15.1 Causes and consequences of biodiversity loss
3 min read•august 7, 2024
Biodiversity loss is a critical issue in Earth's ecosystems. Human activities like , , and pollution are major threats. and further exacerbate the problem, leading to species extinctions and ecosystem disruptions.
Measuring biodiversity involves assessing genetic, species, and . The loss of biodiversity has far-reaching consequences, impacting , stability, and resilience. Understanding these impacts is crucial for developing effective conservation strategies.
Threats to Biodiversity
Human-Induced Habitat Destruction
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- Habitat loss occurs when natural environments are converted for human use (agriculture, urbanization, deforestation)
- Leads to fragmentation, isolating populations and reducing
- Disrupts migration patterns and breeding grounds
- Example: Clearing rainforests for cattle ranching in the Amazon
- Overexploitation involves unsustainable harvesting of species from the wild
- Includes overfishing, poaching, and illegal wildlife trade
- Can cause population declines and extinctions (, )
- Pollution from human activities degrades habitats and harms organisms
- Agricultural runoff (pesticides, fertilizers) contaminates water sources
- Plastic pollution entangles marine life and is ingested by animals (, )
- Oil spills devastate coastal ecosystems and marine life (Deepwater Horizon spill)
Climate Change and Anthropogenic Impacts
- Climate change driven by anthropogenic greenhouse gas emissions alters habitats
- Rising temperatures cause range shifts, phenological mismatches, and coral bleaching
- Changing precipitation patterns lead to droughts, floods, and wildfires
- Ocean acidification hinders shell formation in marine organisms (, )
- Invasive species introduced by human activities outcompete native species
- Lack natural predators in new environments, allowing unchecked population growth
- Example: in the Florida Everglades disrupt food webs
- Extinction occurs when the last individual of a species dies
- Currently in the , primarily driven by human activities
- Extinction is irreversible and leads to permanent loss of genetic diversity
Biodiversity Metrics
Measuring Biodiversity at Different Scales
- Biodiversity encompasses the variety of life at all levels of organization
- Genetic diversity: Variation in genes within a species, enhancing adaptability
- : Number of different species in an ecosystem or region
- Ecosystem diversity: Variety of habitats, communities, and ecological processes
- is the number of different species present in an area
- Does not account for abundance or distribution of individuals within species
- Example: A rainforest has higher species richness than a desert
- refers to how equally abundant the species are in an ecosystem
- Low evenness indicates dominance by one or a few species (Antarctic penguin colonies)
- High evenness suggests similar abundances across species (temperate grasslands)
Ecological Consequences
Importance of Biodiversity for Ecosystem Functioning
- Biodiversity underpins the provision of ecosystem services
- Regulating services: Climate regulation, water purification, pollination
- Provisioning services: Food, timber, medicinal resources
- Cultural services: Recreation, aesthetic value, spiritual significance
- Greater biodiversity often enhances ecosystem stability and resilience
- : Multiple species performing similar roles buffers against disturbances
- Example: Diverse grasslands are more resistant to drought than monocultures
- have disproportionately large effects on ecosystem structure and function
- Their removal can trigger , altering community composition
- Example: Sea otters maintain kelp forests by controlling sea urchin populations
- Trophic cascades occur when changes at one trophic level affect multiple other levels
- Wolves in Yellowstone: Reintroduction reduced elk populations, allowing aspen and willow recovery, benefiting beavers and songbirds
- Loss of apex predators can lead to overgrazing, habitat degradation, and species declines
Key Terms to Review (31)
Atlantic Cod: Atlantic cod is a species of fish found in the North Atlantic Ocean, known for its importance in both commercial fishing and marine ecosystems. It has been a staple of fisheries for centuries, significantly contributing to the economy and food supply of many coastal communities. However, overfishing has led to drastic declines in its populations, making it a crucial example of the impacts of human activity on biodiversity loss.
Biodiversity offsets: Biodiversity offsets are conservation activities designed to compensate for the loss of biodiversity due to development or land-use changes. They aim to ensure that any adverse impacts on species and ecosystems are counterbalanced by the protection, restoration, or creation of biodiversity elsewhere. This practice highlights the importance of mitigating biodiversity loss while pursuing economic development.
Burmese pythons: Burmese pythons are large, non-venomous constrictor snakes native to Southeast Asia, known for their impressive size and distinctive coloration. In recent years, they have become a significant concern in ecosystems outside their natural habitat due to their status as an invasive species, particularly in the Florida Everglades. Their introduction has resulted in severe consequences for local wildlife, leading to declines in biodiversity and disruption of ecological balance.
