Preserving Aquatic Biodiversity

Chapter 12

Lake Victoria

The second largest freshwater lake in the world

How have humans changed it?Introduced Nile perch – killed other fishAdded nutrients – eutrophicationIntroduce water hyacinth – blocks light

Aquatic biodiversity

Greatest marine diversity in coral reefs and deep-sea floor

Higher near coasts than open oceanHigher in benthic layer than near the

surfaceHigher near tropics

How do humans benefit

FoodSeaweed (cosmetics)Chemicals

AntibioticsAnticancerHypertensionBone replacement

Destroying freshwater habitats

Draining wetlands – lost over 50 % of wetlands

Introduction of non-native speciesDams, diversions, canals, flood control

leveesRuin existing habitat or changing flow rate,

sediment deposits, spawning beds, migration patterns, plant life, nutrient cycles

Major loss of aquatic biodiversity by humans

OverfishingHabitat destruction

Coastal developmentRising sea levelTrawler boats

PollutionIntroduction of alien species

Nonnative examples

Asian swamp eel – Florida, eats everything, can breath air, cross to new waterways

Purple loosestrife – wetlands, perennial plant in Eurasia, spreads rapidly, no native predators, displaces native plants, reduces biodiversity

Zebra mussels – Great Lakes, from ship ballasts, no natural predators, displaced other mussels, interrupted food chain, clogged pipes, grows in large masses on everything

Major pollution threats

Oil – especially from runoffAcid depositionPlant nutrients and oxygen demanding

wastesToxic chemicalsSedimentation from development

Protection of Marine Species

CITES1979 Global Treaty on Migratory SpeciesU.S. Marine Mammal Protection Act of

1972Endangered Species Act 1973Whale conservation and protection act

1976Changing fishing nets and fishing

practice

Whaling

International Convention for the Regulation of Whaling formed the IWC to set quotas (often ignored)

IWC set moratorium on commercial whaling since 1986 (Inuits still allowed to hunt whale) many populations recovered

US banned whaling and importing goodsJapan and Norway still are large whaling

countries

Restoring Wetlands

US requires a federal permit to drain/alter a wetland over 3 acres

Mitigation banking – allows development of wetlands if an equal area elsewhere is created or restored

Use proper planning to keep development/Ag away

Prevent introduction of alien species

Florida’s Mistake

Army Corps of Engineers diverted much of the Everglade’s natural flow with levees and canals

Wetlands dried and were converted to farmland

Runoff from fields introduced excess nutrients

Disrupted entire ecosystemNow largest ecological restoration

project (at least $7.8 billion)

Columbia River Basin

Located in Pacific Northwest – 1,200 miles of river

Largest hydroelectric power systemProvides jobs, electricity, flood control,

stimulate industry/agricultureHurts habitats especially migratory fish

(salmon)Northwest Power Act 1980 – find way to

generate power and rebuild wild salmon and other fish populations

Protecting Rivers

National Wild and Scenic Rivers Act 1968 – waterways kept free from development, no motors, no alterations

A river can be designated by congress based on outstanding scenic, recreational, geological, wildlife, historical, or cultural value

The Great Lakes

Faces several threats Alien species, like the zebra mussel, is

the greatest, but also is encounteringThermal pollution from power plantsCommercial fishingHuman sewage (mostly processed)Acid rain (but there is more to the east)

Act Now

Approximately 50% of the world’s original coastal wetlands have been lost

Main reasonsAgricultureHousing/building development

Commercial fishing techniques

While many systems are bad for the environment, these appear to be the worst

Trawling - nets destroy ocean floor habitat

Drift nets (more than 2 miles long) - kill many mammals, turtles and birds

Longlining - creates a lot of bycatch such as dolphin, shark, pilot whales, birds, and turtles

What can you do?

Use comsumer power to buy products that do not threaten aquatic species

Use environmentally friendly cleaners in the home

Prevent soil erosionVote against wetland developmentEat less fish and seafood (more organic

veggies)