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IB Biology - Ecology
Species
A species is a group of organisms that can interbreed and produce fertile offspring. Each species is genetically distinct from others and occupies a specific ecological niche, which is its role in the environment, including how it gets its energy and nutrients, and how it interacts with other species.
Communities
A community is composed of all the different species living together in a particular area at the same time. These species interact with one another in various ways, such as through competition, predation, and mutualism.
Communities are dynamic and can change over time due to various factors, including environmental changes, species migration, and natural selection.
Ecosystems
An ecosystem includes both the living (biotic) components, like species and communities, and the non-living (abiotic) components, such as climate, soil, water, and nutrients.
Ecosystems can vary in size from a small pond to a large forest and are characterised by the flow of energy (through food chains and webs) and the cycling of nutrients (like carbon and nitrogen) between organisms and their environment.
Species Interactions within Ecosystems
Types of Species Interactions:
Competition: Occurs when two or more species vie for the same resources, such as food, light, or space. This can lead to competitive exclusion, where one species outcompetes another, potentially driving it to extinction in that area.
Predation: Involves one species (the predator) hunting and consuming another (the prey). This interaction regulates prey populations and can drive evolutionary adaptations, such as camouflage or speed.
Mutualism: A cooperative interaction where both species benefit. For example, bees pollinate flowers while feeding on nectar, aiding in plant reproduction.
Commensalism: One species benefits while the other is neither helped nor harmed. An example is barnacles attaching to whales; the barnacles get a free ride to nutrient-rich waters without affecting the whale.
Parasitism: One species (the parasite) benefits at the expense of another (the host), often causing harm but not immediate death. Examples include ticks feeding on mammals.
Factors Shaping Community Structures:
Environmental Factors: Climate, availability of resources, and physical features like topography influence which species can survive in an ecosystem.
Biotic Factors: The presence and interactions of other organisms, such as the availability of prey for predators or the competition for resources, shape community structure.
Disturbances: Events like fires, floods, or human activities can drastically alter communities by removing dominant species and allowing new species to colonise the area.
Succession: Over time, ecosystems undergo changes through ecological succession, where species composition gradually changes, leading to a more stable community.
Energy Flow in Ecosystems
Energy flow is a crucial concept in ecology, focusing on how energy moves through an ecosystem from one organism to another. Here’s a detailed explanation:
Source of Energy
The primary source of energy for most ecosystems is the sun. Solar energy is captured by producers (mainly plants, algae, and some bacteria) through photosynthesis. These producers convert solar energy into chemical energy in the form of glucose, which can be used by themselves and other organisms.
Trophic Levels
Trophic levels represent the different stages in the flow of energy:
Producers (Trophic Level 1): Plants and other photosynthetic organisms that convert solar energy into chemical energy.
Primary Consumers (Trophic Level 2): Herbivores that consume producers and obtain energy from them.
Secondary Consumers (Trophic Level 3): Carnivores that eat herbivores.
Tertiary Consumers (Trophic Level 4): Top predators that consume other carnivores.
At each trophic level, energy is transferred from one organism to another when one organism eats another.
Energy Transfer Efficiency
Energy transfer between trophic levels is inefficient. Typically, only about 10% of the energy from one trophic level is passed on to the next. The remaining 90% is lost, mainly as heat due to metabolic processes like respiration.
This inefficiency limits the number of trophic levels in an ecosystem because the energy available decreases with each step up the food chain.
Food Chains and Food Webs
A food chain is a linear sequence of organisms through which energy flows. For example, a simple food chain might be: grass → rabbit → fox.
Food webs are more complex, consisting of multiple interconnected food chains within an ecosystem. They illustrate how different species are interdependent and how energy flows through a community in multiple directions.
Decomposers
Decomposers (like bacteria and fungi) play a vital role in energy flow. They break down dead organisms and waste products, returning nutrients to the environment and releasing energy in the process. This energy is then available for producers to use, thus continuing the cycle.
Energy Pyramids
Energy pyramids visually represent the amount of energy at each trophic level. The broad base of the pyramid represents the large amount of energy available at the producer level, and the pyramid narrows as energy decreases at higher trophic levels.
Carbon Cycling in Ecosystems
The carbon cycle is a fundamental process in ecosystems, describing how carbon atoms move between the Earth's atmosphere, hydrosphere, lithosphere, and biosphere. Here’s an explanation:
Carbon in the Atmosphere
Carbon dioxide (CO₂) is the primary form of carbon in the atmosphere. It enters ecosystems primarily through the process of photosynthesis, where plants, algae, and some bacteria absorb CO₂ and convert it into organic molecules like glucose.
