UNIT

5 Ecosystems

Natural Science 2. Secondary Education

RIVERS

UNIT

5

Natural Science 2. Secondary Education

Rivers• Rivers are ecosystems that are defined by the movement of water. There are two different river zones:

• The upstream portion of the river, where there is a turbulent flow of water. Animals with more hydrodynamic shapes, which are therefore better able to swim, inhabit this area.

• The midstream and downstream area of the river, where animals are adapted to this zone’s characteristic warmer and slower moving water.

Otters are very hydrodynamic, an adaptation to fast river currents.

Perches are adapted to the slow moving water of the midstream and downstream zones.

Biodiversity in rivers

Otter

Kingfisher

Dragonfly

Water snake

Diving beetle

Trout

White-throated dipper

Freshwater mussel

Commonfrog

Iberian newt

Caddisfly

Crayfish

UNIT

5

Natural Science 2. Secondary Education

Rivers

• Rivers are very important because:• They are rich in biodiversity.• They are a source of energy (as they can be used to produce

hydroelectrical power). • They deposit sediment and nutrients that help maintain coastal

ecosystems.

Why rivers are important

Land located downstream of rivers is very fertile because of the sediments deposited by these bodies of water.

UNIT

5

Natural Science 2. Secondary Education

Rivers