This PowerPoint helps students to consider the concept of infinity.
How Humans Threaten Wildlife
1. How Humans Threaten Wildlife Use the overview document to go through these slides and make notes. NB Any questions see the slide author by following the overview and student list on moodle L/O To understand the range of ways that humans threaten wildlife.
5. The threat is to tropical animals and fish that are being taken out of their natural environment and habitat for pets and for the entertainment of humans. Many reptiles are trapped alive in their habitats and then sold on as pets. Larger lizards, snakes and crocodiles are valued for their beautiful skin. Also turtles and tortoises are hunted world wide for pets. Normally turtles can survive high losses of their eggs because they live long lives and can reproduce for many years but when too many turtles are removed the size of turtle populations can decline very quickly. Many countries have passed laws to protect the rare species and an international agreement called the convention in international trade in endangered species of Wild fauna and Flora (CITES) effective in 1975 has helped curtail international commerce in threatened reptile species. ( http://encarta.msn.com/encnet/refpages/RefArticle.aspx?refid=761579044&pn=4 ) Parrots have always been popular because of their colours and behaviour and their ability to be trained to speak. Parrots mainly live in the tropical woods of south America, Australia, new Zealand and south-west Asia. But unfortunately this has lead to the decline of parrots in the wild, people take away the birds for make money. Rare parrot collectors are ready to pay huge amounts of money for rare and beautiful parrots, which unfortunately leads to a decline in their natural habitat. Parrots are also sold in black markets illegally where some of them die during their transportation and then the parrots that do eventually reach their own often suffer from inappropriate climatic conditions and lack of proper care. ( http://www.streetdirectory.com/travel_guide/29775/pets/find_out_everything_about_the_parrots_of_the_world.html ) Plants are being taken out of the forest because of people collecting certain and rare plants to look pretty in their homes. Taking out plants from the forests is leading to less plants being in the forest. Also plants are being used for entertainment, people are realising they can make money out of growing certain plants illegally and then exporting them for use by humans for entertainment. Many plants and animals are being transported out of their natural habitats for use by humans as pets or for their own entertainment leading to a decline which could eventually lead to extinction among with other factors such as deforestation. Pets and Entertainment!
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7. For over 1000 years tiger bone has been used in traditional medicine in Asia. It is believed to have an anti-inflammatory effect; it is often used where people are suffering from arthritis. However, tigers now occupy 40 percent less habitat than they did 10 years ago and in the last 50 years alone, three sub-species of tigers have become extinct in Asia. This may be due to one of the many other threats that face tigers; on of the most dangerous threats is poaching to supply the illegal trade in tiger bones. Raising a farmed tiger to maturity is 250 times as expensive as poaching a wild tiger in India; therefore, tigers are poached from the wild to provide a cheaper alternative to legal sources. Traditional Medicine Traditional medicine is the health practices and beliefs that use plant, animal and mineral based medicines, amongst other treatments as a form of healthcare. Body parts from tigers, rhinoceroses, bears, seahorses and other endangered species have been used historically in these treatments and the practise carries on today. http://www.ifaw.org/ifaw_international/join_campaigns/fight_illegal_wildlife_trade/traditional_medicine_a_major_threat_that_few_suspect/index.php http:// en.wikipedia.org/wiki/Traditional_medicine
