Life Cell Science
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Definition of Species Diversity
Imagine chasing a horned lizard, and it uses a bizarre tactic to deter you, squirting blood at you out of its eye. Imagine scuba diving and encountering one of the ugliest fish in the world, called the anglerfish. This is not science fiction; this is real. There are some bizarre creatures that call Earth home. The diversity of creatures roaming Earth is absolutely astounding.
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Species diversity is defined as the number of species and abundance of each species that live in a particular location. The number of species that live in a certain location is called species richness. If you were to measure the species richness of a forest, you might find 20 bird species, 50 plant species, and 10 mammal species. Abundance is the number of individuals of each species. For example, there might be 100 mountain beavers that live in a forest. You can talk about species diversity on a small scale, like a forest, or on a large scale, like the total diversity of species living on Earth.
Species Diversity of Earth
How many species do you think live on Earth? There are approximately 1.8 million different species classified on Earth. Of all the species identified, nearly one million are insects! New species are being discovered each year. Scientists estimate that there may be between 5 to 30 million species that actually live on Earth. Each year, approximately 13,000 more species are added to this growing list of known species. For example, in 2013, a species of a venomous snake called the green palm-pit viper was discovered in the country of Honduras.
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In 2014, a carnivorous mammal species called olinguito was discovered in Colombia and Ecuador. Who knows what weird creature might be discovered this year!
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The hottest spots for species diversity are tropical rainforests. Tropical rainforests comprise only 7% of all land on Earth yet are home to nearly 50% of all the species on Earth! In Costa Rica, there are over 1,400 species of orchids, 1,200 species of butterflies, and 600 species of birds! Interesting species of mammals live here as well, like howler monkeys, jaguars, and sloths.
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Importance of Species Diversity
There are numerous reasons why species diversity is essential. Each species has a role in the ecosystem. For example, bees are the primary pollinators. Imagine what would happen if bees went extinct. Fruits and vegetables could be next, and subsequently, the animals that feed off them - this chain links all the way to humans. Various species provide us not only with food but also contribute to clean water, breathable air, fertile soils, climate stability, pollution absorption, building materials for our homes, prevention of disease outbreaks, medicinal resources, and more. Let's look at some examples.
Species diversity contributes to ecosystem health. Each species is like a thread holding together an ecosystem. If a species disappears, an entire ecosystem can start to unravel. Species diversity is crucial for ecosystem health. For example, in the Pacific Northwest, salmon holds together the entire ecosystem. Salmon carry rich nutrients from the ocean back to the stream environment. When salmon die, those nutrients are gobbled up by insects, plants, mammals, and birds. If salmon were to disappear, the impacts would be felt through the entire food chain.
The Importance of Species Diversity to the Ecosystem
According to the Encyclopedia of Earth, species diversity is a measurement of an ecosystem’s species richness and species evenness. If an ecosystem has poor species diversity, it may not function properly or efficiently. A diverse species assemblage also contributes to ecosystem diversity.
Species Richness
Species Richness
Species richness is the number of different species in an ecosystem. Environments that can support large numbers of species, such as tropical areas, tend to have greater species richness.
Species Evenness
The Encyclopedia of Earth defines species evenness as “the variation in the abundance of individuals per species within a community.” If a community has a large disparity between the number of individuals within each species it has low evenness. If the number of individuals within a species is fairly constant throughout the community it has a high evenness. If community A has 10 individuals divided between two species, but species 1 represents nine individuals, while species 2 has only one, then community A has a low evenness and lower species diversity. If community B has ten individuals divided between two species, with species 1 having four individuals and species 2 having six, then community B has high evenness and higher species diversity. The more even the number of animals per species within an ecosystem, the greater the species diversity.
Ecosystem Efficiency
A study from the University of Maryland suggests that by increasing species diversity in an ecosystem, both the efficiency and the productivity of an ecosystem will increase. The study “increased the [species] richness…such that the feeding success of individuals [was] enhanced.” A greater species richness and diversity may cause ecosystems to function more efficiently and productively by making more resources available for other species within the ecosystem.
Keystone Species
Keystone species play an important role, both in maintaining species diversity and the health of an ecosystem. A keystone species is an organism that helps maintain species diversity within an ecosystem by keeping the numbers of other species in an ecosystem constant. By not allowing one species or another to become overly dominant, a keystone species maintains species diversity and ecosystem integrity. An experiment conducted in 1969 by Robert Paine observed that if a predatory species of starfish was removed from an ecosystem, it allowed two different species of mussels to outcompete the other species in the ecosystem and reduce species diversity.