Climate change: Climate change refers to significant alterations in global temperatures and weather patterns over time, primarily driven by human activities such as burning fossil fuels, deforestation, and industrial processes. This phenomenon affects various Earth systems, highlighting the interconnectedness of environmental processes and the impact of atmospheric changes on ecosystems and human societies.
Convention on Biological Diversity: The Convention on Biological Diversity (CBD) is an international treaty aimed at conserving the world's biodiversity, promoting sustainable use of its components, and ensuring fair sharing of benefits arising from genetic resources. The CBD highlights the importance of biodiversity in maintaining ecosystem services and addresses the urgent need to tackle biodiversity loss through various conservation strategies.
Coral reefs: Coral reefs are diverse underwater ecosystems formed by the calcium carbonate structures secreted by corals, which are marine invertebrates. These vibrant ecosystems provide essential habitats for countless marine species, contribute to coastal protection, and play a significant role in the global carbon cycle. Their health and diversity are crucial for marine biodiversity and the overall functioning of oceanic environments.
Economic valuation of ecosystems: Economic valuation of ecosystems is the process of assigning monetary value to the benefits and services provided by natural ecosystems. This includes assessing the worth of resources like clean air, water filtration, biodiversity, and recreational spaces, which are often overlooked in traditional economic assessments. By quantifying these ecosystem services, it becomes easier to understand their importance in decision-making and policy formulation related to environmental conservation and sustainable resource management.
Ecosystem diversity: Ecosystem diversity refers to the variety of ecosystems within a specific region, encompassing the different habitats, communities, and ecological processes that exist in a given area. This diversity is essential for the overall health of the planet, as it supports various species and helps maintain ecosystem services such as water purification, climate regulation, and nutrient cycling. Ecosystem diversity also influences resilience against environmental changes and species extinctions.
Ecosystem services: Ecosystem services are the benefits that humans receive from natural ecosystems, including provisioning, regulating, cultural, and supporting services. These services play a crucial role in sustaining human life and well-being, influencing everything from clean water availability to climate regulation.
Evenness: Evenness is a measure of how evenly individuals are distributed among the different species in a given community. It provides insight into the balance of species populations, with higher evenness indicating a more equal representation of species, while lower evenness suggests dominance by one or a few species. This concept is crucial for understanding biodiversity and ecosystem stability, as it reflects the health of an ecosystem and its resilience to disturbances.
Extinction Rate: The extinction rate refers to the rate at which species become extinct over a specific period of time. This measure is crucial in understanding biodiversity loss, as it highlights the speed and severity of species decline, which can have profound ecological consequences, including disruptions in ecosystem functions and loss of genetic diversity. A higher extinction rate can indicate environmental stressors and human impacts that threaten various ecosystems.
Food Security: Food security is the condition in which all people have reliable access to sufficient, safe, and nutritious food to maintain a healthy life. This concept encompasses various dimensions including availability, access, utilization, and stability of food resources. Ensuring food security is crucial for social stability, economic development, and public health, making it deeply interconnected with environmental issues like soil degradation and biodiversity loss.
Functional Redundancy: Functional redundancy refers to the presence of multiple species within an ecosystem that perform similar roles or functions. This concept highlights the idea that biodiversity can provide a buffer against ecosystem disturbances, as different species can fulfill the same ecological roles, thereby maintaining stability and resilience in the face of changes or threats.
Genetic diversity: Genetic diversity refers to the variety of genes within a species, contributing to the overall genetic variation among individuals. This variation is essential for the adaptability and resilience of populations, allowing them to respond effectively to environmental changes and pressures. Higher genetic diversity within a population enhances its ability to survive diseases, adapt to changing habitats, and maintain ecosystem stability, which in turn supports various ecological processes.
Habitat destruction: Habitat destruction refers to the process by which natural habitats are altered or eliminated, leading to the loss of biodiversity and the disruption of ecosystems. This often occurs due to human activities such as urban development, agriculture, deforestation, and pollution. Habitat destruction has significant implications for marine ecosystems and biodiversity, as well as broader environmental issues including the loss of species and ecological balance.
Invasive species: Invasive species are organisms that are non-native to a particular ecosystem and whose introduction causes or is likely to cause harm to the environment, economy, or human health. They disrupt local ecosystems by outcompeting native species for resources, altering habitats, and affecting biodiversity. This disruption can have cascading effects, impacting ecosystem services and leading to biodiversity loss.
Keystone Species: A keystone species is an organism that has a disproportionately large impact on its environment relative to its abundance. These species play a critical role in maintaining the structure and integrity of an ecosystem, influencing the types and numbers of other species present. By supporting various ecosystem functions and services, keystone species are vital to the health of their environments, affecting biodiversity and stability within ecosystems.
