Sustaining Aquatic Biodiversity Unit Four Chapter 13 APES Mrs. Dow.
Sustaining Aquatic Biodiversity
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Transcript of Sustaining Aquatic Biodiversity
Sustaining Aquatic Biodiversity
Core Case Study: A Biological Roller Coaster
Ride in Lake Victoria
Lake Victoria has lost their endemic fish species to large introduced predatory fish.
Core Case Study: A Biological Roller Coaster
Ride in Lake Victoria Reasons for Lake Victoria’s loss of
biodiversity: Introduction of Nile perch. Lake experienced algal blooms from
nutrient runoff. Invasion of water hyacinth has blocked
sunlight and deprived oxygen. Nile perch is in decline because it has
eaten its own food supply.
11-1 What Are the Major Threats to Aquatic
Biodiversity? Concept 11-1 Aquatic species are
threatened by habitat loss, invasive species, pollution, climate change, and overexploitation, all made worse by the growth of the human population.
Three General Patterns of Marine Biodiversity
The greatest marine biodiversity occurs in coral reefs, estuaries, and the deep-ocean floor
Biodiversity is higher near coasts than in the open sea because of the greater variety of producers and habitats in coastal areas
Biodiversity is higher in the bottom region of the ocean than in the surface region because of the greater variety of habitats and food sources on the ocean bottom
Human Activities Are Destroying and Degrading
Aquatic Habitats Human activities have destroyed, disrupted or
degraded a large proportion of the world’s coastal, marine and freshwater ecosystems. Approximately 20% of the world's coral reefs
have been destroyed. During the past 100 years, sea levels have
risen 10-25 centimeters. We have destroyed more than 1/3 of the
world’s mangrove forests for shipping lanes.
Shrimp farms in areas that were once mangrove
forests
Additional ways humans degrade our ocean environment
HUMAN IMPACTS ON AQUATIC BIODIVERSITY
Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Figure 12-2
HUMAN IMPACTS ON AQUATIC BIODIVERSITY
Harmful invasive species are an increasing threat to marine and freshwater biodiversity. Bioinvaders are blamed for about 2/3 of
fish extinctions in the U.S. between 1900-2000.
Almost half of the world’s people live on or near a coastal zone and 80% of ocean water pollution comes from land-based human activities.
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
Treating with natural predators—a weevil species and a leaf-eating beetle—Will it work?
Asian Rice Eel
Population Growth and Pollution
Each year plastic items dumped from ships and left as litter on beaches threaten marine life.
It’s just a plastic bag! It can’t hurt anyone.
Sea turtle off the coast of Florida
What can you do to make sure this does
not continue?
Overfishing and Extinction:
Gone Fishing, Fish Gone About 75% of the world’s
commercially valuable marine fish species are over fished or fished near their sustainable limits. Big fish are becoming scarce. Smaller fish are next. We throw away 30% of the fish we
catch. We needlessly kill sea mammals and
birds.
Human impacts on marine biodiversity
Coral reef destruction
Sea level rising Destruction of
mangrove forests Trawler nets
destroying ocean floor
Invasive species Coastal
development Trash Overfishing
Industrial fish harvesting methods
Trawler fishing: dragging net along ocean floor
Purse-seine fishing: surround fish with net
Long-line fishing: 80 miles of fishing line with thousands of baited hooks
Drift-net fishing: 80 miles of drifting nets below the surface
Problems with industrial fish harvesting methods
Trawler fishing: like clear-cutting forest; destroys ocean floor; captures endangered seals and turtles
Purse-seine fishing: kills hundreds of dolphins
Long-line fishing: hooks endangered sea turtles, albatross, pilot whales, sharks, dolphins
Drift-net fishing: kills non-target fish species and marine mammals
Fig. 11-7, p. 256
Fish farming in cage
Trawler fishing
Spotter airplane
Sonar
Trawl flapTrawl 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
Trawler fishing
By-catch
Purse-seine fishing
Long-line fishing
Several countries have banned the use of drift nets or they
are carefully monitoring the use of
drift nets
Drift-nets catch and
kill anything caught in the net
Why is it Difficult to Protect Aquatic
Biodiversity? Rapid increasing human impacts, the invisibility of problems, citizen unawareness, and lack of legal jurisdiction hinder protection of aquatic biodiversity. Human ecological footprint is
expanding. Much of the damage to oceans is not
visible to most people. Many people incorrectly view the
oceans as an inexhaustible resource.
