BIO-120 Chapter 37 Conservation Biology & Biodiversity PDF

Chapter 37: Conservation Biology & Biodiversity BIO-120 37.1 Conservation Biology and Biodiversity 1 Conservation biology. Interdisciplinary science with the explicit goal of protecting biodiversity and Earth’s natural...

Chapter 37: Conservation Biology & Biodiversity BIO-120 37.1 Conservation Biology and Biodiversity 1 Conservation biology. Interdisciplinary science with the explicit goal of protecting biodiversity and Earth’s natural resources. Relies on many subdisciplines of biology to develop basic scientific concepts used to describe biodiversity. Application of these concepts to manage and conserve biodiversity for future generations. Involves social scientists, economists, public education, government officials. 37.1 Conservation Biology and Biodiversity 2 37.1 Conservation Biology and Biodiversity 3 Ethical principles of conservation biology. Biodiversity is desirable for the biosphere and therefore for humans. Human-induced extinctions are undesirable. Complex interactions within ecosystems and communities support biodiversity and the maintenance of such interactions is therefore desirable. Biodiversity generated by evolutionary change has intrinsic value, regardless of any practical benefit. 37.1 Conservation Biology and Biodiversity 4 Conservation biology has often been called a “crisis discipline” or a “discipline with a deadline.” Facing a sixth mass extinction that is more rapid than the previous five. It is estimated that as many as 10% to 20% of all species may be extinct in the next 30 to 50 years. Some researchers suggest we may lose as many as 50% of all species by the year 2100. Biodiversity 1 Biodiversity. Described as the variety of life found on Earth. The number of species in a given area or ecosystem. Approximately 1.6 to 1.7 million species have been described across the globe. Estimates are that there may be 8.7 million species in all. More than 30,000 species worldwide are endangered species (species in immediate danger of extinction) or threatened species. Number of Catalogued Species Source: www.catalogueoflife.org/. Biodiversity 2 Four levels of biological organization are used by ecologists and conservation biologists. Species diversity – number of species in a given area. Genetic diversity – number of different alleles. High genetic diversity increases capacity to adapt to environmental change. Ecosystem diversity – interactions between species and their abiotic environment. Conserve species that play critical roles in an ecosystem. Landscape diversity – interacting ecosystems. Fragmentation can reduce reproductive capacity by increasing predation risk. Effect of Introduced Opossum Shrimp on Ecosystem Diversity 1 Effect of Introduced Opossum Shrimp on Ecosystem Diversity 2 inset 37.2 Value of Biodiversity Conservation biology strives to reverse the trend toward the extinction of thousands of plants and animals. Biodiversity is a resource of immense value. Direct value. Individual species perform services for humans and contribute to the value we should place on biodiversity. Medicinal Value Most prescription drugs were originally derived from living organisms. Rosy periwinkle – from Madagascar. Medicines derived from this plant are used to treat leukemia and Hodgkin disease. Penicillin – antibiotic derived from a fungus. The bacteria that causes leprosy does not grow in lab, but grows naturally in armadillos. The bacteria can be studied in armadillos to help develop a drug. The blood of horseshoe crabs contains a substance used to ensure medical devices are free of bacteria. Agricultural Value Crops such as wheat, corn, and rice are derived from wild plants. Plants have been modified to be high producers and are grown worldwide. Rice resistant to a virus that destroyed crops was discovered and used in breeding programs to transfer the gene into high-yielding rice plants. Natural predators can be identified and used to control pests of crops. Many animals, such as insects, birds, and bats, are needed to pollinate plants. Consumptive Use Value 1 Aquaculture is the growing of fish and shellfish for human consumption. This type of cultivation has been used minimally. Most freshwater and marine harvests depend on wild fish (tuna, cod, and trout) and crustaceans (lobsters, shrimps, and crabs). These organisms are an invaluable biodiversity resource. Consumptive Use Value 2 The environment provides many other items that are sold in the marketplace. Wild fruits and vegetables. Skins, fibers. Beeswax. Seaweed. Meat. Rubber. Direct Value of Wildlife (periwinkle): ©Steven P. Lynch; (armadillo): Indirect Value 1 Many scientists argue that it is more economical to save ecosystems rather than individual species. Ecosystems perform many services for humans. The services are indirect because they are pervasive, and it is difficult to assign a direct dollar value to them. Human survival depends on the functions that natural ecosystems perform for us. Indirect Value 2 Biogeochemical cycles – Biodiversity within ecosystems contributes to the