Chapter 12: Core Case Study: A Biological Roller Coaster Ride in Lake Victoria Reasons for Lake...
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Transcript of Chapter 12: Core Case Study: A Biological Roller Coaster Ride in Lake Victoria Reasons for Lake...
Chapter 12: Core Case Study: A Chapter 12: Core Case Study: A Biological Roller Coaster Ride in Lake Biological Roller Coaster Ride in Lake
VictoriaVictoria Reasons for Lake Victoria’s loss of Reasons for Lake Victoria’s loss of
biodiversity:biodiversity: Introduction of Nile perch.Introduction of Nile perch. Lake experienced algal blooms from nutrient Lake experienced algal blooms from nutrient
runoff.runoff. Invasion of water hyacinth has blocked sunlight Invasion of water hyacinth has blocked sunlight
and deprived oxygen.and deprived oxygen. Nile perch is in decline because it has eaten its Nile perch is in decline because it has eaten its
own food supply.own food supply.
AQUATIC BIODIVERSITYAQUATIC BIODIVERSITY
We know fairly little about the biodiversity of We know fairly little about the biodiversity of the world’s marine and freshwater systems.the world’s marine and freshwater systems. The greatest marine biodiversity occurs in coral The greatest marine biodiversity occurs in coral
reefs, estuaries and the deep ocean floor.reefs, estuaries and the deep ocean floor. Biodiversity is higher near the coast and surface Biodiversity is higher near the coast and surface
because of habitat and food source variety.because of habitat and food source variety. The world’s marine and freshwater systems The world’s marine and freshwater systems
provide important ecological and economic provide important ecological and economic services.services.
HUMAN IMPACTS ON AQUATIC HUMAN IMPACTS ON AQUATIC BIODIVERSITYBIODIVERSITY
Human activities have destroyed, disrupted Human activities have destroyed, disrupted or degraded a large proportion of the world’s or degraded a large proportion of the world’s coastal, marine and freshwater ecosystems.coastal, marine and freshwater ecosystems. Approximately 20% of the world's coral reefs Approximately 20% of the world's coral reefs
have been destroyed.have been destroyed. During the past 100 years, sea levels have risen During the past 100 years, sea levels have risen
10-25 centimeters.10-25 centimeters. We have destroyed more than 1/3 of the world’s We have destroyed more than 1/3 of the world’s
mangrove forests for shipping lanes.mangrove forests for shipping lanes.
HUMAN IMPACTS ON AQUATIC HUMAN IMPACTS ON AQUATIC BIODIVERSITYBIODIVERSITY
Harmful invasive species are an increasing Harmful invasive species are an increasing threat to marine and freshwater biodiversity.threat to marine and freshwater biodiversity. Bioinvaders are blamed for about 2/3 of fish Bioinvaders are blamed for about 2/3 of fish
extinctions in the U.S. between 1900-2000.extinctions in the U.S. between 1900-2000. Almost half of the world’s people live on or Almost half of the world’s people live on or
near a coastal zone and 80% of ocean water near a coastal zone and 80% of ocean water pollution comes from land-based human pollution comes from land-based human activities.activities.
Overfishing and Extinction: Overfishing and Extinction: Gone Fishing, Fish GoneGone Fishing, Fish Gone
About 75% of the world’s commercially About 75% of the world’s commercially valuable marine fish species are over fished valuable marine fish species are over fished or fished near their sustainable limits.or fished near their sustainable limits. Big fish are becoming scarce.Big fish are becoming scarce. Smaller fish are next.Smaller fish are next. We throw away 30% of the fish we catch.We throw away 30% of the fish we catch. We needlessly kill sea mammals and birds.We needlessly kill sea mammals and birds.
Fig. 12-A, p. 255
Fish farming in cage
Trawler fishing
Spotter airplane
Sonar
Trawl flap
Trawl lines
Purse-seine fishing
Trawl bagFish school
Drift-net fishingLong line fishing
Lines with hooks
Fish caught by gills
Deep sea aquaculture cage
Float Buoy
Why is it Difficult to Protect Aquatic Why is it Difficult to Protect Aquatic Biodiversity?Biodiversity?
