Sustaining Aquatic Biodiversity
Chapter 12
By the Numbers
 About 50% of the human population depends on the seas for
primary source of food.
 About 90% of fish spawn in the world’s coral reefs, mangrove
swamps, coastal wetlands or rivers
 Coral reefs have the greatest biodiversity
 About 1% of Earth’s surface is made of freshwater systems.
Major Causes of Species Loss in Marine
Ecosystems (HIPPCO)
 Habitat destruction
 Pollution
 Erosion
 Climate change
 Invasive species – caused over ½ of fish extinctions of last centuary
in the US
 Overfishing – lower size of fish populations; decreases marine
keystone species
All are made worse by the growth of the human population
A Biological Roller Coaster Ride in Lake
Victoria
 Loss of biodiversity and cichlids
 Nile perch: deliberately
introduced
 Frequent algal blooms
 Nutrient runoff
 Spills of untreated sewage
 Less algae-eating cichlids
Reasons Why Protecting Aquatic
Biodiversity is Difficult
1.
Expanding human ecological footprint
2.
Most of the ocean area lies outside political jurisdiction of any
one country
3.
Damage to oceans is not visible to most people
4.
Many view the ocean as an inexhaustible resource
Human Activities Are Destroying Habitats
 Habitat loss and degradation
 Marine – only 4% of the
world’s oceans are not
affected by pollution
 Coastal
 Ocean floor: fishing
methods
 Freshwater
 Dams
 Excessive water
withdrawal
 Invasive species
Invasive Species Are
Degrading
Biodiversity
 Threaten native species
 Disrupt and degrade whole
ecosystems
 Water hyacinth: Lake Victoria
(East Africa)
 Asian swamp eel: waterways of
south Florida
 Purple loosestrife: indigenous to
Europe
 Treating with natural
predators—a weevil species and
a leaf-eating beetle—
Invasive water hyacinth
Repeated Invasions by Alien
Species in the Great Lakes
 Collectively, world’s largest body of
freshwater
 Invaded by at least 162 nonnative
species
 Sea lamprey
 Zebra mussel
 Good and bad
 Quagga mussel
 Asian carp
Zebra Mussels Attached to a Water
Current Meter in Lake Michigan, U.S.
How Carp Have Muddied Some Waters
 Lake Wingra, Wisconsin (U.S.):
eutrophic, excessive nutrient inputs
from run off with fertilizers from
farms/lawns
 Contains invasive species
 Purple loosestrife and the common
carp, which devour the algae
 Removed carp from an area of the
lake
 This area appeared to recover
Population Growth and Pollution Can
Reduce Aquatic Biodiversity
 Nitrates and phosphates
mainly from fertilizers enter
water
 Leads to algal bloom and
eventual eutrophication,
fish die offs
 Toxic pollutants from
industrial and urban areas,
plastic items
Hawaiian Monk Seal
Climate Change Is a Growing Threat
 Global warming: sea levels will rise and aquatic biodiversity is
threatened
◦ Coral reefs
◦ Swamp some low-lying islands
◦ Drown many highly productive coastal wetlands
 New Orleans, Louisiana, and New York City
Overfishing and Extinction
 Marine and freshwater fish
 Threatened with extinction by human activities more than any other




group of species
Commercial extinction – industrialized fishing fleets can deplete
marine life at a much faster rate. Can cause 80% in 10-15 years
Collapse of the cod fishery of the coast of Newfoundland and its domino
effect leading to collapse of other species
By-catch – non-target species that are caught and killed duringy
commercial fishing practices (seals, dolphins).
34% of marine, 71% of fresh water species face extinction within your
life time.
900,000
800,000
700,000
Fish landings (tons)
600,000
500,000
400,000
1992
300,000
200,000
100,000
0
1900
1920
1940
1960
Year
1980
2000
Fig. 11-6, p. 254
Major Commercial Fishing
Practices
• Trawl fishing – involves dragging a
weighted, funnel-shaped net along ocean
floor in order to catch shellfish, flounder; most
destructive of fishing practices.
