Sustaining Aquatic Biodiversity Chapter 12 Sustaining Aquatic Biodiversity

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.

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

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.

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.

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.

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.

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

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.

Deep sea aquaculture cage Fish caught by gills Fig. 12-A, p. 255 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

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.

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.

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

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

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

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 Natural capital: examples of cetaceans, which can be classified as either toothed whales or baleen whales. Figure 12-5

How Would You Vote? 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.

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.

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.

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.

Solutions Managing Fisheries Figure 12.7 Fig. 12-7, p. 261 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 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? Protected Areas Establish no-fishing areas Establish more marine protected areas Rely more on integrated coastal management 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

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

Solutions Protecting Wetlands Legally protect existing wetlands Fig. 12-9, p. 264 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

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 12-10

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.

How Would You Vote? 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.

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).

Ecological Services of Rivers Natural Capital Fig. 12-11, p. 267 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. 12-11, p. 267