Chapter 11

Sustaining Aquatic Biodiversity

Core Case Study: A Biological Roller Coaster Ride in Lake Victoria

• Loss of biodiversity and cichlids

• Nile perch: deliberately introduced

• Frequent algal blooms– Nutrient runoff– Spills of untreated sewage– Less algae-eating cichlids

Lake Victoria Is a Large Lake in East Africa

Natural Capital Degradation: The Nile Perch

Marine Biodiversity

• #1 is coral reefs• Higher in coastal zone than open sea• Higher on bottom region than surface region

b/c of greater habitat variety and food sources

HIPPCO

• Also applies to marine habitat• Habitat alteration

– Trawlers drag nets weighted with heavy chains– Dams and excess water withdrawal

Invasives

• Water hyacinths in Lake Victoria• Asian Swamp eel can travel over land

• Purple loosestrife: introduced from EuropeEuropean predators have been introduced

Fig. 11-4, p. 252

Lake Wingara

Introduced carp eat algae that stabilize sediment on lake bottom

Fig. 11-A, p. 253

Population, Pollution, Climate Change

• In ten years, 80% of world population will live near coast

• Nitrate runoff continues to increase (fertilizer)• Average sea level rise is 4 – 8 inches in past

100 years– Coral reefs too far from surface – Low lying islands submerged (Maldives: now 5ft

above sea level)– Coastal wetlands (and mangroves) may be lost

Overfishing

• Industrial fishing is unsustainable• Fishprint• Commercial extinction

– Newfoundland’s cod fishery is closed (20,000 fishers and processors out of work)

– When desirable fish go, small, young fish are target, so little chance for recovery

– 1/3 of fish catch is bycatch

Commercial Fishing Methods

• Sonar, GPS, and huge nets increase yield of commercial operations– 75% of commercial fisheries are fished at or

beyond their sustainable yield

3 Fishing Methods

• Trawler fishing– Scrape ocean bottom– Huge, some trawler nets can cover 12 jumbo jets

• Purse-seine fishing– Used for fish near surface (tuna, dolphin safe?)

• Longlining– Up to 80 miles long, thousands of hooks– Can catch sea turtles, dolphins

Fig. 11-7, p. 256

Fish farming in cage

Trawler fishing Spotter airplane

Sonar Purse-seine fishing

Drift-net fishing

Long line fishing Float Buoy

lines with hooks

Deep sea aquaculture cage Fish caught

by gills

Drift Nets

• Tennis net with larger weave that may be 40 miles long and 50 feet deep– May break loose and kill fish for years

• Fish get caught between threads– Bycatch: unwanted fish, sea birds, sea turtles

• UN has banned nets longer that 1.6 miles– Voluntary, hard to monitor

TEDs

• http://www.youtube.com/watch?v=y71cgxmyMO4

Laws and Treaties

• CITES• ESA

Whales

• Cetaceans• Marine mammals• Toothed whales

– Feed on squid, etc (porpoise)• Baleen whales

– Filter feeders; krill (blue whale)• 8/11 major species commercially extinct

Whales

• Blue whale near extinction– 25 years to reproductive age, one offspring every

2-3 years• IWC

– Since 1970, US banned whaling and imports– Since 1986, international ban has been successful– Japan: scientific purposes - restaurants– Norway defies banDebate about current population

Sea Turtles

• 6/7 are endangered• Leatherback has survived 100 million years• Eggs deposited at night on beaches• Babies hatch together and move across beach

to the sea • Nets, long line, hunters affect population• Plastic bags• TEDs

Fig. 11-10, p. 260

Marine Sanctuaries

• Offshore fishing limit is 200 statute miles– exclusive economic zone– Marine protected areas (MPAs)

• High seas• Marine reserves would include areas in high

seas– Population doubles, biodiversity increases– Benefits nearby fisheries– $12-14 billion/year, 1 million jobs

CO2 Problems

• IUCN indicates coral reefs can survive global warming if overfishing, pollution are curbed

• CO2 + water = carbonic acid – Dissolves calcium carbonate shells– Possibly most damaging consequence of increase

of CO2 concentration

Integrated coastal management

– Fishers, business owners, politicians, scientists, citizens develop long term solutions

– Great Barrier Reef Marine Park is managed by ICM

Fishery Populations

• Maximum sustainable yield (MSY) vs optimum sustainable yield (OSY)– OSY takes into account consequences to other

species and error

Subsidies

• Government subsidies encourage overfishing– $30-34 billion given to fishers per year– $10-14 billion encourages overfishing and

expansion of industry

Individual Transfer Rights

• Government gives each fisher a percentage of the total allowable catch (TAC) for a fishery in a year

• Worked in Alaska’s halibut fishery• Problems

– Private fishers own public water, public pays for system

– Monopoly possibility– TACs are usually too high

Sustainable Seafood

• Certification• Marine Stewardship Council (MSC)

– “Fish Forever” ecolabel– Walmart agreed to sell only MSC certified seafood

by 2011

Fig. 11-12, p. 265

SOLUTIONS

Managing FisheriesFishery Regulations BycatchSet catch limits well below the maximum sustainable yield

Use wide-meshed nets to allow escape of smaller fish

Improve monitoring and enforcement of regulations

Use net escape devices for seabirds and sea turtlesBan throwing edible and marketable fish back into the sea

Economic ApproachesSharply reduce or eliminate fishing subsidiesCharge fees for harvesting fish and shellfish from publicly owned offshore waters

AquacultureRestrict coastal locations for fish farmsControl pollution more strictly

Certify sustainable fisheriesProtect Areas

Establish no-fishing areas

Depend more on herbivorous fish species

Establish more marine protected areas

Nonnative Invasions

Rely more on integrated coastal management

Kill organisms in ship ballast water

Consumer InformationFilter organisms from ship ballast water

Label sustainably harvested fish Dump ballast water far at sea and replace with deep- sea waterPublicize overfished and

threatened species

Wetlands

• In US, more than 50% of 1900 wetlands have been lost– What happened?

• Soon, coastal wetlands could be under water– Feeding stops for migratory bird flyways affected– Commercial fish and shellfish populations affected

Government can help

• Zoning laws could be used to prevent further development

• A federal law requires a permit to dump dredged material into wetlands bigger than 3 acres

Mitigation Banking

• Policy that allows development of a wetland as long as another wetland area is created or restored

• Most attempts to create wetlands fail– Why?

The Everglades

• Originally, 60 mile wide sheet of water flowing from Lake Okeechobee to Florida Bay

• Now less than half its original size– In 1948, a water control project was completed– Drained for farmland (sugarcane)– Paved over– Nutrient runoff from agBiodiversity loss: invasives, habitat loss, fragmentation from urbanization

Kissimmee River

• Feeds into Lake Ocheechobee• b/w 1962 and 1971, US Army Corps of Engineers

straightened the river– Flood control, but – rapid flow of water drained land north of Lake

Ocheechobee– Water was diverted for crops and cities, so– Less flow into Florida Bay causes salinity and

temperature to increase– More nutrients cause algae bloom

Fig. 11-14, p. 268

Restoration

• In 1990, US and state government agreed to fund restoration project

• Among other projects, the Corps of Engineers will restore meandering flow of river

• Cost = $10 billion• Sugarcane growers convinced Florida

legislature to increase allowable P discharge limit and delay date of implementation of limit

Dams

• Columbia River in northwest– 119 dams; 19 hydroelectric dams– Interfere with spawning salmon who must return

upstream to lay eggs• Population down by 94%

• Snake River in Washington State– Similar scenario, environmentalists want small

hydroelectric dams taken down