Invasive Species
An invasive species is a foreign species that is introduced to an ecosystem. The Center for Invasive Species and Ecosystem Health states that “these species grow and reproduce rapidly, causing major disturbances to the areas in which they are present.” Invasive species outcompete other species for food and habitat. Since the indigenous species can’t compete, they either are forced to leave the ecosystem or die out. If an invasive species forces out too many other species, the species diversity will drop, which could cause an ecosystem to function inefficiently or fail.
Difference Between Community & Ecosystem
An ecosystem describes all the living organisms (biotic components) with their physical surroundings (abiotic components) in a given area. A community describes only the living organisms and their interactions with each other.
Abiotic Components of an Ecosystem
The non-living parts of the ecosystem, such as nutrients, temperature and water availability, constitute the abiotic components of an ecosystem.
Biotic Components of an Ecosystem
All the living organisms of an ecosystem, such as plants, animals and microbes, constitute the biotic components of an ecosystem.
Community Interactions
The interactions between populations within an ecosystem are described by the benefit or harm caused to each species in the interaction. These interactions relate to the niche which the species occupies within the ecosystem.
Niche
A niche describes the specific role a population plays within an ecosystem. This may be defined by their interaction with other organisms (such as predator or prey), or in the role they play in nutrient cycling (such as primary producer or decomposer).
Niche and Biodiversity
Ecosystems rich in biodiversity (many different species) tend to have very specialized niches. Low biodiversity results in few species available to fill each niche. Hence, in a rich ecosystem, a loss or reduction of one organism may have a lower impact on the overall ecosystem as other organisms fill the void than in a poor ecosystem, where another population may be unavailable to fulfill that role. For example, if a particular species of prey is reduced in number, it has a reduced effect on predators if there are other prey species available.
Four Types of Biodiversity
Biodiversity is a key measure of the health of any ecosystem, and of our entire planet. Every organism in an ecosystem, or biome, relies on other organisms and the physical environment. For example, plant and animal species need each other for food, and depend on the environment for water and shelter. Biodiversity describes how much variety an ecosystem has, in terms of resources and species, and also genetically within species. A more diverse ecosystem will have more resources to help it recover from famine, drought, disease or even the extinction of a species. There are several levels of biodiversity, each indicating how diverse the genes, species and resources are in a region.
Species Diversity
Every ecosystem contains a unique collection of species, all interacting with each other. Some ecosystems may have many more species than another. In some ecosystems, one species has grown so large that it dominates the natural community. When comparing the biodiversity of ecosystems, an ecosystem that has a large number of species, but no species greatly outnumbering the rest, would be considered to have the most species diversity. A large number of species can help an ecosystem recover from ecological threats, even if some species go extinct.
Genetic Diversity
Genetic diversity describes how closely related the members of one species are in a given ecosystem. In simple terms, if all members have many similar genes, the species has low genetic diversity. Because of their small populations, endangered species may have low genetic diversity due to inbreeding. This can pose a threat to a population if it leads to inheritance of undesirable traits or makes the species more susceptible to disease. Having high genetic diversity helps species adapt to changing environments.
Ecosystem Diversity
A region may have several ecosystems, or it may have one. Wide expanses of oceans or deserts would be examples of regions with low ecological diversity. A mountain area that has lakes, forests and grasslands would have higher biodiversity, in this sense. A region with several ecosystems may be able to provide more resources to help native species survive, especially when one ecosystem is threatened by drought or disease.
Functional Diversity
The way species behave, obtain food and use the natural resources of an ecosystem is known as functional diversity. In general, a species-rich ecosystem is presumed to have high functional diversity, because there are many species with many different behaviors. Understanding an ecosystem’s functional diversity can be useful to ecologists trying to conserve or restore damaged it, because knowing the behaviors and roles of species can point to gaps in a food cycle or ecological niches that are lacking species.
What Are the Causes of Animals Becoming Endangered?
Although natural forces can destroy or strain an animal population, increasingly the activities of man have caused a large numbers of animals to become endangered. Admittedly some animals and plants, especially domesticated ones such as crops, livestock, and pets, have benefited and even flourished from the alterations man has made to the world. However, some animal populations have been placed under tremendous pressure as the result of these changes and, in some cases, the populations are dropping to significantly lower levels. Small populations or organisms with a limited distribution are extremely sensitive to the factors causing endangerment, whether one relies on the ordinary sense of the word or the endangered species definition embodied in federal law.
