Freshwater Ecosystems

1. Freshwater Ecosystems
Kinds
Characteristics
Threats

2. A fresh water ecosystem is an aquatic
system that contains drinkable water or
water of almost no salty content. It has
habitats classified by different factors,
including temperature, light penetration,
and vegetation. Its resources include
lakes, ponds, rivers, streams, reservoirs,
wetlands as well as groundwater.

3. Kinds of freshwater habitats
Rivers, streams
–Flowing freshwater
–Source: where it starts
–Mouth: where it ends
Lakes, ponds
Wetlands

4. All freshwater ecosystems
Just a fraction of the Earth’s water
–.01% = one one-hundredth of one percent
Occupy less than 1 percent of the Earth’s
surface

5. Rivers and streams
More than 3.5 million miles of rivers and streams
- Just the U.S.! More than 140 times around the Earth.
www.noaa.gov/str-plan/images/river.gif

6. Rivers
A river is usually cold and full of oxygen
and runs swiftly through a shallow
riverbed. As a river flows down a
mountain, a river may broaden, become
warmer, wider, and slower, and decrease
in oxygen.

7. Rivers
Narrow headwaters Wide channels downstream

8. Lakes and ponds
What’s the difference?
–Ponds typically smaller
–May be seasonal—that is, dry up part
of the year
–Lakes exist hundreds or thousands of
years
But, even lakes can fill in or dry up

9. Parts of a lake

10. Parts of a lake
Littoral zone: near shore
–Nutrient rich, lots of plant and animal life
–Warm
Limnetic zone: near surface, open water
–Lots of light
–Lots of plankton
Profundal zone: deeper, little light
Benthic zone: the bottom, little light, low
oxygen

11. Wetlands

12. Wetlands
Are those areas that are inundated or
saturated by surface or ground water at a
frequency and duration sufficient to
support, and that under normal
circumstances do support, a prevalence
of vegetation typically adapted for life in
saturated soil conditions. Wetlands
generally include swamps, marshes,
bogs and similar areas."

13. Wetlands
May be fresh or brackish
Freshwater types include:
–Marsh
–Swamp
–Bog
–Fen

14. What good are wetlands?
Help clean water by acting like a filter
–The plants and slow water flow in a wetland
help remove pollutants, leaving water
cleaner downstream in a lake or river.
–Too much pollution can leave a wetland
toxic to visiting animals, such as many birds.

15. What good are wetlands?
Protect
shorelines
from
erosion
Erosion in
this case
came from
grazing
animals

16. Marsh
Most common
freshwater wetland in
U.S.
Occur along streams or
in depressions
Characterized by
organic, wet soils and
non-woody (i.e., no
trees) vegetation.

17. Marsh

18. Swamp
Wetland
dominated by
woody plants
Swamps occur on
flat, poorly drained
land often near
streams.

19. Swamp