Ocean currents are an organized flow transporting water and its contents from one region of the oceans to another. Though currents are affected by the wind, other factors also govern current strength and direction; depth, temperature and salinity are contributing factors to current characteristics.

Global currents are interconnected in what is referred to as "The Global Conveyer Belt." This current system carries warm water towards the poles by surface currents while transporting cold water towards the equator by deep water currents. It is driven by the density gradients in the ocean due to variations in temperature and salinity, slowly conveying water through the world�s oceans.


Surface currents are dominated by two main factors: wind velocity and the Coriolis Effect. Winds accelerate fluid particles on the surface by imparting momentum to the fluid through surface stresses. While in the beginning the particles will move in the direction of the wind, over time, the currents are deflected to the right in the northern hemisphere and to the left in the southern hemisphere by the earth's rotation. These predictable rhythms to the currents of the oceans result in the formation of gyres. Notice in the following diagram that the Indian Ocean gyre, the South Pacific gyre, and the South Atlantic gyre all rotate counterclockwise; while the North Atlantic gyre and the Central Pacific gyre rotate clockwise.

In an email dated February 28, 2010, Norton Smith describes the Coriolis Effect.

Gyres are the garbage collectors of the oceans. The garbage is drawn to the center by the circular motion of their currents, causing the refuse to build up in patches.

In an e-mail dated Febuary 22nd, 2010, Norton Smith stated: Any garbage that lasts more than seven years in the Pacific and stays near the surface will migrate to the center of one of the two areas shown below. Today, most of the garbage in these regions is plastic, because of its inability to be biodegraded and because of its abundance - 40% of all plastics are disposed of within a year of production, much of which ends up in the oceans. Plastics can float, carried by the currents for years, until they finally are grouped together with the rest of the trash in the center of the gyres. This causes a long serpent of trash that traces the gyres without out a head or a tail; almost a continuous train of trash until it reaches its final destination, referred to as the Convergence Zone. Within the Pacific Ocean this is principally either the eastern garbage patch in the north east or the western garbage patch in the north west of the gyre.

In an e-mail dated January 30th, 2010, Miriam Goldstein stated: Later, in an e-mail dated February 7, 2010, Miriam added: Records of trash in the ocean and on beaches have been kept since the 70's, however the first actual discovery of the garbage patch was by Captain Charles Moore on August 3 1997, while on a trip from Hawaii to California.



The circulation in the world's gyres accounts for the eventual accumulation of debris to central areas. Two of these locations are located in the North Pacific and have taken on the popular title "The Great Pacific Garbage Patch." In the North Pacific, the currents comprising the gyre travel at varying speeds, Kuroshio's currents travel at an average speed of 3-4 knots or about 1.54 - 2.06 meters per second, while the North Equatorial Current and North Pacific Current move on average between 0.7 knots or 0.36 meters per second.

Derelict fishing gear is a type of marine debris that was originally fishing equipment. It is specifically damaging. Abandoned nets and pots continue to catch marine life, and trap them until they starve to death. This is called ghost fishing. In shallower areas derelict fishing gear can do great damage to reefs, especially with repeated disturbances. Nets and line from fishing vessels can wrap around the neck or apendages of sea life, and studies have shown that of those entangled many suffer death because of it. Some populations are more effected by the entanglement problem than others. Some species of endangered seals do not get entangled often, but the younger ones are more likely to get entangled which causes a signifcant decline in the popluation. California, Hawaii, and Washington state are addressing this problem with new initiatives and removal programs.

A group of researchers lead by Katsuhiko Saido of Nihon University of Chiba, Japan has found that, contrary to popular belief, plastic in the oceans can decompose releasing Bisphenol A (BPA) in the process. BPA is an industrial chemical used as the starting material for the production of polycarbonate plastics and synthetic resins. BPA is found in items or containers that come into contact with foodstuffs such as drinking vessels, baby bottles, plastic tableware and the internal coating on tins for tinned-food. In some circumstances, chemicals in food packaging can migrate into the food product, and vice versa, depending on the nature of the packaging and the food contained within. Studies show that BPA can mimic the effects of the female growth hormone, estrogen. BPA has been linked to heart arrhythmias reproductive problems in females.

Ocean samples around the world, including regions around the United States, Europe, India, and Japan, contain derivatives of polystyrene, styrofoam, and hard plastics; toxic compounds such as styrene trimmer, a polystyrene by-product, and bisphenol A. All of which have leached out of these plastics into the ocean�s water. Scientists have simulated this decomposition of polystyrene in sea water validating the release of these same toxins during the physical breakdown of plastics. These toxins can have substantial effects on the oceans ecosystem; in addition to Bisphenol A (BPA), styrene monomer is a suspected carcinogen.



Dave Gilson says, "But broken down plastics are better than litter, right? Wrong. In fact, plastics often create more environmental harm when broken down than when intact. This is most evident in the oceans, home to billions of pieces of disintegrating plastic and preproduction pellets called nurdles, which can work their way back up the food chain to humans."

In an e-mail dated January 30th, 2010, Mirriam Goldstein stated:
In an e-mail dated February 28, 2010, Norton Smith added that:
There is a great concern that these plastics and toxins are doing damage to the ocean�s food chain. Marine life mistakenly ingests plastic assuming that they are a food source, contaminating themselves with the toxins and consuming indigestible material. An estimated 44% of seabirds consume plastic as part of their diet, many times causing death by starvation or from the plastic's toxic components. These toxins work their way up the food chain becoming more concentrated as animals consume the contaminated food supply. Eventually, it is believed that this will cause dangerous impurities throughout the entire food chain.