Environmental Biology BIOL 107
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Chapter l l What is biodiversity The total genetic species and ecological varieties of organisms found in a given area This includes all genetic variants of a single species and the whole array of species in an area It includes the variety of ecosystems with its communities within particular habitats 0 Genetic diversity different versions of the same gene 0 Species diversity number of different kinds of organisms in a locality o Ecological diversity richness and complexity of the community e g number of niches trophic levels recycling processes etc What is a species A population of similar organisms that can produce fertile offsprings without human intervention 0 In the Wild 0 Rampant genetic exchange between members Reproductive isolation is the idea used in this definition Hybrids occur in nature and sometimes produce fertile offspring There are debates between taxonomists on the species status of many organisms DNA sequencing technology is helping to understand better the evolutionary relationship between species Number of species We know about 21 million species The estimate of the total number of species in the world ranges from 3 million to 50 million Identified Bacteria 4000 Fungi 72000 Invertebrates 1 500000 Fish 27000 Birds 9700 Mammals 4650 Plants 270000 Biodiversity hot spots have a large number of endemics Endemics are species that occur nowhere else The tropics are the centers of the greatest biodiversity Amazonia New Guinea and Congo basin httpwwwmeerorgM16htm BENEFITS OF BIODIVERSITY 1 FOOD 0 As many as 80000 wild plants are edible 0 Few plants used by ethnic minorities in the tropics have been studied for their food potential Indonesia has an estimate of 250 edible fruits of which 43 have been cultivated widely 0 These little known crops are a source of genetic material to improve domestic crops 2 DRUGS AND MEDICINE 0 About 90 of our medicines come from plants bacteria and fungi directly or are derived from them 0 More than 50 of prescribed drugs contain some natural product 0 Pharmaceutical companies are actively investigating the useful natural products of tropical plants 0 Pharmaceutical products derived from the developing world plants animals bacteria and fungi amounts to 30 billionyear 3 ECOLOGICAL BENEFITS Human life is inextricably linked to ecological services provided by other organisms Soil formation nutrient recycling waste disposal air and water purification solar energy absorption chemical cycles pest control etc depend on the biodiversity of life Diverse communities are more stable and withstand stress better than less diverse communities Nature maintains ecological processes at no cost for us and contains a genetic library of information that we could not reproduce It is estimated that 95 of the potential pests and diseasecarrying organisms are controlled by other species that prey upon them 4 AESTHETIC SYMBOLIC VALUE AND CULTURAL BENEFITS 0 Quality of life recreation beauty 0 Contact with nature could be psychologically and emotionally restorative o In some cultures nature carries spiritual connotations and a particular species or landscape may be inextricably linked to a sense of identity and meaning 0 For some simply knowing that a particular species exists is reason enough to protect it and preserve it This is called existence value THREATS TO BIODIVERSITY Extinction is the elimination of a species Natural causes of extinction Over 99 of the species that ever existed are now extinct Periodically mass extinctions have wiped out entire families of organisms eg the dinosaurs at the end of the Cretaceous 65 million years ago During the Permian 250 million years ago two thirds of all marine species and about half of all plant and animal families died out in a period of about 10000 years Human impact has accelerate the rate of extinction in the 20th century Species either die out or are replaced through evolution Evolution can occur at a slow or fast pace Massextinctionshttnquotquot narknrnC 39 39 139 139 39 139 himI Humancaused reduction of biodiversity 0 Habitat destruction The biggest reason forthe current increase in extinction 0 Introduction of exotic species compete and eliminate native species eg kudzu Asian tiger mosquito transmits the West Nile virus deadly to many birds Pollution Pesticides and fertilizers have disastrous effects on organisms o Overexploitation gt Hunting and fishing eg the passenger pigeon bison and several species of whale gt Modern fishing methods eg cod industry elimination of sea predators etc gt Bushmeat trade in Africa Commercial products and live specimens Trade of exotic animals and their products have brought some species to the brink of extinction eg macaws black rhinos whales wild ginseng cactus trade Predator and pest control Some species have been hunted because they are considered dangerous to humans or livestock eg reintroduction of the gray wolf controversy Diseases introduced from abroad can eliminate native species that lack the resistance to deal with the pathogen eg American chestnut American elm blight Genetic assimilation by related opportunistic species Human causes of extinction httpwwwwellcomuserdavidusixthextinctionhtml httpwwweurekalertorgpub releases199908XlBCWbbe020899php ENDANGERED SPECIES MANAGEMENT 1 Hunting and fishing laws 0 To protect human future resources 0 To preserve game animals 2 Endangered Species Act httpillwww qu httpwww redlist Established in 1973 To preserve biodiversity regardless of its usefulness to humans a new approach to wildlife Endangered are those near extinction 395 US species of animals are listed 599 US species of plants are listed Threatened are likely to become endangered at least locally Vulnerable are those species that are rare and can easily become threatened or endangered EAS regulates activities involving endangered species it includes a wide range of activities taking harassing shooting harming etc possessing exporting transporting shipping etc In 1995 the Supreme Court ruled that habitat essential for an endangered species survival must be protected whether on public or private land United States has 1530 species on the endangered or threatened list Expired in 1992 In 1995 the Supreme Court ruled that critical habitat habitat essential of a species39 survival must be protected whether on public or private land n n u u html html I39 I ll LI httpwwwfwsgovendangeredwildlifehtmlSpecies httpecosfwsgovtess publicTessStatReport 3 Recovery plans of listed species Prepared by the Fish and Wildlife Service detailing how populations will be rebuilt to sustainable levels It often takes years to reach an agreement on a specific recovery plan Major difficulties are cost politics and interference on local economic interests Preserving the habitat of the species is a major source of debate eg spotted owl and lumber companies Tellico dam and the snail darter in Tennessee 1978 The total cost of recovery plans for all currently listed species is estimated to be nearly 5 billion Most of the money for protection and recovery 150 million goes to protect ten species 4 Private land and critical habitat Most of the habitat 80 for listed species is on private land Landowners do not want to be told how to use their property Habitat conservation plans HCP are negotiated between the Fish and Wildlife Service and landowners Under HCP plans landowners are allowed to harvest resources or build on part of their land as long as the species benefits overall Resistance where there is a potential economic benefit for the landowner 5 Reauthorizing the Endangered Species Act Expired in 1992 Congress has debated many alternatives from eliminating it altogether to strengthening it o Argument against It places the welfare of plants and animals above humans 0 Argument for Essential to maintaining the viability of the planet A very divisive issue Two main points of view 1 Habitat protection and places a deadline for listing a recovery plan it requires that HCPs do not negatively impact the species and that it should be reviewed by an independent team of scientists N Vested interests should be included the least costly and burdensome measures would be taken Federal agencies will do selfconsultation and avoid dealing with the Fish and Wildlife Service 6 Minimum viable populations A species composed of very few individuals can undergo catastrophic declines due to environmental changes genetic problems and random events Species found on islands located near continents and large islands are less susceptible than those found on small and oceanic islands Loss of genetic diversity due to fewer numbers limits adaptability reproduction and survival Diversity is lost in small populations Founder effect when a few individuals establish a new population Demographic bottleneck arises when only a few individuals survive a catastrophe Genetic drift due to uneven reproductive success Interbreeding 7 Habitat protection We are expanding our concern from individual species to protecting habitat and entire biogeographical regions Many scientists and environmentalist support a continentwide protection of ecosystems that support a maximum biological diversity Gaps between protected areas may contain more endangered species than are preserved within the protected areas Gap analysis is the study of unprotected landscapes that are rich in species computer and geographical information systems allows the analysis of vast amount of data The emphasis is biodiversity rather than on protection of one single rare species Principles for protecting biodiversity in a large scale long range approach 1 Protect enough habitat for viable populations of all native species in a given region 2 Manage at regional scale large enough to accommodate natural disturbances fire wind tc 3 Plan over a period of centuries so that species and ecosystems may continue to evolve 4 Allow for human use and occupancy at levels that do not result in significant ecological degradation 8 International wildlife treaties 0 Convention on International Trade in Endangered Species CITES was established in 1975 o It regulates trade in living specimens and products derived from listed species 0 Investigation and enforcement are especially difficult in developing countries where wildlife is disappearing most rapidly 0 Appendix I of CITES lists 700 species threatened with extinction by international trade httpwww rites quot quot shtml httpwww rites 39 html ZOOS BOTANICAL GARDENS AND CAPTIVE BREEDING PROGRAMS Zoos and botanical gardens are entertaining and educational Most mammals in US zoos are produced now by captive breeding programs Some species rarely breed in captivity There are limits to the number of captive species we could maintain under captive conditions The genealogy of the animal is kept in a database at the Minnesota zoo Botanical gardens and research institutions are repositories for rare and endangered plant species that sometimes have ceased to exists in the wild Chapter6 POPULATION DYNAMICS DYNAMICS OF POPULATION GROWTH POPULATIONS CAN GROW EXPONENTIALLY The unrestricted increase in populations is called exponential growth Exponential growth or geometric growth is the increase that takes place at a constant rate per unit of time e g 2 4 8 16 32 64 W dN change in the number of individuals dt r the average individual contribution to population growth biotic potential dt change in time If r is positive the population is growing if r is negative the population is decreasing in numbers if r is 0 there is not change in numbers Dividing 70 by the annual percentage growth you will get the approximate doubling time of the population 0 Countries growing at a 4 per year will double their population in 175 years Arithmetic growth occurs when a constant amount is added to the population eg 1 2 3 4 or 1 3 5 7 etc Biotic potential refers to the maximum reproductive rate of an organism given unlimited resources and ideal environmental conditions 0 Some species can produce an enormous number of offspring given an unlimited amount of resources eg rabbits housefly POPULATIONS CAN GO THROUGH BOOM AND BUST CYCLES Exponential growth produces a J curve In the real world there are limitations to growth Exponential growth for an unlimited period of time does not happen Carrying capacity refers to the maximum number of individuals of any species that can be supported by a particular ecosystem on a longterm basis 0 Overshoot when the population exceeds the carrying capacity 0 Dieback or crash a fast decrease of the population lrruptive or Malthusian growth takes place when a population crashes after a population explosion POPULATIONS CAN GROW TO A STABLE SIZE Species may grow exponentially at the beginning but their growth slows down as they approach carrying capacity This slow down in growth produces what is called an S curve Logistic growth occurs when a population grows exponentially at first when the resources are unlimited but the growth slows down as the population approaches the carrying capacity of the environment rN 1K N number of individuals dt r biotic potential t time K carrying capacity 1NK represents the relationship of number in the population and K the carrying capacity the number of individuals the environment can support If 1NK is positive the population is below what the environment can support and is growing though slowly if 1KN is negative the population growth is negative MANY FACTORS LIMIT POPULATION GROWTH The growth rate of many species is regulated by internal and external factors so that they come into equilibrium with the environment Various factors affect natality and mortality and regulate population growth These factors may be acting simultaneously on a population Some of these factors are dependent on the number of individuals in the population how crowded is the population density dependent factors Others are independent of the density of the population e g floods droughts density independent factors More on population growth httpir urqr 39 H 71Inr hlrn popuhtm httpusers rrn 39 39 quot ma quot BioloquauesPIquot 39 quot html n STRATEGIES OF POPULATION GROWTH SPECIES CAN BE EITHER KADAPTED OR rADAPTED o radapted species tend to grow exponentially overshoot the carrying capacity and dieback o Kadapted species reproduce slowly as they approach the carrying capacity of their habitat rADAPTED 0 Species that exhibit a radapted type of growth usually occupy low trophic levels in the ecosystem or are pioneer species 0 Generalists and opportunists invade disturbed habitats quickly grow fast mature early and produce many offspring 0 Short life 0 Do not care for the young 0 They are controlled by predators and other outside factors extrinsic o Depend on large numbers for the perpetuation of the species 0 Examples mice and many rodent species housefly and many insects weeds and pests parasites KADAPTED 0 Species that show a logistic growth pattern usually grow more slowly and occupy higher trophic levels in the ecosystem 0 They are normally adapted to stable environments 0 They are usually large live longer grow slowly mature late and produce very few offspring 0 They provide care and protection for their young 0 They have few predators and are usually controlled by intrinsic factors 0 Examples elephants wolves whales monkeys and apes Where do we fit What strategy do we use as a species Are we going to surpass our carrying capacity or are we going to come into balance with the environment More of reproductive strategies httpwww hin miami 39 tombil160bil160qoods16 39 39 quot html FACTORS THAT AFFECT POPULATION GROWTH Natality number of individuals added to the population by birth hatching cloning or germination Fecundity the physical ability to reproduce Fecund individuals may not contribute to the growth of the population due lack of opportunities to mate or other external factor Fertility a measure of the number of individuals produced It is usually describe in terms of the number of individuals per female Immigration introduction of organisms from other communities MORTALITY AND SURVIVORSHIP MEASURE LONGEVITY Mortality or death rate the number of organism that die in a certain time period divided by the number of organisms that were alive at the beginning of the time period Survivorship the percentage of a cohort that survives to a certain age 0 There are four basic patterns of survivorship Life expectancy the probable number of year of survival for an individual of a certain age Life span is the longest period of life reached by a given type of organism o Parasitism disease accidents fighting climate and others influence early mortality 0 The maximum life span for humans appears to be 120 years Emigration the movement of organisms out of a population httneucliddnewvfibernetnetivqENV1O1quot quot39 39 39 html FACTORS THAT REGULATE POPULATION GROWTH Regulatory factors can be biotic or abiotic Intrinsic factors operate within individual organisms or between organisms in the same species Extrinsic factors are imposed from outside the population Densitydependent factors affect the population according to the population density 0 Biotic factors tend to be densitydependent o lnterspecific interactions predation competition parasitism commensalism and mutualism lntraspecific interactions territoriality competition within the species Stress and crowding stress shock and stressrelated diseases Symptoms low fertility low resistance to diseases cannibalism pathological behavior hyper or hypoactivity lack of parental instinct and others 0 Subordinate animals are usually most affected by stress and crowding Densityindependent factors their effect on the population is the same regardless of the population eg weather and climate 0 Abiotic factors tend to be densityindependent factors They an nut regmate the pepmanen m the same way asthe bmtmfacturs an The y ean have strung nnpam m the pepmanen CONSERVATION BIOLOGY envnenrnentax ehange urrandum Events smehasne Events Island Eiogeography exunctmn DTSpErsa Wasthuughttu bathe premern Estabhshed Surne reasuns furthe uvar number elf sperm are s ands an nut have an uver uvvfrum amaeent areas as the mam and dues Lnnneu hamat ean suppun has sperms The Energy base 5 me smaH m prewue furtup carmvures mmmm on of Exlincnon o4 new spasms exmmg snemes Rate ai change in number of spemes Number of specxes Dressm Mare un s and Emgeegraphy mtg NH Emueuurauh the Sueme sarea Cu httpwww neon nx ar 39 39 quot 39 I39 I AbioI hfml Conservation Genetics In large populations the gene frequency in the offspring population is the same as in the parent population HardyWeinberg Law of Equilibrium Genetic diversity is maintained Small isolated populations are subject to decline and extinction due to genetic changes in the population The addition or loss of a few individuals can make great difference in a small population by altering the gene make up of the group A gradual change in the gene frequencies of a population due to random events is called genetic drift Loss of genetic diversity causes a number of harmful effects that limit adaptability reproduction and species survival When a few individuals survive a catastrophic event or colonize a new habitat geographically isolated the gene pool is very limited A genetic bottleneck or founder effect occurs Any deleterious genes present in the founder group will be overrepresented in future generations Inbreeding also makes the expression of rare or recessive genes more likely Population Viability Analysis A minimum viable population MVP size or number of individuals is needed for longterm survival of rare and endangered species for long time 100 years or more The probability of surviving more than 100 years should be 9095 Conservation biologists use the concepts of island biogeography genetic drift and founder effects to determine the minimum viable population size Computer modeling help conservation biologists estimate the MVP Metapopulations A metapopulation is collections of small populations of a species that exchange genes with some frequency Separated population can exchange genes if the there are suitable corridors between the populations If the small populations are well interconnected through immigration they actually function as a single large population Habitat fragmentation can prevent gene flow between subgroups of the species This isolation of subpopulation can bring about genetic bottlenecks When a population becomes extinct in a habitat recolonization of area can take place with relative ease Source habitats produce more individuals that it can support and these excess individuals migrate to other population In sink habitats natality is not high enough and these populations must recruit members from source populations If immigration is prevented for some reason the species will become extinct in sink habitats Interesting site httpwwwenvdukeedulelenv214le popnhtm II 1 httn39lr rssa rutners quotTanvaRohrbach Finalhtm Chapter 10 PEST CONTROL Biological pests are organisms that reduce the availability quality or value resources useful to humans Insects are the most frequent pests but birds small mammals and other invertebrates animals as well as some plant species could be pests Pesticide is a chemical that kills pests The following are some pesticides Biocides kill a broad spectrum of organisms Herbicides kill plants Insecticides kill insects Iarvacide adulticide Fungicides kill fungi Rodenticides kill rodents HISTORY OF PEST CONTROL 1 Sumerians controlled insects with sulfur 5000 years ago 2 Chinese texts 2500 years ago describe mercury and arsenic compounds used to control body lice and other pests 0 They introduced 120 years ago predatory insects and plant derived insecticides into their orchards for protection of their crops 3 Greeks and Romans used ash sulfur and oil sprays to protect themselves livestock and crops from pests 4 The Swiss chemist Paul Muller discovered DDT in 1934 Toxic to insects by relatively nontoxic to mammals The oral dose for humans is LD50 for humans is 113 mgkg Compared with an LD50 of 50 mgkg for nicotine Commercial production began in 1943 He received the Nobel price in 1948 forthe discovery of DDT Current Pesticide Use 5 United States used 53 billion pounds 24 million metric tons of pesticides in 1999 or 20 of the world consumption 0 Most of the pesticides are chlorine compounds used in water purification 491 o Other pesticides are wood preservatives 151 conventional pesticides 233 specialty biocides preservatives sealants etc 64 other sulfur petroleum etc 6 2 In the US 80 of pesticides are used in agriculture food storage and shipping Homes and gardens account for 8 of the pesticides used in US Italy and Germany use about one fifth as much Canada uses about one tenth as much About 90 of all pesticides worldwide are used in agriculture or food storage and shipping Herbicides 59 insecticides 22 fungicides 11 PESTICIDE TYPES Inorganic pesticides arsenic mercury copper lead Highly toxic indestructible biocides most of them are neurotoxins and a single dose can cause permanent damage Natural organic pesticides or quotbotanicalquot nicotine alkaloids pyrethrum turpentine and phenols Extracted from plants Some are biocides Fumigants carbon tetrachloride ethylene dichloride ethylene dibromide etc They gasify easily and are extremely dangerous to humans and animals Most have been banned Chlorinated hydrocarbons DDT chlordane aldrin mothballs etc They are synthetic organic insecticides that affect neural signal transmission They persist in the soil for many years and accumulate in fatty tissues Many have been banned Organophosphates parathion melathion dichlorvos TEPP etc Extremely toxic to mammals birds and fish are derived from alkaloids and are an outgrowth of nerve gas research during WWII They inhibit a n enzyme needed to for removing excess neurotransmitter from synapses in the peripheral nervous system They are extremely toxic a drop of TEPP on the skin can kill a human They are used a herbicides and are biodegradable Carbamates or urethanes are similar to organophosphate including mode of action toxicity and low bioaccumulation Microbial agents and biological control They are living organisms or toxins derived from them The BT used by the Pest Control Center in Memphis is derived from Bacillus thuringiensis Halogenated pyrroles are a new class of compounds based on naturally occurring microbial toxin They have been considered to be a replacement for organophosphates They reduce egg laying and egg survival in ducks PESTICIDE BENEFITS Humans compete with other species for food and shelter and struggle to protect ourselves from disease 1 Disease control 0 Insects ticks lice etc are vectors of diseases 2 Crop protection 0 Postharvest losses often amount to 30 of the harvest 0 Cosmetic damage is reduced PESTICIDE PROBLEMS 1 Effects on nontarget species 0 Estimated that 90 of the pesticide does not reach their target 0 Many beneficial organisms are killed e g honeybees 2 Pesticide resistance and pest resurgence 0 Pesticides seldom kill 100 of the target species 0 Pesticide treadmill constantly increasing doses or use newer or more toxic chemicals in order to obtain the same result 0 Resistance transfer from one species to another 3 Creation of new pests o Beneficial predators keep the prey numbers down 0 When predators are killed prey may become a pest o Highertrophic levels are more likely to be affected by pesticides 4 Persistence and mobility in the environment 0 Bioaccumulation ground water contamination 0 Wind rain etc transport pesticide residue to distant places 5 Human health problems 0 Cancer birth defects immunological problems are long term effects 0 Shortterm effects include acute poisoning and illness ALTERNATIVES TO PESTICIDES 1 Behavioral changes 0 Crop rotation keeps pest populations from building up 0 Habitat diversification hedgerows windbreaks etc o Flooding fields and burning crop residues before planting 2 Biological controls 0 Predators wasps ladybugs praying mantises and pest pathogens o Insect repelling plants marigolds garlic basil and peppermint 0 Genetic engineering e g sterile males resistant species 3 Integrated Pest Management IPM 0 Uses a combination of techniques applied at specific times 0 Mechanical means minimum use of pesticides 0 Pest monitoring to determine economic threshold the point when potential economic damage justifies pesticide REGULATING PESTICIDES Over 500000 metric tons of pesticides are used in the United States every year These pesticides contain over 600 active ingredients combined with 1200 presumably inactive carriers solvents preservatives etc They are marketed in about 25000 commercial products Three federal agencies share the responsibility for regulating pesticides used in food production These federal agencies are 1 Environmental Protection Agency EPA It regulates the sale and use of pesticides o The Federal Insecticide Fungicide and Rodenticide Act FIFRA regulates the sale and use of pesticides It mandates the registration licensing of the substance 0 Federal Food Drug and Cosmetic Act FFDA sets tolerance levels or limits on the amount of pesticide residue may remain on or in foods 0 Based on scientific studies the EPA determines which pesticides will not pose significant risks to human health or the environment when used according to label directions 2 Food and Drug Administration FDA 0 Enforce pesticide and use and tolerance levels set by the EPA 3 Department of Agriculture USDA o Enforce pesticide and use and tolerance levels set by the EPA In Canada Agriculture Canada performs functions similarto the EPA through the Pest Control Products Act and Regulations The Food Quality Protection Act passed by Congress in 1996 directs the EPA to pesticide tolerance levels based on potential aggregate pesticide exposures o This Act requires that the EPA reassess 9700 pesticides by 2006 in order to include their cumulative impact on children lnert ingredients are used to dilute ortransport the pesticides Underthis Act inert ingredients will be also assessed for their impact on humans About half of the inert ingredients that have been studied are carcinogenic occupation hazards or air and water pollutants The EPA is also studying hormonedisrupting chemicals Wood preservatives are pesticides especially dangerous to children These preservatives prevent the growth of molds invasion by termites etc 38 of the fruit and 12 of the vegetables consumed in the US come from abroad but only about 2 ofthese are inspected by the FDA The Province of Quebec Canada has banned the use of most nonfarm pesticides in the province beginning in 2005 0 Many people fear the we are exposed to too many dangerous chemicals 0 Industry claims that it cannot operate without them 0 Eating organic food does no protect the individual from all risks Microbes are present in organic food ChapterS What is a biome A major regional type of ecosystem biogeographical region characterized by distinctive climate and soil conditions and a distinctive biological community adapted to those conditions Temperature and precipitation are major determinants in biome distribution Mountains influence the biological community of a region Biological productivity varies greatly from one biome to another TROPICAL RAINFOREST Precipitation above 200 cm 440 in evenly distributed Temperature 22 to 32 C the year round They occur within the equatorial zone Very little temperature oscillation and high humidity are characteristic a very stable environment 0 Light intensity near the ground is very low Day and night are about the same length 0 Diversity is high many species represented by very few individuals 0 Lianas climbers stranglers and epiphytes are abundant See httpWWW 39 nrnnaIIPryphpmphoto9ampb0ampsrch in 39 A 39 v k v o Parasitic plants See httpwww emn ndx 39 quot quot39 quot quot inn 0 Large mammals are few Many amphibians and reptiles adaptations to arboreal life Source httpwwwrlmet 39 quotLASSESGEOG235biomesrainforestrainfrsthtml TROPICAL CLOUD FOREST 0 Found high in the mountains of the tropics Mist and fog keep the vegetation wet all the time o Temperatures are lower than in the tropical rainforest See httpwww quot nrnnallervphpmphoto23ampb0ampsrch strnqtropical20cloud20fo restampsrchyes httpwww quot nrnnallervphpmphoto433ampb0ampsrch strnqtropical20cloud20f orestampsrchyes TROPICAL SEASONAL FOREST Average temperature is similar to that in the rainforest Precipitation is unevenly distributed with dry and rainy seasons The dry season may be up to six months Vegetation with a large proportion of semideciduous trees during the dry season 0 Vegetation is shorter in stature and simpler in complexity See httpwww radfnrd 39 quotl ASSESGEOG235biomessavannadrIforsthtml GRASSLANDS PRAIRIES AND SAVANNAS Precipitation 20 to 60 cm 10 to 20 in Rain usually occurs in late spring and early summer Average temperature all latitudes ln temperate grasslands summertemperatures can be well over 38 C 100 degrees Fahrenheit while winter temperatures can be as low as 40 C 40 degrees Fahrenheit Grasses and forbs broad leaf herbaceous plant are the dominant vegetation shrubs and trees along streams and rivers Abundant vegetative growth protects and enriches the soil making it among the richest farmlands in the world Large herds of herbivores dominate with their 39 and g TEMPERATE GRASSLANDS Temperate grasslands have rich soils Their communities are a mixture of grasses and herbs Deep roots allow these communities to survive heat cold drought and fire Source39 hftn39lwww runet quot quot IA F lGFr 39 quot html hftn39lwww licmn herkelev 39 html Interesting sites hftn39llwww nine 4 39 A 39 IA F IGFr 39 html Grasslands are known throughout the world by different names prairies pampas steppes and veldt The rise of the Rocky Mountains caused a rain shadow that favored the development of grassland on their eastern side The soil is very rich and most grasslands have been converted to agriculture