Sustaining Aquatic Biodiversity

Ch. 11

Major Threats to Aquatic Biodiversity

• Habitat loss• Invasive species• Pollution• Population• Climate change• Overexploitation

Aquatic Biodiversity

Greatest Marine Biodiversity

• Coral Reefts• Estuaries• Deep-ocean floor

Biodiversity is higher• Near the coast than

in the open sea• In the benthos than

at the surface

Natural Capital

Marine Ecosystems

Ecological Services Economic Services

Climate moderation Food

CO 2 absorption Animal and pet feed

PharmaceuticalsNutrient cycling

Harbors and transportation routes

Waste treatment

Reduced storm impact (mangroves, barrier islands, coastal wetlands) Recreation

Coastal habitats for humans

Habitats and nursery areas

Employment

Genetic resources and biodiversity

Oil and natural gas

Minerals

Scientific information Building materials

Natural Capital

Freshwater Systems

Ecological Services Economic Services

Climate moderation Food

Nutrient cyclingDrinking water

Waste treatment

Irrigation waterFlood control

Groundwater recharge

Hydroelectricity

Habitats for many species

Transportation corridors

Genetic resources and biodiversity Recreation

Scientific information Employment

World Seafood Production, Including Both Wild Catch and

Aquaculture

Fig. 12-9, p. 287

Problem

No single country has exclusive rights to ocean AS A RESULT ocean resources are exploited, depleted and collapsing

Overharvest

• Severly depleted stock #s– Each species has

own maximum sustainable harvest level

– ABOVE this level = numbers decline & harvest is not economically profitable

Taking more than the sustainable yield

Commercial Extinction

No longer profitable to continue harvesting the affected species.

Overharvest EXAMPLE

• Georges Bank, New England

Why do we overharvest?

• Increase demand due to overpopulation

• Advances in fishing equipment and technology

• Tragedy of the commons!

How are fish and shellfish harvested?

Fisheries: concentrations of particular aquatic species suitable for commercial harvesting in a given area

Equipment & Technology

Sonar, Radar, Computers – to locate large schools of fish

Equipment & Technology

Long-line fishing – lines of baited hooks - 130 Km (80 miles) - swordfish, tuna, sharks - ALSO hooks dolphins, endangered sea turtles, pilot whales

Equipment & Technology

Purse-Seine Nets – huge nets that encircle schools to trap them.

Equipment & Technology

Trawl Net – weighted and pulled along bottom, destroys ocean floor habitats.

Equipment & Technology

Drift Nets – Entangle fish, illegal over 2.5 km (1.6 miles)

Bycatch

• Nondesired catch species• Deplete fisheries• Thrown back dead/dying• AKA bykill

Are there solutions?

1. Aquaculture or mariculture- Fastest growing type of food

production in the world- VERY expensive to start up but

requires relatively cheap labor to maintain

Trade-Offs: Aquaculture

Fig. 12-20, p. 296

Are There Solutions?

2. LegislationWhy is it hard to protect marine biodiversity?

1. Human ecological footprint and fishprint are expanding

2. Much of the damage in the ocean is not visible

3. The oceans are incorrectly viewed as an inexhaustible resource

4. Most of the ocean lies outside the legal jurisdiction of any country

Are there solutions?

2. Legislation- 1977 US Magnuson Fishery

Conservation Act- Established management councils & quotas- Not successful – quotas set too high

- 1996 Amended Fishery Act to: - Protect habitat- Rebuild threatened stocks- Reduce overfishing- Minimize bycatch

Are there solutions?

2. Legislation- Endangered Species Act/ESA

- Prohibits harm of harvesting of endangered species; protects habitat

- Marine Mammal Protection Act- Protection and conservation of

marine mammals

Are there solutions?

2. Legislation- Marine Sanctuaries Act

- Protects the habitat for marine organisms and protects the animals from being harvested in that area

- Lacey Act of 1900- Prohibits sale of illegally harvested

species; forces fisherman to harvest legally

Are there solutions?

2. Legislation- CITES (Convention on International

Trade in Endangered Species)- Global treaty on migratory species

(1979)- Whale Conservation and protection

act of 1976- 1995 International Convention on

Biological Diversity

Are There Solutions?

3. Economic Incentives– Sea turtle tourism

Are there solutions?

4. Marine Sanctuaries (MPA)- Offshore fishing – 370km (200

mi)- Exclusive economic zones

- Beyond = high seas (hard to enforce)

Are there solutions?

4. Marine Reserves– Fully protected marine reserves work

fast• Fish populations double• Fish size grows• Reproduction triples• Species diversity increase by almost one-

fourth

– Cover less than 1% of world’s oceans• Marine scientists want 30-50%

Are there solutions?

5. Consumer Wisdom - Know your food origins, support sustainable fishery programs

How are Fisheries Sustained & Managed?

1. Setting quotas2. Restrictions on gear3. Limiting # of boats/fishers4. Reduction of subsidies5. Protecting spawning seasons &

habitat6. Careful Consumer Choices

(Marine Stewardship Council)

How Should We Protect & Sustain Wetlands?

• Maximize Preservation• Restore Degraded & Destroyed

Everglades National Park

• Damaged in the 20th century– Drained – Diverted– Paved over– Nutrient pollution

from agriculture– Invasive plant

species• 1947: Everglades

National Park unsuccessful protection project

Everglades National Park

• Comprehensive Everglades Restoration Plan (CERP)

• Ambitious• Already

unraveling

How Should We Protect & Sustain Freshwater Ecosystems?

• Protect Watersheds• Major Threats–HIPPCO– 40% of world’s rivers are dammed–Many freshwater wetlands

destroyed– Threatened species

Great Lakes & Invasive• 162 Nonnative

Species– Sea lamprey– Zebra mussel– Asian carp

Priorities in Sustaining Aquatic Biodiversity

• Map it• Protect Aquatic Hotspots• Protect Marine Reserves• Protect Freshwater Ecosystems• Restore degraded coastal &

inland wetlands