1. Marine Pollution
12/11/08

2. Ocean pollution

3. Oceans and transportation
Thousands of ships travel the oceans daily
Ships transport ballast water, which is used to balance the ship
When discharged at the end of the journey, aquatic organisms may be transplanted and become invasive species
ex) zebra mussels

4. Ocean sediments We extract minerals and fossil fuels from the ocean
By the 1980’s, about 25% of our oil and natural gas came from beneath the sea floor
Very controversial—ecosystem degradation and potential spills

5. Ocean sediments
Methane hydrate is an ice-like solid consisting of methane in water
Found in the sea floor
Could be used as an alternate energy source
May hole twice as much carbon as all known deposits of oil, coal, and natural gas combined
Can be dangerous to extract

6. Ocean sediments
Miners collect sand and gravel from beneath the sea using a giant vacuum-like machine
Sulfur is collected from salt deposits
Other minerals are also collected from the seafloor

7. Marine pollution
Into the mid-20th century, many coastal cities dumped trash and sewage directly into their oceans
Other potential sources of pollution come from ships and industries
Each September, the Ocean Conservancy picks up trash from beaches
In 2004, they picked up 7.7 million pounds of trash from miles of shoreline in 88 countries

8. Nets and plastic debris
Fishing nets, plastic bags, and other trash is often found in the oceans
It can drift for decades without degrading
Marine animals, sea turtles, birds and fish may eat the debris and die
49 out of 115 marine mammal species eat or become
entangled in plastic, and
111 out of 312 seabird
species

9. Oil pollution Massive spills can cause major problems
The majority of oil pollution in oceans comes from the accumulation of many small sources
Sources: offshore wells, tankers, pipelines and storage tanks

10. Oil spills
Effects: death of organisms, loss of animal insulation and buoyancy, smothering
Significant economic impacts

11. Oil Spill Cleanup
Mechanical means—floating booms, skimmer boats, and absorbent materials

12. Oil Spill Cleanup
Chemical means—chemicals, fires, natural methods

13. Oil Spill Cleanup Bioremediation Fairly new technique
Uses naturally occurring bacteria to biodegrade the oil
Had to add extra nutrients to stimulate the bacterial production
Debatable how well the process is working
Used for the first time in the Exxon Valdez spill

14. Case Study: Exxon Valdez Spill
In March, 1989 an oil tanker hit a reef in Alaska’s Prince William Sound
11 million gallons of crude oil was spilled—largest spill in US history
Killed an estimated 100, ,000 seabirds, sea otters, and harbor seals, and many fish
The local economy was ruined (no fishing or tourism)
Massive cleanup carried on for several years—still finding oil 17 years later
Cost the company around $8 billion dollars

15. Excess Nutrients
Pollution from fertilizer runoff can cause eutrophication
Harmful algae blooms may form from algae species that produce toxins
Some algae produce red pigments that discolor water—red tides

16. Protecting the oceans from pollution
Nonpoint source water pollution mostly comes from agriculture
Reduce soil erosion
Reduce fertilizer runoff
Apply pesticides only when needed
Control runoff with animal wastes
Ex) Smithfield foods built a plant to convert hog waste into biodiesel fuel for vehicles

17. Protecting the oceans from pollution
Point source water pollution
The Clean Water Act set standards for allowed levels of key pollutants
Public consciousness of the problem has increased, putting pressure on governments

18. Overfishing
Half of the world’s marine fish populations are fully exploited
Another 25% are overexploited and being driven toward extinction

19. Case study: Whales
Commercial whale increased throughout the years, pushing the whale population toward extinction
Was slowed in 1986 by international treaties

20. Modern fishing levels
Currently, we are fishing at such high levels, only 1/10 of the large-bodied animals that were once present
This is causing fisheries to collapse
Ex) New England states fist for species such as cod and halibut—the levels have increased so much that the fish are virtually gone

21. Fishery collapse
The overall global catch has been constant for 2 decades
Fishing fleets travel longer distances to reach less-fished areas
They fish in deeper waters
They also spend more time fishing, and have improved technology

22. Fishing practices
By-catch refers to the capture of animals not meant to be caught
Accounts for the deaths of fish, sharks, marine mammals, and birds

23. Fishing Practices
Driftnets—capture large amounts of dolphins, turtles, and seals; most end up drowning
Ex) tuna

24. Fishing practices
Longline fishing—dragging extremely long lines baited with hooks
Kills turtles, sharks, and albatross (sea birds)

25. Fishing practices
Bottom-trawling—dragging weighted nets over the floor of the continental shelf to catch benthic organisms
Crushes many organisms and damages the sea bottom

26. Humans can help fisheries
By buying tuna fish that is labeled “dolphin-safe”
Several nonprofit organizations (ex) Monterey Bay Aquarium) offer guides to tell consumers which fish and shellfish are harvested sustainably