Freshwater Ecosystem Zones and Their Unique Organisms

Freshwater ecosystems range from small puddles to large lakes and include stagnant and running water types. These ecosystems are divided into zones: littoral, limnetic, and profundal, each with unique characteristics and organisms. The littoral zone is near the shore, rich in plant life and photosynthesis. The limnetic zone is open water with diverse fish and high photosynthetic activity. The profundal zone is dimly lit, home to scavengers and decomposers. Organisms adapt to environmental changes, such as temperature and salinity, to survive. Challenges include evaporation, freezing, and nutrient depletion, affecting the ecosystem's balance.

What are the two main types of freshwater ecosystems?

• Marine and terrestrial types

• Tropical and temperate types

• Saltwater and freshwater types

• Stagnant and running water types

Which zone in a freshwater ecosystem is known for high photosynthetic activity and is home to snails and clams?

• Profundal zone

• Littoral zone

• Limnetic zone

• Abyssal zone

What type of fish is commonly found in the limnetic zone?

• Fish with dull and greyish bodies

• Bright shiny fish with silver scales

• Deep-sea fish

• Fish with bioluminescent features

Which zone is characterized by being dimly lit and cold, with scavengers and predators?

• Pelagic zone

• Littoral zone

• Limnetic zone

• Profundal zone

How do freshwater fish maintain their internal salt balance?

• By avoiding salty water

• By absorbing salt through their skin

• By excreting salts through their kidneys and gills

• By drinking large amounts of water

What adaptation helps water hyacinth to float?

• Long roots

• Heavy stems

• Air-filled structures in leaf bases

• Thick leaves

Which plant is known for its ability to grow at low light intensities and absorb carbon dioxide efficiently?

• Water lily

• Balistneria

• Hydrilla

• Moss

What happens to the water in lakes during summer?

• It becomes less oxygenated

• It freezes

• It evaporates

• It becomes more saline

Which organisms are known to migrate between surface and deeper layers of a lake?

• All of the above

• Amphibians

• Mammals

• Insects

What is a critical role of insects like skaters and water beetles in freshwater ecosystems?

• They decompose dead matter

• They provide food for other animals

• They regulate water temperature

• They increase water salinity