water, carbon, nitrogen, phosphorus, and other biogeochemical cycles. Example: provide water, remove carbon dioxide. Waste disposal – Decomposers break down dead organic matter and other types of wastes. Inorganic nutrients produced within ecosystems. Millions of tons of waste material dumped into natural ecosystems each year. Indirect Value 3 Provision of fresh water – Terrestrial organisms especially need fresh water. The water cycle continually supplies fresh water to terrestrial ecosystems. Humans use water for drinking and crop irrigation. Flood prevention – Forests and other natural ecosystems exert a “sponge” effect. They soak up water and release it a regular rate. Indirect Value 4 Prevention of soil erosion – Intact ecosystems naturally retain soil and prevent its erosion. Soil erosion occurs following deforestation. Silt accumulates in nearby waterways with negative consequences. Regulation of climate – Trees provide small- and large-scale benefits. Locally, trees provide shade, buffer noise, and maintain regional rainfall in the tropics. Globally, forests ameliorate the climate because they take up CO2 and release O2. Indirect Value 5 Ecotourism – Many people prefer to vacation in natural areas. Popular activities include fishing, boating, whale watching, hiking, and bird watching. Many want to immerse themselves in the beauty and serenity of nature. Many underdeveloped countries are offering “ecotours,” which generate more money than harvesting the organisms. 37.3 Threats to Biodiversity 1 Humans are contributing to a biodiversity crisis. To identify the role that humans are playing in modern extinctions, researchers examined the records of 1,880 threatened or endangered species in the United States. Five causes for species extinctions are identified. Habitat loss (85%). Exotic species (50%). Pollution (24%). Overexploitation (17%). Disease (3%). Some species are imperiled for more than one reason. 37.3 Threats to Biodiversity 2 (photo) (b): ©Charan Reddy/EyeEm/Getty Images Habitat Loss 1 Habitat loss has occurred in all ecosystems, and human disruption is the greatest factor. Concern is especially centered on tropical rainforests and coral reefs. These habitats are particularly rich in species diversity. In Brazil, a common sequence of events renders rain forest into land uninhabitable by wildlife: Small towns fragment forest, trees are burned to facilitate grazing, land becomes degraded. Habitat Loss 2 Coastal habitats are also being degraded. Large concentration of people living on or near coast. Coastal habitation leads to erosion and input of pollutants into aquatic systems. 60% of coral reefs have been destroyed due to siltation from beach erosion. 45% of mangroves in Indonesia have been lost. Wetlands, estuaries, and seagrass beds are also being rapidly destroyed. Alien Species 1 Alien (exotic) species are nonnative members of a community. Communities are characterized by a unique assemblage of species that evolved together in an area. Introduction of exotic species can disrupt this balance. Interactions between species in a food web are changed. Exotic species can directly compete with or prey upon native species. Alien Species 2 Humans have introduced exotic species into new ecosystems in various ways. Colonization – Europeans brought new species whenever they colonized new areas. Foxes introduced in New Zealand resulted in a loss of nearly 40% of the bird species. Horticulture/agriculture – Exotics escaped their cultivated areas. Kudzu is a vine from Japan introduced to prevent soil erosion. Instead, it spread over much of the landscape of the southern United States. Alien Species 3 Accidental transport – Global trade and travel accidentally bring many new species to new areas. The zebra mussel from the Caspian Sea was introduced into the Great Lakes in 1988. It now forms dense beds that reduce biodiversity by outcompeting native mussels. They also decrease food available for higher levels in the food chain by being more effective filter feeders. Zebra mussels clog pipes, causing millions in damage. The nutria in the Southeast and the Argentinian fire ant are also introduced exotics. Alien Species 4 Exotics on islands. Islands are particularly susceptible to disruption by introduced exotics. Native species are closely adapted to each other. Brown tree snakes in Guam and mongooses in Hawaii prey on native birds and cause drastic population declines. (a): ©Chuck Pratt/Avalon; (b): ©Chris Johns/ Pollution 1 Pollution. Any environmental change that adversely affects the lives and health of living things. It also weakens organisms and makes them more susceptible to disease. Biodiversity is especially threatened by five types of pollution: Acid deposition. Eutrophication. Ozone depletion. Organic chemicals. Climate change. Pollution 2 Acid deposition – Sulfur dioxide and nitrogen oxides are converted to acids when combined with atmospheric water vapor. These acids return to Earth in precipitation or deposition, weaken trees, and make the pH of water too low for organisms to survive. Eutrophication – Lakes are stressed due to over enrichment from runoff. Algae growth is accelerated. Algae death increases decomposer activity, followed by oxygen reduction. Fish kills are often a result from lack of oxygen. Pollution 3 Ozone depletion – Ozone protects Earth from ultraviolet (UV) radiation. The release of chlorofluorocarbons (CFCs) causes ozone to break down. A reduced ozone shield results in impaired growth of crops and trees. It also results in the death of plankton that sustain oceanic life. Skin cancer has increased. Pollution 4 Organic chemicals – Organic chemicals called nonylphenols are used in many products. Many of these chemicals mimic the effect of hormones. They act as endocrine-disruptors, which can disrupt the reproductive potential of certain animals. Pollution 5 Climate change – recent changes in the Earth’s climate. Global warming is a major contributor to the change. Increased levels of greenhouse gases (CO2 and CH4) are causing a temperature increase. Climate change is expected to have detrimental effects. Destruction of coastal wetlands and coral reefs. Shift in suitable temperatures in species’ ranges. Present assemblage of species in ecosystems disrupted. Climate Change and Global Warming 1 Climate Change and Global Warming 2 ©Marco Simoni/Getty Images Overexploitation 1 Overexploitation. This occurs when the number of individuals taken from a wild population is so large that the population becomes severely reduced in numbers. A positive feedback cycle explains exploitation. The smaller the population, the more commercially valuable its members. The greater the incentive to capture remaining organisms. Overexploitation 2 Poachers are people who capture, collect, and sell endangered and threatened species. Other human overexploitation activities. Rare cacti are sold for $15,000. Exotic pets such as parrots and tropical fish are taken from the wild. Poachers hunt for hides, claws, tusks, horns, or bones of endangered mammals. Overexploitation 3 Convention on International Trade in Endangered Species (CITES). An agreement established in 1973 to ensure that international trade of species does not threaten their survival. UN Food and Agricultural Organization. We have overexploited 11 of 15 major oceanic fishing areas. Many efficient methods used in overfishing decimate other sea life and the ocean floor. Overfishing disrupts entire marine ecosystems. Overexploitation 4 (a): ©StrahilDimitrov/iStock/360/Getty Images; (b): ©Peter Disease Wildlife is exposed to new pathogens from domestic animals who move into areas with their encroaching humans. Canine distemper was passed from domesticated dogs to African lions, causing population declines. Almost half of sea otter deaths along the coast of California are due to infectious diseases. Infections of a fungal pathogen may be causing global population declines and extinctions of amphibians. ©Dr. Paul A. Zahl/ Science Source 37.4 Habitat Conservation and Restoration Conservation of habitat is a primary concern because habitat loss is the leading cause of species’ extinction. The priority is to focus on habitats with the highest levels of biodiversity. The tropics have the highest biodiversity. Tropical rainforests and coral reefs. Biodiversity declines toward each pole. Habitat Conservation 1 Biodiversity hotspots. Contain unusually large concentrations of species. 44% of all known higher plant species. 35% of all terrestrial vertebrates. Contain endemic species—species not found anywhere else. Cover only 1.4% of Earth’s land area. Habitat Conservation 2 Example hotspot. Tropical rain forests of Madagascar. 93% of primate species. 99% of amphibians. 80% of plant species. Other hotspots are: Cape region of South Africa. Indonesia. Coast of California. Great Barrier Reef of Australia. Habitat Conservation 3 Effort should also focus on conserving habitat for keystone species. Loss of a keystone species would result in a great number of secondary extinctions. Wolves, bats, grizzly bears, beavers, elephants. Keystone species are not necessarily the most abundant. Flagship species. These species evoke an emotional response from humans. Lions, tigers, dolphins, giant panda. Landscape Conservation and Reserve Design Conservation often occurs at the landscape level. Sufficient habitat may not be available in a single area to sustain a viable population of a particular species. Some species use several types of ecosystems (grasslands, mountains, rivers). Conservation corridors allow animals to move safely between different habitats. Corridors are necessary because landscapes are subdivided due to urbanization, agriculture, and other aspects of human development. Landscape conservation for a single species is often beneficial for other species that share the same habitats. Habitat Preservation When particular species are protected, other wildlife benefits. The protection of grizzly bears in Yellowstone and of northern spotted owls in the Pacific Northwest protects many other species. (a): ©Deb Garside/Design Pics; (b) (forest): Edge Effects 1 Edge effects should be