sustaining aquatic biodiversity ch. 11. major threats to aquatic biodiversity habitat loss invasive...
TRANSCRIPT
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