Sustaining Aquatic Biodiversity
Chapter 11
Core Case Study: A Biological Roller Coaster
Ride in Lake Victoria
 Loss of biodiversity and cichlids
 Nile perch: deliberately
introduced in 1950s and 1960s
to stimulate exports of the fish
 Frequent algal blooms due to
 Nutrient runoff
 Spills of untreated sewage
 Less algae-eating cichlids
Natural Capital Degradation:
The Nile Perch
Nile perch
population is
decreasing due to
reduced food
supply of smaller
fishes (cichlids)
and being
overfished.
What Are the Major Threats to Aquatic
Biodiversity?
 Aquatic species are threatened by habitat loss,
invasive species, pollution, climate change, and
overexploitation, all made worse by the growth of
the human population. (HIPPCO)
We Have Much to Learn about
Aquatic Biodiversity
 Greatest marine biodiversity occurs in
 Coral reefs
 Estuaries
 Deep-sea ocean floor
 Biodiversity is higher
 Near the coasts because of great variety of producers,
habitats, and nursery areas than in the open sea
 In the bottom region than in the surface region of the
ocean due to a greater variety of habitats
Human Activities are Destroying and
Degrading Aquatic Habitats
 Habitat loss and degradation – the “H”
in HIPPCO – the greatest threat to
the biodiversity of oceans
 Marine – only 4% of the world’s
oceans are NOT affected by
pollution
 Coastal – coral reefs, mangrove
forests, and coastal wetlands
 Ocean floor – effect of trawlers
which drag huge nets weighted
with heavy chains and steel
plates, reduce coral reefs to
rubble
 Freshwater Habitats
 Dams
 Excessive water withdrawal
Invasive Species are Degrading Biodiversity
 Invasive species - the “I” in HIPPCO
 Threaten native species
 Disrupt and degrade whole
ecosystems
 Three Examples:
 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—Will it work?
Invasive Water Hyacinth
Science Focus: 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
 Dr. Richard Lathrop
 Removed carp from an area of the
lake
 This area appeared to recover
Population Growth and Pollution Can Reduce
Aquatic Biodiversity
 The two “P’s” in HIPPCO
 By 2020, 80% of the world’s
population will live near coasts
 Population growth and pollution
have drastic effects on ocean
systems
 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 kill some forms
of aquatic life by poisoning them
Hawaiian Monk Seal
Plastic items from ships and litter on
beaches kill seabirds, mammals, and sea
turtles – POLLUTION
Climate Change Is a Growing Threat
 The “C” in HIPPCO
 Global Warming: sea levels will rise and aquatic biodiversity is
threatened – during the past 100 years, average sea levels have
risen an average of 10-20 cm and scientists estimate they will rise
another 18-59 cm, and perhaps as high as 1-1.6 m between 2050
and 2100
◦ Destroy coral reefs
◦ Swamp some low-lying islands
◦ Drown many highly productive coastal wetlands including New
Orleans, Louisiana
Overfishing and Extinction
 Overfishing – the “O” in HIPPCO
 Marine and Freshwater Fish
 Threatened with extinction by human activities more than any other
group of species.
 Commercial Extinction – due to overfishing which occurs when it is
no longer profitable to continue fishing the affected species.
Industrialized fishing fleets can deplete marine life at a much faster rate.
Can deplete 80% of target fish species in 10-15 years.
 Collapse of the cod fishery off the coast of Newfoundland and its domino
effect leading to collapse of other species.
 Bycatch – seals, dolphins (non-target species, 1/3 of annual fish catch)
 Biological Extinction – 34% of marine and 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
Science Focus: Protecting and Restoring
Mangroves
 Protect and restore mangroves because they provide
important ecological services.
 Reduce the impact of rising sea levels
 Protect against tropical storms and tsunamis
 Cheaper than building concrete sea walls
 Due to coastal development in Indonesia, about 70% of
mangroves have been degraded or destroyed. Now
efforts to protect those areas.
Case Study: Industrial Fish Harvesting
Methods are Vacuuming the Seas
 Trawler fishing – fish
and shellfish
 Purse-seine fishing –
surface dwelling species
like tuna, mackerel
 Long-lining – open
ocean fish species like
tuna, swordfish, sharks
 Drift-net fishing –
1992 ban on the use of
drift nets longer than
2.5 km in international
waters
How Can We Protect and Sustain Marine
Biodiversity?