Photosynthesis and Carbon Fixation
Photosynthesis is the process by which producers (plants, algae) use sunlight to convert CO₂ and water into glucose (a form of stored chemical energy) and oxygen. This process removes carbon from the atmosphere and incorporates it into the bodies of producers, forming the base of the food web.
Respiration
Respiration occurs in both producers and consumers. As organisms break down glucose for energy, they release CO₂ back into the atmosphere as a byproduct. This process happens continuously in plants (even at night) and in animals, fungi, and microorganisms.
Feeding and Carbon Transfer
When animals eat plants (or other animals), they incorporate the carbon from those organisms into their own bodies. This carbon can be stored in their tissues, used for energy, or released back into the environment through respiration or waste products.
Decomposition
When plants, animals, and other organisms die, decomposers like bacteria and fungi break down their bodies, releasing carbon back into the atmosphere as CO₂ through respiration. Some carbon may also be stored in the soil as organic matter, contributing to long-term carbon storage.
Carbon Sequestration and Storage
Some carbon is sequestered in long-term storage forms, such as:
Fossil Fuels: Over millions of years, dead plant and animal matter can be converted into coal, oil, or natural gas under pressure and heat. This carbon remains trapped until it is released by human activities, such as burning fossil fuels.
Oceans: The oceans absorb a large amount of CO₂ from the atmosphere. Marine organisms use some of this carbon to form shells and skeletons, which can eventually form sedimentary rocks like limestone.
Forests: Trees and plants store carbon in their biomass for long periods, making forests significant carbon sinks.
Human Impact on the Carbon Cycle
Human activities, such as burning fossil fuels, deforestation, and industrial processes, have significantly increased the amount of CO₂ in the atmosphere. This excess carbon contributes to the greenhouse effect and global warming, leading to climate change.
Population Ecology
Population ecology focuses on the study of populations, particularly how they interact with the environment and factors that influence their growth, structure, and distribution. Here’s a breakdown of key concepts:
Population Size and Density
Population size refers to the total number of individuals within a defined area. Population density is the number of individuals per unit area or volume. Both are important metrics for understanding the health and dynamics of a population.
Populations can fluctuate in size due to various factors like availability of resources, predation, disease, and environmental conditions.
Population Growth
Exponential Growth: When resources are abundant, populations can grow rapidly in an exponential manner, where the population size doubles at a consistent rate. This type of growth is often depicted as a J-shaped curve. It is more common in environments with abundant resources and little competition.
Logistic Growth: As resources become limited, population growth slows and eventually stabilises at the carrying capacity of the environment. This is depicted as an S-shaped curve, where the population size levels off at the carrying capacity (the maximum population size that the environment can sustain indefinitely).
Carrying Capacity (K)
The carrying capacity is the maximum number of individuals of a species that an environment can support indefinitely without degrading the environment. When a population reaches this capacity, growth slows down due to factors like limited food, space, and other resources.
Factors Affecting Population Size
Density-Dependent Factors: These factors have a stronger effect as the population density increases. Examples include competition for resources, predation, disease, and waste accumulation. As the population grows, these factors increase in severity, often slowing population growth.
Density-Independent Factors: These factors affect population size regardless of density. Examples include natural disasters (like floods, fires, and hurricanes), climate changes, and human activities (such as deforestation or pollution). These factors can cause sudden and dramatic changes in population size.
Population Dynamics
Birth Rate and Death Rate: The rates at which individuals are born and die within a population are crucial for understanding its growth. A population grows when the birth rate exceeds the death rate, and it declines when the death rate exceeds the birth rate.
Immigration and Emigration: The movement of individuals into (immigration) and out of (emigration) a population also affects population size and structure. Immigration adds individuals to a population, while emigration removes them.
Age Structure: The distribution of individuals among different age groups in a population affects its growth. A population with a large proportion of young individuals is likely to grow faster than one with a larger proportion of older individuals.
Population Regulation
Negative Feedback Mechanisms: These help regulate population size by increasing the mortality rate or reducing the birth rate as the population approaches the carrying capacity. Examples include resource limitation, territoriality, and increased predation.
Positive Feedback Mechanisms: Sometimes, populations can experience positive feedback, where increased population density can lead to even faster growth, such as in cases where a larger population improves the chances of finding mates.
