Freshwater ecology is the study of freshwater ecosystems and their organisms. Freshwater habitats can be classified as lentic, such as lakes and ponds, or lotic, such as rivers and streams. Lentic habitats are characterized by still water while lotic habitats have flowing water. Organisms in freshwater ecosystems are limited by factors like temperature, current, transparency, gas and nutrient concentrations, and inhabit zones based on their mode of life such as benthic, planktonic, or nektonic.

1. FRESHWATER ECOLOGY
 is the study of a freshwater ecosystem or also
termed as Limnology
 is a specialized subcategory of the overall study
of organisms and the environment.
Freshwater ecosystems are a subset of Earth's
aquatic ecosystems. They include lakes and ponds,
rivers, streams and springs, and wetlands

2. FRESHWATER ECOLOGY
 Freshwater habitats can be classified by different
factors, including temperature, light penetration,
transparency, etc.
 Freshwater ecosystems can be divided into lentic
ecosystems and lotic ecosystems.

3. TYPES OF FRESHWATER HABITAT
I. Lentic habitat
 Calm freshwater habitat or standing water
 refers to standing or relatively still water, from the
Latin lentus, which means sluggish.
II. Lotic Habitat
 Washed or the running water
 refers to flowing water, from the Latin lotus, to
wash

4. Lentic Habitat
a. Lakes - is a body of relatively still fresh water of
considerable size, localized in a basin, that is
surrounded by land.

5. Lentic Habitat
b. Ponds- body of standing water, either natural or
man-made, that is usually smaller than a lake.

6. Lentic Habitat
c. Swamp - is a wetland that is forested

7. Lentic Habitat
d. Bog - is a wetland that accumulates peat, a
deposit of dead plant material—often mosses,
and in a majority of cases, Sphagnum moss.

8. Lotic Habitat
a. Spring – kind of freshwater habitat where water
flows out of the ground

9. Lotic Habitat
b. River - is a body of water with current moving
in one general direction.

10. Lotic Habitat
c. Stream - a thin body of water which has a
continuous flow of water, often referred to as a
creek or a brook.

11. LIMITING FACTORS
I. Temperature
 Water thermal properties combine to minimize
temperature change
II. Current
 Current direction is a very important limiting
factors
 Largely determine the distribution if vital gases,
salts and small organisms

12. LIMITING FACTORS
III. Transparency
 Turbidity, especially when caused by clay and slit
particles
 Can be measured using an instrument called a
Secchi disk

13. LIMITING FACTORS
IV. Concentration of respiratory gases
 Oxygen and carbon dioxide concentration are often
limiting in the fresh water environment
V. Concentration of biogenic salts
 Nitrates and phosphates seem to be limiting in a
freshwater ecosystem
 Calcium and other salts are likely to be limiting in
soft water lakes and streams

14. MAJOR GROUPS OF FRESHWATER
ORGANISMS
Classified into:
1. Major niches (based on their position in the
energy level or food chain)
a. Autotrophs (producers)
b. Phagotrophs (Macroconsumers)
c. Saphotrophs (microconsumers/decomposers)

15. MAJOR GROUPS OF FRESHWATER
ORGANISMS
Classified Into:
2. Life Form Of Habitat (Based On Their Mode Of
Life)
a. Benthos – Resting Or Living In The Bottom Of
Sediments. Ex. Clams And Snail
b. Periphyton – Organisms Living On The Stems And
Leaves Of Rooted Plants. Ex. algae, cyanobacteria

16. MAJOR GROUPS OF FRESHWATER
ORGANISMS
Classified into:
2. Life form of habitat (based on their mode of
life)
c. Plankton – floating organisms whose movements
depend on the current.
d. Nekton – swimming organisms able to navigate at
will. Ex. Fishes
e. Neuston – organisms resting or swimming on the
surface. Ex. protozoans, bacteria

17. MAJOR GROUPS OF FRESHWATER
ORGANISMS
Classified into:
3. Region or subhabitat
…. In lake
a. Littoral zone – shallow water region with light
penetration to the bottom.
b. Limnetic zone – open water zone to the depth of
effective light penetration which photosynthesis
balances respiration.
c. Profundal zone – bottom and deep water area.

18. MAJOR GROUPS OF FRESHWATER
ORGANISMS
Zones of a lake

19. MAJOR GROUPS OF FRESHWATER
ORGANISMS
Classified into:
3. Region or Subhabitat
….in streams
a. Rapid zone – shallow water where velocity of
current is great enough
b. Pool zone – deeper water where velocity of current
is reduced.

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