Tuesday, October 5, 2010

How many albatrosses did you save today?

[Originally posted to MBA Student Oceanography Club (SOC)]

Plastic Bag on Beach
An urchin carries a plastic fork.For our first field experience we all participated in the beach clean-up, which was a great way to start off SOC.  I was pleasantly surprised by how little trash we found, and pleased to keep what trash we did find from entering the ocean.  For photos of some of you keeping trash out of our oceans (and enjoying the barbecue afterwards), scroll down to the bottom of this post.

We rarely think about the impact that trash has on the oceans – too often out of site means out of mind – but our garbage is a serious problem for life in the sea.  Trash, and plastics in particular, entering the environment can have numerous negative impacts on ocean life.  Discarded fishing line and six-pack rings can tangle and strangle birds, mammals, fish and other creatures.  Leatherback turtles may mistake grocery bags for jellyfish and slowly starve to death as they fill up on indigestible plastic.

Plastics in the stomach of a dead Laysan Albatross Chick
Laysan Albatrosses, too, confuse plastic for food. Flying fish frequently lay their eggs on floating bits of plastic, and the albatrosses swallow the items to ingest the eggs.  This isn’t too big of a problem for the adults, since they can regurgitate large items that they can’t digest.  Their young, however, lack the ability to regurgitate large items.  Like the leatherbacks, they may starve to death while their parents slowly fill them up with plastic.  Each piece of plastic you picked up might have saved and albatrosses life!

Even more insidious is the plastic that slowly breaks down.  We tend to imagine that plastics do not degrade.  That is certainly true of plastics sitting on our shelves or moldering in a landfill, but in the dynamic ocean, exposed to wind, waves and sun, many plastics break-down and degrade.  For most types of plastic that means that they are ground down into tiny particles no larger than the smallest plankton.  For other plastics, that means degrading into chemicals that dissolve in the water and may be toxic.  Either way, it is potentially detrimental for organisms living in the water or feeding on plankton.

Map of North Pacific GyreBecause many types of plastic float, they are easily carried by the currents, and remain in the environment for a long time.  For trash in the North Pacific, this means that they are slowly but surely carried around by the North Pacific Gyre.  The gyre is a large-scale clockwise circulation pattern that moves water west along the equator, swings north along the eastern coast of Asia, loops back east about part-way between Hawaii and Alaska, and finally turns back south along our coast.  Because of currents like these, trash from all over the world can end up on our beaches (and likewise, our trash can spread around the world).  In the center of the gyre lies a large area with relatively little current.  Trash that makes its way here tends to stay put, and large amounts of trash have aggregated there over time.  This is commonly known as the Great Pacific Garbage Patch, and recent studies indicate that millions of tons of trash have concentrated in an area roughly twice the size of Texas!

Ironically, floating trash has also helped us better understand ocean currents.  In 1990, a shipping container filled with Nike shoes fell off of a freighter, releasing 80,000 sneakers into the North Pacific.  Shoes began periodically washing ashore along the West Coast of North America, and an enterprising oceanographer named Curtis Ebbesmeyer realized that by tracking shoes and other floating items lost from ships (collectively known as flotsam) we could learn about ocean circulation.  Following the Nike shoe spill, Dr. Ebbesmeyer continued tracking flotsam, including a large spill of bath toys that have spread across the Pacific, passed through the Arctic Ocean, and finally into the Atlantic Ocean.  If you ever visit the Atlantic coast and find a wayward rubber ducky washed ashore, check it out.  It may have travelled half-way around the world over the past two decades:

Dr. Ebbesmeyer displays some of the bath toys he has tracked as they drift around the world. Thousands of rubber ducks to land on British shores after 15 year journey
Read more: http://www.dailymail.co.uk/news/article-464768/Thousands-rubber-ducks-land-British-shores-15-year-journey.html

You can learn more about plastics in the ocean and the Great Pacific Garbage Patch by  visiting some of the links below: