Preserving Aquatic Biodiversity
Chapter 12
Lake Victoria
The second largest freshwater lake in the
world
How have humans changed it?
Introduced Nile perch – killed other fish
Added nutrients – eutrophication
Introduce water hyacinth – blocks light
Aquatic biodiversity
Greatest marine diversity in coral reefs
and deep-sea floor
Higher near coasts than open ocean
Higher in benthic layer than near the
surface
Higher near tropics
How do humans benefit
Food
Seaweed (cosmetics)
Chemicals
Antibiotics
Anticancer
Hypertension
Bone replacement
Destroying freshwater habitats
Draining wetlands – lost over 50 % of
wetlands
Introduction of non-native species
Dams, diversions, canals, flood control
levees
Ruin existing habitat or changing flow rate,
sediment deposits, spawning beds, migration
patterns, plant life, nutrient cycles
Major loss of aquatic
biodiversity by humans
Overfishing
Habitat destruction
Coastal development
Rising sea level
Trawler boats
Pollution
Introduction of alien species
Nonnative examples
Asian swamp eel – Florida, eats everything, can
breath air, cross to new waterways
Purple loosestrife – wetlands, perennial plant in
Eurasia, spreads rapidly, no native predators,
displaces native plants, reduces biodiversity
Zebra mussels – Great Lakes, from ship
ballasts, no natural predators, displaced other
mussels, interrupted food chain, clogged pipes,
grows in large masses on everything
Major pollution threats
Oil – especially from runoff
Acid deposition
Plant nutrients and oxygen demanding
wastes
Toxic chemicals
Sedimentation from development
Protection of Marine Species
CITES
1979 Global Treaty on Migratory Species
U.S. Marine Mammal Protection Act of
1972
Endangered Species Act 1973
Whale conservation and protection act
1976
Changing fishing nets and fishing
practice
Whaling
International Convention for the
Regulation of Whaling formed the IWC to
set quotas (often ignored)
IWC set moratorium on commercial
whaling since 1986 (Inuits still allowed to
hunt whale) many populations recovered
US banned whaling and importing goods
Japan and Norway still are large whaling
countries
Restoring Wetlands
US requires a federal permit to drain/alter a
wetland over 3 acres
Mitigation banking – allows development of
wetlands if an equal area elsewhere is created
or restored
Use proper planning to keep development/Ag
away
Prevent introduction of alien species
Florida’s Mistake
Army Corps of Engineers diverted much
of the Everglade’s natural flow with
levees and canals
Wetlands dried and were converted to
farmland
Runoff from fields introduced excess
nutrients
Disrupted entire ecosystem
Now largest ecological restoration
project (at least $7.8 billion)
Columbia River Basin
Located in Pacific Northwest – 1,200 miles of
river
Largest hydroelectric power system
Provides jobs, electricity, flood control,
stimulate industry/agriculture
Hurts habitats especially migratory fish
(salmon)
Northwest Power Act 1980 – find way to
generate power and rebuild wild salmon and
other fish populations
Protecting Rivers
National Wild and Scenic Rivers Act 1968
– waterways kept free from development,
no motors, no alterations
A river can be designated by congress
based on outstanding scenic,
recreational, geological, wildlife,
historical, or cultural value
The Great Lakes
Faces several threats
 Alien species, like the zebra mussel, is
the greatest, but also is encountering
Thermal pollution from power plants
Commercial fishing
Human sewage (mostly processed)
Acid rain (but there is more to the east)
Act Now
Approximately 50% of the world’s
original coastal wetlands have been lost
Main reasons
Agriculture
Housing/building development
Commercial fishing techniques
While many systems are bad for the
environment, these appear to be the worst
Trawling - nets destroy ocean floor
habitat
Drift nets (more than 2 miles long) - kill
many mammals, turtles and birds
Longlining - creates a lot of bycatch such
as dolphin, shark, pilot whales, birds, and
turtles
What can you do?
Use comsumer power to buy products
that do not threaten aquatic species
Use environmentally friendly cleaners in
the home
Prevent soil erosion
Vote against wetland development
Eat less fish and seafood (more organic
veggies)