Biology

DeforestationLoss of forests, or deforestation, has several effects: Erosion can wash away nutrients in the topsoil.Grazing or plowing can permanently change local soils and microclimates, which prevents the regrowth of trees.

Forest ManagementMature trees can be harvested selectively to promote the growth of younger trees and preserve the forest ecosystem.Tree geneticists are breeding new, faster-growing trees that produce high-quality wood.

Fishery ResourcesFishes and other animals that live in water are a valuable source of food.

OverfishingHarvesting fish faster than they can reproduceHas greatly reduced the amount of fish in parts of the worlds oceansFisheries seemed to be a renewable resource, but overfishing has limited that resource

U.S. National Fisheries Service has issued guidelines that specify how many fish, and of what size, can be caught

Sustainable DevelopmentSustainable Development a way of using natural resources without depleting them and causing long-term environmental harm

Forest ResourcesEarths forests are an important resource for the products they provide and for the ecological functions they perform.

Provide wood for products and fuel.Remove carbon dioxide and produce oxygen.Store nutrients.Provide habitats and food for organisms.Moderate climate.Limit soil erosion.Protect freshwater supplies.

Smog a mixture of chemicals that occurs as a gray-brown haze in the atmosphereIs due to automobile exhausts and industrial emissionsConsidered a pollutant because it threatens peoples healthPollutant a harmful material that can enter the biosphere through the land, air, or waterThe burning of fossil fuels can release pollutants that cause smog and other problems in the atmosphereAir ResourcesStrict automobile emissions standards and clean-air regulations have improved air quality in many cities, but air pollution is still a problem.

Acid precipitation nitrogen and sulfur compounds in the atmosphere combine with water vapor and fall to the Earth in the form of rain, snow, sleet, or fog

Acid precipitation kills plants by damaging their cells and interfere with plant growthFreshwater ResourcesAlthough water is a renewable resource, the total supply of fresh water is limited and is threatened by pollution.Sources of freshwater pollution include:Improperly discarded chemicals that enter streams and rivers.Wastes discarded on land that seep through soil and enter underground water supplies. Domestic sewage containing compounds that encourage growth of algae and bacteria. Sewage containing microorganisms that spread disease.

Sustainable Use of WaterOne way to ensure the sustainable use of water is to protect the natural systems involved in the water cycle that help purify water.

Examples: wetlandsforestsrock layers

Also, by conserving water in:homeindustryagriculture The Fate of Spilled OilAccording to a well-known saying that oil and water dont mix, it might be expected that spilled oil would float around until it was washed ashoreA single gallon of oil can spread enough to cover up to four acres of waterAs soon as the oil is spilled in a marine environment, many changes begin to take placeWithin days, 25% of the oil is lost through evaporationThe remaining oil sinks to the bottom of the oceanIt adheres to almost all objects that it encountersAfter 3 months only 15% of the original oil remains13If a substantial oil spill occurred close to shore rather than at sea, the effects would be different because there would not be sufficient time available for the process described above to affect the total amount of oil involved14Effects of Oil Spills

Reduction of Light TransmissionLight intensity 2m below an oil slick can be reduced by 90%Reduces the rate of photosynthesis so plants and protists die15Reduction in Dissolved OxygenOil film blocks rate of oxygen uptake by waterDO is lower in oil contaminated water

Damage of Marine BirdsBirds covered with oil can drownOil causes bird feathers to mat together and reduces the birds ability to fly and float in waterFeathers lose their insulating abilityBirds die because of exposure to cold weather or inability to get food16Toxic Effects to Marine EnvironmentOil contains benzene, toluene, xylene, which are toxic to plants and animals17Methods of Oil Spill Clean-UpBooms or BarriersContain oil slickMakes it easier to skim the oil off the surface

18SkimmersUsed to remove oil from the surface of the waterThey are attached to ships or may be hand-held along shoreSkimming works best in calm waters

19SorbentsMaterials used to soak up oil spillsExample: straw, powdered clay, sawdust, chopped corn cobs, pine bark

20Chemical Dispersants, Detergents, and SolventsUsed to degrade the oilUnfortunately most of these chemicals are toxic to animals

21FlamesUsed to burn the oilThe black smoke contains toxic components

22BioremediationThe oil spill cleanup methods listed above only recover 10-30% of the spilled oilThe most environmentally safe prospect for the cleanup of oil spills is the use of oil-degrading microbesBioremediation the use of naturally occurring microorganisms that have been genetically engineered and that can be used to degrade petroleum productsA microorganism called petrophiles are spread across an oil spill and they degrade the oil and convert it into food23The microorganisms may be mixed with nutrients such as nitrogen, phosphorus, and cottonseed protein that not only enhance the microbial growth, but also absorb the oil and provide a matrix for the microorganisms to continue to degrade the absorbed oilThe treated oil slick begins to break up and turn into a yellowish substance that eventually diminishes in size24Case Study The Exxon ValdezIn the spring of 1989, the largest oil spill in U.S. history occurred when an oil tanker named the Exxon Valdez hit a reef in Prince William Sound off the coast of AlaskaMore than 10 million gallons of crude oil spilledThe oil slick covered more than 1,000 miles of coastlineCaused an estimated 5 billion dollars in environmental damages25

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27The Exxon Valdez disaster killed more wildlife than any other environmental disaster in our nations history250,000 seabirds died2,800 sea otters died300 harbor seals died250 bald eagles died22 killer whales died28

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6-3BiodiversityThe Value of BiodiversityBiodiversity the number of species that live in a certain areaA rain forest has the greatest amount of biodiversity.