mostly grains corn wheat barley and other cereals Overgrazing is destroying the grasslands in many parts of the world including the American west DESERT Low precipitation and high evaporation The potential to lose water by evaporation exceeds precipitation Precipitation 0 to 25 cm 0 to 10 in Infrequent and unpredictable from year to year Average Temperature a latitudes Vegetation made of succulents shrubs and small trees Some plant adaptations are leaves educed to spines thick epidermis waterstorage tissues Vegetation varies with the amount of annual rainfall Animals with behavioral physiological and structural adaptations to conserve water find and store food and lose heat Vrrlyk MMuhave Greatbasm WSonoran 05er unumcrrrhuahuan i W 2 Me k B Interesting pictures htt IIheliosbtoedacLIklbtoldesbiomelcactihtmitto htt IIheliosbtoedacuklbtoldesbiomelmam alhtmTOP c uklbtolde olo alhtmto htt IIheliosbtoeda melec Deserts are very vdrnerabre to drsrdrbance prams grew very srovvry sorr recovers army CHAPARRAUMEDITERRANEANITHDRN SCRUB FOREST The manner rs haramerrzed by hut dry summer and eererr vatvvrntErs Temperature rrry dd erverzm c Frres are eurnrnern durmg the dry seasun feet Shrubs dumrnate me randseape the Cape Tuvvn area err Serum Afrrca the Wes tem up err Austraha and the eerasrar areas errme Medrterranean See mtg vwwv rreeas HESb edurreasvrebkrdsbrurneehagarrar mm TEMPERATE RAINFDREST Premprtatrun 25m ernmuu rn u en rnthefurm errrerg cundensatmn Temperaturesare rnrrd cddr ramyfurest u en eervered byfug and rervv erddds sdd rs rrch rn numents Pedwrrnd hpm nrk abundant Dummantmamma s are mu e deep mghem sheep muuntam Quiet and em Wum fux cuyutes bears and We ven39ne are the predaturs Suur mt vvvwvmfuramu abuut emmm ee m Unumcumm ca state a Educuursesbu ders EssunsNessbmmesramfuresmem ramtern r am htm BROADLEAVED DECIDUDUS FOREST Prempwtatmn EDIE 17D em Temperature 771 2B C Prexvmtyte the eeean creates de Wmters A Nth bmme vth many mam spemes nak map e ehesmup at Cump ex stramcatmn abuut ve sirata Decwduuus vegetater uf rmxed spemes eharamenzes ms bmme Whnetau dean mack bean Wum fux raccuuns are me eemmen mamma s m Nunh Amenea T e dummant bmme m Eas LEm Nunh Amerma must uf Eurupe Eas LEm Chma Japan eemrax and suuthem CW2 n s heav y cumvated Source httpwwwrlmet quot LASSESGEOG235biomestbdftbdfhtml TAIGA OR BOREAL FOREST 0 Found between 45 and 60 north latitude The growing season is short less than 130 days 0 Precipitation 40 to 100 cm 18 to 50 in mostly in the form of snow 0 Average temperature 40 to 15 C Winters are long and very cold 0 Soil is acidic thin and nutrient poor Bogs muskegs occur in depressions where drainage is poor 0 Very large numbers individuals of very few species of plants mostly conifers needle leaf trees eg spruce fir pine Broad leaf trees are found mixed with the conifers 0 Dominant animals are the moose caribou whitetail deer brown bear wolf fox lynx rabbit owl hawks warblers etc Source httpwwwrlmet quot LASSESGEOG235biomestaiqatai ahtml TUNDRA 0 Far northern latitudes arctic tundra and very high mountain latitude alpine tundra o Precipitation 5 to 25 C 0 Temperature 25 to 8 C 0 Water may be abundant but is locked up in ice and snow 0 Permafrost the frozen soil below the thawed surface There is little drainage as a result 0 Growing season is short 6 to 8 weeks Winters are long and harsh Only the upper layer of soil thaws out in the summer below that the permafrost remains Ponds lakes and bogs are common in the summer time o A grassland type of vegetation lichens grasses mosses sedges and dwarf woody plants dominate vegetation There is little diversity of species but large number of individuals of the same species One stratum of vegetation 0 Large animals found in the tundra are musk ox caribou polar bear wolf fox seals and abundant bird life in the summer Many animals migrate south during the winter and return to breed during the short summer months 0 Animals of the arctic tundra have morphological thick stocky bodies abundant fur and plumage and physiological adaptations ability to accumulate large amounts of fat 0 Alpine tundra occurs at very high altitude throughout the world where trees cannot grow 0 Alpine tundra is exposed to high ultraviolet radiation high ground temperature during daytime and freezing temperature at night 0 Alpine soil is usually windswept and rocky The terrain is sloping and well drained in contrast with the high latitude tundra o Drought is a problem due to the combination of sun slope soil and air currents 0 Animals found in the Alpine tundra are mountain sheep elk pikas marmots and grouse like birds Source httpwwwrlmet quot LASSESGEOG235biomestundratundrahtml 1 Interesting sites httpwww uan herkelev loss5biome quot html httpwwwrlmet LASSESGEOG235biomestundratunillhtmlsed e AQUATIC ECOSYSTE MS 0 Freshwater rivers ponds lakes swamps o Saline ocean salt lakes Basic needs of organisms o Photosynthesis carbon dioxide water light 0 Respiration oxygen sugar 0 Growth and maintenance mineral nutrients food Factors that influence the availability of needed materials Bottom characteristics muddy rocky sandy lnternal convective currents Connection or isolation to other aquatic ecosystems o Substances in solution oxygen carbon dioxide phosphates o Suspended matter turbidity silt plankton 0 Depth 0 Temperature 0 Rate of flow 0 O 0 Deep lakes have a thermocline mesolimnion or a temperature transition zone that separates an upper warm zone from a lower cold zone MARINE ECOSYSTEMS Oceans cover about three fourths of the earth s surface The ocean can be divided into zones Vertical stratification occurs in the ocean and is a key feature of the ecosystem Phytoplankton is usually singlecelled minute floating photosynthetic organisms that drift throughout the surface waters of the ocean Phytoplankton is restricted to the photic zone ofthe ocean The composition of phytoplankton changes with time and place due to seasonal and geographic variations in light temperature nutrients and grazing by zooplankton Stratification A Pelagic region the large body of water the water column Vertical layers of the pelagic region 1 Photic or epipelagic zone 0 From the surface down to about 200 meters 0 Sharp gradients of light temperature and salinity l Mesopelagic zone 0 200 to 1000 meter deep 0 Little light penetrates and gradual changes in temperature 0 An oxygenminimum layer and a high concentration of nitrates and phosphates 3 Bathypelagic zone 0 Total darkness 0 Temperature is low 0 Great pressure 0 Depending on location depth varies between 100 700 m and 2000 4000 meters 4 Abyssal zone covers the broad ocean plains down to 6000 m 5 Hadal zone the benthic region in the trenches between 6000 and 10000 m B Benthic region the bottom Open ocean communities usually have low productivity The first hydrothermal vent was discovered in 1977 They are known to exist in the Pacific and Atlantic oceans Most are found at an average depth of about 2 100 meters 7 000 ft in areas of seafloor spreading along the MidOcean Ridge system the undenIater mountain chain that snakes its way around the globe How do hydrothermal vents form In some areas along the Mid Ocean Ridge the gigantic plates that form the Earth s crust are moving apart creating cracks and crevices in the ocean floor Seawater seeps into these openings and is heated by the molten rock or magma that lies beneath the Earth s crust As the water is heated it rises and seeks a path back out into the ocean through an opening in the seafloor As the vent water bursts out into the ocean its temperature may be as high as 400 C 750 F Yet this water does not boil because it is under so much pressure from the tremendous weight of the ocean above When the pressure on a liquid is increased its boiling point goes up Chimneys top some hydrothermal vents These smokestacks are formed from dissolved metals that precipitate out form into particles when the superhot vent water meets the surrounding deep ocean water which is only a few degrees above freezing Socalled black smokers are the hottest of the vents They spew mostly iron and sul de and copper sul de which combine to form iron monosul de This compound gives the smoker its black color White smokers release water that is cooler than their cousins and often contains compounds of barium calcium and silicon and zinc sulfide which are White httpllwwwoceanudeleduldeepseallevel2lgeologylventshtml University of Delaware College of Marine Science The hydrothermal vents heat the surrounding water to 8 16 C Water at this depth is about 2 C Associated with these vents new life forms have been discovered 3 new orders and 22 new families 97 of the 293 species of vent animals described so far are endemic to the vent habitat The primary producers are chemosynthetic bacteria that oxidize the reduced sulfur compounds such as H28 to release energy which they use to form organic matter from carbon dioxide Chemosynthesis process in which carbohydrates are manufactured from carbon dioxide and water using chemical nutrients as the energy source rather than the sunlight used for energy in photosynthesis TRANSITIONAL COMMUNITIES CORAL REEFS form in clear warm tropical seas They are the accumulated skeletons of corals and the deposits of calcareous algae The reefs are made of calcium carbonate Coral lives where light penetrates and have photosynthetic algae in their tissues About 34 of the coral reefs in the world have destroyed or seriously damaged ESTUARIES bays or semienclosed areas of brackish water where rivers meet the ocean They are usually calm warm and nutrient rich they tend to have great diversity and productivity A great majority of marine fish and shellfish rely on estuaries to spawn and juvenile development BARRIER ISLANDS are narrow sandy islands parallel to the coast they are formed where the continental shelf is shallow and nearby rivers provide sediments they are very important in protecting the continental shoreline wetlands and estuaries The narrow strip of sea between the islands and the coast usually has low salinity DELTAS are formed at the river mouths when the continental shelf is shallow and the sediments brought by the riverform a broad fanshape sediment deposit Deltas are often channeled by branches of the river creating extensive wetlands that are part of the larger estuarine zone OCEAN SHORELINES including rocky shore sandy beaches and offshore barrier islands are particularly rich communities in life forms Barrier islands protect the coast from the surf especially during storms Common along the Atlantic and Gulf coasts of North America FRESHWATER ECOSYSTE MS LAKES have vertical zones the epilimnion is the area mixed by the wind and warmed by the sun the hypolimnion is below dark and cold the thermocline is a sharp temperature boundary that separated the epilimnion from the hypolimnion the bottom is called the benthic zone Lakes are much influenced by the surrounding land that contributes nutrients and suspended matter 0 Thermocline sharp temperature change between surface and deep water Aquatic communities are affected by nutrient availability or excess suspended matter silt etc depth temperature currents bottom characteristics connection or isolation from other bodies of water WETLANDS ecosystems where the land is saturated or covered with standing water at least part of the year eg swamps marshes bogs and fens Wetlands convert to terrestrial communities through sedimentation and draining They provide essential ecosystem services including floodwater storage and water purification o Swamps are wetlands with trees Marshes are wetlands without trees 0 Bogs are saturated ground usually composed of accumulated undecayed vegetation and fed by precipitation o Fens are bogs fed by ground water and have a high mineral content HUMAN DISTURBANCE Humans disturbed more than the world s terrestrial ecosystems Humans preempt bout 40 of the primary productivity of the biosphere either by consuming it directly by interfering with its production or use or by altering the species composition or physical processes Conversion of natural habitats to human uses is the largest single cause of biodiversity losses Humans have disturbed mostly forests grasslands and wetlands o Grasslands have been converted to agriculture eg wheat corn etc o Temperate forests have become cities and farms 0 Wetlands have been drained filled and converted to agriculture aquaculture and human habitation lslands like Java Madagascar and Haiti have lost over 99 of their natural cover The Artic tundra and Antarctica are the least degraded ecosystem but still strongly affected in an indirect way ENVIRONMENTAL HEALTH AND TOXICOLOGY Chapter 8 HEALTH AND TOXICOLOGY Health is a state of complete physical mental and social well being not merely the absence of disease What is a disease A disease is an impairment of the normal body functions a deleterious change in the body39s condition due to environmental factors Environmental health focuses on the environmental factors that could cause a disease These factors could be nutritional chemical biological and psychological A disease could also be a genetic anomaly Morbidity means illness or rate of sickness GLOBAL DESEASE BURSEN Mortality data was used in the past to assess the world health This information does detect the impact of nonfatal diseases on society Absenteeism due to illness impacts the entire society eg no work no planting no learning etc The disabilityadjusted life years DALY is now used by health agencies to measure the disease impact burden on society DALY combines premature death and loss of a healthy life due to illness or disability Cardiovascular diseases and cancer have become the major killers in the world including in developing and poor countries People in poorer countries are adopting the life styles and diets or richer countries resulting in an increase in cardiovascular diseases cancer depression and chronic lung diseases The National Institute of Environmental Health Sciences NIEHS is taking an active role in identifying environmental factors that contribute to obesity one of the nation s most serious health trends Environmental factors being considered include community designs that discourage physical activity limited access to affordable and healthy food choices lifestyles that rely on convenience foods increased time spent in sedentary activities such as viewing television and using computers chemicals in the environment that may affect weight gain interactions between genes and the environment that favor weight gain Source httn39llwww niehs nih quot 39 quot 39 quot nrlf TYPES OF HEALTH HAZARDS 1 INFECTIOUS ORGANISMS Pathogens are diseasecausing organisms Infectious diseases kill 22 million peopleyear or 43 of diseaserelated deaths Bacteria viruses protozoans nematodes and fungi are the most common pathogens Respiratory pneumonia tuberculosis influenza Gastrointestinal diarrhea dysentery cholera Malaria infection of RBC by the protozoan Plasmodium Giardia is a parasitic intestinal protozoan that may be the largest cause of diarrhea in US World Health Organization estimates that 30 million people are infected with the HIV virus Parasitic nematodes and flatworms are debilitating and lead to other health problems e g schistosomiasis onchocerciasis filariasis flukes Parasites most often do not kill but debilitate the individual The quality of life is reduced From a historical perspective cholera smallpox and plague are examples of infectious diseases that spread globally with devastating impact often occurring during periods of rapid economic change or population growth Emergent diseases are those that were not known before orthat have been absent for at least 20 yeast 0 Emerging infectious diseases are diseases of infectious origin whose incidence in humans has increased within the past two decades orthreatens to increase in the near future 0 Ebola virus HIV Marburg fever Many factors or combinations of factors can contribute to disease emergence Newly emergent