ENVIRONMENTAL SCIENCE 13e CHAPTER 8: Sustaining Biodiversity: The Species Approach.
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Transcript of ENVIRONMENTAL SCIENCE 13e CHAPTER 8: Sustaining Biodiversity: The Species Approach.
Core Case Study: Polar Bears and Projected Climate Change
• 20,000 – 25,000 polar bears in Arctic
• Hunt seals on winter sea ice
• Global warming is quickly reducing the amount of sea ice and how long it lasts in winter
• Polar bears have less time to hunt and store fat for summer fasting
• Projected 30-35% decline by 2050
• Potentially extinct from wild by 2100
8-1 What Role Do Humans Play in the Premature Extinction of Species?
• Concept 8-1 Species are becoming extinct 100 to 1,000 times faster than they were before modern humans arrived on earth, and by the end of this century, the extinction rate is expected be 10,000 times higher than the background rate.
Human Activities and Extinction
• Background extinction rate
• Current rate is 100-1000 times background extinction
• Rate likely to rise to 10,000 times
• Is a mass extinction coming?
Current Extinction Rate Estimates Are Conservative
• Species and biodiversity decrease in next 50–100 years
• Biodiversity hotspot rates higher than global average
• Degrading, simplifying, and destroying diverse environments
Science Focus: Estimating Extinction Rates (1)
• Three difficulties1. Not easy to document – takes a long
time
2. Only 2 million species of 8-100 million identified
3. Little is known about the 2 million species
Science Focus: Estimating Extinction Rates (2)
• Study records of post-human extinctions with previous extinctions from the fossil record
• DNA copying mistakes• How habitat reduction increases extinction• Mathematical models• Inadequate data and models• Normal: 1 million to 10 million years• Humans have greatly accelerated this
Ecological Smoke Alarms
• Endangered species
• Threatened species
• The first to go: large, slow, tasty, or have valuable parts
• Some behaviors make species prone to extinction
Siberian tiger
Grizzly bear Kirkland’s warbler
Knowlton cactus Florida manatee African elephant
Utah prairie dog Swallowtail butterfly
Humpback chub Golden lion tamarin
Fig. 8-3, p. 156
Black rhinoceros
Giant panda Black-footed ferret
Whooping crane Northern spotted owl
Blue whale
Mountain gorilla Florida panther California condor Hawksbill sea turtle
Fig. 8-3, p. 156
Large territories
Blue whale, giant panda, rhinoceros
Blue whale, giant panda, Everglades kite
Elephant seal, desert pupfish
Bengal tiger, bald eagle, grizzly bear
Blue whale, whooping crane, sea turtle
African violet, someorchids
Snow leopard, tiger, elephant, rhinoceros, rare plants and birds
California condor, grizzly bear, Florida panther
ExamplesCharacteristic
Low reproductiverate
Specializedniche
Narrowdistribution
Feeds at hightrophic level
Fixed migratorypatterns
Rare
Commerciallyvaluable
Fig. 8-4, p. 157
Stepped Art
Fixed migratory patterns
Blue whale, whooping crane, sea turtle
Feeds at high trophic level
Bengal tiger, bald eagle, grizzly bear
Narrow distribution
Elephant seal, desert pupfish
Commercially valuable
Snow leopard, tiger, elephant, rhinoceros, rare plants and birds
Low reproductive rate
Blue whale, giant panda, rhinoceros
Characteristic Examples
Rare African violet, some orchids
Large territoriesCalifornia condor, grizzly bear, Florida panther
Specialized niche
Blue whale, giant panda, Everglades kite
Fig. 8-4, p. 157
25%
Fish
Amphibians
Mammals
Reptiles
Plants
Birds
34% (51% of freshwater species)
32%
12%
14%
20%
Fig. 8-5, p. 157
Case Study: Extinction of the Passenger Pigeon
• Audubon, 1813: 3 days for a flock to pass over
• Extinct by 1900– Good to eat
– Feathers good for pillows
– Bones good for fertilizer
– Easy to kill
8-2 Why Should We Care about Preventing Species Extinction? • Concept 8-2 We should prevent the
premature extinction of wild species because of the economic and ecological services they provide and because they have a right to exist regardless of their usefulness to us.
Value of Species
• Instrumental value of biodiversity – Food crops– Genetic information– Medicine– Bioprospectors– Ecotourism
• Do not know what we lose when species go extinct
Cathranthus roseus,MadagascarHodgkin's disease,lymphocytic leukemia
Rauvolfia
Rauvolfia sepentina,Southeast AsiaAnxiety, highblood pressure
Foxglove
Digitalis purpurea,EuropeDigitalis for heart failure
Pacific yew
Taxus brevifolia,Pacific NorthwestOvarian cancer
Cinchona
Cinchona ledogeriana,South AmericaQuinine for malaria treatment
Neem tree
Azadirachta indica,IndiaTreatment of manydiseases, insecticide,spermicide
Rosy periwinkle
Fig. 8-7, p. 158
8-3 How Do Humans AccelerateSpecies Extinction?