We can help to sustain marine biodiversity by using laws
and economic incentives to protect species, setting aside
marine reserves to protect ecosystems, and using
community-based integrated coastal management.
Legal Protection of Some Endangered and
Threatened Marine Species
 Why is it hard to protect marine biodiversity?
 Human ecological footprint and fishprint are expanding.
 Much of the damage in the ocean is not visible.
 The oceans are incorrectly viewed as an inexhaustible
resource that can absorb an almost infinite amount of
waste.
 Most of the ocean lies outside the legal jurisdiction of
any country.
 Treaties - CITES, Marine Mammal Protection Act,
Endangered Species Act, Whale Conservation and
Protection Act, International Convention on Biological
Diversity.
Protecting Whales:
A Success Story… So Far
 Cetaceans: two groups – toothed whales
and baleen whales
 Overharvesting has driven some valuable
species to almost extinction.
 1946: International Whaling
Commission (IWC) – set annual quotas
 1970: U.S.
 Stopped all commercial whaling
 Banned all imports of whale products
 1986: IWC imposed a moratorium on
commercial whaling – this worked
 Japan ,Norway, Iceland, Russia do not
support the IWC ban.
Norwegian Whalers Harpooning a
Sperm Whale
Economic Incentives Can Be Used to
Sustain Aquatic Biodiversity
 Tourism – example: sea turtles, worth more to local
communities alive than dead (WWF); brings in almost
three times more money than does the sale of turtle
products such as meat, leather, and eggs.
 Economic Rewards
 Reconciliation Ecology – science of inventing, establishing, and
maintaining habitats to conserve species diversity in places
where people live, work, and play. Example: artificial coral
reef created in Israel.
Case Study: Holding Out Hope for Marine
Turtles (6 of the 7 species are endangered)
 Carl Safina, Voyage of the Turtle
◦ Studies of the leatherback turtle
 Threats to the leatherbacks
◦ Trawlers destroy coral reefs which is their feeding grounds
◦ Entangled in fishing nets and lines
◦ Pollution—discarded plastic bags
◦ Climate change—rising sea levels will flood nesting and feeding
areas
 Communities protecting the turtles
 Turtle Excluder Devices required on trawlers (shrimp boats) by
the U.S. government
An Endangered Leatherback Turtle is
Entangled in a Fishing Net
Marine Sanctuaries Protect Ecosystems
and Species
 Offshore Fishing Zone – extends to 370 kilometers from its
shores
 Exclusive Economic Zones – foreign fishing vessels can take certain
quotas of fish within these zones with a government’s permission.
 High Seas – ocean area’s beyond the legal jurisdiction of any country.
Laws and treaties pertaining to the high seas are difficult to monitor
and enforce.
 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. Most MPAs allow ecologically harmful activities like
trawling, dredging, and resource extraction.
Establishing a Global Network of Marine Reserves:
An Ecosystem Approach to Sustainability
 Primary Objective – protect and sustain whole marine ecosystems for current and
future generations instead of focusing primarily on protecting individual species.
 Marine Reserves closed to extractive activities such as
 Commercial fishing
 Dredging reserves
 Mining and waste disposal
 Core zone – No human activity allowed
 Less harmful activities allowed – recreational boating and shipping
 Fully protected marine reserves work and work fast
 Fish populations double
 Fish size grows by almost one-third
 Reproduction triples
 Species diversity increase by almost one-fourth
 But, less than 1% of the world’s ocean area is closed to fishing in marine reserves.
Protecting Marine Biodiversity:
Individuals and Communities Together
 Integrated Coastal
Management
 Community-based effort to
develop and use coastal
resources more sustainably
 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
An atoll of Australia’s Great Barrier Reef
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, and careful consumer choices in seafood
markets.
Estimating and Monitoring Fishery Populations
Is the First Step
 Maximum Sustained Yield (MSY)—mathematical model where




the maximum number of fish that can be harvested annually without
causing a population drop is calculated. Traditional approach.
Optimum Sustained Yield (OSY)—takes into account
interactions with other species and allows more room for error.
Multispecies Management—of a number of interaction species,
which accounts for competition and predator-prey interactions.
Large Marine Systems—using large complex computer models.
Precautionary Principle—use this method because of the
uncertainty of all the above methods.
Some Communities Cooperate to Regulate
Fish Harvests
 Community Management of the Fisheries – allotment and
enforcement systems. Norway’s Lofoten fishery (cod) is
self-regulated with no participation by the Norwegian
government.
 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) – assigned to each
fisherman – can be bought, sold, or leased like private property.
