Human Impact on Resources, Biodiversity, and Ecosystems
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Transcript of Human Impact on Resources, Biodiversity, and Ecosystems
Human Impact on Resources, Biodiversity, and Ecosystems
Types of Resources
• natural resources – goods and services provided for by nature
• renewable resources – replaced naturally in a reasonable amount of time
• non-renewable resources• commons – resources owned by
everyone
tragedy of the commons
• renewable common resources which tend to be over-exploited
• Why?
• “if I don’t use them then someone else will so it might as well be me”
exploitation of resources
• carrying capacity – the maximum size of a population that can be supported over the long term
• maximum sustainable yield (MSY) – the greatest “use” of a renewable resource
Human Impact on Biodiversity
• species biodiversity – the total number of different kinds of species
• genetic biodiversity – the total gene pool for a given species
• biosphere biodiversity – the total number of species in existence
- known species: 2 million
- unknown species: 3 – 50 million
Value of BiodiversityWhy should we care about protecting other species?
• Foodagriculture and meat production has led to a decline in species biodiversity as well as genetic biodiversity
• Medicinemany modern medicines come from plant extracts* biopiracy
Value of Biodiversity cont.• ecosystem sustainability
the greater the biodiversity, the greater the stability* keystone species
• commercial value- ecotourism- recreation; hunting, fishing, wildlife watching- timber
• intrinsic valuepreservationist philosophy – existence of other species has value aside from any use we make of it
HIPPO
Human Causes of Biodiversity Decline
• habitat destructiondeforestation, wetlands destruction, development
• introduction of exotic speciesmost introduced species do not survive their new habitat – those that do, often out-compete native species (and are termed invasive)
human causes continued …
• overuse (hunting, fishing)
* poaching
• pollution
* climate change
Fig. 9-8a, p. 191
Indian Tiger
Range 100 years ago
Range today(about 2,300 left)
Reduced Ranges
Fig. 9-8b, p. 191
Black Rhino
Range in 1700
Range today(about 2,400 left)
Reduced Ranges
Purple looselife European starling African honeybee(“Killer bee”)
Nutria Salt cedar(Tamarisk)
Marine toad Water hyacinth Japanese beetle Hydrilla European wild boar(Feral pig)
Fig. 9-11a, p. 193
Deliberately Introduced Species
Sea lamprey(attached to lake trout)
Argentina fire ant Eurasian muffleBrown tree snake Common pigeon(Rock dove)
Formosan termite Zebra mussel Asian long-hornedbeetle
Asian tiger mosquito Gypsy moth larvae
Fig. 9-11b, p. 193
Accidentally Introduced Species
Kudzu
Fig. 9-12, p. 194
Fig. 9-13, p. 195
1918
2000
Fire Ant Invasion
Extinction Threats from Poaching
• Profits of poaching
• Causes of poaching: food, fur, pets, traditional medicines, trophies, eliminating pests, etc.
• Bushmeat
• Illegal pets and decorative plants
Bushmeat
Fig. 9-15, p. 196
Confiscated Products From Endangered Species
Fig. 9-18, p. 199
Extinction Threats from Climate Change and Pollution
• Global Warming
• Pesticide threats
• DDT biomagnification (bioaccumulation)
Fig. 9-16, p. 197
DDT in fish-eatingbirds (ospreys)
25 ppm
DDT in largefish (needle fish)2 ppm
DDT in smallfish (minnows)0.5 ppm
DDT in water0.000003 ppm,or 3 ppt
DDT inzooplankton0.04 ppm
Biomagnification of DDT
Litter Kills Seals
Fig. 9-19, p. 200
Extinction• background extinction rate
- naturally occurring extinctions- 99 % of all species are now extinct
• local extinctionextinction of a population but not an entire species
• species extinction- disappearance of an entire species- criteria for claiming this?
• mass extinction 5 major episodes of extinction in Earth’s past
Extinction Crisis Question• the species-area relationship
lose 50% of a habitat, lose 15% of the biodiversity found there
• fragmentation and edge effect
carving up a habitat into several smaller pieces increases edge habitat, decreases interior habitat and results in a loss of biodiversity
• interior species, edge species
HighwayCleared plotsfor grazing
Cleared plotsfor agriculture
Fig. 8-10b, p. 161
Fragmentation
Case Study: Amazonia
• satellite images are used to measure species loss – How?
• deforestation rate is slower than originally thought
• however, the pattern of deforestation (fragmentation) may be causing a faster loss of species
• primary (old growth) vs. secondary forests (less biodiversity)
Strategies for Protecting Biodiversity
• laws and treaties
- CITES Convention on International Trade of Endangered Species
- MMPA Marine Mammal Protection Act
- ESA Endangered Species Act
endangered, threatened, special concern
• captive breeding, zoos, game parks, cloning
Protecting Marine Biodiversity
• why do we use preservation techniques with some species (whales) and conservation techniques with other species (fish)?
• part of protecting biodiversity involves measuring populations and migratory patterns – how is that done with whales?
Case Study: Whale Preservation
• conservation vs. preservation
• commercial whaling
• IWC 1986 commercial whaling ban
• scientific whaling
• subsistence whaling
Study of Whales
• fluke prints
• satellite tags
• captivity