Rapid increasing human impacts, the Rapid increasing human impacts, the invisibility of problems, citizen unawareness, invisibility of problems, citizen unawareness, and lack of legal jurisdiction hinder protection and lack of legal jurisdiction hinder protection of aquatic biodiversity.of aquatic biodiversity. Human ecological footprint is expanding.Human ecological footprint is expanding. Much of the damage to oceans is not visible to Much of the damage to oceans is not visible to
most people.most people. Many people incorrectly view the oceans as an Many people incorrectly view the oceans as an
inexhaustible resource.inexhaustible resource.
PROTECTING AND SUSTAINING PROTECTING AND SUSTAINING MARINE BIODIVERSITYMARINE BIODIVERSITY
Laws, international treaties, and education Laws, international treaties, and education can help reduce the premature extinction of can help reduce the premature extinction of marine species.marine species.
Since 1989 the U.S. government has Since 1989 the U.S. government has required offshore shrimp trawlers to use turtle required offshore shrimp trawlers to use turtle exclusion devices.exclusion devices. Sea turtle tourism brings in almost three times as Sea turtle tourism brings in almost three times as
much money as the sale of turtle products.much money as the sale of turtle products.
PROTECTING AND SUSTAINING PROTECTING AND SUSTAINING MARINE BIODIVERSITYMARINE BIODIVERSITY
Six of the world’s Six of the world’s seven major turtle seven major turtle species are species are threatened or threatened or endangered endangered because o human because o human activities.activities.
Figure 12-4Figure 12-4
Case Study: The Florida Manatee and Case Study: The Florida Manatee and Water HyacinthsWater Hyacinths
Manatee can eat Manatee can eat unwanted Water unwanted Water Hyacinths.Hyacinths.
Endangered due to:Endangered due to: Habitat loss.Habitat loss. Entanglement from fishing Entanglement from fishing
lines and nets.lines and nets. Hit by speed boats.Hit by speed boats. Stress from cold.Stress from cold. Low reproductive rateLow reproductive rate
Figure 12-BFigure 12-B
Case Study: Commercial WhalingCase Study: Commercial Whaling
After many of the After many of the world’s whale world’s whale species were species were overharvested, overharvested, commercial commercial whaling was whaling was banned in 1960, banned in 1960, but the ban may but the ban may be overturned.be overturned.
Figure 12-6Figure 12-6
Case Study: Case Study: Commercial WhalingCommercial Whaling
Despite ban, Japan, Despite ban, Japan, Norway, and Iceland kill Norway, and Iceland kill about 1,300 whales of about 1,300 whales of certain species for scientific certain species for scientific purposes.purposes. Although meat is still sold Although meat is still sold
commercially.commercially.
Figure 12-5Figure 12-5
PROTECTING AND SUSTAINING PROTECTING AND SUSTAINING MARINE BIODIVERSITYMARINE BIODIVERSITY
Fully protected marine reserves make up less Fully protected marine reserves make up less than 0.3% of the world’s ocean area.than 0.3% of the world’s ocean area. Studies show that fish populations double, size Studies show that fish populations double, size
grows by almost a third, reproduction triples and grows by almost a third, reproduction triples and species diversity increases by almost one fourth.species diversity increases by almost one fourth.
Some communities work together to develop Some communities work together to develop integrated plans for managing their coastal integrated plans for managing their coastal areas.areas.
Revamping Ocean PolicyRevamping Ocean Policy
Two recent studies called for an overhaul of Two recent studies called for an overhaul of U.S. ocean policy and management.U.S. ocean policy and management. Develop unified national policy.Develop unified national policy. Double federal budget for ocean research.Double federal budget for ocean research. Centralize the National Oceans Agency.Centralize the National Oceans Agency. Set up network of marine reserves.Set up network of marine reserves. Reorient fisheries management towards Reorient fisheries management towards
ecosystem function.ecosystem function. Increase public awareness.Increase public awareness.
MANAGING AND SUSTAINING MANAGING AND SUSTAINING MARINE FISHERIESMARINE FISHERIES
There are a number of ways to manage There are a number of ways to manage marine fisheries more sustainably and protect marine fisheries more sustainably and protect marine biodiversity.marine biodiversity.
Some fishing communities regulate fish Some fishing communities regulate fish harvests on their own and others work with harvests on their own and others work with the government to regulate them.the government to regulate them. Modern fisheries have weakened the ability of Modern fisheries have weakened the ability of
many coastal communities to regulate their own many coastal communities to regulate their own fisheries.fisheries.