• Concept 8-3 The greatest threats to any species are (in order) loss or degradation of its habitat, harmful invasive species, human population growth, pollution, climate change, and overexploitation.
Fig. 8-8, p. 160
Causes of Depletion and Premature Extinction of Wild Species
• Population growth
• Rising resource use
• Undervaluing natural capital
• Poverty
• Habitat loss
• Habitat degradation and fragmentation
• Introduction of nonnative species
• Commercial hunting and poaching
• Sale of exotic pets and decorative plants
• Predator and pest control
• Pollution
• Climate change
• Overfishing
Underlying Causes
Direct Causes
Natural Capital Degradation
Causes of Endangerment and Premature Extinction (HIPPCO)
• Habitat destruction
• Invasive species
• Population growth
• Pollution
• Climate change
• Overexploitation
Habitat Loss
• Deforestation of tropical areas greatest eliminator of species
• Endemic species
• Habitat fragmentation
Stepped Art
Indian Tiger
Range 100 years agoRange today
Black Rhino
Range in 1700
Range today
African Elephant
Probable range 1600Range today
Asian or Indian Elephant
Former rangeRange today
Fig. 8-9, p. 161
Case Study: Declining BirdSpecies (1)
• Decline of ~70% of ~10,000 known species
• 12% threatened with extinction
• Birds around humans benefited, but forest species declined
• Long-distance migrants – greatest decline
Case Study: Declining BirdSpecies (2)
• Reasons – Habitat loss
– Habitat fragmentation
– Climate change
• Birds are environmental indicators
• Perform economic and ecological services
Species Introductions
• Most beneficial – food crops, livestock, pest control
• 500,000 alien invader species globally
• 50,000 nonnative species in the U.S.
• Some definitely not beneficial
European wild boar(Feral pig)
Deliberately Introduced Species
Purple loosestrife European starling African honeybee(“Killer bee”)
Nutria Salt cedar(Tamarisk)
Marine toad(Giant toad)
Water hyacinth Japanese beetle Hydrilla
Fig. 8-10, p. 163
Gypsy moth larvae
Accidentally Introduced Species
Sea lamprey(attached to lake trout)
Argentina fire ant
Brown tree snake
Eurasian ruffe Common pigeon(Rock dove)
Formosan termite
Zebra mussel Asian long-horned beetle
Asian tiger mosquito
Fig. 8-10, p. 163
Stepped Art
Deliberately introduced species
Purple loosestrife
European starling
African honeybee (“Killer bee”)
Nutria Salt cedar (Tamarisk)
Marine toad (Giant toad)
Water hyacinth
Japanese beetle
Hydrilla European wild boar (Feral pig)
Accidentally introduced species
Sea lamprey (attached to lake trout)
Argentina fire ant
Brown tree snake
Eurasian ruffe
Common pigeon (Rock dove)
Formosan termite
Zebra mussel
Asian long-horned beetle
Asian tiger mosquito
Gypsy moth larvae Fig. 8-10, p. 163
Case Study: The Kudzu Vine
• Kudzu introduced to control erosion• Prolific growth• Uses
– Asians use powdered starch in beverages
– Edible – Source of tree-free paper– Japanese kudzu farm in Alabama
Disruptions from AccidentallyIntroduced Species
• Downside of global trade
• Downside of traveling
• Argentina fire ant
• Burmese python
• Zebra mussel
Prevention of Nonnative Species (1)
• Identify characteristics of successful invaders
• Detect and monitor invasions
• Inspect imported goods
• Identify harmful invasive species and ban transfer
Prevention of Nonnative Species (2)
• Ships discharge ballast waters at sea
• Introduce natural control organisms of invaders
Human Choices Drive Extinction
• Human population growth
• Excessive, wasteful consumption
• Use of pesticides
• Climate change
DDT and Bioaccumulation
• 1950s–1960s fish-eating bird populations drop
• DDT biologically magnified in food webs
• Bird’s eggshells thin and fragile
• Leads to unsuccessful reproduction
DDT in water0.000003 ppm,or 3 ppt
DDT in fish-eatingbirds (ospreys)
25 ppm
DDT in largefish (needle fish)2 ppm
DDT in smallfish (minnows)0.5 ppm
DDT inzooplankton0.04 ppm
Fig. 8-15, p. 166
Stepped Art
DDT in water 0.000003 ppm, or 3 ppt
DDT in small fish (minnows) 0.5 ppm
DDT in zooplankton 0.04 ppm
DDT in fish-eating birds (ospreys)
25 ppm
DDT in large fish (needle fish) 2 ppm
Fig. 8-15, p. 166
Case Study: Where Have All the Honeybees Gone?
