Biodiversity Threats Overview

Major Threats to Biodiversity

• Habitat Loss and Fragmentation:
  • Primary threat; 98% of tropical forests in Mexico/Central America destroyed.
  • 70% of coral reefs are damaged.
• Other Threats:
  • Climate change
  • Overharvesting
  • Introduced species
  • Pollution (toxins, plastics, pharmaceuticals)

Current Biodiversity Loss

• Potential onset of the 6th Mass Extinction:
  • Defined as loss of ≥75% of species in a short period.
  • Global wildlife populations declined by 73% in the past 50 years.

Deforestation

• Tropical rainforests as biodiversity hotspots.
• Projected loss of 40-50% of Amazon tree species within the century.
• Annual loss rate of ~0.25% of species (5,000-25,000 species).

Habitat Fragmentation

• Process of dividing large habitats into isolated patches.
• Reduces biodiversity and increases extinction risks due to isolation.

Pollution Effects

• Air Pollution: Causes 4 million deaths annually.
• Pesticides: Neonicotinoids harm bees/birds; correlation with population decline.
• Plastic Pollution: Harms marine organisms through ingestion and entanglement.

Overexploitation of Species

• Marine Overfishing:
  • Cod stocks dwindled to 1% of their former levels, leading to fishing bans.
  • Global fisheries experiencing unsustainable practices.
• Terrestrial Overexploitation:
  • Poaching of elephants and rhinos for ivory and horn, drastically reducing populations.

Invasive Species

• Introduction of nonnative species disrupts local ecosystems.
  • Estimated 49,000 invasive species in the U.S., causing habitat loss and native extinction.

Indicators of Environmental Health

• Amphibians:
  • Serve as indicators due to sensitivity to environmental changes (e.g., habitat destruction, pollution).
  • One-third of amphibian species are threatened.