Loss of Habitat
One of the most significant causes of endangered animals is habitat loss. While habitat may be lost due to natural forces (climate shifts, geologic changes), much of the habitat lost today is due to human activity. The construction of dams, highways, canals, urbanization, and agriculture dramatically affect the inhabitants of native ecosystems. Even when portions of the ecosystem remain intact creating “islands,” the resulting habitat may be too small or too widely dispersed to support a species.
Invasive Species
Invasive species are one of the key biotic reasons for animals being endangered. Many species arriving in a new ecosystem are ill-adapted and quickly die off. However, some species are able to exploit the ecosystem to the detriment of native organisms. Small ecosystems such as those on islands are significantly affected by the introduction of invasive species but even native continental and oceanic populations can be devastated through competition or predation by the invader.
Overexploitation of Resources
Overfishing a particular fish species is an obvious and direct cause for an animal to become endangered. But other organisms within the ecosystem may also be harmed (or benefitted) by the overexploitation of a particular species. For example, concern that the California sea otter was devastating the abalone population led to indiscriminate killing of the sea otters, altering the balance of the biotic competition between several organisms. The reduction of sea otters led to an explosion in the population of sea urchins which grazed upon the hold fasts of kelp. As the kelp broke free of the bottom and washed ashore, organisms that depended on the kelp forests were placed under increased strain.
Pathogens and Disease
The spread of domesticated animals has also spread the diseases associated with them to new areas of the world. In some cases, the diseases infected native populations which had little resistance to the invading pathogen. These diseases may reach epidemic levels in the native population, decimating their numbers.
Environmental Pollution
Pollution in many forms has endangered many animals. Pesticides and other chemicals introduced to an ecosystem may significantly harm untargeted species. For example, DDT used to fight mosquitoes was eventually linked to declines in the reproductive rates of birds. Other forms of pollution such as thermal, light and noise pollution can each reduce survival rates of local animal populations.
Five Levels of the Biosphere
The biosphere consists of all living organisms on Earth, including human beings and other animals, plants and microorganisms, along with the organic matter they produce. The term "biosphere" was coined by Eduard Suess in 1875 but was further refined in the 1920s by Vladimir Vernadsky to denote its current scientific usage. The biosphere has five levels of organizational structure.
Earth's Biomes
The biosphere is divided into regions called biomes. Biomes are the largest of the five organizational levels. Scientists classify biomes into five main types -- aquatic, desert, forest, grassland and tundra. The main reason for classifying the biosphere into biomes is to highlight the importance of physical geography on communities of living organisms. A biome may contain several ecosystems and is defined by the geography, climate and the species native to the region. Factors to determine climate include average temperature, amount of rainfall and humidity. When classifying species, scientists traditionally focus on the types of vegetation native to a particular region.
Ecosystem Characteristics
Ecosystems are the second organizational classification when examining the five levels of the biosphere. An ecosystem contains biotic factors such as animals and plants, and abiotic factors such as oxygen, nitrogen and carbon. Ecosystems are divided based on the interaction and the transfer of energy. Within each ecosystem, energy is consumed, and matter is cycled in the form of chemicals and nutrients among different groups of organisms and their environment. A basic example is that primary producers, such as plants, obtain energy from the sun through photosynthesis. Consumers, such as animals, eat the plants to obtain energy. When the animals die, decomposers eat the bodies and release chemicals that enrich the soil, allowing plants to grow.
Communities of Species
A community is the third level of organization in the biosphere. Multiple populations of species make up a community. Communities share a particular habitat or environment. The communities in a particular location are limited to species that can survive given the region's abiotic factors such as temperature, pH and nutrients found in the air and soil. The communities of species are also limited by biotic factors such as predators and available food sources.
Population Count
A population, the fourth level of the biosphere, includes all members of a single species living in a particular habitat. A population can include thousands of members or only a few hundred members. The addition or removal of a population can affect an entire ecosystem. Indicator species are important groups that scientists use to determine the health of an ecosystem, while the presence of keystone species can result in profound effects for ecosystem as a whole.