12. Accidental harm from other activities - Introduced species - Competitors A species is defined as introduced (also known as non-indigenous, alien or exotic) in a certain geographical area, if that area is outside the species' native habitat, and the species has arrived there by human activity. The danger of some introduced species is that they may become competitors with indigenous organisms (plants or animals). This could lead to the native species becoming endangered or extinct if they cannot survive with the competitors, as the competitors may beat the indigenous organisms to food. The competitive exclusion principle, sometimes referred to as “Gause's Law”, states that two species that compete for the exact same resources cannot stably co-exist, and less there is an evolutionary shift of the inferior competitor towards a different ecological niche. CASE STUDY Red Squirrel: Sciurus vulgaris Distribution: Scotland, Wales, Ireland: a few habitats in England. Widespread in rest of Europe. Habitat: Coniferous forests of Scotland and Wales; mixed woodland in England and Ireland. Food: seeds of a wide variety of trees, buds, hoots, flowers, berries, nuts, bark and fungi. Numbers: The British Red Squirrel population is estimated at 30,000 in England, whereas the Grey Squirrel population is estimated at 2 million. In England, the Greys outnumber Reds 66:1. --- Introduced competitor: Grey Squirrel Until the 1940s the red squirrel was quite widespread. It has now disappeared from large areas of Britain and its place has been taken by the grey squirrel. The larger grey squirrel was introduced to this country in the mid-19th century. In reality, however, grey squirrels do not physically fight with red squirrels; so why is it that red squirrels disappear when grey squirrels move into their habitat? Research has shown that the answer may lie in the way each species uses the food available to them. It has already been mentioned that grey squirrels put on a lot more body fat than red squirrels which gives them a better chance of surviving. The larger, more robust grey wins in the competition for food and space and it is now widespread in England and Wales. It is more adaptable than the red squirrel and lives happily in hedgerow trees, parks and gardens as well as large woods and forests. http://www.overthegardengate.net/wildlife/squirrel.asp http://www.ypte.org.uk/animal/squirrel-red-/177
16. Habitat Change – Wetland Drainage – Isobel Scott What is wetland drainage and how does it affect the environment? Wetland drainage involves the human activity of removing water from wetlands. The reasons for this are that many of the wetlands are sources of freshwater, which is very valuable because it does not need large scale treatment to remove the salt. However it causes many problems because often the artificially altered habitats can no longer support the same wildlife. The wetland is abandoned once the water has been drained, leaving open space where there is low biodiversity and cannot be put to any other use, as it is unsuitable for building or agriculture. Case Study – Tollesbury Wick, Maldon, Essex Tollesbury Wick is abundant in its diverse range of wildlife. It is a freshwater grazing marsh, owned and protected by the Essex Wildlife Trust, covering around 600 acres of land. It is home to many species such as hunting hen harriers, short-eared owls, reed bunting, restharrow, golden plover and many more. It is protected by a sea wall supporting grassy slopes which contain many species of grass home to many invertebrates. The sea wall prevents the land from flooding which would destroy the many habitats within the area. Draining water from Tollesbury Wick would result in the loss of many rare species that live in the area. If the smaller species at the bottom of the food chain cannot adapt for survival in the new habitat, this will have consequences to the top of the food chain as a lack of food causes predators to move elsewhere. Because of this, the area is protected to ensure that the public remain aware of the importance of the area. The marina within the wetlands also produces funds, some of which go towards the maintenance of Tollesbury Wick. http://www.essexwt.org.uk/sites/Tollesbury%20Wick.htm The bird shown in the image to the left is of the black-tailed godwit, a European bird that often migrates as far as Australia. It is a new red-list entrant, making it a severely endangered species. Its suitable nesting sites in Europe are declining, mainly as a result of wetland drainage and modern agriculture techniques. Numbers have fallen by 30% in 15 years. This is worrying because similar cases may appear as a result of wetland drainage, therefore causing a reduced biodiversity.
17. Selective Logging Selective logging is the removal of just a few trees from a forest so that there are not huge gaps in the forest canopy. As we all know, clear-cutting logging destroys animals and their habitats but there is a way to carry out logging in forests more sustainably and this is by selective logging. Although chopping down just a few trees sounds good, in fact it still has a large environmental impact as all the surrounding trees often get pulled down in the process. Selective logging has been found to reduce global biodiversity by destroying habitat for primary forest species. The impact of pulling just one tree down on the area. The area with no trees is vulnerable to erosion.
