Natural Capital Degradation:
The Nile Perch
Core Case Study: 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
Sustaining Aquatic Biodiversity
Chapter 11
We Have Much to Learn about
Aquatic Biodiversity
• Greatest marine biodiversity
– Coral reefs
– Estuaries
– Continental shelf
• Biodiversity is higher
– Near the coast than in the open sea
– In the bottom region of the ocean than the surface region
Why?
Don’t Forget!
Natural Capital
HIPPCO
Human Activities Are Destroying and Degrading
Aquatic Habitats
• Habitat loss and degradation
– Marine
• Coastal
• Ocean floor: effect of trawlers
– Freshwater
• Dams
• Excessive water withdrawal
Natural Capital Degradation: Area of Ocean
Bottom Before and After a Trawler
Invasive Species Are Degrading
Aquatic Biodiversity
• Invasive species
– 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
Invasive Water Hyacinths
Science Focus: How Carp Have Muddied Some
Waters
• Lake Wingra, Wisconsin (U.S.): eutrophic
– Contains invasive species
• Purple loosestrife and the common carp
• 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 eutrophication
• Toxic pollutants from industrial and urban areas
biomagnification
Hawaiian Monk Seal
Plastics
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
Warming seas . . . Rising seas
. . . Acidic seas
Overfishing and Extinction: Gone
Fishing, Fish Gone
• Marine and freshwater fish
– Threatened with extinction by human activities
more than any other group of species
• Commercial extinction
• Collapse of the cod fishery and its domino
effect
Natural Capital Degradation: Collapse of the Cod
Fishery Off the Canadian Coast
Watery Wasteland
•Bycatch
http://s.ngeo.com/wpf/media-live/photos/000/001/cache/dead-fish-tossed_131_600x450.jpg
Case Study: Industrial Fish Harvesting Methods
• Trawler fishing
• Purse-seine fishing
• Longlining
• Drift-net fishing
Fishprint
Sea Around Us Project
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
– Most of the ocean lies outside the legal jurisdiction of any
country
• Regulatory Approach – CITES, US Marine Mammal
Protection Act, US ESA, 1995 International Convention
on Biodiverstiy (CBD)
Solutions
Case Study: Protecting Whales: A Success
Story… So Far
• Cetaceans: Toothed whales and baleen whales
• 1946: International Whaling Commission (IWC)
• 1970: U.S.
– Stopped all commercial whaling
– Banned all imports of whale products
• 1986: moratorium on commercial whaling
– Pros
– Cons
Fig. 11-8b, p. 258
Norwegian Whalers Harpooning a
Sperm Whale
Economic Incentives Can Be Used to Sustain
Aquatic Biodiversity
• Tourism
• Economic rewards
– Reconciliation ecology- See Red Sea Star Restaurant
Ex: Reuven Yosef, Red Sea Star Restaurant
Coral reef restoration
Case Study: Holding Out Hope for
Marine Turtles
• Carl Safina, Voyage of the Turtle
– Studies of the leatherback turtle
• Threats to the leatherbacks
– Trawlers
– Pollution
– Climate change
• Communities protecting the turtles
Marine Sanctuaries Protect Ecosystems and
Species
• Offshore fishing
– Exclusive economic zones
– High seas
• Law of the Sea Treaty
LOST
• Marine Protected Areas (MPAs)
Establishing a Global Network of Marine
Reserves: An Ecosystem Approach
• Marine reserves
– Closed to
• Commercial fishing
• Dredging
• 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
Other Side
Protecting Marine Biodiversity: Individuals and
Communities Together
• Integrated Coastal Management
– Community-based group to prevent further degradation of
the ocean
fishers, business owners,
developers, scientists, citizens,
politicians
Estimating and Monitoring Fishery Populations
Is the First Step
• Maximum sustained yield (MSY): traditional approach
• Optimum sustained yield (OSY)
• Precautionary principle
Some Communities Cooperate to Regulate Fish
Harvests
• Community management of the fisheries
• Lofoten Fishery - Norway
• Comanagement of the fisheries with the government
Government Subsidies Can Encourage
Overfishing
• 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
• Problems with the ITR approach
(% of TAC)
Consumer Choices Can Help to Sustain Fisheries
and Aquatic Biodiversity
• 1997: Marine Stewardship Council (MSC), London
– Supports sustainable fishing
– Certifies sustainably produced seafood
• Manage global fisheries more sustainably
– Individuals
– Organizations
– Governments
Marine Stewardship Council
Solutions: Managing Fisheries
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
Bolsa Chica Land Trust
We Can Preserve and Restore Wetlands
• Laws for protection
• Mitigation banking
– Ecologists argue this as a last resort
We Need to Set 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