Why is biodiversity important?FoodMedicinesIndustrial products Sun Star/Stock Photos Hawaii

Threats to BiodiversityHuman activity can reduce biodiversity by: altering habitatshunting species to extinctionintroducing toxic compounds into food websintroducing foreign species to new environmentsThreatened species when the population of a species begins declining rapidlyEndangered Species when species numbers become so low that extinction is possibleExtinction the disappearance of a species when the last of its members diesSince 1980s almost 40 species of plants and animals living in the United States have become extinctAlthough extinction can occur as a result of natural processes, humans have been responsible for the extinction of many species

35 MusselsFanshellEndangeredCatspawEndangeredRing PinkEndangeredPink MucketEndangeredLittle-wing PearlymusselEndangeredOrange-foot PimplebackEndangeredRough PigtoeEndangeredFat PocketbookEndangeredCumberland Bean MusselEndangeredNorthern RiffleshellEndangeredClubshellEndangered

Clubshell36 FishBlackside DaceThreatenedPalezone ShinerEndangeredPallid SturgeonEndangered

BirdsBald EagleEndangeredRed-cockaded WoodpeckerEndangeredInterior Least TernEndangeredPassenger PigeonExtinct

37 MammalsGray Myotis (bat)EndangeredIndiana Myotis (bat)EndangeredVirginia Big-eared BatEndangeredSiberian TigerEndangeredTasmanian TigerExtinctPlains ZebraExtinct

InsectsAmerican Burying BeetleEndangered

38 PlantsPrice's Potato-beanThreatenedCumberland SandwortEndangeredCumberland RosemaryThreatenedWhite-haired GoldenrodThreatenedShort's GoldenrodEndangeredVirginia SpiraeaThreatenedRunning Buffalo CloverEndangeredChaffseedEndangered

Running Buffalo Clover

Chaffseed

Cumberland Rosemary39Habitat Alteration Habitat loss is the biggest threat to biodiversityHabitat Fragmentation the separation of wilderness areas from other wilderness areasPresents problems for organisms that need large areas to gather foodHabitat Degradation the damage to a habitat by pollution

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42Introduced SpeciesAnother threat to biodiversity comes from plants and animals that humans transport around the world either accidentally or intentionally.

Exotic (Invasive) species organisms that are not native to a particular area

Reproduce rapidly because their new habitat lacks the predators that would control their population

Example: zebra mussels, amur honeysuckle, kudzu, cane toad, European starling, mongoose in Hawaii

Conservation BiologyConservation the management of natural resources, including the preservation of habitats and wildlife

Many species are in danger due to the actions of humans, so working with people is an important part of conservation biology45Strategies for ConservationMany conservation efforts are aimed at managing individual species to keep them from becoming extinctU.S. Endangered Species Act this law made it illegal to harm any species on the endangered or threatened species listsCreate more natural preservesReintroduction programs release organisms into an area where their species once livedExamples: California condor, wolves in Yellowstone, Black-footed ferret46

Ozone DepletionOzone Layer atmospheric layer in which ozone gas is relatively concentratedThe ozone layer absorbs a good deal of harmful ultraviolet or UV radiation from sunlight before it reaches Earths surface

6-4 Charting a Course for the Future48Early EvidenceIn the 1970s, scientists discovered a hole in the ozone layer over AntarcticaIn 1974, a research team published data showing that gases called chloroflurocarbons, or CFCs could damage the ozone layer49CFCs were once widely used:As propellants in aerosol cansAs coolant in refrigerators, freezers, and air conditionersIn the production of plastic foamsThe U.S. and other nations began reducing the use of CFCs in 1987, and eventually banned themSince the ban the level of CFCs in the atmosphere had decreased, indicating that the ban will have positive, long-term effects on the global environmentCurrent data predict that the ozone holes should shrink and disappear within 50 years50Global Climate ChangeSince the late 19th century, average temperatures have risen about 0.6CGlobal Warming the increase in the average temperature of the biosphereOne sign of global warming is melting polar ice

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52Biologists are concerned about global warming. This map of the Arctic is based on images taken by satellites in 1979 and 1999. Sea ice in the Arctic Ocean has receded so quickly that some scientists suggest that, within the next 50 years, the ice could disappear completely.Evidence of Global WarmingThe geological record shows that Earths climate has changed repeatedly during its historyResearchers must determine whether the current warming trend is part of a larger, natural cycle of climate change, or whether it is caused by human activityA widely accepted hypothesis is that current warming is related, in part, to human activities that add carbon dioxide and other greenhouse gases to the atmosphereData show that concentrations of carbon dioxide in the atmosphere have been rising for 200 yearsAs a result, the atmospheres natural greenhouse effect is intensified, causing the atmosphere to retain more heat

53Possible Effects of Global WarmingMost recent computer models suggest that average global surface temperatures will increase by 1 to 2C by the year 2050Sea levels may rise enough to flood coastal areas, affecting coastal ecosystems as well as human communitiesParts of North America may experience more droughts during the summer growing seasonNew organisms may be able to live in places where they once could notOther organisms may become threatened or extinct in areas where they once thrived54