considered when conserving landscapes. The edge effect reduces the amount of habitat typical of an ecosystem. Edges around a patch have a habitat slightly different from the interior of the patch. The effective habitat shrinks as a patch gets smaller. Example: Songbird populations declining because nesting success is low at the edge of a forest. Edge Effects 2 Edge Effects 3 Songbird nests on the edges of forests are more likely to get parasitized by brown- headed cowbirds. Brown-headed cowbirds lay their eggs in the nests of small songbirds. Cowbird chicks are bigger and can acquire more resources. ©Jeff Foott/Getty Images Reserve Design 1 Conservation reserves – areas set aside with the primary goal of protecting biodiversity within them. Should be protected from human activities. Should have sufficient amount of habitat to sustain the biodiversity. Should include multiple ecosystems connected by corridors. Should account for edge effects. Reserve Design 2 Globally, more than 650 biosphere reserves have been designated by the United Nations. The maintenance of reserves is carried out by each country or territory in which they are located. Each reserve is divided intro three areas. Central core reserve: only research, light eco-tourism, and limited sustainable use for cultural purposes allowed. Buffer zone: only low-impact human activities allowed. Transition area: supports sustainable human development, tourism, agriculture. Habitat Restoration 1 Habitat restoration is an alternative in cases where habitat is modified to the extent that conservation and reserve formation are not viable. Restoration ecology is a subdiscipline of conservation biology that seeks scientific ways to return ecosystems to their state prior to habitat degradation. Although perceived as beneficial, concern is that restored areas are not functionally equivalent to the natural regions once there. Habitat Restoration 2 Three principles of habitat restoration: Begin as soon as possible before the remaining fragments of the original habitat are lost. It is best to use biological techniques that mimic natural processes to bring about restoration. The goal is sustainable development—the ability of an ecosystem to maintain itself while providing services to human beings. 37.5 Working Toward a Sustainable Society 1 Ultimately, biodiversity loss results from human consumption of resources. Nonrenewable resources are limited in supply. Land, fossil fuels, minerals. Renewable resources are not limited in supply and can be replenished. Certain forms of energy, such as solar and wind. Resources Consumed by Humans 37.5 Working Toward a Sustainable Society 2 At present, human society is not sustainable. A considerable proportion of land, and therefore of natural ecosystems, is being altered for human purposes. Our society primarily utilizes nonrenewable fossil fuel energy. Even though fresh water is a renewable resource, we are using it faster than it can be replenished. 37.5 Working Toward a Sustainable Society 3 Agriculture requires large inputs of nonrenewable fossil fuel energy, fertilizer, and pesticides, which create much pollution. At least half of the agricultural yield in the United States goes toward feeding animals. Minerals are nonrenewable, and the mining, manufacture, and use of mineral products is responsible for much environmental pollution. 37.5 Working Toward a Sustainable Society 4 Sustainable society. Able to provide the same goods and services for future generations as it does now. Should shift our efforts to using renewable energy resources and recycle materials. Consider alternative energy use, water conservation, modifications to modern agriculture. Current Human Society ©Imantsu/Shutterstock Sustainable Human Society ©Jeff Whyte/Shutterstock Energy The majority of the world’s energy supply comes from finite, nonrenewable sources. 14% from nuclear power. 61% from fossil fuels. Fossil fuels are derived from compressed remains of plants and animals that died millions of years ago. Comparatively speaking, each person in a more- developed country uses about as much energy in one day as a person in a less-developed country uses in one year. Renewable Energy Sources 1 Hydropower. Hydroelectric plants convert the energy of falling water into electricity. Hydroelectric power presently generates 17% of electricity worldwide. Large dams can have detrimental environmental impacts. Small dams generate less power per dam, but do not have the same negative environmental impact. Renewable Energy Sources 2 Geothermal energy. Earth has an internal heat source due to elements such as uranium undergoing radioactive decay underground. The surrounding rocks are heated to hundreds of degrees Celsius. When rocks are in contact with underground streams, steam is produced. The steam can be piped to the surface and used to heat water or run steam-driven turbogenerators. Renewable Energy Sources 3 Wind power. Wind power is expected to account for a significant percentage of our energy needs in the future. Not as much land for “wind farms” is required as is commonly