Aquatic ecosystems: Freshwater, marine

1. Aquatic ecosystems are water-based ecosystems where organisms interact with the aquatic environment.
2. They are classified into freshwater and marine ecosystems based on salinity levels.

Freshwater Ecosystems

1. Freshwater ecosystems have low salt concentration, typically less than 1% salinity.
2. They include rivers, lakes, ponds, wetlands, and streams.
3. Freshwater ecosystems support a wide variety of flora and fauna.
4. Lakes are large, stationary bodies of freshwater that may be nutrient-rich (eutrophic) or nutrient-poor (oligotrophic).
5. Ponds are smaller water bodies that often support diverse aquatic life due to sunlight penetration.
6. Rivers and streams are flowing water systems that transport nutrients and sediments.
7. Wetlands are areas where water covers the soil, supporting unique ecosystems like marshes and swamps.
8. Freshwater ecosystems are crucial for drinking water, irrigation, and supporting biodiversity.
9. Plankton, nekton, and benthos are the main groups of organisms in freshwater ecosystems.
10. Plankton are free-floating organisms, including phytoplankton (plants) and zooplankton (animals).
11. Nekton includes swimming organisms like fish and amphibians.
12. Benthos refers to organisms living at the bottom of water bodies, such as snails and worms.
13. Freshwater ecosystems play a significant role in nutrient cycling and supporting terrestrial ecosystems.
14. Pollution from agriculture, industry, and urbanization threatens freshwater ecosystems.
15. Conservation efforts aim to maintain water quality and protect freshwater habitats.

Marine Ecosystems

1. Marine ecosystems have high salt concentration, typically around 3.5% salinity.
2. They include oceans, seas, estuaries, and coral reefs.
3. The ocean is the largest marine ecosystem, covering more than 70% of the Earth's surface.
4. Phytoplankton in marine ecosystems are primary producers that drive the global carbon cycle.
5. Marine ecosystems are divided into zones: intertidal, pelagic, benthic, and abyssal.
6. The intertidal zone is the area between high and low tides, home to diverse organisms adapted to changing conditions.
7. The pelagic zone is the open water region, supporting organisms like fish, whales, and plankton.
8. The benthic zone includes the ocean floor, home to benthic organisms like crabs and sea stars.
9. The abyssal zone is a deep, dark region with unique organisms adapted to high pressure and no sunlight.
10. Coral reefs are biodiversity hotspots in shallow marine waters, often called the "rainforests of the sea."
11. Estuaries are transitional zones where freshwater rivers meet salty ocean waters, supporting diverse life forms.
12. Marine ecosystems regulate the Earth's climate and are a major source of oxygen.
13. They provide food, medicines, and livelihoods for millions of people worldwide.
14. Marine ecosystems are under threat from overfishing, pollution, and climate change.
15. Ocean acidification, caused by increased CO₂ absorption, affects marine biodiversity.
16. Coral bleaching due to rising sea temperatures poses a severe threat to coral reef ecosystems.
17. Efforts such as marine protected areas (MPAs) and sustainable fishing practices aim to conserve marine ecosystems.

Comparison of Freshwater and Marine Ecosystems

1. Freshwater ecosystems have low salinity, while marine ecosystems have high salinity.
2. Marine ecosystems are larger and more diverse compared to freshwater ecosystems.
3. Freshwater ecosystems are more directly influenced by terrestrial ecosystems.
4. Both ecosystems are vital for biodiversity and play key roles in the Earth's ecological balance.

Importance of Aquatic Ecosystems

1. Aquatic ecosystems support life processes by providing oxygen, food, and habitat.
2. They help regulate climate and act as natural buffers against storms and floods.
3. Conserving aquatic ecosystems is essential for maintaining the Earth's ecological health.