Chapter 11

1. Chapter 11 Sustaining Aquatic Biodiversity

2. Core Case Study: A Biological Roller Coaster Ride in Lake Victoria • Lake Victoria has lost their endemic fish species to large introduced predatory fish. Figure 12-1

3. 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.

4. HUMAN IMPACTS ON AQUATIC BIODIVERSITY • 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.

5. HUMAN IMPACTS ON AQUATIC BIODIVERSITY • Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Figure 12-2

6. 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.

7. Population Growth and Pollution • Each year plastic items dumped from ships and left as litter on beaches threaten marine life. Figure 12-3

8. 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.

9. Trawler fishing Fish farming in cage Spotter airplane Sonar Purse-seine fishing Trawl flap Trawl lines Fish school Trawl bag Drift-net fishing Long line fishing Buoy Float Lines with hooks Deep sea aquaculture cage Fish caught by gills Fig. 12-A, p. 255

10. 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. • Sea turtle tourism brings in almost three times as much money as the sale of turtle products.

11. PROTECTING AND SUSTAINING MARINE BIODIVERSITY • Six of the world’s seven major turtle species are threatened or endangered because o human activities. Figure 12-4

12. Case Study: The Florida Manatee and Water Hyacinths • Manatee can eat unwanted Water Hyacinths. • Endangered due to: • Habitat loss. • Entanglement from fishing lines and nets. • Hit by speed boats. • Stress from cold. • Low reproductive rate Figure 12-B

13. Case Study: Commercial Whaling • After many of the world’s whale species were overharvested, commercial whaling was banned in 1960, but the ban may be overturned. Figure 12-6

14. Case Study: Commercial Whaling • Despite ban, Japan, Norway, and Iceland kill about 1,300 whales of certain species for scientific purposes. • Although meat is still sold commercially. Figure 12-5

15. 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.

16. MANAGING AND SUSTAINING MARINE FISHERIES • There are a number of ways to manage marine fisheries more sustainably and protect marine biodiversity. • Some fishing communities regulate fish harvests on their own and others work with the government to regulate them. • Modern fisheries have weakened the ability of many coastal communities to regulate their own fisheries.

17. 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 12-8

18. 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.

19. Restoring the Florida Everglades • The project has been attempting to restore the Everglades and Florida water supplies. Figure 12-10

20. 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.

21. 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.