infectious diseases may result from changes or evolution of existing organisms known diseases may spread to new geographic areas or new human populations previously unrecognized infections may appear in persons living or working in areas undergoing ecological changes such as deforestation or reforestation that increase their exposure to insects animals or environmental sources that may harbor new or unusual infectious agents ABSTRACT When the underlying causes and mechanisms of emerging infectious disease problems are studied carefully human behaviour is often involved Even more often the only methods of control or prevention available are to change human behaviour Several major recent emerging disease problems can be cited l t is sometimes emphasized that it is human carelessness human excesses human ignorance or human habits of conquest or leisure which contribute directly to the biological niches that microorganisms are all too capable of exploiting We must look at ourselves as the engines of microbial opportunism l t is not likely that we will ever conquer the microbial world we must look instead to control the human factors that contribute to emergence Source httn39llwww emrn who intlquot 39 quot quot EMHJl0201lO3htm The great influenza epidemic of 1918 killed between 30 and 40 million people around the globe o It probably is the largest loss of life from an individual disease in a single year Highdensity population increases the chance of contamination and infection due to increase contact pollution and lack of hygiene Emerging infections such as acquired immunodeficiency syndrome AIDS and TB vividly illustrate that no nation can be complacent regarding human vulnerability to the microorganisms with which we share our environment Since the early 1970s the US public health system has been challenged by many newly identified pathogens and syndromes such as Lyme disease Legionnaires39 disease toxic shock syndrome human immunodeficiency virusAIDS hepatitis C virus cryptosporidiosis and most recently hantavirus Examples of Emerging Infectious Diseases United States 1993 E coli O157H7 disease Cryptosporidiosis Coccidioidomycosis Multidrugresistant pneumococcal disease Vancomycinresistant enterococcal infections Influenza ABeijing32l92 Hantavirus infections Examples of Emerging Infectious Diseases Outside the United States 1993 Cholera in Latin America Yellow Fever in Kenya Vibrio cholerae 0139 in Asia E coli O157H7 in South Africa and Swaziland Rift Valley Fever in Egypt Multidrugresistant Shigella dysenteriae in Burundi Dengue in Costa 39ca Diphtheria in Russia Avian virus Antibiotic and pesticide resistance strains have appeared in many parts of the world Natural selection and the ability of many organisms to evolve new forms are responsible for the emergence of many diseases that were under control a few years ago Highly pathogenic avian influenza Viruses of the H5N1 subtype are circulating in eastern Asia with unprecedented epizootic and epidemic effects 1 Nine Asian countries reported H5N1 outbreaks in poultry in 2004 Cambodia China Indonesia Japan Laos Malaysia South Korea Thailand and Vietnam 1 Between 2004 and the first3 months of 2005 a total of 89 laboratoryconfirmed human infections 52 of which were fatal were reported to the World Health Organization WHO bypublic health authorities in Vietnam Thailand and Cambodia These records indicate that this outbreak of human H5N1 infections is the largest documented since its emergence in humans in 1997 2 Efficient viral transmission among poultry caused the Virus to spread regionaly leading to the loss of gt100 milion birds from disease and culling In contrast humanto human transmission of the virus is exceptional but has been described most recently in a family cluster in Thailand Q Source httpwwwchqovncidodElDvol11no10050644htm Other sources httpwwwcdc 39 39 quot quot quot 39 iphtmm httpwwwniaidnihgovdmideiderdhtm the World Health Organization estimates that 90 of all disease burden occurs in developing countries where less than one tenth of all health care dollars is spent Millions of people are dying of treatable infections and parasitic diseases 0 2 of people with AIDS have access to modern medicines 0 600000 infants acquire HIV every year through mothertochild transmission during birth or breast feeding o Wealthy countries spend about 1 per person per year on global health Improving health in poor countries may help prevent the spread of emergent diseases in globally interconnected world will help to prevent mass social instability and the spread of pathogens across borders may help to reduce population growth by helping infants survive Ecological diseases Domestic animals and wildlife suffer from epidemics Some pollutants disrupt hormone function and reduce immunity in animals Chronic wasting disease CWD is spreading in deer and elk in North America It is caused by a prion a protein that belongs to the family of the madcow disease and CreutzfeltJacob disease in human o It was first identified in Saskatchewan Canada in 1967 Oaks Douglas fir and redwoods are being infected with a fungus that causes death These are commercially valuable trees Coliform bacteria has been found in corals dying of blackband disease caused by cyanobacteria bluegreen alga Scientists suspect a connection between the human coliform bacteria and the cyanobacteria outbreak o This coral disease was first detected in the early 1970s Domoic acid is produced by a marine phytoplankton This chemical is nerve toxin that kills marine mammals and birds Algal outbreaks have been caused by agricultural fertilizers washed to the sea Antibiotic and pesticide resistance Natural selection and ability of many organisms to evolve rapidly has spread pesticide resistant species Many pests and pathogens have been exposed only minimally to control measures allowing those with natural resistance to survive and spread their genes through the population 0 This is a case of a bottleneck effect caused by pesticides TOXICOLOGY Toxicology is the study of toxins in living systems Toxins are poisons Toxicology is broad filed that includes biochemistry histology pharmacology and other fields of biology and chemistry Toxins react with cellular chemicals and disrupt metabolic functions Some of their damage can be irreversible Toxins can be dangerous even in very small amounts eg on trillionth of a gram All toxins are hazardous but not all hazardous materials are toxic Hazardous materials include explosives acids irritants caustic etc Some are hazardous only in large quantities They could be natural or synthetic 0 Hazardous dangerous Toxins poisonous specific or general Allergens activate the immune system causing hypersensitivity e g formaldehyde sick building syndrome Immune system depressants lower or suppress the immune system increasing susceptibility to opportunistic infections e g several pesticides Endocrine disruptors are synthetic chemicals that block mimic or otherwise interfere with naturally produced hormones the body39s chemical messengers that control how an organism develops and functions 0 Endocrine disruptorrelated effects interrupted sexual development thyroid system disorders inability to breed reduced immune response and abnormal mating and parenting behavior 0 Species such as terns gulls harbor seals bald eagles beluga whales lake trout panthers alligators turtles and others have suffered more than one of these effects o Neurotoxins are poisons that attack the nervous system e g mercury lead DDT some anesthetics like ether and chloroform o Mutagens damage the genetic material 0 Teratogens cause deformities and birth defects e g thalidomide alcohol Fetal alcohol syndrome is a common teratogen o Carcinogens cause cancer DIET There is a strong correlation between certain diseases and diet eg cardiovascular diseases and the amount of animal fat and salt in the diet Some dietary elements seem to have anticancer elements eg vitamins A C and E substances produced by cabbage cauliflower broccoli and the element selenium Certain groups of people seem to live much longer than the rest up to 120 to 140 years old These groups have in common Clean air and water Little stress due to uniform and predictable life Dry and sunny climate at middle altitudes Active and vigorous life in nonindustrialized setting All ages work together for the benefit of the community The elderly are respected Family shares in work religion and recreation Low fat diet rich in fiber and vegetables and fruits MOVEMENT DISTRIBUTION AND FATE OF TOXINS Chemicals move through he ecosystem Chemical composition solubility stability and reactivity are important Availability of a vehicle such a solvent to carry the toxic agent is important Stability and storage characteristics of toxic agent are determining factors of toxicity for certain chemicals eg short live in the environment SOLUBILITY and MOBILITY Chemicals can be fatsoluble or watersoluble Watersoluble chemicals move fast through the environment due to the abundance of water in the ecosystem Fatsoluble or oilsoluble substances need a carrierto move through the environment Once in the fatsoluble molecules penetrate the tissues they tend to accumulate in lipid deposits where they will not be degraded by metabolic reactions Exposure and Susceptibility Airborne toxins generally cause more ill health than any other exposure source The lining of the lungs which is designed to exchange gases also absorbs toxins readily The largest exposure for many toxins are found in industrial settings where workers may encounter doses thousands of times higher than would be found anywhere else Time of the exposure and health of the organism have strong influence on toxicity 0 Healthy adults may not be affected by doses that will be lethal to children or to those with a weakened immune system Bioaccumulation and biomagnification Cells can selectively absorb and accumulate certain chemicals 0 This is called bioaccumulation o eg nutrients minerals o Toxins can also be accumulated in body tissues and reach dangerous levels Biomagnification occurs when there is an increase in concentration of certain substances in successive higher trophic levels of the food chain Persistence Some chemicals are very unstable and degrade or break down easily Other substances are more stable and persist in the environment for a long time persistence o Eg many modern herbicides quickly lose their toxicity Persistent Organic Pollutants POPs are chemical substances that persist in the environment bioaccumulate and become magnified through the food web and pose a risk of causing adverse effects to human health and the environment Some of the most useful chemicals are valuable because they resist degradation o Eg DDT chlorofluorocarbons PVC plastics asbestos chlorinated hydrocarbon pesticides Chemical interaction Chemical interaction is a common phenomenon o Antagonistic interactions are those that interfere with the effects or stimulate the breakdown of other chemicals 0 Additive interaction occurs when the exposure to two substances results in twice the harmful effect when compared to those produced by those chemicals separately Eg Rats exposed to arsenic and lead show twice the toxicity of only one of these elements 0 Synergistic effects are the result of one substance increasing the harmful effects of another Eg Asbestos exposure increases the chances of cancer 20fold and so does smoking Asbestos exposure and smoking have a 400fold increase in cancer rates MECHANISMS FOR MINIMIZING TOXIC EFFECTS Most if not all materials can be poisonous under some conditions but most chemical have some safe level or threshold below which their effects are undetectable Taken in small doses most toxins can be broken down and excreted before they cause harm Metabolic degradation and excretion Organisms have enzymes that process waste products and environmental poisons to reduce toxicity The body has degradation excretion and repair mechanisms 0 The liver is great detoxification center where most of the degradation takes place 0 Kidneys are for excretion of degraded materials 0 Highcell replacement rate in some tissues eg skin lining of the gastrointestinal track blood vessels lungs and urogenital systems 0 Cells have enzymes that repair damaged DNA Defense mechanism that protect us from toxins and hazards early in life are selected for by evolution Factors or conditions that affect postreproductive ages like cancer or premature senility usually don t affect reproductive success or exert selective pressure Some tissues have high cellular reproduction rate that repair damaged caused by wear and tear or toxic chemicals MEASURING TOXICITY Toxicity is the virulence or pathogenicity of a substance SOME BASIC IDEAS ABOUT TOXICITY 1 quotThe dosage makes the poisonquot Paracelsus 1540 0 Concentration and volume 0 Not all chemicals behave the same way 2 How the chemical is delivered is important in determining the toxicity of a substance 0 Route rate and site of exposure 0 Duration and frequency of exposure 3 Different substances have different toxicity P Different species have different sensitivity to the same chemical or dosage due to differences in physiology ANIMAL TESTING Animal testing is the most commonly used and widely accepted toxicity test 0 Time consuming o Expensive o Often painful and debilitating to the animal New tests involving cell culture and computer models are being developed Toxicity tests are set to determine the dose to which 50 of the test population is sensitive In the case of a lethal dose LD it called LD50 Difficulty in assessing results Of 226 chemicals that cause cancer in rats and mice 95 cause cancer in one species but not the other A problem for regulators and politicians is whether we should set pollution levels that will protect everyone including the most sensitive people or only aim to protect the average person Toxicity ratings Estimates of health risks for large diverse populations exposed to very low doses of extremely toxic materials are inexact due to 0 Biological variation 0 Experimental error 0 Necessity of extrapolating from results with small populations of laboratory animals Supertoxic chemicals may kill with a dose of a few micrograms 1 x 10396 gram one millionth of a Very toxic take 001 gram or a few drops Moderate toxic substance takes about 1 gram per kilogram 22 pounds of body weight to kill a person Acute versus chronic doses and effects Acute effects are caused by a single dosage exposure and results in an immediate health crisis 0 The individual often survives o The effects disappear they are reversible Chronic effects can result from a single dosage of a very lethal poison or by receiving sublethal doses repeatedly 0 Permanent or long lasting 0 Longlasting exposures are also referred as chronic even if their effects do not persist after stopping the exposure to the toxin It requires very large populations of experimental animals to obtain statistically significant results for lowlevel chronic exposures Organisms may have defense mechanisms that inactivate the toxin or repair the damage 0 In these cases a minimal dose must be necessary before any harmful effects can be detected There is a threshold Very small amounts are not harmful to the animal There is no need to keep the exposure to zero Detection limits Twenty years ago we could detect parts per million Now we can detect parts per trillion Advances in technology may lead to the perception that toxic chemicals are now more widespread than a few years ago o It is true for some chemicals but not for all RISK Risk is the probability of harm times the probability of exposure Risk assessment is the scientific process of estimating the threat that particular hazards pose to human health This process includes risk identification dose response assessment exposure appraisal and risk characterization 0 Exposure assessment is the estimation determination of the magnitude frequency duration and route of exposure to a possible