At the Base: Organisms
Organisms, the final level of the biosphere, are defined as living creatures that use DNA to replicate. Single organisms are referred to as individuals, while groups of organisms are considered a species. Organisms are usually classified in one of two ways: by their cellular structure or by the way they obtain energy. Cellular structure divides organisms into prokaryotes, with free-floating DNA inside cells without a nuclei, and eukaryotes, whose DNA is contained in cell’s nucleus. Organisms are considered either autotrophs, such as plants, which obtain energy by feeding themselves, and heterotrophs, such as animals, which must consume other organisms to obtain energy.
How to Maintain Biodiversity in the Forest's Ecosystems
Variety in the natural world is an inherent part of its beauty and interest. But it can also be a critical factor in the survival of whole ecosystems. Biodiversity, defined as the variety of species living in an ecosystem as well as the genetic diversity that exists within populations of each species, provides stability to ecosystems, especially when they face changes. Factors that threaten biodiversity must be mitigated to help keep ecosystems and their members intact.
How Biodiversity Promotes Stability
In a forest ecosystem, living members are interdependent, and they are also dependent on abiotic, or nonliving, factors in the environment, such as water, light, temperature, space, topography, soil type, chemicals, nutrients and other factors. If something in an ecosystem changes drastically or rapidly -- for example, if fire sweeps through, if there is a sudden change in weather or if disease breaks out -- the changes could cause the death of many organisms, or even entire species. The resiliency of an ecosystem depends on having a diversity of species with varied adaptations to survive changes and help the ecosystem recover. Fire-hardy plant species will continue to live after a fire and can help keep soils intact and provide food for the surviving animals. Disease-hardy varieties of a species will pass on their genes after an epidemic, helping make the population stronger.
Restricting Exploitation of Forest Resources
Since the organisms in forest ecosystems are interdependent, if one or more species or populations of a species disappears, it can have harmful effects on the rest of the ecosystem. Taking large populations of plant species from forests, such as trees for lumber, can greatly impact the survival of species that depend on trees for food, nesting or cover. Cutting down all mature trees from an old-growth forest can threaten populations of owls or other creatures that require the larger trees for nesting spaces. Even removing old logs or brush can reduce necessary cover that some animals depend on. Over-hunting or trapping carnivores can cause herbivore populations to explode, eventually resulting in a shortage of edible plants for the herbivores and possibly starvation. To help preserve biodiversity in forests, the harvesting and exploitation of forest resources -- old-growth trees, other plants and animals -- must be limited to sustainable levels that will help keep the ecosystem in balance.
Controlling and Preventing Invasive Species
Introduced or invasive species -- non-native organisms, including diseases, that are introduced to an ecosystem from other locations – can greatly disrupt ecosystems by killing, out-competing or even interbreeding with native species. For example, a non-native fungus, chestnut blight, wiped out millions of American chestnut trees after the disease was brought to North America, and the emerald ash borer, an Asian beetle, threatens ash trees across North American. Laws and practices that limit the unnatural dispersal of species to other areas can help reduce loss of biodiversity in forests. In addition, targeted manual removal of invasive species or removal by careful biological controls, such as the mottled water hyacinth weevil, which has had excellent results in controlling water hyacinth, can help give native species populations a chance to recover.
Reducing Pollution
Pollution can damage organisms in a forest and cause loss of biodiversity. Acid rain, caused in part by pollution from coal-burning power plants, has weakened and destroyed many tree species, especially trees in high altitudes such as the Appalachian Mountains of North America. In addition, global warming, intensified by rising levels of carbon dioxide emissions from burning of fossil fuels, has been changing climate patterns and threatening biodiversity in forests. As global temperatures rise and complex changes occur in ecosystems, including changes in precipitation levels and shifts in species' geographic ranges, species adapted to cooler climates suffer and may die off. Reducing the overall “carbon footprint” – the burning of fossil fuels – by reducing energy use and using non-polluting energy sources such as solar, wind and other forms of "clean" energy, can help reduce global warming and help forest species to survive.
