Biodiversity, or biological diversity, encompasses the vast variety of life on Earth, ranging from microscopic organisms to complex ecosystems. It includes the diversity within species (genetic diversity), between species, and of ecosystems themselves. This intricate web of life is fundamental for the planet’s health, providing essential services such as clean air and water, food, medicines, and stable climates. Ecosystems with rich biodiversity are more resilient and adaptable to changes, supporting human well-being and the natural world.
Habitat Loss and Fragmentation
Habitat loss, degradation, and fragmentation are major threats to biodiversity. Habitat loss occurs when natural environments are converted for human uses like agriculture, urbanization, and infrastructure development, such as the transformation of forests and prairies into croplands.
Deforestation, urban expansion, and road construction directly destroy habitats, reducing space and resources for species. Habitat degradation diminishes quality through pollution, invasive species, and disruption of natural processes like fire or flooding. When large, continuous habitats break into smaller, isolated patches, it is known as fragmentation. This creates barriers to species movement, limits access to food and mates, and reduces genetic diversity, often leading to population declines and extinctions.
Invasive Species
Invasive species are non-native organisms introduced to an ecosystem through human activities like trade, travel, or horticulture. They cause significant ecological and economic harm in new environments. They disrupt native ecosystems by outcompeting native species for resources, preying on them, or transmitting diseases.
Their introduction can reduce native species diversity and lead to extinctions. For example, invasive lionfish prey on native herbivores in coral reefs, leading to increased algae growth detrimental to coral health. Invasive plants can also alter soil chemistry and fire regimes, further impacting native flora and fauna.
Pollution
Pollution introduces harmful substances or energy into the environment, harming ecosystems and living organisms. Forms include chemical, plastic, light, noise, and nutrient runoff. Pollutants directly harm organisms, degrade habitats, and disrupt ecological processes.
For example, water pollution from chemicals, plastics, and agricultural runoff affects aquatic life, causing fish deaths and marine biodiversity loss. Air pollutants, like sulfur and nitrogen compounds, acidify lakes and streams, damage trees, and reduce plant diversity by favoring species tolerant to excess nutrients. Pollutants like pesticides and heavy metals accumulate in the food chain, leading to biomagnification and severe health issues for species at higher trophic levels.
Climate Change
Climate change, driven by human activities, impacts global biodiversity. Rising temperatures, altered precipitation patterns, and extreme weather events disturb natural habitats and species. These changes force species to adapt, migrate, or face extinction if they cannot keep pace with rapid environmental shifts.
Ocean warming and acidification threaten marine life, making it difficult for organisms like corals and shellfish to form skeletons and shells. Increased wildfires and droughts, exacerbated by climate change, destroy vast habitats, as seen in the Australian bushfires that impacted many species. Climate change also facilitates invasive species spread and disrupts natural cycles, such as breeding or migration timing, which can lead to mismatches in food availability for some species.
Overexploitation
Overexploitation is harvesting species from the wild faster than their populations can recover. This unsustainable practice depletes populations and can lead to species collapse or extinction. Examples include industrial fishing, overhunting, and unsustainable logging.
Overfishing has led to a decline in global fish stocks, with many harvested faster than they reproduce. Poaching animals for parts, such as ivory from elephants or rhino horns, severely threatens these species. Overexploitation not only impacts targeted species but also disrupts entire food webs, causing cascading effects throughout ecosystems and diminishing their resilience and ability to provide essential services.