Human ImpactHuman Impact

Human ImpactHuman Impact

• Human Population Growth and Ecological Footprint

• Water Quality

• Threats to Biodiversity

• Conservation

Human Population Growth and Human Population Growth and Natural ResourcesNatural Resources

Why does the human population keep growing?

(Sanitation, Agriculture, Medicine)

According to this chart, when will humans reach carrying capacity?

When the slope of the line = 0 and remains that wayl

This is completely hypothetical. Carrying capacity could be 10, 20, or even 50 billion. In fact maybe we already passed it!

Ecological Footprint:Ecological Footprint:The amount of land necessary to produce The amount of land necessary to produce

and maintain enough natural resources and and maintain enough natural resources and store waste for an individual person.store waste for an individual person.

The size of the footprint depends on a number of factors:

Bioproductive Land- land required to produce crops, grazing (pasture), timber (forest) etc.

Bioproductive Sea- sea area required to provide fish and seafood.

Energy Land- forest required to absorb CO2 emissions to stabilize levels in atmosphere.

Built Land- land already used up by buildings/roads

Biodiversity- land needed to preserve natural flora/fauna.

Ecological FootprintEcological Footprint

Ecological FootprintEcological Footprint

The average American’s ecological footprint is around 9.7 hectares.

(1 hectare = 10,000 square meters)

That’s larger than 24 football fields.

We may have a large footprint, but other countries have many more “feet”.

US population: 301,140,000

China: 1,321,852,000

India: 1,129,866,000

Water Quality

Pollution has major impacts on water ecosystems.

Detergents and fertilizers can stimulate plant and algae overgrowth in lakes.

Medical waste can expose fish to hormones that can cause them to change gender.

Amphibians with water permeable skin come into direct contact with pollutants, that can cause deformities like extra arms and legs.

Indicator SpeciesIndicator SpeciesThese previous organisms are all

examples of indicator species, a species that provides a sign, or indication of the quality of the ecosystem’s environmental conditions.

Algal blooms are indications of negative effects on the ecosystem.

Detergents and fertilizers provide nutrients for large algal populations that then suck all the oxygen out of the area, killing anything living there.

This keeps detritivores from breaking down waste materials, and the lake or pond will eventually fill up, which is called eutrophication.

Caspian Sea

Eutrophication

Biomagnification

Pollutants can move from one organism to another through a process called biomagnification. This occurs when a pollutant moves up the food chain as predators eat prey, and ends up accumulating in higher concentrations in the bodies of predators.

Scientists measure pollutants this way in parts per million (ppm).

The Great Pacific Garbage Patch

BiodiversityBiodiversity

Biodiversity is the variety of life within an area.

An ecosystem’s health is typically measured in how much biodiversity it has.

The loss of even a single species can harm the overall stability of an ecosystem

BiodiversityBiodiversity

The most biodiversity occurs in warm humid areas like rainforests.

What decreases Biodiversity?What decreases Biodiversity?

The two big ones are:

Habitat Loss

Introduction of new species

Loss of HabitatAs humans take up

more and more land, there is less wilderness available for organisms and many risk going extinct.

Habitat fragmentation occurs when a barrier forms that prevents an organism from accessing its home range.

Wildlife crossing to prevent fragmentation.

Introduced SpeciesIntroduced SpeciesAn introduced species is any organism that was brought to

an ecosystem as a result of human actions.If an environment has a niche that the introduced species

can exploit, or if the introduced species is a better competitor, original species may be pushed out or die. This particularly happens when there are no predators for the introduced species.

When an introduced species has established itself in a new ecosystem, it is called an invasive species.

Nile Perch KudzuBurmese Python

Invasive SpeciesInvasive Species

ConservationConservationSustainable development is a practice in which natural resources are used and managed in a way

that meets current needs without hurting future generations.

Example: Global Fisheries:Overfishing has depleted fish populations worldwide. Fish stocks are not as hardy as they once

were. One reason for this is that the fish that are caught represent the healthy, reproducing age groups of the fish population.

Researchers found that 29 percent of species had been fished so heavily or were so affected by pollution or habitat loss that they were down to 10 percent of previous levels, their definition of “collapse.”

To continue fishing at our current rate, the year we see a collapse in 100% of species is quite surprisingly within our lifetimes: 2048

The Atlantic cod has, for many centuries, sustained major fisheries on both sides of the Atlantic. However, the North American fisheries have now largely collapsed.

Making Fisheries Sustainable1) Rotation: rotating catches between

different species gives the “off” species time to recover their numbers.

2) Fishing Gear Review: choosing gear that doesn’t hurt the sea floor or unintentionally catch other species.

3) Harvest Reduction: Slowing the harvests of deep-water species that grow very slowly allows more time for them to recover.

4) Fishing Bans: Creating and enforcing bans in certain areas and on certain species helps to replenish numerous populations in the area.

Bottom-Trawling

Bottom-Trawling catch

Which species do we save?

Conservationists try to focus efforts on umbrella species, which are species whose being protected leads to the preservation of its habitat and all the other organisms in its community.

Manatee

Bay Checkerspot Butterfly

1) What density-independent and density-dependent limiting factors may prevent the human population from continued growth?

2) What are 3 factors that determine how big your footprint will be?

3) What’s the difference between renewable and non-renewable resources? Give an example for each and explain why they are renewable or non-renewable.

4) How are the concepts of carrying capacity and indicator species related?

5) Are humans likely affected by biomagnification? If so, what foods might be dangerous?

6) Give two reasons why biodiversity is important to humans.7) How might the introduction of a predator to an invasive

species cause more problems?8) Give 2 examples of sustainable development.9) In terms of conservation, why focus on umbrella species?

1) What density-independent and density-dependent limiting factors may prevent the human population from continued growth?

2) What are 3 factors that determine how big your footprint will be?3) What’s the difference between renewable and non-renewable resources?

Give an example for each and explain why they are renewable or non-renewable.

4) Where does the energy burned off in coal or oil originally come from?5) How does the greenhouse effect keep Earth warm?6) How could the build-up of CO2 in the atmosphere increase Earth’s global

temp?7) What contributes to the formation of ground level ozone and smog?8) Describe how acid rain falling in a forest could disrupt the trophic structure

of the ecosystem.9) How are the concepts of carrying capacity and indicator species related?10) Are humans likely affected by biomagnification? If so, what foods might be

dangerous?11) Give two reasons why biodiversity is important to humans.12) How might the introduction of a predator to an invasive species cause

more problems?13) Give 2 examples of sustainable development.14) In terms of conservation, why focus on umbrella species?