drinking water for many regions of the United States. For example, one wetland in Massachusetts was found to recharge a shallow aquifer with more than 240 million gallons per month.

In addition to slowing and cleansing water, the wetland's dense vegetation creates a tough buffer zone that can deflect waves and other heavy water surges that might otherwise erode shorelines and threaten human habitations.

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