Download Chapter 12

Chapter 12
Sustaining Aquatic Biodiversity
Aquatic Biodiversity

What do we know?




Only have explored 5% of the oceans
Greatest marine biodiversity occurs in coral reefs,
estuaries and deep ocean floor.
Biodiversity is higher by the coast then the open
sea
Biodiversity is greater in the bottom region of the
ocean then the surface region
Aquatic Biodiversity

Values of Aquatic Biodiversity




Provide us with an estimated $21 trillion a year
At least 3.5 billion people depend on the oceans
for survival
Many marine organisms have chemicals used in
medicines
Freshwater systems provide services worth $1.7
trillion.
Human Impacts on Aquatic
Biodiversity

Loss and degradation






90% of fish living in the oceans spawn in coral reefs,
mangroves, coastal wetlands or rivers.
20% of coral reefs have been destroyed. Up to 58% could
be lost by 2050.
15% of worlds seagrass beds have disappeared since
1995
Sea level is rising- over the past 100 years level has risen
by 10-25 cm
Mangroves and wetlands have been lost to development
Trawlers are destroying bottom ecosystems
Human Impacts on Aquatic
Biodiversity

Invasive Species



Blamed for about 2/3 of fish extinctions in the US
between 1900 and 2000 and cost an average of
$16 million per HOUR.
Most arrive in ballast water
Examples:

Asian swamp eel eats many types of fish. It can
withstand cold weather, drought, fires and predators
because it can burrow. It can also breath air.
Human Impacts on Aquatic
Biodiversity

Population Growth and Pollution


2006 45% of the worlds population lives on or
near a coast.
Estimated that 80% of ocean pollution comes
from land based activities



Amount of nitrate fertilizers has doubled since 1860.
Excess nutrients can cause eutrophication which can
lead to algae blooms and then fish die offs.
Toxic pollutants from industrial and urban areas
Plastic pollution kills 1 million seabirds and 100,000
sea turtles.
Human Impacts on Aquatic
Biodiversity

Overfishing and Extinction





Modern industrialized fishing can deplete marine life very
rapidly. Can cause 80% depletion of a target fish species in
only 10-15 years.
Usually leads to commercial extinction.
In 1992 Canada’s cod fishery collapsed. Still has not
recovered.
90% of the large open ocean fish have disappeared since
1950
Can cause bycatch – organisms caught unintentionally in
nets.
Human Impacts on Aquatic
Biodiversity

Why is it difficult to protect?




Human ecological footprint is expanding so
rapidly that it is difficult to monitor the impacts.
Damage to oceans is not visible to humans
People view the sea as an inexhaustible resource
that can absorb an infinite number of pollutants
Most oceans lie outside the legal jurisdiction of
any country.
Protecting and Sustaining
Marine Biodiversity

Legal and economic approaches






1975 CITES
1979 Global Treaty on Migratory Species
US Marine Mammal Protection Act of 1972
US Endangered Species Act of 1973
US Whale and Conservation and Protection Act of
1973
1995 International Convention on Biological
Diversity
Case Study: The Florida
Manatee and Water Hyacinths


Manatee can eat unwanted
Water Hyacinths.
Endangered due to:





Habitat loss.
Entanglement from fishing
lines and nets.
Hit by speed boats.
Stress from cold.
Low reproductive rate
Figure 12-B
Case Study: 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
Case Study:
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

Marine sanctuaries

International law states that a country’s offshore
fishing zone extends to 370km (200 miles) from
its shores.




Exclusive economic zones:
High seas:
Marine protected areas (MPAs):
Marine reserves:

Works and works fast – fish populations double, fish size
grows by a third, fish reproduction triples, species diversity
increases by a fourth.
Protecting and Sustaining
Marine Biodiversity



Less than 0.3% of the world’s ocean area
consists of fully protected marine reserves.
Scientist call for 30% of the ocean to become
protected marine reserves.
World’s largest marine reserve was created
in 2006.

360,000 sq km (140,000 sq miles) surrounding
some Hawaiian island.
Protecting and Sustaining
Marine Biodiversity

Integrated coastal management


Community based effort to develop and use coastal
resources more sustainably.
Revamping US Ocean Policy






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.
Managing and Sustaining
Marine Fisheries

Make better estimates of fish populations.

Traditional approach is to use a maximum
sustainable yield (MSY):

Hasn’t been very successful

Optimum sustainable yield (OSY):

Multispecies management:
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 no-fishing areas
Depend more on herbivorous fish
species
Establish more marine protected areas
Nonnative Invasions
Rely more on integrated coastal
management
Kill organisms in ship ballast water
Consumer Information
Label sustainably harvested fish
Publicize overfished and threatened species
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

US has lost more then ½ of its wetlands since
1900



Louisiana has 40% of US salt marshes. Much is
lost due to sinking. Dams and levees block
sediment from flowing down Mississippi River that
would normally be deposited. Plus, sea level is
rising due to climate change.
Federal permits are required now to fill or dredge
a wetland. This has help cut he average annual
wetland lost by 80% since 1969.
Mitigation banking:
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
Case Study:
Restoring the Florida Everglades

The world’s largest ecological restoration
project involves trying to undo some of the
damage inflicted on the Everglades by
human activities.




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.
For decades, invasions by nonnative species
have caused major ecological and economic
damage to North America’s Great lakes.

Sea lamprey ($15 million/yr for chemical to kill
young), zebra mussel ($140 million a year),
quagga mussel, Asian carp.
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 by
building and protecting populations of
desirable species, preventing over-fishing,
and decreasing populations of less desirable
species.
A federal law helps protect a tiny fraction of
U.S. wild and scenic rivers from dams and
other forms of development.

National Wild and Scenic Rivers Act (1968).
Natural Capital
Ecological Services of Rivers
• Deliver nutrients to sea to help sustain
coastal fisheries
• Deposit silt that maintains deltas
• Purify water
• Renew and renourish wetlands
• Provide habitats for wildlife
Fig. 12-11, p. 267