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19. The inability to survive reservoir creation. Reservoir creation results in the decomposition of flooded organic matter and increased rates of mercury methylation. Methylmercury (MeHg), the most toxic form of mercury, accumulates through aquatic food webs. Also when rivers are dammed, habitat is not only drowned at the site, but hydrology and ecology of rivers and hardwood bottomlands downstream can suffer. Reservoirs may capture, in whole or part, floods that are critical to these ecosystems and to the coastal estuaries into which they empty. The Mattaponi River, considered by the Mattaponi Tribe in Virginia to be the place where life begins, will be impacted by a proposed reservoir and dam project that will pump water from the river and could damage its ecosystem. The Mattaponi River flows for 85 miles across the coastal plain of eastern Virginia, before joining the Pamunkey to form the York River. The Cohoke Creek lies between the two rivers and is the site of a dam and associated reservoir proposed by the city of Newport News, Virginia to support the region’s growing demand for water. They propose a pipeline that would take up to 75 million gallons of water a day from the river and store it in a 1500-acre reservoir, to be used by the city. The proposed King William Reservoir would fill over the Cohoke Creek and surrounding wetlands, and reach out to a point 2 1/2; miles west of the Mattaponi Reservation, which lies on the western bank of the Mattaponi River. Supersaturation occurs when air becomes trapped in water spilled over a dam as it hits the pool below, creating turbulence. Because air is comprised of 78% nitrogen, the level of nitrogen dissolved in the water can increase dramatically. The affected water does not lose the excess nitrogen quickly. For fish and other species, supersaturated water can enter tissues. If fish swim from an area supersaturated with nitrogen to a lower pressure area, a condition similar to "the bends" in scuba diving can occur. This effect causes injury and can even cause death to fish. Changing water levels and a lack of streamside vegetation can also lead to increased erosion. For example, the lack of vegetation along the shoreline means that a river or reservoir can start cutting deeply into its banks. This can result in further changes to a riparian zone and the species which it can support. Increases in erosion can also increase the amount of sedimentation behind a dam. When habitat is lost, animals are forced to move to higher ground or other areas where habitat conditions may be less suitable, predators are more abundant, or the territory is already occupied. As an example, ground birds like pheasant and grouse require cover and cannot successfully move to higher, more open, ground.
24. Habitat destruction Expansion of Farmland Case Study: New Zealand http://www.biodiversity.govt.nz/picture/biodiversity/state/destruction.html Habitat loss in New Zealand has been caused by whole ecosystems being converted into farmland, exotic forests and settlements. After humans arrived, large areas of New Zealand forest were destroyed by fire. Some fires occurred naturally (started by lightning strikes, for example), or were caused by humans hunting food or clearing land. After the the Treaty of Waitangi was signed in 1840, a flood of European settlers arrived. Half New Zealand’s remaining forest had been converted to farmland and towns by 1920, and many more plants and animals had been introduced, some of which displaced or preyed on native species. Most of New Zealand’s lowland forests, wetlands, dunes and estuaries have been converted into pasture or towns. Many lakes, rivers and streams have been modified by dams, drainage and irrigation schemes and by pollution from farms and urban areas. The increased area of farmland has increased the effect of pollution on lakes and rivers. Expanding farmland, most commonly in the countryside, means destroying the surrounding area leading to a loss of habitat and biodiversity. Farming and logging have severely disturbed at least 94% of temperate broadleaf forests; many old growth forest stands have lost more than 98% of their previous area because of human activities. An increase in the area of agriculture may often cause environmental problems because it changes natural environments and produces harmful by-products. Agriculture can also cause a decrease in biodiversity and the consolidation of diverse biomass into a few species. Intensive agriculture can create a surplus of nitrogen and phosphorus in rivers and lakes. Herbicides, fungicides, insecticides, and other biocides can hurt the environment. As well, natural ecosystems of all types are converted into arable land. Agriculture can also cause soil erosion, deforestation, and the depletion of minerals in the soil. When a habitat is destroyed, the plants, animals, and other organisms that occupied the habitat have a reduced carrying capacity so that populations decline and extinction becomes more likely.The single greatest threat to species worldwide is the loss of habitat. [
