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