Transcript Chapter 11 Sustaining Aquatic Biodiversity Lake Victoria: A Case Study in sustainablity.

Chapter 11 Sustaining Aquatic Biodiversity
Lake Victoria: A Case Study in sustainablity
AQUATIC BIODIVERSITY
• We know fairly little (only explored 5%)
– The greatest marine biodiversity: coral reefs,
estuaries and the deep ocean floor
– Biodiversity: higher near coast and surface
because of habitat and food source variety
• The world’s marine and freshwater
systems provide important ecological and
economic services.
HUMAN IMPACTS ON AQUATIC
BIODIVERSITY
• Human activities destroy, disrupt or degrade a
large proportion of the world’s coastal, marine
and freshwater ecosystems.
– About 20% of the world's coral reefs – destroyed
– During the past 100 years, sea levels have risen 1025 cm
– We have destroyed more than 1/3 of the world’s
mangrove forests for shipping lanes.
HUMAN IMPACTS ON AQUATIC
BIODIVERSITY
• Area of ocean before and after a trawler
net, acting like a giant plow, scraped it.
Figure 12-2
Overfishing and Extinction:
Gone Fishing, Fish Gone
• 75% of the world’s commercially valuable
marine fish species: Over fished or fished
near their sustainable limits.
– Big fish are becoming scarce.
– Smaller fish are next.
– We throw away 30% of the fish we catch.
– We needlessly kill sea mammals and birds.
Fish farming
in cage
Trawl flap
Trawler
fishing
Spotter airplane
Sonar
Purse-seine fishing
Trawl
lines
Trawl bag
Long line
fishing
Fish
school
Drift-net fishing
Float Buoy
Lines with
hooks
Deep sea
aquaculture cage
Fish caught
by gills
Fig. 12-A, p. 255
HUMAN IMPACTS ON AQUATIC
BIODIVERSITY
• Harmful invasive species:
– Bioinvaders are blamed for about 2/3 of fish
extinctions in the U.S. between 1900-2000.
• Almost half of the world’s people live on
or near a coastal zone and 80% of ocean
water pollution comes from land-based
human activities.
Population Growth and Pollution
• Each year plastic
items dumped
from ships and left
as litter on
beaches threaten
marine life.
Figure 12-3
Why is it Difficult to Protect
Aquatic Biodiversity?
• Rapid increasing human impacts, the
invisibility of problems, citizen
unawareness, and lack of legal jurisdiction
– Human ecological footprint is expanding.
– Much of the damage to oceans is not visible
to most people.
– Many people incorrectly view the oceans as
an inexhaustible resource.
PROTECTING AND SUSTAINING
MARINE BIODIVERSITY
• Laws, international treaties, and education
• Since 1989 the U.S. government has
required offshore shrimp trawlers to use
turtle exclusion devices.
PROTECTING AND SUSTAINING
MARINE BIODIVERSITY
• Six of the
world’s seven
major turtle
species are
threatened or
endangered
because of
human activities.
Figure 12-4
Commercial Whaling
• After many of
the world’s
whale species
were
overharvested,
commercial
whaling was
banned in 1960,
but the ban may
be overturned.
Figure 12-6
Commercial Whaling
• Despite ban, Japan,
Norway, and Iceland kill
about 1,300 whales of
certain species for
scientific purposes.
– Although meat is still sold
commercially.
Figure 12-5
PROTECTING AND SUSTAINING
MARINE BIODIVERSITY
• Fully protected marine reserves make up
less than 0.3% of the world’s ocean area.
- If protected: fish populations double, size
grows by almost a third, reproduction triples
and species diversity increases by almost one
fourth.
• Some communities work together with
integrated plans for coastal management
Revamping Ocean Policy
• Two recent studies called for an overhaul of
U.S. ocean policy and management.
– Develop unified national policy.
– Double federal budget for ocean research.
– Centralize the National Oceans Agency.
– Set up network of marine reserves.
– Reorient fisheries management towards
ecosystem function.
– Increase public awareness.
Solutions
Managing Fisheries
Fishery Regulations
Bycatch
Set catch limits well below the
maximum sustainable yield
Use wide-meshed nets to allow
escape of smaller fish
Improve monitoring and enforcement
of regulations
Economic Approaches
Use net escape devices for sea
birds and sea turtles
Sharply reduce or eliminate fishing
subsidies
Ban throwing edible and
marketable fish back into the sea
Aquaculture
Charge fees for harvesting fish and shellfish
from publicly owned offshore waters
Restrict coastal locations for fish
farms
Certify sustainable fisheries
Protected Areas
Control pollution more strictly
Establish Rely more on integrated
coastal management
no-fishing areas
Establish more marine protected areas
Consumer Information
Label sustainably harvested fish
Publicize overfished and threatened species
Depend more on herbivorous fish
species
Nonnative Invasions
Kill organisms in ship ballast water
Filter organisms from ship ballast
water
Dump ballast water far at sea and
replace with deep-sea water
Fig. 12-7, p. 261
PROTECTING, SUSTAINING,
AND RESTORING WETLANDS
• Requiring government permits for filling or
destroying U.S. wetlands has slowed their
loss, but attempts to weaken this protection
continue.
Figure 12-8
Solutions
Protecting Wetlands
Legally protect existing wetlands
Steer development away from existing wetlands
Use mitigation banking only as a last resort
Require creation and evaluation of a new wetland before
destroying an existing wetland
Restore degraded wetlands
Try to prevent and control invasions by nonnative species
Fig. 12-9, p. 264
Restoring the Florida Everglades
• The world’s largest ecological restoration
project
– 90% of park’s wading birds have vanished.
– Other vertebrate populations down 75-95%.
– Large volumes of water that once flowed
through the park have been diverted for crops
and cities.
– Runoff has caused noxious algal blooms.
Restoring the
Florida
Everglades
• The project has
been attempting
to restore the
Everglades and
Florida water
supplies.
Figure 12-10
PROTECTING, SUSTAINING,
AND RESTORING LAKES AND
RIVERS
• Lakes are difficult to manage and are
vulnerable to planned or unplanned
introductions of nonnative species
– Boating industry!
PROTECTING, SUSTAINING,
AND RESTORING LAKES AND
RIVERS
• Dams can provide many human benefits
but can also disrupt some of the ecological
services that rivers provide.
– 119 dams on Columbia River have sharply
reduced (94% drop) populations of wild
salmon.
– U.S. government has spent $3 billion in
unsuccessful efforts to save the salmon.
– Removing hydroelectric dams will restore
native spawning grounds.
PROTECTING, SUSTAINING,
AND RESTORING LAKES
AND RIVERS
• We can help sustain freshwater fisheries
– building and protecting populations of
desirable species
- preventing over-fishing
- decreasing populations of less desirable
species.
NATIONAL WILD & SCENIC RIVERS ACT
OF 1968
1. Wild river: inaccessible & untamed
you can: camp, swim,
hunt, fish, non-motorized
boating
2. Scenic river: no dams,
accessible in some
places by roads, great
scenic value
3. Recreational
river: some
dams, readily accessible