Water: a natural resource

The world’s water plays a very important role in all aspects of our lives, providing food, employment and other benefits.

Over two-thirds of the world’s population lives within 400 km of the sea, and just over half of the world’s population lives in a coastal strip 120 miles wide. As many as half a billion people draw their livelihoods from the sea in one way or another—processors, packers, shippers, ship builders and others.

Ocean ecosystems provide goods and services valued at at least several trillion dollars per year, and millions of people earn their living directly from the sea.

What Is the Marine Environment?

Oceans, covering over 70% of our planet (i.e. 139 million square miles, or 360 million square kilometers):

• Contain 97% of the earth’s water
• Marine ecosystems hold 80% of all life on the planet

Why Is the Marine Environment Important?

• Most of the earth’s oxygen is a product of photosynthesis in ocean organisms
• The fresh water on the earth’s surface comes from the oceans
• The ocean moderates the earth’s climate and affects the weath

What Benefits Does the Marine Environment Provide Humankind?

• Food (Every year, about 75 million tons of fish are caught.)
• Jobs
• Medicines
• Minerals
• Coastline protection

What Impact Do Humans Have on the Marine Environment?

Human activity can alter the oceans with:

• Natural resource development (e.g., offshore drilling)
• Aquaculture (e.g., farm-raised fish)
• Shipping
  —Pollution (e.g., oil, chemicals, trash, sewage)
  —Exotic Species Introduction
  (i.e. ships moving from place to place bring organisms with them to places where they don’t belong, disrupting the local marine environment)
• Fishing
  —Over-fishing
  —Practices that damage the environment
  (e.g., bottom trawling, drift nets, bycatch)
• Recreation

With the rise in the world’s population, the use of the ocean and its resources has increased, as has the devastation that results from the accumulation of pollutants into the marine environment.

Pollution has an effect on:

• Entire marine ecosystems
• Public health
• Our marine resources (fisheries, tourism and shipping costs)

To ensure the ocean’s survival for future generations, we all must do our part to protect it.

What is marine pollution?

Marine pollution occurs when hazardous materials enter the ocean. These materials can come from:

• Marine transportation
• Marine dumping
• Offshore facilities

Because of the vastness and complexity of marine ecosystems, we may not always know the extent of marine pollution’s effects.

Marine pollution can take many forms, such as:

Garbage

• Plastics thrown into the sea can stay there for many years and harm marine life. A huge number of marine animals die every year from either ingesting or becoming entangled in plastic trash.
• Garbage can also threaten ships and raise costs when it becomes trapped on propellers and in seawater intakes.

Sewage

• Sewage contains chemicals that alter the marine environment, causing some marine life to die and other marine life to flourish. This throws off the natural balance of marine ecosystems.
• Sewage can also deprive marine environments of oxygen, killing off entire populations in affected areas.

Products with Potentially Harmful Effects

• When released into the oceans, chemicals used in the shipping industry (sometimes referred to as chemical runoff) can cause harm to marine life as well as to maritime workers.
• Oil poisons marine life, and oil slicks keep sunlight from penetrating the ocean’s water, killing plants and damaging the entire marine ecosystem.
• Noise from a ship’s sonar can have devastating effects on marine animals like whales and dolphins that use sound to communicate with one another.

How does shipping pollution impact the marine environment?

Ocean currents take pollutants far from the site of the initial contamination.

Shipping pollution can have devastating effects on the marine environment. These effects include:

• Mechanical effects on marine life which damage the organisms’ functions
• Eutrophic effects, which cause some forms of bacteria to flourish at the cost of other forms of ocean life
• Saprogenic effects, which cause oxygen deficiency and kill ocean organisms
• Toxic effects, which damage reproduction, feeding and respiration
• Mutagenic effects, which cause cancer and wound marine organisms
• Effects from oil spills can quickly devastate the marine environment. (Ten minutes after a spill of one ton of oil, it can spread to a radius of 50 meters, forming an oil slick 10 millimeters thick.)

Conclusion

Humans depend on the marine environment for many things, and we have a very large impact on it. If we want to continue to depend on the marine environment, we have to do a better job of controlling our use of it.

Seafarers play a critical role, as they earn their living from the sea and can set an example for each other and for the rest of the world.