believed. Similar to amount of land required for coal-fired power plants or solar thermal energy system. Communities can solve the problem of uneven energy production by selling electricity when excess is available or buying when it is in short supply. Renewable Energy Sources 4 Solar energy. Solar energy is diffuse—more steps are required if it is to be competitive with other forms of energy. Must be collected. Must be converted to another form. Must be stored. A photovoltaic (solar) cell contains an electron- emitting metal in contact with another metal that collects electrons, then passes the electrons to wires in a steady stream. Renewable Energy Sources 5 Fuel cells use hydrogen to produce electricity. Hydrogen fuel can be produced by using energy from photovoltaic cells. Hydrogen can be piped to filling stations using the natural gas pipelines in place. Solar-hydrogen energy has two advantages: The world would no longer depend on its limited oil reserves. Environmental problems such as global warming, acid rain, and smog would lessen. Renewable Energy Sources 6 Hydropower (Figure 37-13): ©Maxim Burkovskiy/ Shutterstock; (Figure 37-14 a): Water 1 Some areas of the world do not have access to clean and safe drinking water. It is considered a human right for people to have clean drinking water. The reality is that most fresh water is utilized by industry and agriculture. Worldwide, 60% of fresh water is used to irrigate crops. In developed countries, more water is typically used for bathing, flushing toilets, and watering lawns than for drinking. Water 2 The needs of the human population overall do not exceed the renewable supply of water. This is not the case in certain regions of the United States and the world. When needed, humans increase the supply of fresh water by damming rivers and withdrawing water from aquifers. But dams have drawbacks. Water 3 Drawbacks of dams. Reservoirs behind the dam lose water due to evaporation and seepage. Salinity increases due to evaporation and agricultural runoff. Sediment buildup reduces capacity of dams; reservoirs become full of silt. Alteration of a river or stream has a negative impact on the natural wildlife. Water 4 Aquifers – underground water reservoirs. To meet freshwater needs, vast amounts of water have been pumped from aquifers. Groundwater depletion has become a problem in many areas of the world over the last 50 years. Removal of water is causing land subsidence, or settling of soil as it dries out. Subsidence causes the surface of the ground to drop and can damage canals, buildings, and underground pipes. Conservation of Water By 2025, two-thirds of the world’s population may be facing serious water shortages. Suggested solutions. Planting drought- and salt-tolerant crops. Using drip irrigation to save 50% over traditional methods. Reusing water and adopting conservation measures by industries. Limiting lawn watering to dusk or dawn to reduce evaporation. Agriculture 1 Today, current agricultural practices produce enough food to provide everyone on Earth a healthy diet consisting of 2,500 calories per day. However, one-sixth of the world’s population is currently considered malnourished. Grain is used to feed livestock rather than humans. Agriculture 2 Modern farming methods are environmentally destructive. Monocultures can be destroyed by a single pathogen. Heavy use of pesticides, herbicides, and fertilizers is required. Pesticides reduce soil fertility and create artificial resistance in insects. All three contribute to pollution. Significant amounts of fresh water are used for irrigation. Large amounts of fuels are used. Agriculture 3 Alternatives to modern agriculture methods. Polyculture – planting several varieties of crop in the field simultaneously. To reduce susceptibility of crops to pests or disease. Crop rotation – planting nitrogen-fixing crops on alternating years to reduce the need for nitrogen- based fertilizers. Helps increase the amount of organic matter and nutrients in the soil. Agriculture 4 Organic farming – avoids the use of synthetic pesticides or herbicides. This is more profitable recently because people are more willing to purchase organic products, even at a higher cost. Biological pest control often used. Methods to reduce erosion and topsoil loss. Contour farming conserves topsoil in gently sloping areas. Terrace farming converts steep slopes into step-like hills. Natural fences (tree rows) reduce wind. Cover crops stabilize soil between crop rows. Alternative Agricultural Methods (a): ©David R. Frazier/Science Source; (b): ©Inga Spence/Alamy; Urban Growth The growth of cities increases pollution. Automobile exhaust, runoff of pollutants on impervious surfaces and into waterways, noise pollution, industrial and domestic wastes. Energy use can be curtailed through public transportation. High-rise buildings and the renovation of older parts of a city combat urban sprawl. Modern cities are now incorporating green spaces that can be used for recreation as well. Methods such as porous surfaces can be used for storm-water management.