Overexploitation: Overexploitation refers to the unsustainable use of natural resources, particularly through excessive harvesting or hunting, leading to the decline or extinction of species. This practice not only threatens biodiversity but also disrupts ecosystems and the services they provide, ultimately impacting human communities that rely on these resources for their livelihoods.
Oysters: Oysters are marine mollusks belonging to the family Ostreidae, commonly found in coastal waters around the world. They play a crucial role in marine ecosystems as filter feeders, enhancing water quality, and providing habitat for various species. Their decline can significantly affect biodiversity, leading to altered ecosystems and a loss of species that depend on them.
Passenger Pigeon: The passenger pigeon was a North American bird species that was once abundant, known for its remarkable flocking behavior and migratory patterns. It became a symbol of biodiversity loss after its population dramatically declined due to overhunting and habitat destruction, ultimately leading to its extinction in the early 20th century.
Protected Areas: Protected areas are designated regions of land or water that are set aside to conserve biological diversity, maintain ecosystem services, and protect natural and cultural resources. They play a critical role in preserving habitats and species from the threats of human activities, ensuring that ecosystems remain intact and resilient against biodiversity loss.
Pteropods: Pteropods are small, marine mollusks that belong to the class Gastropoda and are often referred to as 'sea butterflies' or 'sea angels' due to their wing-like structures used for swimming. These creatures play a significant role in ocean ecosystems and are important indicators of ocean health, particularly in the context of climate change and biodiversity loss.
Restoration ecology: Restoration ecology is a scientific discipline focused on the recovery and restoration of ecosystems that have been degraded, damaged, or destroyed. It emphasizes the importance of understanding ecological processes and interactions to effectively restore biodiversity and ecosystem functionality. This field plays a crucial role in mitigating biodiversity loss and enhancing the health of various habitats, such as wetlands and lakes, while also informing conservation strategies and the management of protected areas.
Sea Turtles: Sea turtles are marine reptiles that belong to the order Testudines, known for their distinctive bony or cartilaginous shell that protects them from predators. These ancient creatures play vital roles in marine ecosystems, including maintaining healthy seagrass beds and coral reefs, which are crucial for biodiversity. Their existence is significantly impacted by human activities, leading to declines in populations and contributing to the broader issue of biodiversity loss.
Seabirds: Seabirds are a group of birds that have adapted to life primarily in marine environments, often spending significant time at sea. These birds are known for their ability to travel long distances over the ocean and include species such as gulls, albatrosses, and puffins. Their dependence on marine ecosystems makes them vital indicators of ocean health, and they face numerous threats that contribute to biodiversity loss.
Sixth mass extinction: The sixth mass extinction refers to the ongoing event of species loss on Earth, driven primarily by human activities such as habitat destruction, climate change, pollution, and overexploitation. This extinction event is unique because it is largely caused by anthropogenic factors rather than natural phenomena, posing severe consequences for global biodiversity and ecosystem health.
Species diversity: Species diversity refers to the variety of different species within a given ecosystem or on the entire planet. It encompasses both the number of species present (species richness) and their relative abundance, highlighting the balance and distribution of various species in an area. High species diversity is often associated with healthy ecosystems, contributing to resilience against disturbances and supporting essential ecosystem functions.
Species richness: Species richness refers to the number of different species represented in a given ecological community, ecosystem, or habitat. It is an important measure of biodiversity that reflects the variety of life forms within a specific area, contributing to ecosystem stability and resilience. The higher the species richness, the more diverse and potentially stable the ecosystem, which is crucial for processes such as nutrient cycling and habitat provision.
Sustainable development: Sustainable development is a holistic approach to growth that aims to meet the needs of the present without compromising the ability of future generations to meet their own needs. This concept emphasizes the interdependence of economic growth, environmental protection, and social equity, ensuring that natural resources are used responsibly and preserved for the future. By balancing these aspects, sustainable development seeks to promote well-being and maintain biodiversity, which is crucial for ecosystem services.
Trophic cascades: Trophic cascades are ecological phenomena that occur when a change in the population of one species, particularly a predator or herbivore, causes ripple effects throughout an ecosystem, impacting multiple trophic levels. These cascades illustrate how interconnected species are within food webs and demonstrate the importance of maintaining balanced ecosystems. The disruption of these interactions can lead to overpopulation of certain species, decline of others, and significant changes in habitat structure and function.
World Wildlife Fund: The World Wildlife Fund (WWF) is an international non-governmental organization focused on wildlife conservation and reducing human impact on the environment. It works to protect endangered species and their habitats while promoting sustainable practices globally. WWF plays a critical role in addressing the causes of biodiversity loss, advocating for conservation strategies, and establishing protected areas to ensure the survival of diverse ecosystems.