 Use to control access to fisheries
 New Zealand – 1986 and Iceland - 1990
 Difficult to enforce
 U.S. - 1995 introduced tradable quotas to regulate Alaska’s
halibut fishery
 Problems with the ITR approach
 Transfers public ownership of fisheries in publically owned
waters to private fishers
 Squeezes out small fishing companies
 Fishing quotas are often set too high
Consumer Choices Can Help to Sustain
Fisheries and Aquatic Biodiversity
 1997: Marine Stewardship Council (MSC), London –
operates in more than 20 nations
 Support sustainable fishing and certifies that fish are
caught using sustainable practices.
 Manage global fisheries more sustainably.
 Individuals
 Organizations
 Governments
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
Use net escape devices for
seabirds and sea turtles
Ban throwing edible and
marketable fish back into the
sea
Economic Approaches
Sharply reduce or eliminate
fishing subsidies
Charge fees for harvesting fish
and shellfish from publicly
owned offshore waters
Protect Areas
Certify sustainable fisheries
Establish no-fishing areas
Establish more marine protected
areas
Rely more on integrated coastal
management
Consumer Information
Label sustainably harvested fish
Publicize overfished and
threatened species
Aquaculture
Restrict coastal locations for
fish farms
Control pollution more strictly
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. 11-12, p. 265
How Should We Protect and Sustain
Wetlands?

To maintain the ecological and economic services of
wetlands, we must maximize preservation of
remaining wetlands and restoration of degraded and
destroyed wetlands.
Coastal and Inland Wetlands are
Disappearing around the World
 U.S. has lost more than half of its coastal and inland
wetlands since 1900.
 Ecological Value:
 Highly productive wetlands
 Provide natural flood and erosion control
 Maintain high water quality; natural filters
 Effected by rising sea levels due to global warming
which will degrade aquatic biodiversity
We Can Preserve and Restore Wetlands
 Laws for protection
 Mitigation Banking
 Allows destruction of existing wetlands as long as
an equal area of the same type of wetland is created
or restored.
 Ecologists argue this should be used only as a
last resort.
Individuals Matter: Restoring a Wetland
 Jim Callender: 1982
 Scientific knowledge + hard work =
a restored wetland in California, U.S.
 Marsh used again by migratory fowl
Natural Capital Restoration:
Wetland Restoration in Canada
Case Study: Can We Restore the Florida
Everglades?
 “River of Grass”:
South Florida, U.S.
 Since 1948: damages
 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 for 20 years
 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
 Why isn’t this plan working?
 Cannot undue 120 years of ecological damage done by
agriculture and urban development
 Will take at least 50 years and too expensive
The World’s Largest Restoration Project
How Can We Protect and Sustain
Freshwater Lakes, Rivers, and Fisheries?
 Freshwater ecosystems are strongly affected by human
activities on adjacent lands, and protecting these ecosystems
must include protection of their watersheds.
Freshwater Ecosystems are Under
Major Threats
 HIPPCO – major threats
 40% of the world’s rivers have been dammed or otherwise
engineered.
 Invasive species, pollution, climate change
Case Study: Can the Great Lakes Survive
Repeated Invasions by Alien Species?
 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.
Managing River Basins is
Complex and Controversial
 Columbia River: U.S. and Canada
 Dam System: 119 dams, 19 of which are hydroelectric power
plants.
 Pro–electricity; Con–salmon affected
 Snake River: Washington State, U.S.
 Hydroelectric dams removed
 Pro–salmon saved ; Con–economy affected
Natural Capital: Ecological Services of Rivers
We Can Protect Freshwater Ecosystems
by Protecting Watersheds
 Freshwater ecosystems protected through
 Laws
 Economic Incentives
 Restoration Efforts
 National Wild and Scenic Rivers Act—passed in 1968 to protect
rivers and river segments with outstanding scenic, recreational,
geological, wildlife, historical, or cultural values.
 Sustainable management of freshwater fishes involves encouraging
populations of commercial/sport species, prevents overfishing, and
reduces or eliminates less desirable fish populations.
What Should Be Our Priorities for Sustaining
Biodiversity and Ecosystem Services?
 Sustaining the world’s biodiversity and ecosystem
services will require mapping terrestrial and
aquatic biodiversity, maximizing protection of
undeveloped terrestrial and aquatic areas, and
carrying out ecological restoration projects
worldwide.
What Should Be Our Priorities for Sustaining
Biodiversity and 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.