Dead Zones
The Mass Murderers
Imagine a blob spreading through the ocean and leaving vast areas without fish or shellfish. This is not a scene from a sci-fi movie but a description of a phenomenon that is occurring in our oceans. Scientists call these blobs "dead zones." They silently suffocate sea life. Some extend thousands of kilometres.| A Lifeless Ocean |
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A suffocating mystery
A dead zone starts when too many nutrients spur the growth of thick algae – metres deep, often stretching for thousands of kilometres. Underneath the heavy green slime, the oxygen vanishes and a quiet carnage ensues. Fish and crabs die en masse. In fact, most sea life suffocates, except bacteria and jellyfish. What's left is eerie – a murky, lifeless abyss.
A multiplying mystery
Dead zones are multiplying... rapidly! In 2004, the United Nations counted 146 dead zones. In 2008, the world had 406. Many ocean scientists believe dead zones are among the world's most pressing environmental problems.
Dead zones are silently killing parts of the world's oceans. But why? What's happening in our big, blue seas?
An ocean without animals
Imagine the view from above a dead zone – expanses of algae stretch out as far as you can see. A lone black-footed albatross circles the water and dives in for a meal. But the albatross soon surfaces with no fish in its beak, no food for its chicks…
Dead zones kill most marine life. When an unsuspecting fish hits a dead zone, it may lose consciousness before it has the time to escape. Even fish that do escape are forced to move to shallower, more oxygen-rich waters, where they can't always hide from predators.
But a fish in a dead zone is still better off than a clam in a dead zone – shellfish can't move, so they suffocate and die en masse. And crabs? Sure, they can scuttle away, but fishermen have brought up trap after trap of dead crabs along the Oregon coast, where a massive dead zone has occurred each year since 2002.
Is B.C. on the brink of more dead zones?
Oxygen-Starved Straits: In B.C., scientists are alarmed because they're recording increasingly lower levels of oxygen in ocean waters. In parts of B.C.'s waters, the level of low oxygen, or "hypoxic," waters is now 25 metres closer to the surface than it was 50 years ago.
Is this the warning bell for the arrival of more B.C. dead zones – like the one in Saanich Inlet, that has existed for many years and is now growing?
Finding out what is causing this trend of increasing hypoxia is crucial to understanding how, and if, we can prevent dead zones from developing in B.C. waters.
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