Ribbons of Life

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Published on: Sep. 2, 1998

Last revision: Nov. 2, 2010

swimmers who engineer dams that assure a minimal level of water all year long. And they build flood-prone homes.

Beavers make low, solid dams to withstand inevitable floods. When the river floods, the water tops the dam and spreads out over the floodplain. When flood waters recede the beaver colony immediately tends to repairs. Their entire life history is one of adaptation to the changing river.

Successful floodplain living is not limited to mammals, birds or even to vertebrates. The brown fishing spider lives along many rivers and streams. At night they wait on the surface of the water to feed on insects and small fish. They catch fish as effectively as the yellow and black spider in your garden catches grasshoppers.

This is one of the largest members of the wolf spider group. The legs of a fully grown brown fishing spider can appear as large as your outstretched hand. Fishing spiders are prepared to ride the rising waters as the river comes up and goes back down. Fishing spiders and the fish they eat are also part of the river.

Rivers are unpredictable and constantly changing. Sometimes they run placidly along, and sometimes they rage and flood, killing the animals and plants that depend on them.

Silver maples, cottonwood and willows tolerate frequent flooding, bald cypress can even thrive in saturated soils, but blackberries, locusts, pines and walnuts suffocate when high water levels prevent them from bringing oxygen to their roots. We lost a lot of these species during the floods of 1993 and 1995 because they are not designed to be permanent residents of the floodplain.

Annual and some perennial plants are not as seriously affected. They die off when the water is high, but reestablish themselves when water conditions are not threatening.

Low water also threatens the creatures that depend on the river. When river levels drop, fish are often cut off from the main flow. Trapped in evaporating overflow waters, they are doomed. Too little water can be as dangerous as too much water.

Standing knee-deep in an Ozark stream on a warm September day, there seems little doubt where the river is. You feel its pressure on your legs, you hear it lapping against the bank. But look around you and see the sandbars marked with animal tracks, the cut banks dotted with animal nests, the water-loving trees that attract countless birds and the thick growth on the floodplains that stretch to the bluffs. You realize that flowing water is only a small part of the river's ribbon of life.

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