Chapter 12 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. Figure 12-1

Reasons for Lake Victoria’s loss of biodiversity: Introduction of Nile perch for sport fishing Introduction of Nile perch for sport fishing Ate majority of other fishAte majority of other fish Lake experienced algal blooms from nutrient runoff. Lake experienced algal blooms from nutrient runoff. Invasion of water hyacinth has blocked sunlight and deprived oxygen. Invasion of water hyacinth has blocked sunlight and deprived oxygen. Nile perch is in decline because it has eaten its own food supply. Nile perch is in decline because it has eaten its own food supply.

AQUATIC BIODIVERSITY  We know little about the biodiversity of the world’s marine and freshwater systems.  However, established 3 general patterns The greatest marine biodiversity occurs in: The greatest marine biodiversity occurs in: coral reefs, coral reefs, estuariesestuaries deep ocean floor.deep ocean floor. Biodiversity is higher near the coast than open sea because of habitat and food source variety Biodiversity is higher near the coast than open sea because of habitat and food source variety Biodiversity is higher is higher on the ocean bottom than surface Biodiversity is higher is higher on the ocean bottom than surface

AQUATIC BIODIVERSITY  Provides important ecological and economic services. Twice that of cropland Twice that of cropland  About ½ world’s population relies on ocean for main food source.  Chemical compounds: many medical uses Antibiotic, anticancer, hypertension, bone reconstruction Antibiotic, anticancer, hypertension, bone reconstruction

HUMAN IMPACTS ON AQUATIC BIODIVERSITY  Human activities have destroyed, disrupted or degraded a large proportion of the world’s coastal, marine and freshwater ecosystems.

Habitat Destruction  Coral reef Approximately 20% of the world's coral reefs have been destroyed. Approximately 20% of the world's coral reefs have been destroyed. 58% severely damaged 58% severely damaged  Sea grass & kelp beds Provides habitat, food source, erosion protection Provides habitat, food source, erosion protection Disappearing at alarming rate Disappearing at alarming rate

Habitat Destruction  Ocean Levels During the past 100 years, sea levels have risen centimeters. During the past 100 years, sea levels have risen centimeters. Levels are predicted to continue to rise Levels are predicted to continue to rise Coastal cities at risk Coastal cities at risk Maldives Maldives Low lying chain of islands in Indian oceanLow lying chain of islands in Indian ocean Threat of being submergedThreat of being submerged

Habitat Destruction  Mangrove Forests We have destroyed more than 1/3 of the world’s mangrove forests We have destroyed more than 1/3 of the world’s mangrove forests Critical for habitat, beach erosion protection, storm surge protection, & flood control Critical for habitat, beach erosion protection, storm surge protection, & flood control

Habitat Destruction  Coastal Wetlands We have destroyed more than 1/2 We have destroyed more than 1/2 Mainly beach development: houses, resorts Mainly beach development: houses, resorts Critical for habitat, beach erosion protection, storm surge protection, & flood control Critical for habitat, beach erosion protection, storm surge protection, & flood control

Habitat Destruciton  Ocean bottom Being destroyed by dredging and trawler fishing boats Being destroyed by dredging and trawler fishing boats “Plowing” the sea bed “Plowing” the sea bed Takes decades to centuries to recover Takes decades to centuries to recover Scientists call it the most destructive fishing practice Scientists call it the most destructive fishing practice Figure 12-2

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

Invasive Species  Invasive species are an increasing threat Arrive in ballast from ships, dumped aquariums, or intentional released Arrive in ballast from ships, dumped aquariums, or intentional released Bioinvaders are blamed for about 2/3 of fish extinctions in the U.S. between Bioinvaders are blamed for about 2/3 of fish extinctions in the U.S. between Asian Swamp Eel: rapid reproduction, burrows into mud banks, wriggles across dry land Asian Swamp Eel: rapid reproduction, burrows into mud banks, wriggles across dry land Purple Loosestrife: called purple plague, spreads rapidly Purple Loosestrife: called purple plague, spreads rapidly

Population Growth and Pollution  Almost 1/2 of world’s people live on or near a coastal zone  80% of ocean water pollution comes from land-based human activities. Fertilizer runoff causes algae blooms & fish die-offs Fertilizer runoff causes algae blooms & fish die-offs Industrial waste Industrial waste Trash Trash

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

 Fishing is an ancient human tradition that is now a worldwide resource extraction industry.  Several decades of overfishing in all of the world’s oceans has pushed commercially important species, e.g. cod, into steep declines from which recovery is unlikely.  In 1992, Canada’s 500 year old cod fishery collapsed, destroying 40,000 jobs Total ban on fishing Total ban on fishing Stocks still have not recovered Stocks still have not recoveredOverfishing Fishing fleet Fish market, Norway

