Major zones of fresh water habitats - SS2 Biology Lesson Note

Freshwater habitats are diverse and can be categorized into several major zones based on their characteristics and the organisms that inhabit them. Here are the major zones commonly found in freshwater habitats:

              Lentic Zone (Still Water):

a.       Littoral Zone: This is the shallow area along the shoreline of lakes, ponds, and reservoirs. It is characterized by emergent vegetation and is home to a variety of plants, insects, amphibians, and small fish.

b.       Limnetic Zone: The limnetic zone is the open water area beyond the littoral zone, where sunlight penetrates and supports photosynthesis. It is occupied by free-floating algae, phytoplankton, and zooplankton, which form the base of the food chain.

c.       Profundal Zone: The profundal zone is the deep, dark region of lentic habitats, where light cannot penetrate. It is often low in oxygen and is inhabited by specialized organisms adapted to low-light and low-oxygen conditions.

(eduinputs.org)

Lotic Zone (Flowing Water):

Source Zone: The source zone is the headwater or the beginning of a river or stream. It is typically characterized by fast-flowing, cold, and clear water. Organisms found in this zone include cold-water fish, insects, and algae.

Transition Zone: The transition zone is the middle course of a river or stream. It has a mix of fast and slow currents, with a more diverse array of habitats and organisms. Here, you may find a variety of fish species, insects, plants, and amphibians.

Floodplain Zone: The floodplain zone is the area surrounding a river or stream that periodically floods. It consists of slow-moving or still water during floods and supports wetland habitats like marshes and swamps. It is home to a wide range of plants, mammals, reptiles, and birds.

Delta Zone: The delta zone is the area at the mouth of a river where it meets a larger body of water, such as a lake, sea, or ocean. Deltas often have complex channels, estuarine habitats, and wetlands. They provide important nesting and feeding grounds for many bird species and support diverse aquatic life.

Zones of a flowing water habitat (researchgate.net)

Wetlands: Wetlands are areas where water is present either permanently or seasonally. They include marshes, swamps, bogs, and fens. Wetlands are characterized by water-saturated soils and a wide range of hydrophytic (water-loving) plants. They are important for water filtration, flood control, and provide habitat for numerous species of plants, birds, reptiles, amphibians, and insects.

Wetlands (Britannica.com)

Each of these zones within freshwater habitats supports distinct ecological communities and plays a crucial role in the overall health and functioning of freshwater ecosystems. They provide diverse niches and habitats for a wide variety of organisms adapted to their specific conditions.