Aquatic Ecosystems and Biodiversity Management Notes

Aquatic Biological Resources Management

  • Management considerations relating to aquatic organisms.

  • Types of aquatic ecosystems:

    • Marine Ecosystem

    • Freshwater Ecosystem

    • Estuaries (region between freshwater and ocean)

Marine Ecosystems

  • Largest aquatic ecosystems: Oceans, estuaries, salt marshes, coral reefs, and coastal areas.

  • Oceans cover 71% of the Earth's surface and contain 97% of the planet’s water.

  • Salinity of seawater approximately 35 ‰ (3.5%).

  • Coastal areas account for one-third of all marine biological productivity.

  • Large biodiversity includes species like crustaceans, squid, tuna, and whales.

Major Ocean Basins

  • Pacific Ocean: Deepest and largest, features the Mariana Trench.

  • Atlantic Ocean: Warmest and shallowest.

  • Indian Ocean: Smallest major basin.

  • Oceans make up 96.5% water, 3.5% salt.

Marine Ecosystem Zones

  1. Oceanic Zone: Open ocean habitat for large animals (e.g., whales, sharks).

  2. Intertidal Zone: Area between high and low tides.

  3. Neritic Zone: Extends from low tide to continental shelf edge.

  4. Pelagic Zone: Between the oceanic and benthic zones.

  5. Benthic Zone: Seabed habitat.

  6. Photic Zone: Light-penetrated area promoting photosynthesis.

  7. Aphotic Zone: No light, below the photic zone.

  8. Abyssal Zone: Great depths, no light.

  9. Continental Shelf: Submerged part of the continent with shallow water.

Freshwater Ecosystems

  • Covers 0.8% of Earth’s surface and contains 0.009% of total water.

  • Houses 41% of the world’s known fish species.

  • Low salt content (usually 0.005%), exceptions include Great Salt Lakes and Dead Sea.

  • Types of freshwater ecosystems:

    • Still water (lentic): Lakes, ponds (less oxygen).

    • Moving water (lotic): Rivers, streams (higher oxygen).

    • Inland wetlands: Soil saturated or inundated.

Lake Ecosystem Components

  • Littoral Zone: Emergent plants, significant photosynthesis.

  • Limnetic Zone: Open water, lower light.

  • Profundal Zone: Below limnetic; bacteria and fungi.

Stream Ecosystem

  • Ephemeral Streams: Flow during specific seasons.

  • Perennial Streams: Flow year-round.

  • Classification based on stream order and Rosgen methods.

Estuaries

  • Partly enclosed coastal waters where rivers meet the sea.

  • High nutrient levels, brackish water, and rich biodiversity.

  • Acts as nurseries for aquatic species.

Wetlands

  • Diverse ecosystems; mangroves illustrate transition zones between land and water.

Aquatic Biodiversity Factors

  • Influenced by water temperature, depth, dissolved oxygen, food availability, light, and nutrients.

Threats to Aquatic Biodiversity

  • Habitat loss, invasive species, pollution, climate change, overexploitation, human activity growth.

Human Activities Impacting Aquatic Habitats

  • Habitat destruction from coastal development and building projects.

  • Coral reefs and mangrove forests severely affected.

Coral Bleaching Causes

  • Increased ocean temperatures, runoff and pollution, overexposure to sunlight, and extreme low tides can stress coral.