Download Impacts on Biodiversity

IMPACTS ON
BIODIVERSITY
Honors Biology
2011-2012
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

Increases
Sea Urchin Population = _____________
Decreases
 Sea Weed Population = ______________
Decreases
 Fish Population = _________________
Decreases
 Seal Population = _________________
 Orca Population = _________________
Decreases
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)