In act like a balance. However, one

In this lesson you will learn about two ways humans contribute to species extinction. We break up habitats by building roads and clearing land, and we pollute both land and water. You will also learn about the specific terms used to describe the processes, habitat fragmentation and anthropogenic pollution.

Human Impacts

Ecosystems function quite well when left alone; they act like a balance. However, one small change to an ecosystem disturbs that balance, and humans are typically directly responsible for those changes. Due to practices such as destroying habitats for room to build and clearing land for crops and roads, as well as polluting the environment, humans are responsible for hundreds of species’ extinctions (extinctions means ‘ceasing to exist’).

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When humans alter the environment, there are consequences for the animals and plants that utilize that particular environment. When we break an ecosystem into smaller chunks by building structures or roads, this is termed ‘habitat fragmentation‘ (fragmentation means to break into smaller chunks). When building, humans also inevitably pollute the environment as well. The term used to describe pollution that is caused by humans is ‘anthropogenic.’

Habitat Fragmentation

When habitats are fragmented, the animals and plants in that habitat must in essence, relearn how to survive. Food resources that were once there may be gone, or their homes may have been destroyed. In some cases, the areas where young were once hatched or raised may be gone.

This may cause many species to die off quickly, affecting the biodiversity, or variation of life, in a given habitat. Recall that ecosystems act like a balance. So, what happens when the scales are tipped in one direction or another?Let’s look at an example where a road and buildings were built in the middle of a forest. Before the habitat was fragmented, there were plants which fed several herbivores, or animals which only eat plants, such as deer and elk.

These large animals in turn fed the carnivores, or animals which consume meat, such as wolves and mountain lions. With the destruction of many of the plant species, the herbivores start to die off because they don’t have enough food. This causes the carnivores to die off because there aren’t enough herbivores to sustain their population numbers.

Within several months, this habitat is considered dead, as the animals which once lived within it are now gone.

Anthropogenic Pollution

The majority of pollution we see on a daily basis is the direct result of humans, and human actions contribute to pollution both on land and in water. Burning of non-renewable resources, or resources which are not easily regenerated, such as fossil fuels (oil), and throwing massive amounts of garbage into landfills are ways in which humans alter the atmosphere and land. Run-off from farms, which is filled with fertilizer, drastically changes both fresh and oceanic waters, which has direct implications for organisms which live in the water.So how do these processes affect ecosystems? If we follow run-off from an agricultural farm to the ocean, we see that sediments from that farm are carried into the water, as well as fertilizers.

The sediments block sunlight and inhibit the growth of organisms, which photosynthesize, or get their energy from the sunlight, such as corals and algae. These animals and plants provide food for grazing fish, which in turn provide food for larger predators, such as barracuda and sharks.The fertilizers input nutrients into the waters, and while this may seem like a good thing, these nutrients cause blooms of algae, which are considered harmful. Red tide is a harmful algal bloom which affects fish and filter feeders, such as clams and oysters. In fact, if humans were to eat an animal which had ingested some of this harmful algae, it would make us extremely sick!

How Do We Help?

While humans are the direct cause of many organism extinctions, we can also help prevent future extinctions by becoming aware of how humans impact the environments around us. While it is impossible to prevent any future roads and buildings from being constructed, we can make an effort to conserve habitats which are home to currently endangered, or in danger of becoming extinct, species.Reducing our fossil fuel consumption by using renewable energy sources, or easily regenerated sources of energy, such as solar power and wind power, and keeping our cars in good condition are ways to decrease emission output into the atmosphere.

Practicing the credo ‘reduce, re-use and recycle’ can also help decrease the amount of waste which goes into landfills.

Lesson Summary

Humans are directly responsible for the majority of animal and plant extinctions today. We clear land for agricultural use, as well as buildings and roads. By fragmenting, or breaking up established habitats, we force the organisms in an ecosystem to ‘relearn’ how to survive. In some cases, this is impossible and the organisms go extinct.

Anthropogenic, or human-caused pollution, is another factor which contributes to organism endangerment and extinction. Burning of non-renewable resources, such as fossil fuels, throwing garbage into landfills and introducing fertilizer into bodies of water all contribute to the alteration of ecosystems and eventual organism extinction, where these organisms no longer exist. We can try to prevent animal and plant extinctions by conserving established habitats, reducing fossil fuel consumption and recycling.

Learning Outcomes

When this video lesson is over, you should be able to:

  • Name the two ways humans contribute to species extinction
  • Summarize how habitat fragmentation can lead to species extinction
  • Explain how the different types of pollution caused by humans contribute to species extinction
  • List some steps we can take to reduce future extinctions
  • Define extinctions, habitat fragmentation, anthropogenic, biodiversity, red tide, renewable and non-renewable resources, photosynthesize and endangered
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