Born Free Foundation - Keep Wildlife in the Wild

lakes, RIVERS & STREAMS

Freshwater habitats cover about 10% of the earth’s surface.  They range from marshes to ponds, inland lakes, streams and rivers.

From deep icy pools of the north, to the great rivers of the tropical rainforests and the oasis springs of deserts, all provide habitats for plants, animals and people.

Lake, Photo (c) Peter Prehn

HOW IS A RIVER FORMED?

Rivers flow from high ground to low ground into a sea or a large inland lake.  A river can be divided into three sections, known as ‘stretches’.  These are the upper, the middle and the lower stretches.

The Upper Stretch

Rivers start as tiny trickles from underground springs on hillsides or mountains, which roll over the vegetation and join other trickles.  These form small fast flowing streams over rocky beds.  Few plants can survive this swift current, except algae which clings to rock surfaces.

The Middle Stretch

On flatter ground small, fast-flowing streams, called tributaries, join together and the current becomes slower as they widen into a river.  Animals such as the otter will be found in this stretch of water.

The Lower Stretch

In its final stage the river winds its way slowly across the flatland towards the sea.  This flatland sometimes floods and the banks of the river are slowly worn away.  As the flow of the river varies in this section, so too does the animal life that lives here.

ISSUES & CHALLENGES

Plants and animals in any stretch of river vary according to the levels of pollution and disturbance. There are certain plants and animals, such as dragonfly nymphs (young) which only survive in areas where pollution levels are low. Scientists can often tell how polluted a stream of river is by the plants and animals which survive there.

Throughout the world, many freshwater ponds and streams are in danger from pollution.  Factories discharging waste, over-use of pesticides from farmland and the construction of more roads and towns all add to the threat.

Many animals and plant species have disappeared from areas or entire countries because of the high levels of pollution.  In many parts of Britain, otter numbers dropped because of water pollution and habitat destruction.

Born Free Foundation
Broadlands Business Campus, Langhurstwood Road
, Horsham, RH12 4QP, UK - Charity Reg. No. 1070906


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