Population Interactions
Predation: Predators can control the population size of prey species, preventing them from exceeding the carrying capacity of their environment.
Competition: When two or more species compete for the same resources, it can limit population growth for all competing species.
Symbiosis: Relationships such as mutualism, commensalism, and parasitism also affect population sizes and dynamics.
Application in Conservation and Management
Understanding population ecology is essential for wildlife conservation, pest control, and the management of natural resources. By studying population dynamics, scientists and resource managers can predict changes in populations and develop strategies to protect endangered species or control invasive species.
Nitrogen and Phosphorus Cycles
The nitrogen and phosphorus cycles are essential biogeochemical processes that recycle nutrients in ecosystems, ensuring the availability of these elements for living organisms. Here’s an explanation of each cycle:
Nitrogen Cycle
The nitrogen cycle is crucial because nitrogen is a key component of proteins, DNA, and other biological molecules. Although nitrogen gas (N₂) makes up about 78% of the Earth's atmosphere, most organisms cannot use it in this form. The nitrogen cycle converts nitrogen into forms that can be used by plants and animals.
Nitrogen Fixation
Nitrogen fixation is the process of converting nitrogen gas (N₂) from the atmosphere into ammonia (NH₃) or related compounds, which plants can absorb. This can occur through:
Biological Fixation: Certain bacteria, such as those in the roots of legumes (e.g., Rhizobium), convert N₂ into ammonia.
Industrial Fixation: The Haber-Bosch process synthesises ammonia from nitrogen gas and hydrogen for use in fertilisers.
Lightning: High-energy lightning can break nitrogen bonds, allowing it to combine with oxygen to form nitrogen oxides, which dissolve in rain and enter the soil.
Nitrification
Nitrification is the conversion of ammonia into nitrites (NO₂⁻) and then into nitrates (NO₃⁻) by nitrifying bacteria. Nitrates are the form of nitrogen most easily absorbed by plants.
Assimilation
Assimilation occurs when plants absorb nitrates or ammonium (NH₄⁺) from the soil and incorporate the nitrogen into organic molecules like amino acids and proteins. Animals obtain nitrogen by consuming plants or other animals.
Ammonification
Ammonification is the process by which decomposing bacteria and fungi convert organic nitrogen (from dead organisms and waste products) back into ammonia, which can then be reused by plants or undergo nitrification.
Denitrification
Denitrification is the process by which bacteria convert nitrates back into nitrogen gas (N₂), which is released into the atmosphere. This process closes the nitrogen cycle and prevents the excessive accumulation of nitrogen in ecosystems.
Phosphorus Cycle
The phosphorus cycle is vital because phosphorus is a component of DNA, RNA, ATP (energy molecules), and cell membranes. Unlike nitrogen, phosphorus does not have a gaseous form and is mainly found in rocks, soil, and water.
Weathering of Rocks
Phosphorus is primarily found in rocks as phosphate ions (PO₄³⁻). Through the process of weathering, rocks break down, releasing phosphates into the soil and water. This process is slow and makes phosphorus one of the limiting nutrients in many ecosystems.
Absorption by Plants
Plants absorb phosphate ions from the soil, which they use to build essential molecules like nucleic acids (DNA and RNA) and ATP. This phosphorus is then passed through the food chain as animals consume plants and other animals.
Decomposition
When plants and animals die, decomposers like bacteria and fungi break down their bodies, releasing phosphorus back into the soil in the form of phosphate ions. This phosphorus can then be reused by plants, continuing the cycle.
Sedimentation
In aquatic environments, phosphorus can settle into sediments at the bottom of bodies of water. Over long periods, these sediments can form new rocks, completing the cycle as geological processes eventually bring these rocks to the surface, where they weather and release phosphorus again.
Human Impact on the Nitrogen and Phosphorus Cycles
Human activities, such as the use of synthetic fertilisers, agriculture, and industrial processes, have significantly altered the nitrogen and phosphorus cycles. For example:
Nitrogen Cycle: Excessive use of nitrogen-based fertilisers can lead to nutrient runoff into water bodies, causing eutrophication (over-enrichment of water with nutrients), which leads to algal blooms and dead zones (areas with very low oxygen levels).
Phosphorus Cycle: Similarly, overuse of phosphorus-containing fertilisers and detergents can lead to eutrophication, which has harmful effects on aquatic ecosystems.
