AQUATIC-BIODIVERSITY-CHAPTER-3-4

AQUATIC BIODIVERSITY

Intended Learning Outcomes

• At the end of the coverage, the student should be able to:

  • Explain the importance of Aquatic Biodiversity.

  • Discuss the general nature of aquatic ecosystem.

  • Explain the importance of marine aquatic ecosystem.

  • Discuss the impact of human activities in marine ecosystem.

  • Explain the importance of fresh water ecosystem.

  • Discuss the impact of human activities in fresh water ecosystem.

  • Explain the roles of humans in the extinction of species.

  • Discuss reasons for caring about rising rates of species extinction.

  • Explain and discuss how to protect wild species from extinction.

Aquatic Ecosystems

• Defined as ecosystems found in bodies of water.

• Two main types of aquatic ecosystems:

  • Marine Ecosystems

  • Freshwater Ecosystems

Freshwater Ecosystems

• Interactive systems involving biotic species, growth, adaptation, biological productivity, nutrient cycling, and energy flows within aquatic microbial, plant, and animal communities integrated with their environment.

Marine Ecosystems

• Aquatic environments characterized by high levels of dissolved salt, including:

  • Open ocean

  • Deep-sea ocean

  • Coastal marine ecosystems

General Nature of Aquatic Ecosystems

• Global Coverage: Water covers 71% of Earth's surface; landmass covers 29%.

• Most aquatic species inhabit the upper, middle, or bottom layers of water, contributing to ecosystem complexity.

• Human impacts, including climate change and pollution, affect aquatic biodiversity.

Marine Aquatic Ecosystem Importance

• Provides ecosystem services vital for climate regulation, commercial activities, subsistence fishing, and recreational use.

• Habitat for various marine and coastal species.

Major Life Zones in Marine Ecosystems

Coastal Zone

• Warm, shallow water full of nutrients, where diverse ecosystems like estuaries and coral reefs flourish.

Open Sea & Ocean Floor

• Divided into vertical zones based on sunlight penetration:

  • Euphotic Zone: Light penetration, phytoplankton productivity.

  • Upwelling Zone: Nutrient-rich, supports high productivity.

  • Bathyal Zone: Dimly lit, lacks photosynthesizing producers.

  • Abyssal Zone: Dark, cold, teeming with life, relying on organic matter from upper zones.

Human Activities Affecting Marine Ecosystems

• Major Threats:

  • Coastal development and habitat destruction.

  • Pollution from agriculture and sewage.

  • Overfishing depletes fish stocks.

  • Climate change leads to ocean warming and acidification.

• Impacts include habitat loss, species endangerment, and ecosystem degradation.

Importance of Freshwater Ecosystems

• Includes standing (lentic) and flowing (lotic) water systems providing vital ecological and economic services despite covering less than 2.2% of the Earth’s surface.

• Lakes and wetlands play crucial roles in nutrient cycling and habitat support.

Nutrient Status of Lakes

• Lakes classified by nutrient levels:

  • Oligotrophic: Low nutrient input, deep with clear water.

  • Eutrophic: High nutrient supply, supports abundant plant life, may lead to algal blooms.

Eutrophication Process

• Caused by excess nutrient runoff, leading to algal blooms that deplete oxygen, endangering aquatic life.

Human Activities Affecting Freshwater Ecosystems

• Dams and canals disrupt natural freshwater flow.

• Pollution from urban and agricultural runoff promotes algal growth, harming biodiversity.

• Altered wetlands through drainage lead to increased flooding and habitat loss.

Conservation Strategies

Species Approach

• Protect endangered species through habitat management and legal protection.

Ecosystem Approach

• Maintain sufficient protected habitats and restore degraded ecosystems.

Causes of Habitat Loss

• Primarily human activity, including agriculture, urban development, and climate change, leading to increased extinction rates.

Why Care About Species Extinction

• Indicates ecosystem imbalance, with cascading effects on biodiversity and human well-being.

• Healthy ecosystems support clean air, water, food supply, and medicinal resources.

Protecting Wild Species from Extinction

• Strategies involve monitoring ecosystems, managing human impacts, and ensuring habitat integrity while combating invasive species.