toxin Factors that affect our perception of risks in a given situation 1 Social political or economic interests tendency to downplay some factors and to emphasize others 2 Many people do not understand probabilities and the role of chance 1 in a million risk 3 Personal experience is often misleading If we have not experienced something we tend to think that it is rarer than it actually is 4 An exaggerated view of our own abilities to control our fate 5 News media gives a biased perspective on the frequency of certain health hazards overreporting or underreporting 6 lrrational fear of or distrust of certain technologies eg nuclear power We tend to react more to emotion than to statistics The Environmental Protection Agency generally assumes that a risk of 1 in l million is acceptable for most environmental hazards We tend to accept greater risk in activities we enjoy or find profitable Our perception of risk is strongly affected by whether risks are known or unknown whether we feel in control of the outcome and how dreadful the results are SETTING STANDARDS FOR ENVIRONMENTAL TOXINS We need to consider 1 The combined effects of exposure to many different sources of the toxin 2 The different sensitivities of members of the population 3 The effects of chronic and acute exposures SOME QUESTIONS 1 Which are the most dangerous environmental factors that we face 2 How can we evaluate the hazards of all the natural and synthetic chemicals that now exist 3 What risks are acceptable Chapter 17 WATER USE AND MANAGEMENT The Earth is the only planet in the universe as far as we know where liquid water exists in substantial quantities Water is essential to life Water is The medium in which life processes occur Nutrients are dissolved and distributed to cells Regulates body temperature Supports structures Removes waste products Every day 43000 housesize ice comets enter the Earth s atmosphere and melt adding about 40 tons of water to the atmosphere Water covers more than 70 of the earth s surface The total amount of water on the Earth is about 370 billion gallons or 1404 million km3 About 98 of the water in the world is salt water found in the oceans 99 of the fresh water is locked up in ice and snow or buried as ground water Bodies of fresh water rivers lakes ponds etc make about 001 of the all the water in the world HYDROLOGIC CYCLE This is the movement of water between ocean atmosphere and land It constantly purifies and redistributes fresh water Physical processes that make it possible are Evaporation liquid is changed to gas vapor Sublimation change from solid to liquid Condensation gas changes to liquid Precipitation falling of liquid water upon the surface of the earth Plants absorb water from the ground and pump it into the atmosphere by a process called transpiration Air can support so much water vapor at a given temperature Relative humidity is the amount of water vapor in the air at a given temperature expressed as a percentage of the maximum amount The amount of water vapor in the air increases with temperature The maximum amount the air can hold at a given temperature is called the saturation point Dew point is temperature at which condensation occurs for a given amount of water vapor the temperature at which the air becomes saturated BALANCING THE ATER BUDGET Evaporation is highest near the equator More water evaporates over the oceans than over land 80 of an estimated total of 496000 km3 of the water evaporated by the sun About 90 of the water evaporated from the oceans return to the oceans in precipitation The remaining 10 falls on land Rain falls unevenly over the earth Reasons A Global atmospheric circulation creates regions of persistent high air pressure and low rainfall about 20 and 40 north and south of the equator N When the prevailing winds come from the ocean they bring moisture to the land 9 Mountains help in the formation of clouds and act as rain catchers As air moves up the windward side of a mountain it cools and the relative humidity increases Eventually the air becomes saturated and rain falls and the relative humidity decreases The air becomes cooler and drier and continues to move to the leeward side of the mountain As it descends it warms again and reduces the relative humidity further This warm air has a drying effect upon the land The dry area on the leeward side of the mountain range is called the rain shadow DESERT BELTS Hot air over the equator rises cools and drops its moisture as rain This drier air moves toward the poles it contracts and moves downward toward the earth surface along the tropics of Cancer and Capricorn It becomes warmer as it descends This hot and dry air causes high evaporation on the subtropical regions of the earth and creates the great deserts on all continents About 10 of the water evaporated from the oceans fall upon the land The rest is returned to the oceans as precipitation MAJOR WATER COMPARTMENTS Oceans Oceans contain 976 of all the liquid water in the world They contain 90 of the living biomass Oceans have different composition climatic effect and surface elevation They play a crucial role in moderating temperature They are too salty for human use In high latitudes surface water is cold and denser This water sinks to the bottom and move toward the equator Warm water on the equator sits on top of this cold water forming sharp boundaries Oceans absorb and store heat energy Water has unique properties in heat absorption and energy of vaporization These properties help to maintain the planet s temperature relatively constant 0 Redistribution of heat that results from the massive evaporation precipitation and transport of water is a major factor in keeping world temperatures relatively constant and making the world habitable Glaciers Ice and Snow 23 of the liquid water in the world is fresh water About 207 is tied up in glaciers ice caps and snowfields Antarctica holds about 85 of all the ice in the world There is no land on the North Pole The ocean here is covered with a sheet of ice Groundwater 028 of the liquid water in the world is held in the ground as groundwater Water percolates down the soil infiltration through the zone of aeration and accumulates in the zone of saturation The upper boundary of the zone of saturation is the water table The water table undulates according to topography and subsurface geologic features Porous waterbearing layers of sand gravel and rock are called aquifers Aquifers are held in between two layers of impermeable rock Pressurized aquifers make artesian wells where it intersects the surface Recharge zones are areas where the infiltration of water into the aquifer occurs Rivers streams ponds lakes and wetlands Rivers and streams carry about 00001 of the liquid water in the world The discharge of a river is the volume of water that passes a specific point in a given amount of time The volume of water carried by a river its discharge is measured in cubic feetsecond or in literssecond o The Mississippi River has an average discharge of 14 million literssecond Ponds are temporary or permanents small bodies of water shallow enough for rooted plants to grow over most of the bottom Lakes are larger and deeperthan ponds Lake Baikal is the deepest lake in the world 1600 meters or 1 mile deep Lakes and ponds are eventually filled in dried up or drained by newly formed outlets Bogs swamps wet meadows and marshes play a vital role in the hydrological cycle Wetland vegetation slows down runoff and allow infiltration to take place into aquifers and zone of saturation Disturbed wetlands have a reduced water absorbing capacity httpwaterusgsgovnwsumWSP2425historyhtml httpwwwhumboldteduere deptmarsh Atmosphere The atmosphere holds about 0001 of the world water It has a very rapid turnover rate Movement of water vapor through the atmosphere provides the mechanism for distributing fresh water over the landmasses and replenishing terrestrial reservoirs WATER AVAILABILITY Runoff is the excess of precipitation over evaporation and infiltration it is the water left on the surface to flow or to accumulate in lakes 0 About 23 of the runoff water is lost as seasonal flow 0 About 13 of the runoff water is available for human use Only about 9000 km3 of water are available for human consumption South America and Asia have about 24 of the world land mass and receive about 25 of the global runoff Most of runoff in Asia occurs in areas suitable for agriculture This is one of the reasons why Asia has close to 60 of the world population In South America most of the runoff occurs in the Amazon jungle Kuwait and Bahrain do not have any runoff and depend almost completely on desalinized water Rainfall is never uniform and there are drought cycles 0 In the US the drought cycle seems to be about 30 years Drought cycles have their most devastating effect in semiarid zones Types of water use Withdrawal is the amount of water taken from a reservoir or river 0 Consumption is the fraction of withdrawn water that is lost in evaporation absorption chemical transformation or made unavailable as a result of human use 0 Degradation is a change in water quality due to contamination so that it is unsuitable for other services The three sectors that use most of the water are the domestic agricultural and industrial sectors Of the water we withdraw in the US about 110 is for personal use Agriculture uses about 69 of the water withdrawal 0 Irrigation methods are usually very inefficient o Evaporation or seepage loses 7090 of the irrigation water Worldwide industry accounts for about 25 of the water withdrawal Some industrialized European countries use about 70 of the water they withdraw Cooling water for power plants is the largest single industrial use of water 0 In US paper making food processing petroleum refining and metal smelting are major users of water 0 Developing countries allocate on the average 10 of their water withdrawal to industry FRESHWATER SHORTAGES Water shortages in many parts of the world result from o Rising demand 0 Unequal distribution 0 Increased contamination Arid zones are especially vulnerable to drought and land abuse by human and domestic animals Natural causes can cause water shortages drought hot winds Lake rivers and groundwater reservoirs are being depleted at an alarming rate Problems associated with the depletion of groundwater are Water shortage due lowering of the water table Subsidence of the surface land Sinkhole formation Saltwater intrusion INCREASING WATER SUPPLIES The amount of water on the earth is for all practical purposes fixed Desalination plants 0 It is three or four times more expensive than other sources of water 0 It is used extensively in Middle East countries Oman and Bahrain Dams reservoirs canals and aqueducts For the purpose of increasing the water supply and control floods Dams and reservoir fill in very fast with silt Destruction of human and wildlife habitat due to flooding by newly built dam Diversion of rivers have upset the balance of entire regions by drying up lakes International and domestic conflicts due to water rights WATER MANAGEMENT 1 Watershed management and conservation are often the most economical and environmentally sound ways to prevent floods and to store water 2 Domestic conservation 0 Toilet flushing is the largest domestic use of water 0 We use about 13000 gallons of drinkingquality water to flush toilets annually 9 lrrigation methods 0 Drip irrigation is very effective in avoiding water loss due to evaporation and reduces salt buildup 0 Improve the technology of cooling towers 4 Price mechanisms 0 Conservation is not attractive because of the low cost of water due to government subsidies 0 Federal water supply projects charge only for the delivery of water The building of the project is subsidized o If water users were charged the real cost for environmental damage and subsidies conservation would be more attractive 5 Recycling of water 0 Industrial water from cooling towers can be used most of the time for irrigation of parks golf courses street cleaning etc Chapter 7 HUMAN POPULATIONS HUMAN POPULATION HISTORY Human population was a few million people before the invention of agriculture and domestication of animals about 10000 years ago 50 million by 5000 B C 300 million at the time of Christ 6 billion in 1900 6 billion in 2000 About 63 billion in 2003 In October 10 2006 the world population was 665 billion The number of humans tripled during the 20th century It took 12 years to go from 5 to 6 billion people Check httbwww ihihlin quot 39 39 39 39 httpwww census quot 39 39 html httpwww census vmain 39 39 html LIMITS TO GROWTH SOME OPPOSING VIEWS THOMAS MALTHUS English clergyman and sociologist Wrote An Essay on the Principle of Population as it Affects the Future Improvement of Societyquot in 1798 0 Human population increases at an exponential rate Resources increase arithmetically or not at all Excess population will exhaust its food supply and collapse into crime starvation and eventually war Excess population growth is the cause of many social problems Human population can become stabilized through positive check famine disease and preventive checks anything that prevents human births He believed that people were too lazy and immoral to prevent births he opposed helping the poor Karl Marx disagreed with Malthus 0 Population growth is a symptom rather than the root of poverty resource depletion pollution etc The real causes of poverty are exploitation and oppression Workers will always provide if they have access to means of production and a fair share of the fruits of their work Social justice will slow down population growth and will alleviate crime disease starvation and environmental degradation NeoMalthusians believe that we are approaching the carrying capacity of the earth and that we should address the issue of surplus population directly by making birth control the highest priority NeoMarxians believe that the elimination of oppression and poverty through social justice and technology will solve population problems 1 Today Can technology make the world more habitable Food supplies have increased fasterthan population growth since Malthus time Politics rather than lack or resources have caused most of the terrible famines in the last two centuries Technological advances have increased the carrying capacity of the earth The increase in population we have seen was caused by the industrial and technological p In a sanitation and medicine Whether progress will continue remains to be seen 2 More people could be beneficial because More people means larger markets more workers mass production etc It provides more intelligence and enterprise New resources can be created through substitution o Is the problem excessive population growth or the inordinate consumption of the world39s resources by people in rich countries Some developingcountry leaders insist that instead of being obsessed with population growth we should focus on the inordinate consumption of resources by people in richer countries HUMAN DEMOGRAPHY The word demography is derived from the Greek demos people and graphos to write or to measure Two demographic worlds a Poor young growing rapidly developing countries in Asia Africa and Latin America b Rich slow growth or no growth at all North America Europe Japan Australia and New Zealand Many European countries and Japan have negative growth their populations are decreasing AIDS is killing many people especially in Africa Africa is still expected to reach one billion people by the end of the XXI century Population growth rates httpwwwphotiuscomwfb1999rankingspopulation growth 0htm El n t Whoa I m t 1 I qahtml httpwwwlexas growth rateasp I In H II 1 39 39 tapeo Fertility and Birth Rates The statistical studies of human populations relating to growth rate age structure geographic distribution etc and their effects on society and the environment Crude birthrate number of births in a year perthousand persons Total fertility rate number of children born to an