1. Sustaining Aquatic Biodiversity
Chapter 12
Sustaining Aquatic Biodiversity

2. Chapter Overview Questions
What do we know about aquatic biodiversity, and what is its economic and ecological importance?
How are human activities affecting aquatic biodiversity?
How can we protect and sustain marine biodiversity?
How can we manage and sustain the world’s marine fisheries?

3. Chapter Overview Questions (cont’d)
How can we protect, sustain, and restore wetlands?
How can we protect, sustain, and restore lakes, rivers, and freshwater fisheries?

4. Updates Online
The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at to access InfoTrac articles.
InfoTrac: Green to the gills. Paul Greenberg. The New York Times Magazine, June 18, 2006 p54(L).
InfoTrac: Net losses. H. Bruce Franklin. Mother Jones, March-April 2006 v31 i2 p54(4).
InfoTrac: Fish and your health. Lynn Keiley. Mother Earth News, April-May 2006 i215 p128(4).
Sustainable Ecosystems Institute
Marine Protected Areas
USGS: Coastal Ecosystems

5. Video: Whaling, Overfishing, Fishery Management
This video clip is available in CNN Today Videos for Environmental Science, 2004, Volume VII. Instructors, contact your local sales representative to order this volume, while supplies last.

6. 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

7. 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.

8. AQUATIC BIODIVERSITY
We know fairly little about the biodiversity of the world’s marine and freshwater systems.
The greatest marine biodiversity occurs in coral reefs, estuaries and the deep ocean floor.
Biodiversity is higher near the coast and surface because of habitat and food source variety.
The world’s marine and freshwater systems provide important ecological and economic services.

9. 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 centimeters.
We have destroyed more than 1/3 of the world’s mangrove forests for shipping lanes.

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

11. 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
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.

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

13. 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.

14. Deep sea aquaculture cage Fish caught by gills
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
Float
Buoy
Figure 12.A
Natural capital degradation: major commercial fishing methods used to harvest various marine species. These methods have become so effective that many fish species have become commercially extinct.
Lines with hooks
Deep sea aquaculture cage
Fish caught by gills
Fig. 12-A, p. 255

15. 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.

16. 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.

17. 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

18. 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

19. 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

20. 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

21. Toothed whales Sperm whale with squid Killer whale Narwhal
Bottlenose dolphin
Baleen whales
Blue whale
Fin whale
Bowhead whale
Right whale
Figure 12.5
Natural capital: examples of cetaceans, which can be classified as either toothed whales or baleen whales.
Sei whale
Humpback whale
Gray whale
Minke whale
Fig. 12-5, p. 258

22. How Would You Vote?
To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living in the Environment.
Should carefully controlled commercial whaling be resumed for species with populations of 1 million or more?
No. The hunting of whales is no longer necessary and simply encourages disrespect for these intelligent giants.
Yes. Some whale species have recovered and products from them are valuable resources for humans.

23. 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.

24. 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.

25. 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.

26. Solutions Managing Fisheries Fishery Regulations
Set catch limits well below the maximum sustainable yield
Improve monitoring and enforcement of regulations
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
Economic Approaches
Sharply reduce or eliminate fishing subsidies
Charge fees for harvesting fish and shellfish from publicly owned offshore waters
Certify sustainable fisheries
Aquaculture
Restrict coastal locations for fish farms
Control pollution more strictly
Depend more on herbivorous fish species
Protected Areas
Establish no-fishing areas
Establish more marine protected areas
Rely more on integrated coastal management
Figure 12.7
Solutions: ways to manage fisheries more sustainably and protect marine biodiversity. QUESTION: Which four of these solutions do you think are the most important?
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
Consumer Information
Label sustainably harvested fish
Publicize overfished and threatened species
Fig. 12-7, p. 261

27. 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

28. 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
Figure 12.9
Solutions: ways to help sustain the world’s wetlands. QUESTION: Which two of these solutions do you think are the most important?
Fig. 12-9, p. 264

29. 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.

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

31. 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.

32. 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.

33. How Would You Vote?
To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living in the Environment.
Should federal efforts to rebuild wild salmon populations in the Columbia River Basin be abandoned?
a. No. Restoring salmon populations is critical for the environmental health of the river and surrounding forests.
b. Yes. The restoration program would create unnecessary and severe economic hardships for local residents.

34. 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).

35. Ecological Services of Rivers
Natural Capital
Ecological Services of Rivers
Deliver nutrients to sea to help sustain coastal fisheries
Deposit silt that maintains deltas
Purify water
Renew and renourish wetlands
Provide habitats for wildlife
Figure 12.11
Natural capital: important ecological services provided by rivers. Currently, the services are given little or no monetary value when the costs and benefits of dam and reservoir projects are assessed. According to environmental economists, attaching even crudely estimated monetary values to these ecosystem services would help sustain them. QUESTIONS: Which two of these services do you think are the most important? Which two of these services do you think we are most likely to decline?
Fig , p. 267