Human Impact

Human Impact

• Human Population Growth and Ecological Footprint

• Water Quality

• Threats to Biodiversity

• Conservation

Human Population Growth and

Natural 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:

The amount of land necessary to produce

and maintain enough natural resources and

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 Footprint

Ecological 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 Species

These 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

Biodiversity

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

Biodiversity

The most biodiversity occurs in warm humid areas like rainforests.

What decreases Biodiversity?

The two big ones are:

Habitat Loss

Introduction of new species

Loss of Habitat

As 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 Species An 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 Kudzu Burmese Python

Invasive Species

Conservation

Sustainable 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 Sustainable

1) 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