• Purse seine – practice used to capture
schooling fish (tuna); surrounds and encloses
with a net.
• Drift net – uses hanging vertical nets in the
water column with buoys to catch fish by gills.
• Longline fishing – involves putting out lines
hung with thousands of baited hooks.
Industrial Fish Harvesting Methods
are Vacuuming the Seas
• Trawl fishing –
shrimp & scallops
• Purse seine – tuna &
mackarel
• Longline fishing –
tuna, swordfish &
sharks
• Drift net – 1992 ban
on using nets longer
than 2.5 km
Aquaculture
• Deep sea aquaculture cage
– Form of “fish farming”
– These strains of fish are usually weaker than
the “wild” form of the species. If weaker
strains escape into the wild, could weaken
wild population.
Protect and Sustain Marine
Biodiversity
• We can help to sustain marine biodiversity
by
– Using laws and incentives to protect species
– Setting aside marine reserves to protect
ecosystems
– Using community-based coastal management
– Page 261
Legislation
1. Convention on International Trade in
Endangered Species (CITES) 1973
2. Global Treaty on Migratory Species 1979
3. US Marine Mammal Protection Act 1972
4. US Endangered Species Act 1973
5. US Whale Conservation & Protection Act
1976
6. International Convention on Biological
Diversity 1995
International Whaling
Commission
• Established by the International
Convention for the Regulation of Whaling
in 1946
• Allows Eskimos to continue hunting
whales (cultural reasons)
• Japan, Norway and Iceland kill about 1300
whales per year for “scientific purposes”
– Japan more than doubled whaling catch in
2005
Protecting Whales: Success
Story… So Far
 Cetaceans: Toothed whales and baleen
whales
 1946: International Whaling
Commission (IWC) – set annual quotas
 1970: U.S.
 Stopped all commercial whaling
 Banned all imports of whale products
 1986: moratorium on commercial
whaling
 Japan ,Norway, Iceland, Russia do not
support the IWC ban
Economic Incentives Can Be Used to
Sustain Aquatic Biodiversity
 Tourism – example : sea turtles, worth more to local
communities alive than dead (WWF)
 Economic rewards
Marine Sanctuaries Protect Ecosystems
and Species
 Offshore fishing extends to 370 kilometers
 Exclusive economic zones-can take certain quotas of fish
 High seas-beyond legal jurisdiction of any country
 Law of the Sea Treaty – world’s coastal nations have jurisdiction
over 36% of the ocean surface and 90% of the world’s fish stocks
 Marine Protected Areas (MPAs) – 4000 world wide, 200 in US
waters
 In 2006, President George W. Bush created the world’s largest
marine reserve in Hawaii.
Ecosystem approach to sustainability
 Core zone
 No human activity allowed
 Less harmful activities allowed
 E.g., recreational boating and shipping
 Fully protected marine reserves work fast
 Fish populations double
 Fish size grows
 Reproduction triples
 Species diversity increase by almost one-fourth
Protecting Marine Biodiversity:
Individuals and Communities Together
 Integrated Coastal
Management
 Community-based group
to prevent further
degradation of the ocean
 More that 100 such
groups
 seek reasonable short
term trade offs that can
lead to long term
ecological and economic
benefits
How Should We Manage and Sustain Marine
Fisheries?
 Sustaining marine fisheries will require
 improved monitoring of fish populations,
 cooperative fisheries management among communities and nations,
 reduction of fishing subsidies,
 careful consumer choices in seafood markets.
Estimating and Monitoring Fishery
Populations is the First Step
 Maximum Sustained Yield (MSY) – model to project
the maximum number of fish that can be harvested from a
fish stock without causing a population drop.
 Optimum Sustained Yield (OSY) – takes into account
interactions with other species and provides more room for
error.
 Tragedy in the commons activity
Some Communities Cooperate to
Regulate Fish Harvests
 Community management of the fisheries – allotment and
enforcement systems. Norway’s Lofoten fishery (cod)
 Co-management of the fisheries with the government – sets
quotas for various species and divide the quotas among
communities.
