Biodiversity represents the variety of life on Earth. Unfortunately, it is under threat due to multiple human-induced factors. Delving deeper into these causes will provide a clearer understanding and underline the urgent need for action.
Population Growth
Rapid human population growth has intensified pressures on our planet's resources and ecosystems:
- Increased Consumption: As the global population swells, so does the consumption of food, water, and energy.
- Land for agriculture: To meet the growing food demand, forests and grasslands are being converted into farmland, pushing many species out of their habitats.
- Water resources: Overdrawing of freshwater affects aquatic ecosystems, reducing habitats and food sources for numerous species.
- Waste Production: Increased population leads to more waste, including plastics and toxins, which can harm both terrestrial and aquatic life.
- Habitat Alteration: Urban expansion and infrastructure development modify and fragment natural habitats.
Image courtesy of Owengaffney
Over-exploitation
The increased demand and consumption of resources have led to over-exploitation:
- Overfishing:
- Many fisheries around the world are facing depletion due to uncontrolled fishing practices.
- Overfishing disrupts the aquatic food chain, as primary predators are removed.
- Wildlife Hunting and Poaching:
- Animals are hunted for their meat, skin, tusks, and other body parts, often leading to reduced populations or even extinction.
- The illegal wildlife trade can introduce non-native species into new areas, leading to ecological imbalances.
- Deforestation:
- Beyond timber extraction, forests are cleared for agriculture and urban development.
- This not only reduces the habitat for forest-dependent species but also impacts the global carbon cycle.
Image courtesy of Asc1733
Urbanisation
The growth of urban areas affects biodiversity in several ways:
- Habitat Fragmentation: Urban areas split natural habitats into smaller patches, isolating species populations and reducing their genetic diversity.
- Pollution: Urban centres are significant sources of different pollutants that harm local ecosystems.
- Light pollution: Affects nocturnal animals and birds, disturbing their natural behaviours.
- Noise pollution: Can disturb wildlife communication and mating calls.
- Heat Islands: Urban areas, due to concrete structures and lack of greenery, tend to be warmer, affecting local weather patterns and species distributions.
Image courtesy of chensiyuan
Deforestation
Forests play a critical role in maintaining global biodiversity:
- Habitat Loss: Forests are home to more than half of terrestrial species. Their destruction leads to a direct loss of species habitat.
- Water Cycle Disruption: Trees play a pivotal role in the water cycle by helping in cloud formation and maintaining groundwater levels.
- Soil Degradation: Forests prevent soil erosion. Their removal can lead to loss of fertile topsoil, affecting agriculture and leading to sedimentation in rivers.
Pollution
Pollution, in its various forms, is a significant threat to biodiversity:
Air Pollution
- Smog: Urban air pollution can harm plants, reducing their growth and harming the animals dependent on them.
- Acid Rain: Sulphur and nitrogen emissions lead to acidic precipitation, harming aquatic systems and forests.
Effects of acid rain, woods, Jizera Mountains, Czech Republic.
Image courtesy of Lovecz
Water Pollution
- Industrial Effluents: Many industries release untreated wastewater into rivers, harming aquatic life.
- Pharmaceuticals: Often, medicines are not entirely metabolised in our bodies and end up in water systems, potentially harming aquatic organisms.
- Microplastics: Tiny plastic particles are ingested by aquatic organisms, leading to internal injuries and introducing toxins into the food chain.
Foaming due to industrial effluents and domestic sewage in Mutha river at Loni Kalbhor.
Image courtesy of Pooja Tendulkar
Land Pollution
- Agricultural Chemicals: Pesticides and herbicides can harm beneficial insects and birds, and run-off can poison aquatic systems.
- Landfills: These can release methane, a potent greenhouse gas, and introduce toxins into the soil, harming plants and underground aquifers.
Invasive Species
Human movement around the globe has led to the introduction of non-native species to new areas:
- Competition: Many invasive species outcompete native species for resources, leading to declines in native populations.
- Predation: Some introduced species might have no natural predators in their new environment, allowing them to proliferate and prey on native species.
Globalisation
The modern interconnected world has both direct and indirect impacts on biodiversity:
- Resource Demand: Global trade can lead to resource depletion in biodiversity-rich areas as they cater to global markets.
- Habitat Destruction: Infrastructure development for global trade routes, such as shipping lanes and highways, can destroy crucial habitats.
Climate Change
While this encompasses multiple areas, it's vital to understand its overarching impact:
- Habitat Alteration: As temperatures rise, many habitats become unsuitable for the species that live there, pushing them to migrate or face extinction.