Controlling Development
Cutting down forests for development or agricultural purposes obviously reduces their biodiversity. While some forest ecosystems can survive limited development within their boundaries or edges, taking down whole forests or causing their fragmentation can result in the loss of other species. For example, mountain lions, or cougars, require a large habitat range to hunt their prey or corridors between pieces of habitat. Fragmentation of that habitat results in mountain lions infringing on human spaces or having trouble finding mates. In addition, some animals, including northern goshawks, require large stands of mature forest with a closed canopy. And because forests, especially tropical rainforests, absorb large quantities of carbon dioxide from the atmosphere, cutting down large swathes can contribute to global warming, reducing biodiversity worldwide. By keeping as much of a forest system as intact and undisturbed as possible and avoiding "suburban sprawl" -- that is, by centralizing human development, preserving large, undisturbed natural areas around cities and neighborhoods and finding alternatives to destroying tropical rainforests -- habitat loss and fragmentation and the resulting loss of forest biodiversity can be minimized.
How Does Sediment Affect Ecosystems?
No ecosystem is entirely free of sediment. In aquatic environments, its presence can threaten the health of ecosystems. Sediment can cloud the water, which in turn can negatively impact the plants and animals of these places. Also, depending upon the type of sediment, additional issues can also occur. It can have both organic and inorganic sources, whether it is algae floating in the water or suspended particles of soil from an eroded shoreline.
Sediment Contamination
One of the primary negative effects of sediment in the ecosystem concerns the nature of the sediment. Agricultural and urban runoff may contain toxic materials, which can damage or even kill the organisms within an ecosystem. According to the U.S. Environmental Protection Agency (EPA), runoff from farmlands is the main cause of pollution in U.S. waterways. The runoff can include sediment from pesticide and fertilizer applications as well as animal waste and bacteria.
Filter Feeders
Some animal species are especially sensitive to the effects of sediment, with contamination quickly accumulating in animal tissues. Filter feeders such as mussels and clams get food by filtering water through their bodies, making them especially vulnerable to the presence of sediment. Other species such as salmon require clear waters in order to locate their prey. High levels of suspended sediment can interfere with their ability to find food, risking the health of the ecosystem by disrupting the prey-predator relationships.
Wetlands and Water Filtering
Wetlands affect the sediment load in the ecosystem by slowing water flow, which allows suspended particles to drop down to ground level. This filtering action is an important environmental benefit because it removes the sediment from the water. In essence, the sediment, whether it contains contaminants or not, becomes locked into the sediment layer of the wetlands. The effects of the pollutants are then mitigated.
Soil Erosion
One way in which sediment enters an ecosystem is through soil erosion. Water flowing over bare soils will easily dislodge sediment, where it will later be deposited within the environment. Impervious surfaces, such as roads and parking lots, facilitate soil erosion. Without plants to slow it, water flow increases, allowing it to dig deeply into stream banks.
Prevention/Solution
The best way to control the negative environmental effects of sediment is to prevent its introduction into the environment. Planting dense groundcover along stream banks and coastal areas will help keep soils intact and prevent them from washing away. Restoration of wetlands within floodp
What Causes the Extinction of Plants & Animals?
Scientists theorize that the next mass extinction on earth could occur as soon as 2050, according to National Geographic News. Plant and animal species become extinct for different reasons, both natural and man-made. The loss of animal and plant life has negative implications for the survival of the human race. Because of this, it's important to understand what causes plant and animal extinction.
Habitat Loss
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Deforestation and urbanization combine to create two reasons why plants and animals become extinct. Deforestation is leveling forests to harvest the wood or create space for building or agriculture, while urbanization is the turning of once-rural areas into cities. As the human population grows, more and more land has to be cleared and urbanized for living space. This shrinks habitat for animals and plants. Each year, 36 million acres of natural forest is leveled, according to the World Wildlife Fund. The forest provides habitat for 80 percent of the world's species, the group reports.
Global Warming
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Global warming is the ongoing increase in the Earth's atmospheric and ocean temperatures created by the greenhouse effect; a temperature increase of even 1 degree can affect plant and animal life. The report cited by National Geographic News looked at 25 biodiverse areas around the world, such as the Caribbean Basin and the Cape Floristic Region in South Africa, and concluded that current carbon dioxide amounts eventually will double in the areas studied. This could lead to the extinction of 56,000 plant species and 3,700 animal species in those areas alone, the study found.
Exotic Species Introduction
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When animals and plants that are not native to a region are introduced to the ecosystem, they can cause serious damage to the local plants and animals, and potentially contribute to their extinction. Native species must compete with the exotic species for basic needs such as food and water. If the exotic species is more aggressive than the native species, the native species then runs the risk of extinction. The introduction of the Nile perch into the Lake Victoria ecosystem in Africa represents a prime example of this, according to "Causes and Consequences of Species Extinctions," a paper published by Princeton University Press. The Nile perch was introduced to the area in the 1950s and by the 1980s, a population boom of these fish contributed to the extinction of between 200 and 400 native fish species.
