Freshwater Habitat SS1 Biology Lesson Note

FRESHWATER HABITATS

This is a body of water formed mainly from inland waters and it contains very low or no salt. Fresh water is of two types based on its mobility; 

1. Lotic fresh waters: – These are running waters flowing continuously in a specific direction e.g. rivers, springs, streams
2. Lentic fresh waters: – These are stagnant waters which do not flow e.g. lakes, ponds, puddles, swamps and dams

 CHARACTERISTICS OF FRESHWATER HABITATS

1. It contains little or no salt. Salinity is 5 parts per thousand i.e. 0.5%.
2. It is small in size.
3. Oxygen concentration is high, being available in all parts of the water body, especially at the surface.
4. The water is shallow, hence sunlight penetrates to the bottom.
5. The temperature varies with seasons and depth.
6. It has seasonal variation; decreasing or drying up in the dry season and increasing in the rainy season
7. Water currents affect the distribution of organisms, salts and gases, especially in lotic freshwaters

PLANTS DISTRIBUTION AND ADAPTATION IN FRESHWATER

Plants of fresh water include water lilies, spirogyra, water lettuce, water weeds etc.. and they have the following adaptive features;

1. Water lily has 

• air bladder 
• Expanded tips and lightweight which keep it afloat.

2. Spirogyra has mucillagenous cover for protection
3. Water lettuce has hairs in leaves to trap air and keep it afloat
4. Water weed (elodea) has a long and flexible petiole for swinging with water currents. 

    ANIMAL DISTRIBUTION AND ADAPTATION

Animals of freshwater habitats include protozoa, ducks, pond skaters, hydra, fishes etc. Their adaptive features include:

1. Protozoa have contractile vacuole for osmoregulation in water.
2. A duck has webbed feet for locomotion and sea rrated beak for sieving food in water into its mouth. 
3. Hydra has a slippery surface, hooks and suckers for attachment to water particles.
4. Pondskatters have long legs for skating on the water’s surface 
5. Fishes have swim bladders for buoyancy and gills for respiration

 FOOD CHAIN IN FRESHWATER HABITATS

1. Diatoms → fish fry →tilapia
2. Spirogyra → tad poles → carps → kingfish
3. Algae → mosquito larva → small fish