average woman in a population during her entire reproductive life 0 Paternity in many cases is difficult to establish 0 Some demographers ague that more attention should be given to paternity because in some cultures men have more children than women multiple wives female mortality and extramarital affairs Zero population growth ZPG the number of births plus immigration equals deaths plus emigration o Adverse results of zero population growth are the lack of manpower to sustain the economy army and to support those retiring Crude death rate crude mortality rate number of deaths per thousand persons in a year Wealthier countries generally have mortality rates around 101000 Eg Costa Rica 41000 many young people in fast growing countries Eg Denmark 121000 more older people in slow growing countries 0 O O 0 There are proportionately more younger than elderly people in rapidly growing countries Check httpenwikipediaorgwikiList of countries by death rate Natural increase crude death rate crude birth rate Total growth rate includes natural increase immigration and emigration Doubling time divide 70 by the annual or total growth rate The world growth rate is 12 per year 0 What is the doubling time for the entire world Potential for longevity Life span and life expectancy describe the potential for longevity Life span is the longest period of life a particular species is known to have survived Life expectancy is the average age a newborn can expect to attain in a given society 0 It has risen steadily in most countries overthe past 25 years In the US life expectancy for men is 75 and for women 80 years 0 Declining mortality ratherthan rising fertility is the primary cause of most population growth 0 Social and environmental factors are responsible forthe decline in mortality ls life expectancy reaching a plateau or advances in science and medicine will extend longevity Demographic implications of living longer Dependency ratio number of nonworking compared to the number of working individuals in a population There is considerable worry that not enough workers will be available to support retirement systems Countries with a large number of prereproductive age people will continue to grow for several years even if the fertility rate decreases This is called the population momentum or echo boom Immigration and emigration The UN High Commission on Refugees reported in 2002 there were 198 million refugees who had left their country because of political or economic reasons there were also 20 million of displaced people in their own countries Without immigration the population of the wealthier nations would be declining POPULATION GROWTH OPPOSING FACTORS Pronatalist pressures These are factors that increase people39s desire to have children Children could be Sources of enjoyment pleasure and pride A help with household chores A source of current income A source of support for elderly parents A status symbol in society Society needs to replace members who die or become incapacitated This need is often codified in cultural and religious values that encourage having children Birth reduction pressures Factors that tend to reduce fertility 0 Higher education and personal freedom for women often results in decisions to limit childbearing o Desire for activities that interfere with childbearing 0 Cost of raising a child Education and socioeconomic status are usually inversely proportional to fertility in developed countries Birth dearth Birth dearth occurs when the birth rate falls below the replacement level Italy Russia Austria Germany Hungary Denmark Greece Spain Japan Singapore and Taiwan have negative growth There is a concern about falling military strength economic strength and declining social systems due to lack of soldiers workers and taxpayers Europe and North America populations have fallen from 22 of the world s population in the 195039s to 15 in the 198039s It is estimated that by the year 2030 Europe and North America will probably make up around 9 of the world population This might erode the powers of western democracies Toxins and endocrine hormone disrupters in our environment interfere with sperm production Lower sperm production may be the reason for fewer pregnancies in industrialized countries DEMOGRAPHIC TRANSITION Is the pattern of falling birth rates and death rates as living conditions improve due to economic development 0 This was first noted by the demographer Frank Notestein in 1945 Birth rate increases at first but then fall as societal improvements become permanent Populations grow rapidly during the time that death rates have already fallen but birth rates remain high It takes some years to change attitudes and values Stability is restored at a higher population level Most countries in northern and Western Europe went through demographic transition in the 19th or early 20th century There are signs that demographic transition is already in progress in many developing countries e g Morocco Colombia Mexico Jamaica Thailand Indonesia etc VIEWS OF THE FUTURE 1 Optimistic view birthrate is going down according to some demographers 0 Many developing countries have entered demographic transition 0 Fertility rates have fallen dramatically nearly everywhere in the world Factors that affect fertility rates are 0 Growing prosperity and social reform that reduce the need for large families 0 Communication has caused a rise in expectations that spur change 0 Less developed countries can learn from mistakes of the past 2 Pessimistic view developing countries are caught in a demographic trap that prevents them from escaping from the middle phase of demographic transition 0 Birth rate will continue to rise people will live longer and a catastrophe will occur in the future 0 Environmental deterioration due to human demands political instability and economic decline prevent these countries from completing modernization 3 Social Justice View a fair share of the world resources is the key to demographic transition 0 The world has enough resources but inequitable social and economic systems cause maldistribution of those resources 0 Focus on population growth alone will encourage racism and hatred of the poor 0 Poverty environmental degradation hunger etc are symptom of injustice ratherthan lack of resources 0 Establish fair system and do not blame the victims 0 Many developed countries were colonial powers and extracted the wealth to pay for their progress from the colonies 4 Ecojustice view considers the rights of humans and also other species 0 Ecojustice seeks an optimum number of humans at which we can provide a decent life while causing a minimum impact on other species 0 Converting landscape into urban and industrial parks crowds out species that have the right to exist When infant mortality is high families tend to have many children to ensure that some will survive to adulthood Reduction in infant mortality has often accompanied a drop in birth rate 5 Women s rights affect fertility Child survival usually results in fewer births When infant mortality is high parents tend to have many children to insure that some will survive to adulthood Land reform political rights opportunities to earn an independent income and improved health status of women often are better indicators of total fertility and family welfare than rising GNPgt Check httpwwwfan quot onn1htm FAMILY PLANNING AND BIRTH CONTROL Family planning allows couples to determine the number and spacing of their children 0 Barrier methods condoms diaphragm IUD intrauterine devices spermicides vaginal sponge Chemical methods pills implantable or injectable progesterone analogs Surgical methods vasectomy tubal ligation Filshie clip Mechanical methods IUD intrauterine devices Rhythm method abstinence from sexual contact during the fertile period of the woman Abstinence Abortion THE FUTURE OF HUMAN POPULATIONS Many demographers believe that the world population will become stabilized in the XXI century The total number of humans will be between 8 and 10 billion Birth rates have begun to fall in East Asia and Latin America South Asia is expected to start showing a decline in birth rate soon Africa will probably continue to increase in population in the 21 century Cultural changes needed to make family planning successful Improve the status of women and children Acceptance of responsibility for our own lives Social security and political stability 0 O O 0 Knowledge and availability of birth control Chapter4 BIOLOGICAL COMMUNITIES SPECIES INTERACTION WHO LIVES WHERE AND WHY Every living organism has limits to environmental condition it can endure Each environmental factor has a maximum and minimum level beyond which the species cannot survive or reproduce Some of these factors are temperature moisture light living space nutrients reproductive space nests caves salinity and acidity LIMITING FACTORS 0 Chemical and physical factors that limit the growth abundance or distribution of an organism 0 Environmental factors have both a maximum and minimum levels called tolerance limits Beyond these levels the species cannot survive This has been called Leibig s or Shelford s law afterthe scientists that first proposed it and modified it 0 We now recognize that the interaction of all these factors ratherthan a single one determine the distribution of many species CRITICAL FACTOR o The single environmental factor in shortest supply relative to the demand and closest to the tolerance limit of a species Sometimes the requirements and tolerances of species are useful indicators of specific environmental characteristics The presence or absence of that species can tell us something about the community and the ecosystem as a whole ENVIRONMENTAL INDICATORS o Organisms that are characteristic of a particular habitat because of its quality or set of conditions are called environmental indicators or bioindicators o Organisms bioindicators or physical factors that serve as gauge for environmental changes ADAPTATION The inheritable characteristics that enable an organism to survive in a given environment are called adaptations lndividual organisms adapt to changes in the environment giving them a range of tolerance Adaptation also operates at the population level through the inheritance of specific genetic traits that allow a species to live in a particular environment Evolution is a process by which populations of organisms change over time 0 Response to the environmental changes 0 Mutations changes in the DNA structure Natural selection is the mechanism by which evolution occurs It acts on preexisting genetic diversity created by mutations lt favors organisms with certain traits that allow them to survive and reproduce Mechanism of Natural Selection Individuals of a population vary from one another 0 Many more offspring are produced than will survive and reproduce There is competition between the members of the population for needed resources 0 Those best adapted survive and reproduce The environment exerts a selective pressure on populations of organisms by eliminating some individuals and allowing others to survive and reproduce This is called differential reproduction Examples of environmental factors that cause selective pressure and influence fertility and survivorship of organisms 0 Physiological stress due to temperature light pH etc o Predation including parasitism and disease 0 Competition 0 Overpopulation high density 0 Chance Selection acts on the individual Evolution and adaptation act the population level Selection can cause with similar origin to become different in appearance and habits o This is called adaptive radiation 0 Examples the finches in the Galapagos Islands marsupials in Australia In some cases organisms with different origin become similar in their appearance and actions 0 This is called convergent evolution 0 Examples flippers of dolphins and fins of sharks webbed feet of otters and ducks ECOLOGICAL NICHE HABITAT A description of the place or environmental conditions in which a particular organism lives Ecological niche is the description of the role a species play in a community It includes the resources it uses how it uses them and how it interacts with other populations 0 Type of food 0 How it relates to other species LAW OF COMPETITIVE EXCLUSION Not two species can occupy exactly the same niche and coexist in the same habitat for very long One group will gain a larger share of resources while the other will either migrate become extinct or change in such a way that it will minimize competition 0 The fundamental niche of a species refers to the entire range of conditions and resources available to be used and exploit if there were no competition 0 Competition can decrease the fundamental niche of a species This reduced habitat and resources due to competition is called the realized niche The realized niche is less than the fundamental niche Resource partitioning occurs when species living in the same habitat specialize to minimize competition SOME KEY CONCEPTS 1 SPECIES Organisms ofthe same kind that are genetically very similar and can breed in the wild or without human interference and produce live fertile offspring 2 POPULATION A population consists of all the members of a species living in a given area at the same time 3 BIOLOGICAL COMMUNITY A biological community is made of all of the populations of organisms living in a particular area 4 ECOSYSTEM An ecosystem is made by the interaction of the biological community and its physical nonliving environment Abiotic nonliving components eg temperature weather soil Biotic living components eg animal and plant species Interaction between all living and nonliving factors SPECIES INTERACTIONS Predation and competition are important factors in evolution and adaptation Predation and parasitism Predators are organisms that feed directly on other living organisms whether or not it kills its prey In a broad sense it includes carnivores herbivores parasites and pathogens In a narrow sense it means only carnivores It does not include decomposers scavengers and detritivores Predation can occur at any of the stages of the life cycle of the predator or prey e g egg larva young adult Predators have evolved specialized foodobtaining mechanisms Predatorprey adaptations have evolved that encourage or resist predation Predator and prey exert selective pressure on each other in a process called coevolution Parasites are organisms that feed on another living organism called the host without killing it Pathogens are diseasecausing organisms and are usually considered parasites Keystone species A species or group of species that exert a larger and more influential impact in the community that would be expected from mere abundance o e g wolves top predators bees pollinators some wild fig species mycorrhizae Competition The struggle for resources food space light etc in the same habitat There are two types of competition 1 Intraspecific competition between member of the same species 2 Interspecific competition between members of different species It occurs when niches of two species overlap Territoriality an individual defines an area as home or nesting site and defends it primarily against members of their own species It is a form of intraspecific competition Symbiosis The intimate living together of two or more species It includes Commensalism one benefits the other remains unaffected Mutualism both partners benefit from the association Parasitism is considered by some as a type of symbiosis where one organism benefits and the other is harmed Defensive mechanisms Toxic chemicals irritants poisons etc Body armor Weapons claws fangs stings etc Camouflage Mimicry Batesian mimicry harmless imitates harmful Muellerian mimicry two harmful species look alike When predators learn to avoid one of the two species the other benefits U39PP N COMMUNITY PROPERTIES o PRODUCTIVITY refers to the rate of energy storage or increase in organic matter biomass Energy left after respiration is the net primary production