Extinction In Marine Life

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When new species evolve, older species vanish when they encounter the condition to which they cannot adapt. Currently, more than 95 percent of all organisms that have lived on earth are extinct. This illustrates that extinction is a very important evolutionary process which is only slightly less common than speciation. It opens up the planet for new lifeforms to emerge when dominating species fade away. Extinction is an on-going process and occurs on an uncorrelated manner at very low rates. ‘The fossil record shows that the background extinction rate for marine life is 0.1-1 extinctions per million species per year; for mammals it is 0.2-0.5 extinctions per million species per year’ (Rockström, 2009 p. 473). However, when the rates of extinction…show more content…
Although it is still doubtable whether there is a mass extinction happening right now or not, many scientists are already convinced and have facts that prove their point. A leading expert from Harvard ‘speculated that the human presence in the last 12 millennia produced an average extinction of one species every 20 minutes’ (Pievani, 2013 p.90). We are currently destroying the book of life before reading it, as many species have not even been classified before they went extinct Also, when looking at the time lapses between the mass extinction periods, it is remarkable that the time between to mass extinction events is slightly the same each time. Using simple calculations, it appears to be highly likely that a mass extinction will happen around the time period in which we are living now. The unusual high rates of extinction also indicate a possible mass extinction. However, most mass extinctions that have happened before were caused by sudden catastrophes, while this mass extinction event seems to be more gradual. This does not add to the evidence of today’s mass extinction, but on the other hand, it could be explained by the fact that humans has been using an extremely high amount of fossil fuels over a relatively short period of time, which could have led to a sudden change in the atmosphere, the enhanced greenhouse effect. Moreover, human activities…show more content…
For instance, the global temperature has rising, the oceanic organic productivity has increased and the weathering of silicate rocks has been more than before over the past few decades. However, not only these conditions causing anoxic events are a problem for planet earth, the consequences of anoxic events are even worse. In extreme cases, anoxic events can lead to mass extinctions of marine organisms because there is less oxygen in the oceans. Furthermore, anoxic events also allow algae and bacteria to grow on the upper layers of the ocean, forming a shield on the ocean which blocks sunlight. As the sunlight would not be able to reach the deeper zones of the oceans anymore, marine plants cannot survive as photosynthesis is not possible without the energy from sunlight. This does not only cause the extinction of these flora, but also the fauna that feeds from these plants. Moreover, in the case of euxinia, the anoxic events might even have led to the poisoning of plants and animals. The hydrogen sulphide could rise to the upper atmosphere and cause ozone depletion, which then again leads to an increase of UV radiation that amplifies the destruction of plant and animal life (Ward, 2006 p. 70). On the other hand, there might be a small advantage from these anoxic conditions which could be economically beneficial. These conditions namely helped produce most of the world’s petroleum and natural gas

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