Threats to biodiversity

Direct threats target species directly (e.g., poaching), whereas indirect threats damage ecosystems as a side effect (e.g., habitat loss, climate change).

An invasive species is a non-native organism introduced by humans that spreads rapidly and harms native ecosystems.

Human activity is the main driver, including habitat destruction, overexploitation, pollution, and climate change.

It occurs when individuals overuse a shared resource for short-term gain, leading to long-term depletion and collective loss.

Habitat loss, overexploitation, pollution, climate change, and invasive species are major threats.

Overharvesting and poaching are direct threats because they remove individuals from populations.

They disrupt ecosystem balance by outcompeting native species and altering food webs.

They may lack natural predators, compete strongly for resources, or reproduce quickly in the new ecosystem.

Because individuals act in their own short-term interest while the costs of overuse are shared by everyone.

Habitat loss reduces available food, shelter, and breeding space, causing population decline and increased extinction risk.

Habitat loss and climate change are indirect threats because they alter ecosystems and affect many species at once.

Small populations have lower genetic diversity, are more affected by random events, and may struggle to reproduce successfully.

Overfishing in open oceans where no single country controls the resource can lead to stock collapse.

They outcompete, prey on, or bring diseases to native species, causing population declines or extinctions.

Because without regulation, individuals maximise personal benefit, leading to overuse and depletion.

Without natural enemies, invasive predators can rapidly reduce prey populations and disrupt entire food webs.

Multiple interacting threats reduce resilience and make ecosystems less able to recover.

By introducing regulations, quotas, enforcement, or shared agreements that limit overuse and promote sustainability.

Poaching or overharvesting directly reduces population size and can push species toward extinction.

Because they change habitat conditions or ecosystem processes that multiple species depend on.

Fragmentation isolates populations, limits gene flow, increases edge effects, and reduces overall ecosystem stability.

Name the threat, describe how it affects species or habitats, and explain the consequences for population size or ecosystem stability.

They directly harm native species but also indirectly alter ecosystem structure and processes.

When several pressures act at once (e.g., habitat loss plus climate change), recovery is harder and tipping points are more likely.

Because preventing decline is easier and cheaper than restoring ecosystems after severe damage or species extinction.

Conservation status describes how close a species is to extinction and how urgently it needs protection.

The International Union for Conservation of Nature (IUCN) publishes the IUCN Red List categories.

Population size, population trend (increasing/decreasing), geographic range, and known threats are key factors.

Near Threatened (NT) → Vulnerable (VU) → Endangered (EN) → Critically Endangered (CR).

It helps prioritise action and funding by showing which species are most at risk and need urgent protection.