Sustaining Aquatic Biodiversity
Chapter 11
 Loss of biodiversity and cichlids
 Nile perch: deliberately
introduced
 Frequent algal blooms
 Nutrient runoff
 Spills of untreated sewage
 Less algae-eating cichlids
A Biological Roller
Coaster Ride in
Lake Victoria
Natural Capital
Degradation:
The Nile Perch
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.
We Have Much to Learn about
Aquatic Biodiversity
 Greatest marine biodiversity
 Coral reefs
 Estuaries
 Deep-ocean floor
 Biodiversity is higher
 Near the coast than in the open sea
 In the bottom region of the ocean than the surface region,
greater variety of habitats
Human Activities Are Destroying Habitats
 Habitat loss and degradation -
HIPPCO
 Marine – only 4% of the world’s
oceans are not affected by
pollution
 Coastal
 Ocean floor: effect of trawlers,
which drag huge nets weighted
with heavy chains and steel
plates, reduce coral reefs to
rubble
 Freshwater
 Dams
 Excessive water withdrawal
 Invasive species
 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 Species Are
Degrading
Biodiversity
Invasive water hyacinth
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
 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 – in the past 100 years , average 10-20 cm and
scientists estimate another 18-59 cm, perhaps as high as 1-1.6 m
◦ 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
 Bycatch – 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
Protecting and Restoring Mangroves
 Protect and restore mangroves
 Reduce the impact of rising sea levels
 Protect against tropical storms and tsunamis
 Cheaper than building concrete sea walls
 Mangrove forests in Indonesia
Industrial Fish Harvesting Methods are
vacuuming the seas
 Trawler fishing-
shrimp, scallops
 Purse-seine fishing
tuna, mackarel
 Longlining – tuna,
swordfish, sharks
 Drift-net fishing –
1992 ban on the use of
drift nets longer than
2.5 km
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 fish print 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: 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
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)
 Economic rewards
Holding Out Hope for
Marine Turtles(6 out of 7 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 on shrimp boats
An Endangered Leatherback Turtle is
Entangled in a Fishing Net
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
Ecosystem approach to sustainability
 Marine
 Commercial fishing
 Dredging reserves
 Mining and waste disposal
 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, and careful consumer choices in seafood
markets.
Estimating and Monitoring Fishery
Populations Is the First Step
 Maximum sustained yield (MSY): maximum number of fish that




can be harvested annually without causing a population drop
Optimum sustained yield (OSY)-interactions among species
Multispecies management – of a number of interacting species
Large marine systems: using large complex computer models
Precautionary principle 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)
 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
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
 Highly productive wetlands
 Provide natural flood and erosion control
 Maintain high water quality; natural filters
 Effect of rising sea levels
Natural Capital Restoration: Wetland
Restoration in Canada
Can We Restore the Florida Everglades?
 “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
 Why isn’t this plan working?
The World’s Largest Restoration Project
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
 40% of the world’s rivers have been dammed or otherwise
engineered
 invasive species, pollution , climate change
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.
Managing River Basins Is Complex
and Controversial
 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
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