What is a lake?
1. a non-moving body of water
2. holds aquatic life
3. Can not freeze all the way to the bottom
4. has to be deeper than 2 meters (6 feet) in a portion of the
lake
How does a lake form?
1. has to have something on the bottom to retain water (ex. clay)
2. glaciation
3. hunk of ice (forms kettle lakes)
4. rivers (change path separate forming an oxbow lake)
5. impede water
6. natural depression that fills with water
Is a lake permanent?
No, never. Lakes are formed to fill up with sediment. Gets
shallower and shallower creates a bog lake with material (plants)
covering over the lake with a hole in the middle continues to
become a swamp then a field and then a Forest through a process
called ecological sucession.
Regions within a lake
Benthic- bottom regions
Benthos- deals with life lives on bottom -community of bottom
dwellers
Littoral zone - courser sediments, well lit, fluctuating temps.,
wakes, erosional forces, ice, algae, plants, large biodiversity,
high annual production, high dissolved oxygen level
Sublitoral zone - dimly lit, no big plants, also called shell
zone
Profoundle zone (hypolimnion) hardly any sunlight, very little
O2, high CO2 and methane temp. same throughout, decomposition
Pelagic zone (open water or epillimnion) contains plankton
(phytoplankton and zooplankton)
Photic or Aphotic?
sublitoral and up is Photic
hypolimnion and down is aphotic
Lake typology
Oligotrophic (bluish color)
Eutrophic (yucky green color)
Types of Lakes
1. oligotrophic
deep
steep banked
epillimnion smaller than hypolimnion
low organic mater
dissolved oxygen plentiful all over
rosette style leaves littoral plants
small quantity of phytoplankton
never see a water bloom (no algae blooms)
fauna diverse (intolerant of low dissolved oxygen level)
deep water fish
2. eutrophic
shallow
gradually banked
broad littoral zone
epillimnion volume greater than hypolimnion
green yellow brown water
low transparency
loaded with plant nutrients
Profundle sediments loaded with organic matter
in summer hypolimnion O2 becomes depleted
lots of plants in littoral zone and phytoplankton
go through algae blooms
Lentic communities
1.Littoral Community- Cray fish, crustaceans, mollusks, snails,
insects, arachnids, turtles, snakes, protists, algae, aquatic
vegetation, amphibians, frogs, salamander, newts, ducks, insects,
fish, ducks, reptiles, decomposition done by bacteria
2. Openwater zone community - plankton (photosynthetic)
3. Benthic community - algae, herbivores, decomposers
4. Nekton community- open water plankton eaters, big fish (swim
all over)
Lakes in Cumberland county
Mary Elmer Lake
Sunset Lake
Silver Lake
Seeley Lake
Boswick Lake
Ceader Lake
Eddies Pond
East Lake
Arrowhead Lake
Davis Mill pond
Elk Lake
Clarks Pond
Union Lake
Menantica Lake
Willowgrove Lake
Laurel Lake
Shawsmill Pond