2. LAKES
Range in size from just a few square
meters to thousands of square
kilometers.
Lakes may exist for hundreds of
years or more.
3. LAKES
May have limited species diversity
They are often isolated from one
another and from other water
sources like rivers and oceans.
Most lakes have outlet streams and
they are generally temporary
features on the landscape
4. FORMATION OF LAKES :
Some of the oldest lakes (more than
three hundred thousand years old) were
formed by tectonic activity related to
movement of Earth's crust.
EXAMPLE: Lake Baikal in Siberia formed
from the movement of tectonic plates and
is the largest freshwater lake by volume
in the world.
5. FORMATION OF LAKES:
Lakes are formed through a variety of
events, including glacial, tectonic, and
volcanic activity.
Most lakes form as a result of glacial
processes.
As a glacier retreats, it may leave behind
an uneven surface containing hollows
that fill with water.
6. FORMATION OF LAKES :
Volcanic activity can also lead to lake and
pond formation.
EXAMPLE: the collapse of a volcanic cone
of Mount Mazama in Oregon led to the
formation of Crater Lake, the seventh
deepest lake in the world.
8. Lakes
Temperature varies seasonally.
During summer the temp. is from
4°C near the bottom to 22°C at the
top.
During winter the temp. is from 4° C
while the top is 0° C (ice).
during the spring and fall seasons is
a mixing of the top and bottom
layers resulting in a uniform water
temperature of around 4° C.
9.
10. Lakes
divided into four different
“zones” determined by depth and
distance from the shoreline
•littoral zone
•limnetic zone
•profundal zone
•Photic zone
•Benthic zone
12. Littoral Zone
warmest since it is shallow and can absorb
more of the Sun’s heat
sustains a fairly diverse community
several species of algae (like diatoms)
rooted and floating aquatic plants
grazing snails
Clams
Insects
Crustaceans
Fishes
amphibians
13. Littoral Zone
the egg and larvae stages of some insects are
found in this zone
vegetation and animals living in the littoral
zone are food for other creatures such as
turtles, snakes, and ducks
14. Limnetic Zone
near-surface open water surrounded by
the littoral zone
well-lighted (like the littoral zone) and is
dominated by plankton, both
phytoplankton and zooplankton
plankton are small organisms that play a
crucial role in the food chain – most life
would not be possible without them
variety of freshwater fish also occupy this
zone
15. Profundal Zone
much colder and denser
little light penetrates all the way
through the limnetic zone into the
profundal zone
Plankton have short life spans—when
they die, they fall into the deep-
water part of the lake/pond
Animals found are decomposers
16. Benthic Zone
The area of the bottom.
Many groups and varieties of animals live here, a few
are worms, crustaceans, and protozoa.
The life in this zone is mostly made up of bottom
dwellers which get most of their food from dead and
decaying organisms.
most of the organisms in the benthic zone are
scavengers because they depend on dead flesh as
their main food source.
18. Clasification of Lake
Oligotrophic lakes- deep, nutrient-poor lakes
in which the phytoplankton is not very
productive.
The water is usually clear
Eutrophic lakes-shallow, nutrient-rich lakes
with very productive phytoplankton.
The waters are usually murky due to large
phytoplankton populations
the large amounts of matter being
decomposed may result in oxygen depletion.
19. Lakes Ecosystem
A lake is bigger than a pond, and is too deep to
support rooted plants except near the shore.
Some lakes are big enough for waves to be
produced.
Lakes may exist for hundreds of years or more.
Lakes are often classified as oligotrophic or
eutrophic, depending on the amount of organic
matter produced.
