Chapter 11
Sustaining Aquatic Biodiversity

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

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
Are Degrading
Biodiversity
 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 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

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.

Fig. 11-6, p. 254
900,000
800,000
700,000
600,000
500,000
400,000
Fish
landings
(tons)
1992
300,000
200,000
100,000
0
1900 1920 1940 1960 1980 2000
Year

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

Fig. 11-12, p. 265
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
Aquaculture
Restrict coastal locations for
fish farms
Control pollution more strictly
Certify sustainable fisheries
Protect Areas
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
Filter organisms from ship
ballast water
Label sustainably harvested fish Dump ballast water far at sea
and replace with deep- sea
water
Publicize overfished and
threatened species

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