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
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
PROTECTING AND SUSTAINING MARINE
BIODIVERSITY Laws, international treaties, and
education can help reduce the premature extinction of marine species.
Since 1989 the U.S. government has required offshore shrimp trawlers to use turtle exclusion devices (TEDs). Sea turtle tourism brings in almost
three times as much money as the sale of turtle products.
PROTECTING AND SUSTAINING MARINE
BIODIVERSITY Six of the
world’s seven major turtle species are threatened or endangered because of human activities.
Figure 12-4
Laws and international treaties protecting marine
biodiversity CITES (Convention on International Trade in
Endangered Species ) Global Treaty on Migratory Species Marine Mammal Protection Act ESA (Endangered Species Act of 1973 ) Whale Conservation and Protection Act International Convention on Biological Diversity Offshore fishing
Exclusive economic zones High seas
Law of the Sea Treaty Marine Protected Areas (MPAs)
Exclusive Economic Zone
PROTECTING AND SUSTAINING MARINE
BIODIVERSITY Fully protected marine reserves
make up less than 0.3% of the world’s ocean area. Studies show that fish populations
double, size grows by almost a third, reproduction triples and species diversity increases by almost one fourth.
Some communities work together to develop integrated plans for managing their coastal areas.
Fisheries scientists
Conservationists
Citizens Business
interests Developers Politicians
Integrated Coastal Management
Competing for the same resource – identify shared problems and goals and attempt to develop workable, cost-effective, and adaptable solutions that preserve biodiversity and environmental quality while meeting economic and social needs.
Revamping Ocean Policy Two recent studies called for an
overhaul of U.S. ocean policy and management. Develop unified national policy. Double federal budget for ocean research. Centralize the National Oceans Agency. Set up network of marine reserves. Reorient fisheries management towards
ecosystem function. Increase public awareness.
PROTECTING, SUSTAINING, AND
RESTORING WETLANDS
Requiring government permits for filling or destroying U.S. wetlands has slowed their loss, but attempts to weaken this protection continue.
Figure 11.13 Natural capital restoration: wetland restoration at
Fort Erie, Ontario, Canada before (right) and after (left).
Case Study: Restoring the Florida
Everglades The world’s largest ecological
restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities. 90% of park’s wading birds have
vanished. Other vertebrate populations down 75-
95%. Large volumes of water that once
flowed through the park have been diverted for crops and cities.
Runoff has caused noxious algal blooms.
Restoring the Florida Everglades The project
has been attempting to restore the Everglades and Florida water supplies. Figure
similar to 11-14
PROTECTING, SUSTAINING, AND RESTORING LAKES
AND RIVERS Lakes are difficult to manage and are vulnerable to planned or unplanned introductions of nonnative species.
For decades, invasions by nonnative species have caused major ecological and economic damage to North America’s Great lakes.
Sea lamprey, zebra mussel, quagga mussel, Asian carp.
PROTECTING, SUSTAINING, AND RESTORING LAKES AND
RIVERS Dams can provide many human benefits but
can also disrupt some of the ecological services that rivers provide. 119 dams on Columbia River have sharply
reduced (94% drop) populations of wild salmon.
U.S. government has spent $3 billion in unsuccessful efforts to save the salmon.
Removing hydroelectric dams will restore native spawning grounds.
PROTECTING, SUSTAINING, AND RESTORING LAKES AND
RIVERS We can help sustain freshwater fisheries
by building and protecting populations of desirable species, preventing over-fishing, and decreasing populations of less desirable species.
A federal law helps protect a tiny fraction of U.S. wild and scenic rivers from dams and other forms of development. National Wild and Scenic Rivers Act
(1968).
Fig. 11-16, p. 270