Overexploitation
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Overexploitation, also called overharvesting, is the excessive harvesting of an animal or plant species, making it harder for the species to renew its numbers. The Princeton University Press paper points to the Steller’s sea cow, which was discovered in 1741, overexploited, and then became extinct in 1768. Save the Frogs, a frog conservation group, notes that several frog species feel the effects of overharvesting for food, pet and scientific purposes. Fish also fall prey to overexploitation. According to Greenpeace, more than 70 percent of fisheries worldwide are either “fully exploited, over exploited, or significantly depleted.”
lains and other areas will improve water quality by removing suspended sediment from the water.
Limiting Factors of the Freshwater Biome
A biome is large regional area of similar communities characterized by a dominant plant type and vegetative structure. Traditionally, biomes have been used to describe large contiguous geographical regions such as deserts, grasslands, forests, and tundras. However, many researchers also include aquatic systems, marine and freshwater. Aquatic systems are characterized by their water temperature, salinity, dissolved nutrients, wave action, currents, depth and substrate. Limiting factors determine the maximum population of a species a given region can maintain.
Freshwater Biomes
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Freshwater biomes include lakes, ponds, rivers, streams and wetlands. Any area partially covered by water for part of the year constitutes a wetland. Some wetlands, such as cyprus swamps, estuaries, and intertidal zones, could be considered separate biomes. While terrestrial biomes are characterized by a dominant plant or vegetative structure, aquatic systems are determined by the salt content, or salinity, of the water. Freshwater contains less than 1 percent salt.
Limiting Factors Generally
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Limiting factors include any factor that inhibits an increase in population numbers of a species in a given area. A square foot of land or a cubic foot of water can only support so many pounds of an animal. For instance, a pond may be able to support several small alligators, but only one large alligator. Limiting factors determine the carrying capacity of the environment, that is, the maximum population of a species an environment can sustain.
Biotic Limiting Factors
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Biotic limiting factors describe the relationship of living organisms to the maximum population size of a species. These factors include the amount of available food, the number of a species' predators, diseases and parasites. As the population of a species nears its carrying capacity, the number of predators, diseases and parasites increases, while the amount of food available to the species decreases.
Abiotic Limiting Factors
Abiotic limiting factors are factors in the physical world that affect carrying capacity. In the freshwater biomes, limiting factors include salinity, sunlight, temperature, dissolved oxygen, fertilizers and pollutants. Fertilizers flow into the system from yards and farms. The fertilizers contribute to algae growth, the algae remove the dissolved oxygen from the water, and the fish die. In this case, the fertilizer indirectly limits the amount of oxygen available, thus limiting the fish population.
What Limits Exponential Growth of a Population?
In an ideal environment with unlimited resources, population growth would be exponential, as each reproduction cycle produces a larger pool of candidates for the next cycle. In nature, however, there are always limiting factors that cause the growth to level off. These factors are weak when the population is low and become stronger as the population increases, making the population tend toward a stable equilibrium, known as the carrying capacity.
Disease
As the population of a species in an environment increases, communicable diseases become a powerful limiting factor. A thinly distributed population will not transmit disease to as high a percentage of the population as a dense population. Once population density exceeds a certain point, highly communicable and lethal viruses affect a high enough percentage of the population to curtail population growth.
Food Scarcity
The supply of resources, especially food, is a near universal limiting factor of population growth. Every ecosystem has a specific amount of resources that can only sustain population levels of a species to a certain point. Competition and starvation limit the growth of the population beyond this point.
Predation
Every environment also comes with a variety of predators that limit the growth of a population. As a species' population grows exponentially, predators who previously preyed upon other species may begin preying on the more abundant species as a survival strategy. Additionally, overpopulation may result in crowding of an environment, pushing the species outside of its natural habitat into areas where it is more susceptible to predation.
Environmental Factors
Environmental factors such as pollutants and climate extremes also act to limit a population's growth. As a population grows, it expands its range of habitation to avoid overcrowding. This expansion may incur upon areas that have been heavily polluted by humans or deforested by lumber companies, leaving them vulnerable to disease and predation. As the population expands to other environments, it also may encounter less suitable habitats, causing extremes of hot and cold weather to be more lethal than in ideal habitats.