IMPACTS ON BIODIVERSITY

Honors Biology2011-2012

Impacts on Biodiversity:

Over fishing and Over hunting

Invasive species

Over fishing and Over Hunting One threat to biodiversity

occurs when humans cause ecosystems to collapse by using too many natural resources or taking away a Key Stone Species.

Over fishing and Over Hunting

Key Stone Species: An organism that is necessary for keeping an ecosystem in balance.

Example: Sea Otter

Sea Otter Facts Only marine mammal without blubber… How do they stay warm in the cold

ocean? Otters have the densest fur of any mammal. Fur is so thick that their skin never gets wet

when they swim: 400,000 hairs per square centimeter.

Sea Otter Facts During the fur trade Humans hunted

otters almost to extinction for their thick warm pelts.

By 1911 the sea otter population had dropped to roughly 1, 000 individuals!

How will this effect

the ecosystem

?

Sea Otter’s Niche: Eats sea urchins. Uses rocks and shells to break opened sea

urchins

Predators: Sharks and Humans (now Orcas)

Uses seaweed to anchor themselves while they eat and sleep.

How sea otters keep their ecosystem in balance: Otters keep the sea urchin population

down. Sea urchins eat away at the base of sea

weed. Fish and other sea life rely on the sea

weed forests for food and shelter.

Over Hunting Key Stone Species

How do you think the decreasing otter population effects the ocean ecosystem?

Otter Population is Down Sea Urchin Population = _____________ Sea Weed Population = ______________ Fish Population = _________________ Seal Population = _________________ Orca Population = _________________

Increases Decreases

DecreasesDecreasesDecreases

Results?

What are the long term implications on the food web in this situation?

Over Hunting Key Stone Species

Result: Urchin Barrens

Over fishing and over hunting By over

fishing and over hunting humans have the power to irreversibly change an ecosystem.

Sea Otters and Orcas Sea Otters and CO2

Invasive Species Species that are brought to an

ecosystem by humans and harm the ecosystem because they do not have any natural predators in their new environment.

50,000 exotic species live in the US

$138 billion per year spent to help undo the damage they cause

Invasive species also threaten nearly half of the species currently protected under the Endangered Species Act.

Invasive Species (Animal Planet videos)Example: Burmese Python in Florida (Article)