Government Subsidies Can Encourage
Overfishing-$30-34 billion around the world
 2007: World Trade Organization, U.S.
 Proposed a ban on fishing subsidies
 Reduce illegal fishing on the high seas and in coastal waters
 Close ports and markets to such fishers
 Check authenticity of ship flags
 Prosecution of offenders
Some Countries Use the Marketplace
to Control Overfishing
 Individual transfer rights (ITRs)
 Control access to fisheries
 New Zealand and Iceland
 Difficult to enforce
 US 1995 to protect the halibut fishery
 Problems with the ITR approach
 transfer ownership of fisheries in publically owned waters
to private owners
 squeeze out small fishing companies
Consumer Choices Can Help to Sustain
Fisheries and Aquatic Biodiversity
 1997: Marine Stewardship Council (MSC), London – 20 nations
 Certifies that fish caught using sustainable practices
 Manage global fisheries more sustainably
 Individuals
 Organizations
 Governments
How Should We Protect and Sustain
Wetlands and Beach Areas?

To maintain the ecological and economic services of
wetlands, we must maximize
 preservation of remaining wetlands and
 restoration of degraded and destroyed wetlands.
 Best long-range strategy to reduce beach erosion:
 Prevent development on beach areas or allow development only
behind protective dunes
Coastal Wetlands
1.
Serve as buffers against storms
2.
Trap sediments and filter water
3.
Act as nurseries for fish, shellfish and birds
4.
More than half of the coastal wetlands have disappeared
Florida Everglades – Largest Ever
Wetlands Restoration Project
 “River of Grass”: south Florida, U.S.
 Since 1948: damaged
 Drained
 Diverted
 Paved over
 Nutrient pollution from agriculture
 Invasive plant species
 1947: Everglades National Park unsuccessful protection
project
Can We Restore the Florida Everglades?
 1970s: political haggling
 1990: Comprehensive Everglades Restoration Plan
(CERP)
 Restore the curving flow of most of the Kissimmee
River
 Remove canals and levees in strategic locations
 Flood 240 sq. km farmland to create artificial marshes
Can We Restore the Florida Everglades?
 Comprehensive Everglades Restoration Plan (CERP) cont…
 Create reservoirs and underground water storage areas
 Build new canals, reservoirs and efficient pumping systems
 US Army Corps of Engineers – federal agency responsible for
undoing development (dredging canals, levees)in Everglades.
Ironically, this same agency oversaw the development of the
Everglades since the 1940s.
 Plan isn’t working……not sure why.
The World’s Largest Restoration Project
Managing River Basins Is Complex
and Controversial
 40% of the world’s rivers have been dammed or otherwise
engineered
 Columbia River: U.S. and Canada
 Dam system 119 dams , 19 of which are hydroelectric power
plants
 Pros –electricity ; con –salmon affected
 Snake River: Washington state, U.S.
 Hydroelectric dams removed
 Pro – salmon saved ; con – economy affected
Dams and Reservoirs
1.
May kill young salmon as they pass through turbines
2.
Slow downstream migration, exposing juvenile salmon to
more predation
3.
May prevent upstream migration of mature salmon
Columbia River Rehabilitation and
Restoration
 Ecosystem rehabilitation and salmon restoration on the
Columbia River includes
1.
Building new hatcheries upstream of the dams
2.
Putting 40,000 miles of stream off limits to hydropower
development
3.
Reducing runoff of silt from logging roads.
Natural Capital: Ecological Services
of Rivers
Protect Freshwater Ecosystems by
Protecting Watersheds
 Freshwater ecosystems protected through
 Laws
 Economic incentives
 Restoration efforts
 National Wild and Scenic Rivers Act-reestablish protection
of rivers
 Sustainable management of freshwater fishes
Priorities for Protecting Biodiversity,
Ecosystem Services
 2002: Edward O. Wilson
 Complete the mapping of the world’s terrestrial and
aquatic biodiversity
 Keep old-growth forests intact; cease their logging
 Identify and preserve hotspots and deteriorating
ecosystem services that threaten life
 Ecological restoration projects
 Make conservation financially rewarding