Levels of light temperature moisture and nutrients regulate photosynthesis o ABUNDANCE is a measure of the total number of organisms present in a biological community 0 DIVERSITY is a measure of the total number of different species ecological niches and genetic variation present in an ecosystem The abundance of a species is often inversely related to the diversity of the community Usually diversity decreases and abundance increases from the equator to the poles Productivity is related to abundance and diversi Productivity is regulated by light levels moisture temperature and nutrient availability COMPLEXITY 0 Complexity refers to the number of species at each trophic level and the number of trophic levels in a community A diverse community may have a simple food chain high diversity and low complexity if all its species are clustered in only a few trophic levels and form a relatively simple food chain Connectedness refers to the number of interactions between the member species of a community 0 Resilience and stability Complex and interconnected communities tend to be more resilient and stable in the face of disturbance Stability is due to the selfperpetuating mechanisms of the species in the ecosystem o Constancy lack of fluctuations in composition or functions 0 Inertia resistance to perturbations o Renewal ability to repair damage after disturbance EDGES AND BOUNDARIES The boundary between two habitats is an important aspect of community structure Ecotone refers to the boundary between adjacent communities It could be a sharp boundary or gradual and indistinct Species may be adapted to live in the ecotone e g deer and cardinals in North America The forest edge or ecotone may have a different combination of plant and animal species than the interior of the forest the forest core COMMUNITIES N TRANSITION Organisms occupying a site often gradually change environmental conditions by creating soil shade shelter or increasing humidity This process is called ecological succession Ecological succession is the replacement of communities one community by another on an area It involves a change in numbers and kinds of organisms primary succession occurs in sites that were previously unoccupied by a community e g lava flows silt deposits after a flood sand bars etc secondary succession takes place when an existing community is disrupted and new community develops at the site Pioneer species are the first colonizers of a disturbed area Each community prepares the way for a new set of invaders by modifying the area This is called ecological development Eventually a community develops that resists change the climax community Some communities are disturbed periodically and are adapted to disruption They are called disclimax communities or equilibrium communities Disclimax communities never reach the climax stage Grasslands the chaparral of southern California and some pine forests are maintained by periodic fires The plants are adapted to resist fires The dominant species in these fireclimax communities depend on periodic fires to eliminate competition open their cones or thick seed coats and prepare the ground for seeding Without fires these communities will have a different structure Introduced species are on of the greatest modern threats to biological diversity When introduced species are free of predators they can disrupt the balance of the community and cause catastrophic changes for native species UNDERSTANDING OUR ENVIRONMENT Chapter 1 ENVIRONMENT 1 Circumstances and conditions that surround an organism or group of organisms 2 Complex social or cultural conditions that affect an individual or community ENVIRONMENTAL SCIENCE 0 Systematic study of our environment and our proper place in it Interdisciplinary biology chemistry geology economics political science sociology statistics history psychology ethics religion business etc Holistic study of the world around us 0 Mission oriented creates a responsibility to get involved in trying to solve the problems we have created 0 We know the remedies for environmental issues are often understood but there is an increasing difficulty in making them socially economically and politically acceptable ECOLOGY 0 Scientific study of the relationships between organisms and their environment HISTORY Environmental Movement Timeline httpwwwecotopiaorgehoftimelinehtm There have been four stages 1 Pragmatic resource conservation utilitarian conservation 2 Moral and aesthetic nature preservation biocentric preservation the fundamental right of other organisms to exist Concern about health and ecological damage caused by pollution environmentalism Global environmental citizenship our modern human activities rival those of geological forces e g atmospheric changes 3 4 Eighteen century French and British colonial administrators attempted to conserve some of nature resources In USA 0 George Perkins Marsh 1801 1882 Man and Nature 1864 Born in Vermont Marsh was a member of the State House of Representatives and served as ambassador to Turkey and Italy He spoke at least six languages He warned of the ecological consequences of the destruction of grass cover and waste of resources occurring on the American frontier Europe China and North Africa As a result of his efforts forest reserves were established in 1873 to protect dwindling supplies of timber and endangered watersheds o Gifford Pinchot and Theodore Roosevelt pragmatic utilitarian conservation First director of the Forest Service 1905 Resources should be used for the greatest good for the greater number of people for the longest time Development of natural resources existing now for those who live here now With the cooperation of Theodore Roosevelt he established the framework of our national park forest and wildlife refuge system Multiple use policies ofthe Forest Service reflect this pragmatic utilitarian conservation approach Resources should be used for the greatest good for the greatest number for the longest timequot This is called a policy of utilitarian conservation quotPinchot and Roosevelt de ned it as the wise use of the Earth39s natural resources so that renewable ones like timber could regenerate and nonrenewable ones like coal could be prudently utilized to last as long as possible The central idea was to scienti cally manage natural resources for the present and the future That39s why the Forest Reserves now called National Forests were originally established Unlike the National Parksbasically managed for preservation and recreationtrees are cut minerals are mined cattle are grazed on National Forestsexamples of uses that arouse controversy in some quarters today quot httpwwwpinchotorggt Additional information about Pinchot httpwww lih duke 39 quot quot rchusfscollpeoplePinchotPinrhnt html 0 John Muir altruistic preservation Geologist author first president of the Sierra Club Opposed Pinchot39s policies Nature deserves to exist for its own sake regardless of its usefulness to us Aesthetic and spiritual values formed the core of his philosophy of nature protection Emphasis on the fundamental right of other organisms to exist this point of view is called biocentric preservation National Park Service 1916 is oriented to the preservation of nature in its purest forms 0 Aldo Leopold January 11 1887 April 21 1948 A United States ecologist forester and environmentalist Professor of wildlife management at the University of Wisconsin Wrote the book A Sand County Almanacquot He was influential in the development of modern environmental ethics and in the movement for wilderness preservation He is considered to be the father of wildlife management in the United States httpwwwaldoleopoldorg httpwww erntnnia 39 quot39 39 quot39 39 html Rachel Carson Silent Spring 1962 environmentalism Environmentalism was brought to consciousness by Rachel Carson39s Silent Spring 1962 Pointed out the threats of pollution and toxic waste to humans and other organisms Environmentalism includes resources and pollution problems Pioneers of this movement were David Brower and Barry Commoner Activism litigation mass media for campaigns books intervention in regulatory hearings Research and activism are characteristic ofthe movement International environmental conventions In the 1960s and 1970s Environmental agenda has expanded to include global concerns human population growth atomic weapons recycling fossil fuel dependency biodiversity etc httpwww nhn M r 39 quotquot 39 quot Vietsrvaid1125 SUMMARY IDEAS OF THE ENVIRONMENTAL MOVEMENT Active participation in attempts to solve environmental pollution and resource problems Links to poverty injustice exploitation etc Global perspective CURRENT CONDITIONS OF THE NATURAL WORLD A unique hospitable world different from any other planet we know Rich diversity of life Interrelated communities of living organisms in balance with the nonliving environment Dilemmas Environmental problems population growth food shortage energy supplies Elimination of biodiversity Pollution toxic waste waste disposal There are solutions to many of the problems HUMAN DIMENSIONS OF ENVIRONMENTAL SCIENCE POLITICAL ECONOMIES According to the World Bank one fifth of the world peoples live in acute poverty lack of adequate diet housing clean water basic sanitation health care education The poor of the world have become the victims and the agents of environmental degradation and destruction Elimination of poverty and of the 39 are 39 o The cycle of poverty illness and limited opportunities can become a selfsustaining proves that passes from one generation to another 0 Rich countries tend to be in the north and are industrialized 0 Poor countries tend to be in the tropics and are agricultural Classification based on the economic system FIRST WORLD COUNTRIES Industrialized marketoriented democracies of Western Europe North America Japan Australia New Zealand SECOND WORLD COUNTRIES Centrally planned socialist communist countries The former Soviet Union and its Eastern European allies China North Korea Vietnam Cuba Most of these countries are changing to market economies Many eastern European countries in this category will join the European Union in 2005 and will quickly transform and move into the firstworld category THIRD WORLD COUNTRIES Nonaligned nonindustrial excolonial nations like India Indonesia South American countries Middle East countries some African countries FOURTH WORLD COUNTRIES Newly suggested by some economist It includes the poorest nations like Mozambique Tanzania Ethiopia Sahel countries Myammar Bangladesh HUMAN DEVELOPMENT What is Human Development Human development is about much more than the rise or fall of national incomes It is about creating an environment in which people can develop their full potential and lead productive creative lives in accord with their needs and interests httphdrundporghd The first Human Development Report 1990 introduced a new way of measuring development by combining indicators of life expectancy educational attainment and income into a composite human development index the HDI The Human Development Index HDI measures the average achievements in a country in three basic dimensions of human development a long and healthy life knowledge and a decent standard of living It is calculated for 177 countries and areas for which data is available httphdrundporghdr2006statisticsindicesdefaultcfm The breakthrough for the HDI was to find a common measuring rod for the socioeconomic distance traveled The HDI sets a minimum and a maximum for each dimension and then shows where each country stands in relation to these scales expressed as a value between 0 and 1 0 Since the minimum adult literacy rate is 0 and the maximum is 100 the literacy component of knowledge for a country where the literacy rate is 75 would be 075 Similarly the minimum for life expectancy is 25 years and the maximum 85 years so the longevity component for a country where life expectancy is 55 years would be 05 o For income the minimum is 100 estimated earned income or PPP and the maximum is 40000 PPP Income above the average world income is adjusted using a progressively higher discount rate The scores for the three dimensions are then averaged in an overall index The HDI facilitates the determination of priorities for policy intervention and the evaluation of progress over time It also permits instructive comparisons of the experiences within and between different countries Check this site httpwwwundporghdro SUSTAINABLE DEVELOPMENT quotmeeting the needs of the present without compromising the ability of future generations to meet their own needsquot httpwww 39 39 quot nrnTradeRelatedlquot 39 39ntroasp Our Common Future the 1987 report of the World Commission on Environment and Developmen Gro Harlem Brundtland Norwegian Prime Minister and Chair of the Commission Improving people39s lives over many generations rather than just a few years Political stability democracy and equitable economic distribution are needed to minimize poverty Many see economic growth as the only solution to poverty These two sites deal with sustainable development in depth highly recommended httpWWW 39 39 quot nrnTradeRelatedlquot 39 1 ash httpwwwunidoorgendoc3563 CAN DEVELOPMENT BE TRULY SUSTAINABLE Can the environment continue to function as it should indefinitely Limitations 1 Fixed nonrenewable resources 2 Capacity of the biosphere to absorb waste Many ecologists consider sustainable growth impossible in the long run because of the limits imposed by nonrenewable resources and the capacity of the biosphere to absorb our wastes Economic growth makes life more comfortable but it doesn39t necessarily result in a cleaner environment quot stationary condition of capital and population implies no stationary state of human improvement There would be just as much scope as everfor all kinds of mental culture and moral and social progressquot economist John Stuart Mill 1857 1995 United Nations Summit for Human Development Some of the goals of this action plan to eliminate poverty and injustice 1 Primary education for both boys and girls 2 Adult illiteracy rates to be cut in half with female illiteracy rate to be no higher than the male one Elimination of severe malnutrition Family planning services for all who wish them Safe drinking water and sanitation for all Credit for all to ensure selfemployment opportunities 9301 4 Indigenous or native peoples are generally among the poorest and most oppressed of any group in both rich and poor countries Indigenous people make about 10 of the world population Unique cultures are disappearing along with biological diversity There are about 6000 recognized cultures of which 5000 are indigenous About 3000 languages are dying because they are no longer being taught to children There are about 6000 languages in the world ENVIRONMENTAL PERSPECTIVES SOMETHING TO THINK ABOUT Pessimism based on views of competition and scarce resources 0 Many people fight for very few resources o NeoMalthusian point of view overpopulation leads to misery vice crime starvation and war Optimism based on 0 Technology technological optimism is based on the believe that technology will find a solution to present environmental problems The world is one of abundance and opportunity Criticism business as usual denial of real issues apathy Also called quotcornucopian fallacyquot by critics wishful thinking or denial Some progress has been made towards building a just and sustainable world Chapter lS AIR CLIMATE AND WEATHER WEATHER is a description of the physical conditions of the atmosphere e g humidity temperature pressure wind velocity CLIMATE is a description of the longterm pattern of weather in a particular area o It is based on the average measurement of several weather conditions e g temperature precipitation ATMOSPHERE The earth39s atmosphere is about 500 km 300 mi The composition of the atmosphere has changed over the millions of years of the earth existence Original atmosphere lacked oxygen and contained gases like ammonia methane