• Honeybees responsible for 80% of pollination of insect-pollinated plants
• Population down 30% since the 1980s– Pesticides– Parasitic mites– Invasive African honeybees
• 2008: 36% of honeybee colonies lost– Colony collapse disorder– New nicotine-based pesticides to blame?
Illegal Killing and Trading of Wildlife
• Poaching endangers many larger animals, rare plants
• Over two-thirds die in transit
• Illegal trade: $1.1 million per hour
• Wild species depleted by pet trade
• Exotic plants often illegally gathered
The Value of Wild Rare Species
• Declining populations increase black market values
• Rare species valuable in the wild – eco-tourism
• Some ex-poachers turn to eco-tourism
Rising Demand for Bush Meat
• Demand increasing with population growth
• Increased road access
• Loggers, miners, ranchers add to pressure
• Local and biological extinctions
• Spread of HIV and Ebola virus
8-4 How Can We Protect Wild Species from Premature Extinction?
• Concept 8-4 We can reduce species extinction and help to protect overall biodiversity by establishing and enforcing national environmental laws and international treaties, creating a variety of protected wildlife sanctuaries, and taking precautionary measures to prevent such harm.
International Treaties
• Convention on International Trade of Endangered Species (CITES)
• Convention on Biological Diversity (CBD)
U.S. Endangered Species Act (1)
• National Marine Fisheries Services – ocean species
• U.S. Fish and Wildlife Service – other species
• Listings based on biological factors
• Forbids federal agency projects that jeopardize listed species or habitats
U.S. Endangered Species Act (2)
• Fines violations on private land
• Illegal to sell or buy listed species
• 1,318 species listed
• USFWS and NMFS supposed to prepare recovery plan – 86% species in 2009
U.S. Endangered Species Act (3)
• Successful recovery plans include American alligator, grey wolf, and bald eagle
• Lax enforcement of imports and exports
• Amended to give private landowners economic incentive to save species
Science Focus: Accomplishments of the Endangered Species Act
• Biologists defend limited success– Species listed only when gravely threatened– Takes long time for species to recover– >50% endangered species improving
• Need more funding
• Develop recovery plans more quickly
• Core habitat established when listed
Protection of Marine Species
• ESA and international treaties protect endangered marine reptiles and mammals
• Challenges to protecting marine species– Limited knowledge of species
– Difficulty in monitoring and enforcing treaties – open oceans
Sea Turtles Threatened
• Six species critically endangered
• Loss or degradation of habitat
• Illegal harvest of eggs
• Threats from fishing methods
• Protection measures have helped
Case Study: Protecting Whales (1)
• Easy to kill
• International Whaling Commission– Sets quotas
– Often ignored
– No enforcement powers
• 1986: Whaling ban, although violated, greatly decreased whale kills
Case Study: Protecting Whales (2)
• Key countries that violate whaling ban– Japan
– Norway
– Iceland
Establish Wildlife Refuges
• National Wildlife Refuge System• Wetland refuges: ~75%• 40 million American visitors• 20% of listed species in refuge system• Many refuges in disrepair, and many
allow mining, oil drilling, and off-road vehicles
Storing Genetic Information
• Gene or seed banks
• Botanical gardens and arboreta
• Farms – commercial sale of endangered species removes pressure
Zoos and Aquariums for Protection
• Collect species with long-term goal of returning them into habitat
• Egg pulling• Captive breeding• 100–500 captive individuals to avoid
extinction• 10,000 individuals to maintain
capacity for biological evolution
Case Study: Trying to Save the California Condor
• Last 22 individuals captured
• Released a few at a time
• 2009: 167 condors in the wild
• Threatened by lead poisoning from animal carcasses and gut piles
The Precautionary Principle
• When substantial preliminary evidence indicates an activity could harm humans or the environment, we should take precautionary measures to prevent or reduce the harm
• Do even if cause-and-effect relationships are not yet clearly established
• “Better safe than sorry”
Three Big Ideas from This Chapter - #1
We are greatly increasing the premature extinction of wild species by destroying and degrading their habitats, introducing harmful invasive species, and increasing human population growth, pollution, contributing to projected climate change, and over-exploitation.
Three Big Ideas from This Chapter - #2
We should prevent the premature extinction of wild species because of the economic and ecological services they provide and because they have a right to exist regardless of their usefulness to us.
Three Big Ideas from This Chapter - #3
We can work to prevent the premature extinction of species and to protect overall biodiversity by using laws and treaties, protecting wildlife sanctuaries, and making greater use of the precautionary principle.