Fig. 12-7, p. 261
SolutionsManaging Fisheries
Fishery Regulations
Set catch limits well below the maximum sustainable yield
Improve monitoring and enforcement of regulationsEconomic Approaches
Sharply reduce or eliminate fishing subsidies
Charge fees for harvesting fish and shellfish from publicly owned offshore waters
Certify sustainable fisheriesProtected Areas
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
Bycatch
Use wide-meshed nets to allow escape of smaller fish
Use net escape devices for sea birds and sea turtles
Ban throwing edible and marketable fish back into the sea
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
PROTECTING, SUSTAINING, AND PROTECTING, SUSTAINING, AND RESTORING WETLANDSRESTORING WETLANDS
Requiring government permits for filling or Requiring government permits for filling or destroying U.S. wetlands has slowed their destroying U.S. wetlands has slowed their loss, but attempts to weaken this protection loss, but attempts to weaken this protection continue.continue.
Figure 12-8Figure 12-8
Fig. 12-9, p. 264
Solutions
Protecting Wetlands
Legally protect existing wetlands
Steer development away from existing wetlands
Use mitigation banking only as a last resort
Require creation and evaluation of a new wetland before destroying an existing wetland
Restore degraded wetlands
Try to prevent and control invasions by nonnative species
Case Study: Case Study: Restoring the Florida EvergladesRestoring the Florida Everglades
The world’s largest ecological restoration The world’s largest ecological restoration project involves trying to undo some of the project involves trying to undo some of the damage inflicted on the Everglades by damage inflicted on the Everglades by human activities.human activities. 90% of park’s wading birds have vanished.90% of park’s wading birds have vanished. Other vertebrate populations down 75-95%.Other vertebrate populations down 75-95%. Large volumes of water that once flowed through Large volumes of water that once flowed through
the park have been diverted for crops and cities.the park have been diverted for crops and cities. Runoff has caused noxious algal blooms. Runoff has caused noxious algal blooms.
Restoring the Restoring the Florida Florida
EvergladesEverglades
The project has The project has been attempting been attempting to restore the to restore the Everglades and Everglades and Florida water Florida water supplies.supplies.
Figure 12-10Figure 12-10
PROTECTING, SUSTAINING, AND PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERSRESTORING LAKES AND RIVERS
Lakes are difficult to manage and are Lakes are difficult to manage and are vulnerable to planned or unplanned vulnerable to planned or unplanned introductions of nonnative species.introductions of nonnative species.
For decades, invasions by nonnative species For decades, invasions by nonnative species have caused major ecological and economic have caused major ecological and economic damage to North America’s Great lakes.damage to North America’s Great lakes. Sea lamprey, zebra mussel, quagga mussel, Sea lamprey, zebra mussel, quagga mussel,
Asian carp. Asian carp.
PROTECTING, SUSTAINING, AND PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERSRESTORING LAKES AND RIVERS
Dams can provide many human benefits but Dams can provide many human benefits but can also disrupt some of the ecological can also disrupt some of the ecological services that rivers provide.services that rivers provide. 119 dams on Columbia River have sharply 119 dams on Columbia River have sharply
reduced (94% drop) populations of wild salmon.reduced (94% drop) populations of wild salmon. U.S. government has spent $3 billion in U.S. government has spent $3 billion in
unsuccessful efforts to save the salmon.unsuccessful efforts to save the salmon. Removing hydroelectric dams will restore native Removing hydroelectric dams will restore native
spawning grounds.spawning grounds.
PROTECTING, SUSTAINING, AND PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERSRESTORING LAKES AND RIVERS
We can help sustain freshwater fisheries by We can help sustain freshwater fisheries by building and protecting populations of building and protecting populations of desirable species, preventing over-fishing, desirable species, preventing over-fishing, and decreasing populations of less desirable and decreasing populations of less desirable species.species.
A federal law helps protect a tiny fraction of A federal law helps protect a tiny fraction of U.S. wild and scenic rivers from dams and U.S. wild and scenic rivers from dams and other forms of development.other forms of development. National Wild and Scenic Rivers Act (1968).National Wild and Scenic Rivers Act (1968).
Fig. 12-11, p. 267
• Deliver nutrients to sea to help sustain coastal fisheries
• Deposit silt that maintains deltas
• Purify water
• Renew and renourish wetlands
• Provide habitats for wildlife
Natural Capital
Ecological Services of Rivers