IB Biology - Ecology
Species
A species is a group of organisms that can interbreed and produce fertile offspring. Each species is genetically distinct from others and occupies a specific ecological niche, which is its role in the environment, including how it gets its energy and nutrients, and how it interacts with other species.
Communities
A community is composed of all the different species living together in a particular area at the same time. These species interact with one another in various ways, such as through competition, predation, and mutualism.
Communities are dynamic and can change over time due to various factors, including environmental changes, species migration, and natural selection.
Ecosystems
An ecosystem includes both the living (biotic) components, like species and communities, and the non-living (abiotic) components, such as climate, soil, water, and nutrients.
Ecosystems can vary in size from a small pond to a large forest and are characterised by the flow of energy (through food chains and webs) and the cycling of nutrients (like carbon and nitrogen) between organisms and their environment.
Species Interactions within Ecosystems
Types of Species Interactions:
Competition: Occurs when two or more species vie for the same resources, such as food, light, or space. This can lead to competitive exclusion, where one species outcompetes another, potentially driving it to extinction in that area.
Predation: Involves one species (the predator) hunting and consuming another (the prey). This interaction regulates prey populations and can drive evolutionary adaptations, such as camouflage or speed.
Mutualism: A cooperative interaction where both species benefit. For example, bees pollinate flowers while feeding on nectar, aiding in plant reproduction.
Commensalism: One species benefits while the other is neither helped nor harmed. An example is barnacles attaching to whales; the barnacles get a free ride to nutrient-rich waters without affecting the whale.
Parasitism: One species (the parasite) benefits at the expense of another (the host), often causing harm but not immediate death. Examples include ticks feeding on mammals.
Factors Shaping Community Structures:
Environmental Factors: Climate, availability of resources, and physical features like topography influence which species can survive in an ecosystem.
Biotic Factors: The presence and interactions of other organisms, such as the availability of prey for predators or the competition for resources, shape community structure.
Disturbances: Events like fires, floods, or human activities can drastically alter communities by removing dominant species and allowing new species to colonise the area.
Succession: Over time, ecosystems undergo changes through ecological succession, where species composition gradually changes, leading to a more stable community.
Energy Flow in Ecosystems
Energy flow is a crucial concept in ecology, focusing on how energy moves through an ecosystem from one organism to another. Here’s a detailed explanation:
Source of Energy
The primary source of energy for most ecosystems is the sun. Solar energy is captured by producers (mainly plants, algae, and some bacteria) through photosynthesis. These producers convert solar energy into chemical energy in the form of glucose, which can be used by themselves and other organisms.
Trophic Levels
Trophic levels represent the different stages in the flow of energy:
Producers (Trophic Level 1): Plants and other photosynthetic organisms that convert solar energy into chemical energy.
Primary Consumers (Trophic Level 2): Herbivores that consume producers and obtain energy from them.
Secondary Consumers (Trophic Level 3): Carnivores that eat herbivores.
Tertiary Consumers (Trophic Level 4): Top predators that consume other carnivores.
At each trophic level, energy is transferred from one organism to another when one organism eats another.
Energy Transfer Efficiency
Energy transfer between trophic levels is inefficient. Typically, only about 10% of the energy from one trophic level is passed on to the next. The remaining 90% is lost, mainly as heat due to metabolic processes like respiration.
This inefficiency limits the number of trophic levels in an ecosystem because the energy available decreases with each step up the food chain.
Food Chains and Food Webs
A food chain is a linear sequence of organisms through which energy flows. For example, a simple food chain might be: grass → rabbit → fox.
Food webs are more complex, consisting of multiple interconnected food chains within an ecosystem. They illustrate how different species are interdependent and how energy flows through a community in multiple directions.
Decomposers
Decomposers (like bacteria and fungi) play a vital role in energy flow. They break down dead organisms and waste products, returning nutrients to the environment and releasing energy in the process. This energy is then available for producers to use, thus continuing the cycle.
Energy Pyramids
Energy pyramids visually represent the amount of energy at each trophic level. The broad base of the pyramid represents the large amount of energy available at the producer level, and the pyramid narrows as energy decreases at higher trophic levels.
Carbon Cycling in Ecosystems
The carbon cycle is a fundamental process in ecosystems, describing how carbon atoms move between the Earth's atmosphere, hydrosphere, lithosphere, and biosphere. Here’s an explanation:
Carbon in the Atmosphere
Carbon dioxide (CO₂) is the primary form of carbon in the atmosphere. It enters ecosystems primarily through the process of photosynthesis, where plants, algae, and some bacteria absorb CO₂ and convert it into organic molecules like glucose.
