Floatable marine debris items, once they enter the ocean, move via oceanic currents and atmospheric winds. Factors that affect currents and winds, such as El Niño and season, also affect the movement of marine debris in the ocean. Debris items can be carried far from its origin, which makes it difficult to determine exactly where an item came from (i.e., source).
Below is a description of various oceanographic features that concentrate marine debris on a large, medium, and small scale in the North Pacific Ocean.
Marine debris items become entrained within the North Pacific Subtropical Gyre and thus get transported within the clockwise circulation. Debris can also accumulate within the center of the Gyre based on an overall convergence in the center of this anticyclonic gyre. This is similar to debris concentration within the North Pacific Subtropical High (aka "garbage patch").
Debris within the North Pacific Transition Zone often concentrates at the frontal convergence; the one of main interest being the North Pacific Subtropical Convergence Zone. This is an area of high productivity, pelagic species feeding and migration, and documented marine debris concentration – and one of the reasons for marine debris accumulation in Hawaii (see our page on the “garbage patch” for more information).
Within the transition and convergence zones there are a multitude of meso-scale features such as oceanic eddies and frontal meanders*. These features can concentrate and scatter debris within the convergence zone depending on the location and type of feature.
* Think of meanders as the deviation from a straight line. As energy (wind/currents) hit the front there are undulations and "curvature" which are described as frontal meanders (movements to the north and south along the front)).Micro-scale (small)
On a micro-scale, marine debris may be concentrated by Langmuir circulation. “Langmuir circulation is the result of the interaction between wind-driven surface currents and surface waves. Though Langmuir circulation may be present in weak or no-wind situations, it is most often seen when the wind speed is 1.5 m/s or greater.” (NOAA Office of Response and Restoration)
This map is an oversimplified illustration of the oceanographic features in the North Pacific Ocean.
For more information on the movement of marine debris in the North Pacific Ocean and what is being done to address this issue visit:
- What is the "Great Pacific Garbage Patch?"
- Focusing Efforts to Detect Derelict Fishing Gear at Sea in the North Pacific (Pacific, 2008)
- At-Sea Detection of Derelict Fishing Gear Debris in the North Pacific
- NWHI Derelict Fishing Gear Accumulation (NOAA Pacific Islands Fisheries Science Center website)
- High Seas GhostNet Project
- List of Related Publications and Literature
There is little information on marine debris in the high-seas Atlantic Ocean. Much like in the Pacific there is a North Atlantic Gyre made up of four major currents – North Equatorial, Gulf Stream, North Atlantic, and Canary Current. There is also a North Atlantic Subtropical Convergence Zone (STCZ), however little to no research on debris concentration within this STCZ has been conducted.