- Ocean Acidification: Increased carbon dioxide levels lead to more acidic oceans, harming marine life, especially coral reefs.
FAQ
Coral reefs are intricate ecosystems built by coral polyps secreting calcium carbonate to form a hard skeleton. Ocean acidification, a result of increased carbon dioxide (CO2) in the atmosphere dissolving in oceans, leads to a decrease in the pH of seawater. As the seawater becomes more acidic, the availability of carbonate ions, essential for calcium carbonate formation, reduces. This hampers the corals' ability to produce their skeletons and can even lead to the dissolution of existing structures. Without their protective skeletons, corals become more susceptible to diseases, temperature changes, and other stressors. As corals deteriorate, the myriad of species that rely on coral reefs – from fish to invertebrates – are also threatened, leading to a decline in the overall biodiversity of these vibrant ecosystems.
Soil degradation, often a result of deforestation, unsustainable farming practices, and pollution, has far-reaching implications on biodiversity. As the topsoil becomes less fertile, plant growth is hindered, directly affecting herbivores and, in turn, the predators that feed on them. This has a cascading effect, leading to a decline in the entire food chain. Furthermore, degraded soil cannot hold water efficiently, leading to decreased groundwater levels and affecting nearby aquatic habitats. Over time, as soil loses its capability to support plant life, it becomes more prone to erosion, further accelerating degradation. This cyclical process can convert once fertile areas into deserts, leading to a permanent loss of the associated biodiversity.
The development of global trade routes, whether they are shipping lanes, highways, or rail networks, often requires significant alteration of natural habitats. For instance, constructing a highway through a forest not only directly destroys a portion of the forest but also fragments it, creating barriers for wildlife movement. Similarly, dredging for shipping lanes can destroy delicate aquatic habitats. Beyond direct habitat destruction, global trade routes facilitate the movement of invasive species across regions, leading to disruptions in local ecosystems. Moreover, increased trade can drive demand for resources, leading to over-exploitation and further habitat loss. In essence, while global trade routes are essential for economic growth, they can, if not managed sustainably, pose significant threats to biodiversity.
Light pollution, resulting from excessive and misdirected artificial lighting in urban areas, significantly impacts nocturnal animals and some bird species. For nocturnal animals, such as bats and certain insects, artificial lighting can disorient them and make them more susceptible to predators. For migratory birds, city lights can interfere with their navigation, leading them off course or causing them to collide with buildings. Furthermore, some bird species that rely on moonlight and starlight for their nocturnal behaviours, like feeding or mating rituals, can get disrupted. In essence, light pollution alters the natural behaviours of these animals, leading to reduced survival rates and, in some cases, population declines.
Pharmaceuticals find their way into water systems through human waste, improperly disposed medications, and wastewater from pharmaceutical manufacturing. Once in the water systems, these compounds can have detrimental effects on aquatic life. For instance, some pharmaceuticals can disrupt the endocrine system of aquatic organisms, affecting their reproduction and development. Antibiotics in the water can lead to the proliferation of antibiotic-resistant bacteria, presenting a long-term challenge for both aquatic ecosystems and human health. Furthermore, even at low concentrations, certain medications can modify the behaviour of aquatic organisms, making them more vulnerable to predators. Over time, these effects can disrupt the balance of aquatic ecosystems, with potential cascading effects on food chains and nutrient cycles.
Practice Questions
Deforestation leads to a direct loss of habitat for a multitude of species, many of which are forest-dependent. As trees play a pivotal role in the water cycle, their removal disrupts local rainfall patterns and groundwater levels, indirectly affecting other ecosystems. Moreover, forests prevent soil erosion, so their removal can cause the loss of fertile topsoil. On the other hand, urbanisation fragments habitats, isolating populations and reducing their genetic diversity. Urban centres also introduce pollutants harmful to local ecosystems. Both factors contribute to the biodiversity crisis by causing a decline in species numbers and reducing the genetic variability within populations.
Over-exploitation, such as overfishing or poaching, leads to a direct decrease in specific species numbers. When a species is exploited faster than it can reproduce, it risks extinction. Reduced numbers can disrupt food chains and ecological balances, affecting other species in the ecosystem. The introduction of invasive species, often facilitated by human movement, presents challenges for native populations. Invasive species can outcompete native species for resources, leading to a decline in native species numbers. Furthermore, invasive species might introduce new diseases or become predators, further endangering native species. In both scenarios, the ecological balance is disturbed, compromising the health and stability of ecosystems.
