Environmental issues: Threats to Biodiversity

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In the previous post, we have discussed the importance of conserving biodiversity. To be able to successfully do that, we have to understand and identify the threats to biodiversity.

There are several major threats to biodiversity. These include habitat loss, introduction of invasive species, over harvesting, climate change and pollution.

1. Habitat loss
This happens when an area is changed dramatically that it is no longer able to support species it once sustained[2].

Loss of habitat is usually caused by alterations by humans to meet their needs. This can be clearing forest areas to make way for agriculture or urban development. Mining and logging for use in constructions is also an example of habitat loss caused by humans. These activities can lead to species extinction as resources also needed by species living in that area is removed[1].

2. Introduction of invasive species
Invasive species are species not native to an area. Introduction of such species to new areas causes a big threat to native species because often times they do not have predators in the new area. The absence of a predator will mean that the invasive species will be able to reproduce and their population will increase in number overcrowding the habitat. Such increase in number of an invasive species will create ecological imbalance and this will disrupt the community where they will compete with native species for resources. Because of high competition, native species which have natural predators will eventually go extinct[1][3].

 3. Over harvesting
Over harvesting happens when the rate of collection of natural resources exceeds the ability of nature to replenish such resources. Highly susceptible to over harvesting are large organisms with low reproductive rate. Examples are the elephants, whales, and rhinoceros. One cause of over harvesting is the need to feed the growing human population. For example, the increasing demand of protein by humans has lead to over fishing by large fishing companies. To recover from over harvesting, organisms has to be allowed to reproduce for a couple of generations. Thus, recovery will take years[1].

 4. Climate change and Pollution
Climate change happens where there is alteration in the climate, atmospheric chemistry, and broad ecological systems that reduce the capacity of Earth to sustain life. A slow and gradual change in the climate can allow organisms to migrate or move to a better suited habitat. However, the abrupt changes in the climate can cause extinction. Pollution is a major cause of climate change[1]. There are two events that cause climate change: a) Rise in CO2 levels in the atmosphere, and b) Depletion of the ozone layer.

a) Rise of CO2 levels
The rise in CO2 levels results to global warming. This is caused by burning huge amounts of fossil fuels. Large factories, power plants, and most vehicles are examples of sources of CO2. The accumulation of high CO2 in the atmosphere causes increase in temperature which leads to increase in the likelihood of forest fires and melting of ice in the Arctic. In both cases, biodiversity is at risk. Forest fires can cause loss of habitat for small species like insects, as well as birds. The melting of ice in the Arctic also means decrease of habitat for some species like polar bears, seals, and seabirds [1].

The rise in CO2 levels will also cause increased productivity by plants. C3 plants like corn, will increase and spread in habitats that currently favor C4 plants like wheat and soybeans. Therefore, although rise in CO2 levels can increase plant productivity, this can also cause species displacement in plants.

b) Ozone depletion
Ozone (O3) depletion means decreased protection from the damaging ultra violet radiation. The cause of ozone depletion is the accumulation of chloroflourocarbon (CFC). CFC reacts with ozone reducing it to O2.  CFC was used by refrigeration manufacturing in the past [1]. Today, the use of CFC has substantially decreased leading to the gradual restoration of the ozone layer.


 References
[1]Reece, J. B., Urry, L. A., Cain, M. L. 1., Wasserman, S. A., Minorsky, P. V., & Jackson, R. (2011). Campbell biology (Ninth edition.) Pearson Benjamin Cummings
[2] https://www.biodiversitya-z.org/content/habitat-destruction
[3] https://mashable.com/2015/05/23/biodiversity-threats/?europe=true
[4] http://www.biodiv.be/biodiversity/threats

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