What does gyre mean?
The definition of gyre: a circular or spiral motion or form. It is where the word gyrate comes from.
What is an ocean gyre?
An ocean gyre is a very large gyrating mass of water located in the Atlantic, Pacific and Indian Oceans. The water spins around a central axis at a very slow speed similar to a whirlpool. The water in the middle of these oceans tends to stay put and does not circulate nearly as much as water closer to the coasts. This allows the forces that form these gyres to be more pronounced. The same forces act on coastal water but friction with the land masses negate its effect.
Here is a graphic representation of the 5 ocean gyres:
Why do large masses of water start spinning and forming these ocean gyres?
There are 2 powerful forces at work that must be present for these ocean gyres to exist. The Coriolis effect aka the spinning of the earth and wind.
What keeps them going? Why don’t theses gyres just stop spinning at some point?
The spinning of the earth and wind sustain these gyres. Neither will be stopping soon so there will always be ocean gyres.
How many ocean gyres are there?
There are 5 major ocean gyres and many minor ones. The 5 major gyres:
- North Atlantic Gyre
- South Atlantic Gyre
- North Pacific Gyre
- South Pacific Gyre
- Indian Ocean Gyre
Which ocean gyre is the largest?
The North Pacific Gyre is the largest. It also contains the largest collection of ocean debris as well, an estimated 11 million tons.
What percentage of the open ocean consists of these gyres?
80% of the open ocean (not including coastal areas) are made up of gyres.
What is a good analogy of what ocean gyre is?
They are essentially supersized ocean deserts. Their land equivalents are large deserts like the Sahara and Gobi.
What sea life lives in these gyres?
These large expanses of water tend to be low in nutrients which keeps bigger fish and mammals away and are home to mainly plankton and other microbial organisms. These micro-organisms can generate their own food from sunlight and CO2.
Is the water in gyres clearer or murkier than coastal waters?
Because there is a much lower density of sea life in these ocean deserts, the water is clearer.
Why are ocean gyres in the news so much?
Improperly disposed of plastics that find their way into the oceans tend to accumulate into one of these 5 ocean gyres. The swirling action of ocean gyres causes any debris caught in it to gradually make its way to the center where there is little water movement. It is concerning because its effect on sea-life like plankton is uncertain but assumed to be detrimental.
What is the Great Pacific Garbage Patch?
Every ocean gyre has garbage in it with the Great Pacific Garbage Patch, located in the North Pacific Gyre, being the largest (twice the size of Texas), most polluted and most studied.
Does it look like a big trash heap?
No. It’s mostly particles too small to see due to ocean action breaking the plastics down to smaller sizes.
Where do the plastics come from?
300 million tons of plastic are produced worldwide. Not all of it is properly disposed of and some of it ends up in the ocean where currents carry it to the center of these ocean gyres where they can remain for hundreds of years.
Are there mainly plastics in these gyres?
Most other marine debris either breaks down or sinks, so the majority of the garbage in these gyres is plastics.