Photosynthesis and Carbon Fixation
Photosynthesis is the process by which producers (plants, algae) use sunlight to convert CO₂ and water into glucose (a form of stored chemical energy) and oxygen. This process removes carbon from the atmosphere and incorporates it into the bodies of producers, forming the base of the food web.
Respiration
Respiration occurs in both producers and consumers. As organisms break down glucose for energy, they release CO₂ back into the atmosphere as a byproduct. This process happens continuously in plants (even at night) and in animals, fungi, and microorganisms.
Feeding and Carbon Transfer
When animals eat plants (or other animals), they incorporate the carbon from those organisms into their own bodies. This carbon can be stored in their tissues, used for energy, or released back into the environment through respiration or waste products.
Decomposition
When plants, animals, and other organisms die, decomposers like bacteria and fungi break down their bodies, releasing carbon back into the atmosphere as CO₂ through respiration. Some carbon may also be stored in the soil as organic matter, contributing to long-term carbon storage.
Carbon Sequestration and Storage
Some carbon is sequestered in long-term storage forms, such as:
Fossil Fuels: Over millions of years, dead plant and animal matter can be converted into coal, oil, or natural gas under pressure and heat. This carbon remains trapped until it is released by human activities, such as burning fossil fuels.
Oceans: The oceans absorb a large amount of CO₂ from the atmosphere. Marine organisms use some of this carbon to form shells and skeletons, which can eventually form sedimentary rocks like limestone.
Forests: Trees and plants store carbon in their biomass for long periods, making forests significant carbon sinks.
Human Impact on the Carbon Cycle
Human activities, such as burning fossil fuels, deforestation, and industrial processes, have significantly increased the amount of CO₂ in the atmosphere. This excess carbon contributes to the greenhouse effect and global warming, leading to climate change.
Population Ecology
Population ecology focuses on the study of populations, particularly how they interact with the environment and factors that influence their growth, structure, and distribution. Here’s a breakdown of key concepts:
Population Size and Density
Population size refers to the total number of individuals within a defined area. Population density is the number of individuals per unit area or volume. Both are important metrics for understanding the health and dynamics of a population.
Populations can fluctuate in size due to various factors like availability of resources, predation, disease, and environmental conditions.
Population Growth
Exponential Growth: When resources are abundant, populations can grow rapidly in an exponential manner, where the population size doubles at a consistent rate. This type of growth is often depicted as a J-shaped curve. It is more common in environments with abundant resources and little competition.
Logistic Growth: As resources become limited, population growth slows and eventually stabilises at the carrying capacity of the environment. This is depicted as an S-shaped curve, where the population size levels off at the carrying capacity (the maximum population size that the environment can sustain indefinitely).
Carrying Capacity (K)
The carrying capacity is the maximum number of individuals of a species that an environment can support indefinitely without degrading the environment. When a population reaches this capacity, growth slows down due to factors like limited food, space, and other resources.
Factors Affecting Population Size
Density-Dependent Factors: These factors have a stronger effect as the population density increases. Examples include competition for resources, predation, disease, and waste accumulation. As the population grows, these factors increase in severity, often slowing population growth.
Density-Independent Factors: These factors affect population size regardless of density. Examples include natural disasters (like floods, fires, and hurricanes), climate changes, and human activities (such as deforestation or pollution). These factors can cause sudden and dramatic changes in population size.
Population Dynamics
Birth Rate and Death Rate: The rates at which individuals are born and die within a population are crucial for understanding its growth. A population grows when the birth rate exceeds the death rate, and it declines when the death rate exceeds the birth rate.
Immigration and Emigration: The movement of individuals into (immigration) and out of (emigration) a population also affects population size and structure. Immigration adds individuals to a population, while emigration removes them.
Age Structure: The distribution of individuals among different age groups in a population affects its growth. A population with a large proportion of young individuals is likely to grow faster than one with a larger proportion of older individuals.
Population Regulation
Negative Feedback Mechanisms: These help regulate population size by increasing the mortality rate or reducing the birth rate as the population approaches the carrying capacity. Examples include resource limitation, territoriality, and increased predation.
Positive Feedback Mechanisms: Sometimes, populations can experience positive feedback, where increased population density can lead to even faster growth, such as in cases where a larger population improves the chances of finding mates.