Sustainable Yields  The maximum sustainable yield (MSY) has been exceeded by too many vessels catching too many fish, especially fish of reproductive age, often using wasteful and destructive methods Bycatch: unwanted species thrown back into sea dead or dying Bycatch: unwanted species thrown back into sea dead or dying  Modern industrial fishing can cause 80% depletion of a species in years

Sustainable Yields  Sustainable yields apply to all harvests that require some organisms to be left after harvesting to replenish the stock.  Yields above the sustainable limit will eventually cause the depletion of the stock. Fisheries especially need to use sustainable yields (SY). Population growth Population at 1 / 2 K (carrying capacity) Yield Population replenished by time of next harvest SY = Total biomass Energy at time t Total biomass Energy at time t = (annual growth and recruitment) - (annual death and emigration)

 The build up of large scale fishing fleets has contributed to widespread overfishing and damage to the marine environment. Bottom trawls and dredges cause large scale physical damage to the sea floor. Sea mounts are particularly vulnerable. Lost fishing gear (particularly drift nets) threatens marine life, including birds and mammals that are non-target species. Purse seines can catch whole schools of fish and non-target species (bycatch) Drift net Purse seine Overfishing

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

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. 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.

Why is it Difficult to Protect Aquatic Biodiversity? Human ecological footprint is expanding. Human ecological footprint is expanding. Much of the damage to oceans is not visible to most people. Much of the damage to oceans is not visible to most people. Many people incorrectly view the oceans as an inexhaustible resource. Many people incorrectly view the oceans as an inexhaustible resource. Most of world’s ocean lies outside legal jurisdiction Most of world’s ocean lies outside legal jurisdiction

PROTECTING AND SUSTAINING MARINE BIODIVERSITY  Laws, international treaties, and education can help reduce the premature extinction of marine species CITIES 1979 Global Treaty on Migratory Species 1975 CITIES 1979 Global Treaty on Migratory Species 1972 Marine Mammal Protection Act 1972 Marine Mammal Protection Act 1973 Endangered Species Act 1973 Endangered Species Act 1976 US Whale Conservation & Protection Act 1976 US Whale Conservation & Protection Act 1995 International Convention on Biological Diversity 1995 International Convention on Biological Diversity IWC – International Whaling Commission IWC – International Whaling Commission

PROTECTING AND SUSTAINING MARINE BIODIVERSITY  Six of the world’s seven major turtle species are threatened or endangered because of human activities.  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. Sea turtle tourism brings in almost three times as much money as the sale of turtle products. Reconciliation ecology Reconciliation ecology

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

Case Study: Commercial Whaling  8 of 11 species – hunted to commercial extinction.  Blue whale – to brink of biological extinction  1970 – US stopped whaling & banned all whale imports  International Whaling Commission (IWC) banned commercial whaling in 1986

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. Although meat is still sold commercially.  Hope to reverse international ban

MARINE SANCTUARIES  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. Studies show that fish populations double, size grows by almost a third, reproduction triples and species diversity increases by almost one fourth.  Call for 30% protected  Some communities work together to develop integrated plans for managing their coastal areas Australia’s Great Barrier Reef;1/3 protected 1975 Australia’s Great Barrier Reef;1/3 protected

Revamping Ocean Policy  Two recent studies called for an overhaul of 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 ecosystem function: Catch Limits Reorient fisheries management towards ecosystem function: Catch Limits Increase public awareness. 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. Modern fisheries have weakened the ability of many coastal communities to regulate their own fisheries.

Fig. 12-7, p. 261 Solutions Managing Fisheries Fishery Regulations Set catch limits well below the maximum sustainable yield Improve monitoring and enforcement of regulations Economic Approaches Sharply reduce or eliminate fishing subsidies Charge fees for harvesting fish and shellfish from publicly owned offshore waters Certify sustainable fisheries Protected 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 RESTORING WETLANDS  US has lost ½ of wetlands  Federal permit is required to develop wetlands – has cut wetland loss by 80%  Attempts by developers to weakened this law  Mitigation – allows destruction of existing wetland as long as equal area of same type is created or restored Figure 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: 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. 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 the park have been diverted for crops and cities. Large volumes of water that once flowed through the park have been diverted for crops and cities. Runoff has caused noxious algal blooms. 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. 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. 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. U.S. government has spent $3 billion in unsuccessful efforts to save the salmon. Removing hydroelectric dams will restore native spawning grounds. 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). National Wild and Scenic Rivers Act (1968).

Fig , 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