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The human species have gone extinct since the beginning of life, but human fingerprint is a useful marker that differentiates current and past extinctions. Environmental factors have been shown to cause human threats with regard to biodiversity (Duffy 440).
Human species are threatened when they come under pressure from different factors in the environment. It has also been shown that some factors act in a synergistic manner to cause combined threats. For example, research was conducted in Ontario to investigate the impact of climate change and acid rain on lakes.
The study found that the two environmental factors acted in a combined way to make water more penetrable by UV. The observation was that the climate change and acid rain removed materials that acted as barriers to UV.
The materials that acted as barriers to UV were identified as organic carbon and other natural products from soils and plants, which protect biological activities of aquatic organisms from the harmful effects of UV (Bradshaw, Sodhi, and Brook 80; Chivian and Bernstein 30).
Habitat loss: On land
Human beings have caused varying degrees of changes on the earth’s surface due to their activities. It is expected that the level of habitat destruction will increase by about 70% in the next few decades (Chivian and Bernstein 34). This causes an alarm because habitat for many organisms will be destroyed in the near future.
Human activities have resulted in varying degrees of deforestation, which has resulted in the loss of habitat for many big and small animals. This has also contributed to disturbances of ecosystems.
Some of the human activities that cause deforestation include tree cutting, selective logging, wood harvesting, and forest fires, among others. Most of the deforested areas do not grow back and are left as land with limited capacity to support diversity.
In the recent past, an increasing number of natural endemics have contributed to significant losses of forest cover on the surface of the earth. It has been asserted that a good understanding of localization of natural endemics will be essential in deciphering recent and future extinctions due to deforestation (Chivian and Bernstein 35).
Habitat loss: In the oceans
Although the level of marine biodiversity has not yet been established, it is widely acknowledged that human beings cause significant impacts on the oceans (Duffy 440). It is evident that about 50% of the total world populations live within a distance of about 60 kilometers from the oceans.
Thus, human activities have caused high levels of water pollution and large scale losses of wetland habitat. Most of the marine biodiversity is found in the tropics, especially coral reefs that support the growth of organisms (Bradshaw et al 83).
In fact, coral reefs support the growth of about 100,000 species of organisms in the oceans. Twenty percent of the world’s coral reefs have already been destroyed by humans. Also, 50% of the remaining coral reefs are at risk of collapse due to increasing human activities around the oceans (Chivian and Bernstein 38).
Habitat loss: Fresh water
Although rivers and lakes cover about 1% of the earth’s surface, they support a considerable amount of biodiversity. For example, freshwater fishes comprise about a quarter of vertebrates found on the earth. Other organisms found in freshwater are crocodiles, turtles, otters, river dolphins and water shrews, among others.
Most of the freshwater species are found mostly in tropical regions, but this is not a universal observation. The extent to which freshwater biodiversity is being destroyed by humans is greater than that of terrestrial and marine systems.
This could be best explained by the Living Planet Index, which estimated the trends of vertebrates from 1970 to 2000. Among the three categories of indices that were studied, freshwater index fell by 50%.
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One reason that has contributed to the destruction of freshwater habitat is that the freshwater is an important resource for human activities. For example, it supports human health, production of food, generation of hydropower, economic growth and development.
It is also essential for many cultures and religions across the world. Overfishing, extraction of water for irrigation, construction of massive engineering systems for water storage and alteration of water flows are some of the activities that have caused destruction of freshwater biodiversity (Chivian and Bernstein 39).
Another important threat to freshwater biodiversity is coal mining. After mining, coal is washed in freshwater systems to remove various forms of impurities so that it could fetch better prices in the market. The process of washing leaves a lot of waste in freshwater systems.
Some of the impurities that cause threat to organisms in freshwater systems are mercury, lead and arsenic, which are all heavy metals characterized by high levels of toxicity.
In order to protect freshwater systems from biodiversity destruction, it would be important to control upstream network, the surrounding land and downstream regions (Chivian and Bernstein 40).
Overexploitation on land
Overexploitation occurs when organisms are harvested at a rate that they cannot maintain their population numbers. Some of the examples of organisms that have become extinct due to overexploitation are the Great Auk and the Passenger Pigeon.
Some of the plant species that have become extinct as a result of overharvesting are Vinca rosea and Prunus africana. Trade in live animals is another form of overexploitation that resulted in the extinction of some animal species.
In fact, income from the world trade in endangered animal species and plants is over $10 billion on an annual basis (Chivian and Bernstein 43; Duffy 440).
The number of nonhuman primates has been on the decrease due to hunting practices that aim at obtaining meat for food from wild animals. Expanding global populations have resulted in high demand for bush meat.
The proliferation of wildlife restaurants across the world will further endanger animal species across the world.
Overharvesting in the oceans
Overexploitation in the oceans is caused by overfishing and fishing practices that cause destruction of biodiversity. The threats are caused by activities such as the use of chemicals that poison organisms in the oceans.
The destruction of coral reefs results in the oceans that have limited capacities of supporting life. Thus, biodiversity and ecosystems in oceans are at risk due to human activities. Some of species of fish that have become extinct due to overfishing are Dugongs, Steller’s Sea Cows, Gray Whales and Atlantic Sturgeon (Chivian and Bernstein 44).
Some human activities have resulted in the introduction of species into new environments. However, some species could be introduced into new environments by other events that are not related to human activities. The species that are moved into new environments could be a threat to the existing organisms.
Some of the species that have caused destruction of biodiversity in new environments are Soybean Rust, P. pachyrhizi, Aspergillus sydowii, Sturnnus vulgaris, Euglandina rosea, Achitina fulica, and Partula turgid (Chivian and Bernstein 50). In the recent past, invasive alien species have received attention by organizations across the world because they cause more harm to biodiversity than non-invasive species.
Bradshaw, Corey JA, Navjot S. Sodhi, and Barry W. Brook. “Tropical turmoil: a biodiversity tragedy in progress.” Frontiers in Ecology and the Environment 7.2 (2008): 79-87. Print.
Chivian, Eric, and Aaron Bernstein, eds. Sustaining life: how human health depends on biodiversity. Oxford University Press, United Kingdom, 2008. Print.
Duffy, J. Emmett. “Why biodiversity is important to the functioning of real-world ecosystems.” Frontiers in Ecology and the Environment 7.8 (2008): 437-444. Print.