sulfur oxides nitrogen oxides and water The main components of our atmosphere are nitrogen 78 and oxygen 21 Water vapor concentrations vary from O to 4 depending on air temperature and available moisture C02 makes about 003 of the atmosphere Aerosols are small droplets suspended in the air ATMOSPHERIC LAYERS TROPOSPHERE is the layer immediately adjacent to the earth39s surface 18 km thick at the equator to about 8 km thick at the poles It is here where most of the weather occurs Air circulates in great vertical and horizontal convection currents Redistributes heat and moisture around the planet uniform composition due to wind flow More dense than other layers it contains about 75 of the atmospheric gases STRATOSPHERE extends from the troposphere up to about 50 km 31 mi Tropopause is the imaginary line that separates the troposphere from the stratosphere Temperature increases with altitude It is more diluted and calm than the troposphere 11000 less water 0 Ozone layer it absorbs ultraviolet radiation UV rays MESOSPHERE extends from the stratopause up to 80 km above sea level 0 Stratopause is the imaginary line that separates the stratosphere from the mesosphere 0 Temperature drops in the mesosphere down to 80 C THERMOSPHERE extends above the mesopause up to about 1600 km Mesopause is the imaginary line that separates the mesosphere from the thermosphere A region of highly ionized gases Temperature increases dramatically due to solar and cosmic radiation above 150 C There is no sharp boundary marking the end of the atmosphere 0 O O 0 THE WEATHER ENGINE The flow of energy from the sun causes the cycling of air and water This cycling creates climate and distributes the energy and materials through the environment Solar energy can be absorbed by the earth or reflected Visible light passes through the atmosphere until it reaches the ground Ultraviolet UV rays are mostly absorbed by the ozone layer in the stratosphere Infrared radiation is mostly absorbed by C02 and H20 in the troposphere Albedo is the name given to the reflective properties of the surface 0 Clouds snow and ice have a high albedo 0 Forest canopy oceans and dark surfaces have a low albedo o The net average global albedo is 30 Eventually all of the energy absorbed is emitted back into the atmosphere in the form of infrared energy Infrared radiation has long wavelength and low energy Infrared radiation is reabsorbed by gases C02 and H20 in the atmosphere These gases release the energy very slowly providing most of the heat in the lower atmosphere The rising warm air is replaced by colder air from above creating convection currents CONVECTION AND ATMOSPHERIC PRESSURE Most of the solar energy is used to evaporate water Every gram of evaporating water absorbs 580 calories of energy as it changes from liquid to gas Water contains a great amount of energy called latent heat When water changes back to liquid it releases the 580 caloriesgram Warm air close to the equator and cold air close to the poles produce pressure differences that cause wind rain storms and other weather changes Pressure differences drive great air masses around the globe and generate winds that determine both immediate weather and longterm climate WHY DOES IT RAIN Water condenses as air cools air cools as it rises Air rises in convection currents where solar heating is intense As the warm air moves up it cools down and water condenses and precipitates Air also rises when it encounters mountains As the cool air sinks it warms and the available moisture is evaporated The sinking air also compresses and causes the areas of high pressure which are dry and cloudless THE CORIOLIS EFFECT AND JET STREAMS Winds above the Earth s surface tend not to move in a straight line across the earth s surface Earth39s rotation causes a wind deflection called the Coriolis Effect As air moves from high to low pressure in the northern hemisphere it is deflected to the right by the Coriolis force In the southern hemisphere air moving from high to low pressure is deflected to the left by the Coriolis force httpww2010atmosuiuceduGhlguidesmtrfwcrlsrxml Ocean currents similarly curve clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere httpabyssuoregonedu39sglossarycoriolis effecthtml httpwww39 quot 39 quot 39 quot 39 quot quot 1304es1QnAhnnn O1cfmchapter no19 Jet streams are powerful currents of air moving very fast at 200 kmh or more 125 mih located between 6 and 12 km 37 75 mi above the earth39s surface at the top of the troposphere Jet streams cannot be felt on the earth s surface but they greatly influence the weather Jet streams are formed by the deflection of upper layer winds by Coriolis flow They move west to east See httpwww39 39 quot 39 html OCEAN CURRENTS Surface ocean currents are the result of wind pushing the surface water and of the Coriolis effect As surface water moves deeper water moves up to replace it creating deep ocean currents Cold water at high latitudes sinks where the temperatures are near 4 C the temperature at which water is the densest See this site for the causes of ocean currents and other explanations httpearthuscedustottCatalinaOceanshtml httpwww quot ocean currentshtm Cycling currents bring water north and south and redistribute heat SEASONAL WINDS AND MONSOONS Monsoons are seasonal winds especially in the Indian ocean and SE Asia Monsoon is a seasonal reversal of wind patterns due to the change of seasons causing different warming and cooling of the oceans Monsoons are created by the earth s tilt in relation to the sun 0 In December and January the sun is most intense just south of the equator o In June and July during the northern summer the sun is most intense just north of the equator o The land reaches higher temperatures than oceans There is more land in the northern hemispheres o The air warms and rises and cool air from the south flows north to replace it bringing with it moisture and rains This is called the summer monsoon Where the sun shines most intensely evaporation and convection currents are very strong FRONTAL WEATHER Solar energy hits the equator directly perpendicular and the poles at an oblique angle Air pressure is the greatest and the air the warmest at sea level This is due to the pull of gravity and the weight of the air above Cold air moves closer to the ground and lifts the warm air up The boundary between two air masses with different temperature and density is referred to as a cold front A moving cold front displaces warm air with cold air Air pressure and air density decrease with increasing altitude Air becomes cooler and less dense as it rises and its water vapor condenses and precipitates Approaching cold fronts cause towering clouds called thunderheads which reach the stratosphere where the jet stream pushes the cloud top into a characteristic anvil shape lfthe advancing mass of air is warmer than the local air a warm front results Warm fronts often have many layers of clouds at different levels The warm air slides over the cold air mass and bring drizzle and cloudy skies See animation httpWWW I II I I 4 39 II I I II 39 I39 139 I annalnqonmmnn O1cfmchapter novisualization CYCLONIC STORMS Low pressure areas are caused by rising warm air Winds swirl into these lowpressure areas turning counterclockwise in the Northern Hemisphere due to the Coriolis effect Hurricanes or typhoons are caused by large differences in temperature between air and ground and a large supply of moisture o A low pressure area sucks in wind laden with moisture from the adjacent areas 0 The Coriolis Effect causes spiraling of the winds httpwwwweatherguestionscomNVhat causes hurricaneshtm See animation and explanation of how hurricanes form httn39lnews hhr r n 39 39 39 quot quot 39 39 407nnnnhmnlsir 40221004022129stm Hurricanes typhoons and cyclones are different names for the same phenomenon Tornadoes Tornadoes are cyclonic storms formed over land but the rotation is not caused by the Coriolis Effect of the earth Turnadues farmed where my em ahhem the henh eemues thh hurmd Warm a 1 n ah muvmg henh frum the Guv uf Mexmu A thunders mrm SthE rs L step m the creatmn Elf a turnadu A thundersiurm happens vheh there 5 meme m a as here and the m p Warm ah hses rapwd y aver dEnSE emu ah The WIEHSE venma currents generate a thunder Ead Large puvverfu thundersiurms are named supErEEH aux awx nearlhe gruund Ah rushes m m m area causmg addmuna damage m areas Hut uhemy mt by the turnadu cm W W HrP Pr rnnhrm VHF vapur h the ah mm the turnadu sfammarfunnehshaped duud mn darker mm m nrannn red hue by pmkmg up red um quotWmdshearr Whele Me Wmdcharyes dwetnon mm hegmemeceues ma mmadoes Na 50th Wmdrs heame 97 he orange arrows and a wee Wmd wows above n Due anoW Wmd shear may cause a commquot 0 av 20 maze h hegroundwmk arrows EvemuaM PlysrcaYorces me Me vonexmzo a vemcaposbon andyou have a m 0 041 ean mad A 4R3 ran hn Wm mesur maturhaduZ hm Downdra s When rain falls into dry unstable air aloft much of it evaporates This process causes the air aloft to become cooler and more dense relative to the surrounding atmosphere Under certain conditions the cool air aloft descends rapidly to the ground where it spreads violently outward resulting in strong damaging downdrafts which are sometime referred to as or 39 L hl ln39llvwvw rh nnaa INbeul6 l 4htm Hail Hail is caused when falling water droplets rise on powerful updrafts freeze and fall again and rise again Droplets accumulate water or ice as they rise and fall until they become heavy enough to resist being lifted upwards Caribbean hurricanes In years when the Atlantic temperatures are high a stronger than average monsoon through forms over Africa This pulls in moist air from the ocean and brings rain to the Sahel of Africa This trough gives rise to tropical depressions that follow one another in regular succession across the Atlantic and some become the hurricanes in the Caribbean and Gulf of Mexico Weather modification Seeding clouds with ionized particles can initiate precipitation if water vapor is present and air temperatures are near condensation point Hail suppression by cloud seeding also can be effective CLIMATE Climate is the pattern of weather over a large region of the globe over a long period of time There have been abrupt climatic changes in the past e g ice ages Theories about the causes for climatic changes A Interaction of unrelated events e g radiation from supernovas volcanic activity and seafloor spreading solar radiation l Cyclic changes in the sunspots and magnetism 9 Milankovitch cycles Orbital variations every 100000 year of the earth rotation around the sun shifts in the tilt of the earth39s axis 40000 years and wobbling of the axis 26000 years EL NINO El Ni o is also called El Ni o Southern Oscillation or ENSO Warm surface water is kept near Indonesia in the Pacific Ocean by prevailing trade winds There is an upwelling of cold water near the coast of South America Every few years 35 years there is a reversal of the winds that keep the surface warm water on the western Pacific During El Ni o years there is shift of the jet stream to a more southerly position creating more rain and storms over California and the midwest of US La Ni a is the name given to the intervening years httpibramthinkguestorg20901overview 5htm The Pacific Decadal Oscillation is a pattern similar to El Ni o that occurs in the north Pacific A very large pool of warm water moves back and forth every 30 years or so Ocean surface temperatures are warmer in western North America and cooler in the western Pacific then the reverse occurs This shift affects the salmon run which is significantly affected by the warm sea temperatures ANTHROPOGENIC IMPACT HUMANCAUSED Intergovernmental Panel on Climate Change IPCC is a UN sponsored working group that studied human impact on climate Scientists disagree about the causes timing and consequences of global climate change the overwhelming majority agree that there are unmistakable signals of human impacts on the world s climate Conclusions of IPCC published in 1955 1 World climate has changed significantly in the last century 2 There is evidence of human influence on the climate 3 Models suggest that the trend is to increase the global mean temperatures between 1 C and 35 C by 2100 In the third climate report released by the IPCC in 2001 it is stated that recent changes in the world climate have had discernible impacts on physical and biological systemsquot There are many skeptics in the scientific community about climate changes Faulty models and selective data have been used in making predictions There is skepticism on the part of a number of scientists We don t know enough to make predictions Current computer models are still inadequate Politicians lobbying groups and industry have unduly influenced the IPCC reports The troposphere is not warming like the surface of earth GREENHOUSE GASES Burning fossil fuels agriculture deforestation and industrial processes contribute to the production of greenhouse gases C02 has increased steadily this century 0 Increase is attributed to the burning of fossil fuels 0 This trend could bring the concentration up to 500 ppm by the year 2100 twice the preindustrial level 0 C02 traps infrared radiation emitted from the earth39s surface Methane is released by ruminants rice paddies landfills coal mines etc o It traps 2030 times more heat than C02 0 13 billion cattle producing over 100 million tons of methane annually can have a significant effect on the world39s balance of greenhouse gases Chlorofluorocarbons CFCs and N20 nitrous oxide also trap heat 0 Produced by industry and burning organic material respectively CLIMATE CHANGES THIS CENTURY There is trend toward warming Frostfree season is eleven days longer in the north Spring arrives about seven days earlier now than in 1950 Average night temperatures are higher Precipitation rate has increased and floods and storms are more frequent More frequent El Ni o effect Middle latitudes may get warmer higher altitudes will get wetter precipitation will decrease in some areas Sahel and increase in other lowland areas Central Africa South Asia melting of glaciers and ice caps will raise the sea level vectors will invade the warmer zones Siberia and Northern Canada will enjoy warmer winters and longer growing season Most of the world s largest urban areas are along the coastline Rising sea level due the melting of ice caps in Greenland and Antarctica will flood many cities and low lying areas Some small island countries will become uninhabitable g Bahamas Maldives Marshall Islands and Tuvalu The leaders of Tuvalu a tiny island country in the Paci c Ocean midway between Hawaii and Australia have conceded defeat in their battle with the rising sea announcing that they will abandon their homeland After being rebuffed by Australia the Tuvaluans asked New Zealand to accept its 11000 citizens but it has not agreed to do so Earth Policy Institute November 2001 httplwwwearthpoIicyorglUpdatesUpdate2htm Other site httpwww quot 39 39 39 39 39 39 39 c an html INTERNATIONAL CLIMATE NEGOTIATIONS Cutting emissions was one of the most publicized agreements of the Earth Summit held in Rio de Janeiro in 1992 United States is the major contributors to the annual increase of C02 concentration in the atmosphere 0 US with 5 of the world population produces 28 of the anthropogenic C02 0 China is second 0 Japan and the European Union produce about half as much as the US per capita Little progress has been made in this area The Kyoto Protocol was an agreement made 1997 by 160 nations to cut back on the emissions of C02 N20 and CH4 0 An average of 52 below the 1990 level by the year 2012 0 Individual nations have different limits In 2002 all nations of the European Union and Japan ratified the agreement United States did not ratify the agreement Many are opposed to limits on greenhouse gas emissions 0 It has not been proven scientifically 0 Cost of making the changes 0 Fear ofjob loss
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