Aquatic ecology and Biodiversity

Practical 15- Study of river habitat and organisms

Experiment 15
Date: Date & Time of Visit:
Place of Visit: Name of the Teacher:
Name of the Class:
Rivers are called running water systems. River waters are characterized by movement of water and it is the unique characteristic of river waters. The interchange between the soil and water is higher in the river waters than the pond waters. Dissolved oxygen content is more and uniformly distributed in running waters and there is no physical and chemical stratification. Depending on the water movement in different zones, the nature of bottom materials is changing with sandy, muddy, rocky or pebbles.
Adaptations of organisms
The living organisms of the running water systems possess a variety of adaptations to maintain their position against the fast moving waters. They are as follows:
The plants and animals are permanently attached to the hard substratum like stones and pebbles. Some animals are able to maintain their position against the moving water currents by possessing strong hook like structures. Lotic animals have the inherent behaviour to adhere close to the surface of the bottom or substratum. The animals have a streamlined body shapes which offers minimum resistance to the water flowing over them. Most of the animals inhabiting the streams and rivers are positively rheotatic and they are capable of moving against the water flow or currents. Freshwater animals body fluids are hypertonic to their environment and constantly take in water by osmosis which is referred as endosmosis. Special types of adaptations for respiration are seen in the freshwater animals.
Morphology of natural ponds:

• Depth
• Width
• Speed
• Point of joining to estuary

Characteristics of water
Physical:Temperature--------- Colour / Odour----------- Turbidity------------------
Chemical: pH-------------- Do-------------- Salinity / chloride---------------------
River water communities

• Plankton
• Benthos
• Fishes
• Aquatic weeds / macro algae

Species diversity and association
Infrences