Population Interactions
Predation: Predators can control the population size of prey species, preventing them from exceeding the carrying capacity of their environment.
Competition: When two or more species compete for the same resources, it can limit population growth for all competing species.
Symbiosis: Relationships such as mutualism, commensalism, and parasitism also affect population sizes and dynamics.
Application in Conservation and Management
Understanding population ecology is essential for wildlife conservation, pest control, and the management of natural resources. By studying population dynamics, scientists and resource managers can predict changes in populations and develop strategies to protect endangered species or control invasive species.
Nitrogen and Phosphorus Cycles
The nitrogen and phosphorus cycles are essential biogeochemical processes that recycle nutrients in ecosystems, ensuring the availability of these elements for living organisms. Here’s an explanation of each cycle:
Nitrogen Cycle
The nitrogen cycle is crucial because nitrogen is a key component of proteins, DNA, and other biological molecules. Although nitrogen gas (N₂) makes up about 78% of the Earth's atmosphere, most organisms cannot use it in this form. The nitrogen cycle converts nitrogen into forms that can be used by plants and animals.
Nitrogen Fixation
Nitrogen fixation is the process of converting nitrogen gas (N₂) from the atmosphere into ammonia (NH₃) or related compounds, which plants can absorb. This can occur through:
Biological Fixation: Certain bacteria, such as those in the roots of legumes (e.g., Rhizobium), convert N₂ into ammonia.
Industrial Fixation: The Haber-Bosch process synthesises ammonia from nitrogen gas and hydrogen for use in fertilisers.
Lightning: High-energy lightning can break nitrogen bonds, allowing it to combine with oxygen to form nitrogen oxides, which dissolve in rain and enter the soil.
Nitrification
Nitrification is the conversion of ammonia into nitrites (NO₂⁻) and then into nitrates (NO₃⁻) by nitrifying bacteria. Nitrates are the form of nitrogen most easily absorbed by plants.
Assimilation
Assimilation occurs when plants absorb nitrates or ammonium (NH₄⁺) from the soil and incorporate the nitrogen into organic molecules like amino acids and proteins. Animals obtain nitrogen by consuming plants or other animals.
Ammonification
Ammonification is the process by which decomposing bacteria and fungi convert organic nitrogen (from dead organisms and waste products) back into ammonia, which can then be reused by plants or undergo nitrification.
Denitrification
Denitrification is the process by which bacteria convert nitrates back into nitrogen gas (N₂), which is released into the atmosphere. This process closes the nitrogen cycle and prevents the excessive accumulation of nitrogen in ecosystems.
Phosphorus Cycle
The phosphorus cycle is vital because phosphorus is a component of DNA, RNA, ATP (energy molecules), and cell membranes. Unlike nitrogen, phosphorus does not have a gaseous form and is mainly found in rocks, soil, and water.
Weathering of Rocks
Phosphorus is primarily found in rocks as phosphate ions (PO₄³⁻). Through the process of weathering, rocks break down, releasing phosphates into the soil and water. This process is slow and makes phosphorus one of the limiting nutrients in many ecosystems.
Absorption by Plants
Plants absorb phosphate ions from the soil, which they use to build essential molecules like nucleic acids (DNA and RNA) and ATP. This phosphorus is then passed through the food chain as animals consume plants and other animals.
Decomposition
When plants and animals die, decomposers like bacteria and fungi break down their bodies, releasing phosphorus back into the soil in the form of phosphate ions. This phosphorus can then be reused by plants, continuing the cycle.
Sedimentation
In aquatic environments, phosphorus can settle into sediments at the bottom of bodies of water. Over long periods, these sediments can form new rocks, completing the cycle as geological processes eventually bring these rocks to the surface, where they weather and release phosphorus again.
Human Impact on the Nitrogen and Phosphorus Cycles
Human activities, such as the use of synthetic fertilisers, agriculture, and industrial processes, have significantly altered the nitrogen and phosphorus cycles. For example:
Nitrogen Cycle: Excessive use of nitrogen-based fertilisers can lead to nutrient runoff into water bodies, causing eutrophication (over-enrichment of water with nutrients), which leads to algal blooms and dead zones (areas with very low oxygen levels).
Phosphorus Cycle: Similarly, overuse of phosphorus-containing fertilisers and detergents can lead to eutrophication, which has harmful effects on aquatic ecosystems.
