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Pathogens and their Effect on the Ecosystem

Despite common belief, pathogens, microscopic organisms that cause disease, are an essential part of the ecosystem. They get a bad reputation, mainly because they relentlessly kill other organisms. While pathogens can be dangerous if not controlled, they also bring numerous benefits to an ecosystem, which should not be overlooked.

  1. Pathogens

    • Pathogens are disease-causing microorganisms. Pathogens exist as viruses, bacteria, protozoan, fungi, and certain types of microscopic worms. Anything from the common cold to the deadly Ebola virus is caused by a pathogen. Certain pathogens such as bacteria and fungi can be fought with medication. However, virus diseases such as smallpox can only be prevented with a vaccine. Pathogens affect a variety of larger organisms including humans, other animals, trees, and plants.

    Ecosystem

    • An ecosystem is a complex combination of relationships of organism living together in an environment. Ecosystems can exist in all climates, including forests, deserts, and rainforests. The size of an ecosystem can vary from a small area to millions of square acres. Organisms living in an ecosystem are dependent on each other to survive. A sustainable ecosystem is one that is considered healthy, meaning the food chain and populations are balanced.

    Weakening Populations and Pathogens

    • Pathogens exist as part of an ecosystem. If pathogens become too powerful, they can weaken an entire population. An example of an animal pathogen that could negatively affect an ecosystem is avian influenza. Mortality for avian influenza is high--it kills around 95 percent of those infected. An outbreak in 1983 and 1984 in the northeastern United States saw the loss of 17 million domesticated birds. An outbreak of this size has the potential to destroy entire poultry species.

    Balancing Populations

    • Pathogens infect and kill other organisms in the ecosystem every day. This is considered natural, and it can keep a population under control. If a species becomes too dominant in an ecosystem, it can make the ecosystem unsustainable. When this happens, competition for food and living space between rival species no longer exists. One species will have complete dominance over the other. The losing species could become endangered or, even worse, extinct. By affecting all species, pathogens infect and kill local species at an equal rate and maintain competition.

    Altering Relationships

    • The oxpecker bird and the hippopotamus have a mutualistic relationship.

      Pathogens can also change relationships organisms have with each other. When one species is infected by a pathogen outbreak, the species that feeds on it is affected as well because it is losing its food source. Besides affecting feeding, mutualistic relationships can be strained. A mutualistic relationship is one that benefits both species. An example of a mutualistic relationship is the red-billed oxpecker and the hippopotamus. This type of bird will feed on ticks on the hippopotamus. The bird benefits by being able to feed, while the hippopotamus benefits by being freed from pests. A large loss of one species to a pathogen can completely alter, and even destroy, this type of relationship.

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