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Gyres and Eddies! I recently stumbled on a really amazing visualisation by NOAA, showing a view of what was described as "doughnuts" in the ocean (original link at the bottom of the post). These donuts are called Gyres and Eddies.
DIVING FOR DEEP-SEA…GARBAGE
The Great Pacific Garbage Patch is a collection of trash and debris in the North Pacific Ocean. The center of this region of water is very calm because it lies within a gyre. A gyre is a circulating current in the ocean formed by wind patterns and the Earth’s rotation. Garbage does not escape easily from this region, and the rotation of the water here tends to draw trash in. The majority of the debris is composed of small plastic pieces that may not be visible to the naked eye but also do not biodegrade. Similar areas also exist in the Atlantic Ocean. This phenomenon is well-documented in shallow ocean depths. Now, according to scientists at the Monterey Bay Aquarium Research Institute (MBARI) in Moss Landing, California, significant amounts of trash are also accumulating in deeper regions of the ocean. These deeper areas are only now being documented due to the high cost and limited technology available to explore these remote areas.
The researchers involved in the study examined 18,000 hours of underwater video captured by MBARI’s remotely operated vehicles (ROVs). The footage was recorded over 22 years and captured virtually every living and non-living thing that moved into the cameras’ lenses from a depth range of 25 m to 3,971 m. The scientists have created a database of all information collected from this footage, which is called the Video Annotation and Reference System (VARS). The database was searched for every image and video clip that contained marine debris. Then, the debris was analyzed to determine type and location.
The findings have documented over 1500 instances of marine debris in deep-ocean zones. This trash was found at widespread dive sites, spanning from Vancouver Island to the Gulf of California to Hawaii. Monterey Bay in California was the main focus for this research paper, where over 1150 pieces of trash were discovered. Most of the debris documented was made of plastic. More than half of the plastic objects found were the remains of plastic bags. The second most commonly found items were made of metals such as aluminum and tin cans. Other items included rope, fishing equipment, glass bottles, military debris, and paper.
These items can be harmful to marine life. Plastic can be a choking hazard to organisms, and when these pieces of waste are ingested by marine creatures, unknown effects may perpetuate throughout ecosystems. Also, fishing gear can trap creatures. However, many animals have adapted to the presence of these items and have even used debris for shelter.
Much of the trash accumulated on rocky slopes, where currents flow. The slopes are obstacles, so the trash is deposited in these regions. Much of the trash was discovered more than 2000 meters (6500 feet) down, in the deeper zones. Water may be carrying this trash to deeper regions, or it could be buried by underwater landslides or sediment movement. This region does not have high oxygen levels or sunlight, which impedes bacterial breakdown. As a result, the trash persists in these regions for many years. The trash in these regions was mixed with items that originated on land, such as kelp and wood, which means that much of the trash is most likely from land-based sources rather than boats.
The researchers noted that the most frustrating aspect of this study was that much of the debris discovered could have been recycled. They believe that public awareness of the issue will help to prevent some of the trash from entering the ocean.
-Jeanne K.
Photo of soda bottle from Asia found 1,727 meters (5,666 feet) beneath the ocean surface near California courtesy of MBARI/NOAA.
References: http://www.sciencedirect.com/science/article/pii/S0967063713001039
http://www.mbari.org/news/news_releases/2013/deep-debris/deep-debris-release.html
http://www.sciencedaily.com/releases/2013/06/130605144328.htm
http://education.nationalgeographic.com/education/encyclopedia/great-pacific-garbage-patch/?ar_a=1
http://news.nationalgeographic.com/news/2013/06/pictures/130606-deep-sea-trash-monterey-canyon-seafloor/#/deep-sea-garbage-found-soda-bottle_68215_600x450.jpg
Great Pacific Garbage Vortex
In 1997, oceanographer Charles Moore was returning to California from Honolulu after a sailboat race. Cutting across an area in the midst of the North Pacific Gyre (one of five large rotating systems of oceanic currents), he began to notice plastic debris floating on the surface of the water. When he spotted more awhile later, he began making hourly entries in his logbook, noting what he saw. Empty plastic bottles and bottle caps, fishing nets and floats, even toothbrushes were noted. Moore had discovered what has become known as the Great Pacific Garbage Patch (a.k.a. Great Pacific Garbage Vortex). The possibility of the trash patch was predicted in a 1988 paper published by NOAA (National Oceanic and Atmospheric Administration).
When you read about the Garbage Patch, you see referrals to the size of it and descriptions of “an island”. A 2005 report from the United Nations Environmental Program estimated that on average, more than 13,000 visible pieces of plastic litter were floating on any square kilometer of ocean and extrapolated that the convergence zone in the North Pacific Gyre contained as much as a million items per square kilometer. However, another study done by the NOAA Marine Debris Program describes it as multiple areas (some in mats of up to 15 ft. in diameter) of tiny micro plastics (like the micro-beads found in soaps and body washes) with scattered larger items all over the world in places where debris naturally accumulates, such as the Pacific Gyre. In fact, marine litter is found in every ocean on Earth, floating on the surface and on the sea floor. NOAA’s calculations show that just cleaning up 1% of the North Pacific Ocean would take 67 ships a year—and then it would have to be done all over again, because littering and dumping isn’t stopping. Beach cleanups have shown similar amounts of trash on beaches in heavily populated places and remote shorelines. Plastic containers, fishing gear, toys, flip -lops, and even a sofa have been found on beaches far from any urban area.
Besides the sheer ugliness of all that garbage, the UNEP report on marine litter and plastic debris identified 267 different species that are known to have suffered from entanglement in or ingestion of marine debris. Turtles, seals, sea lions, whales, manatees, and fish are just a few. Sea birds have been known to pass plastic bits on to their chicks in regurgitated food. Because the chicks then feel a false satisfaction of their hunger, without any nutritional value, they fail to thrive and gain the fat stores needed for migration. Larger pieces of debris can act as rafts, carrying invasive species for long distances.
So what can be done?
One suggestion would be a move towards greater use of biodegradable plastics made from plant materials. More research needs to be done in this area, though, to see how quickly the materials break down under varying conditions. Plus, there is the concern that people would consider these items to be “safe” to discard in the environment. The most obvious solution would be to prevent plastics and other synthetic materials from entering the marine environment in the first place. For that to happen, there would need to be widespread cooperation and implementation of strategies to “reduce, reuse, and recycle” materials rather than disposing of them so freely. CW
Image source
http://bit.ly/1djPvCs
Our recent post on a possible solution: http://on.fb.me/1l7tOJM
Sources
http://marinedebris.noaa.gov/info/patch.html
http://1.usa.gov/1smYzdZ
http://1.usa.gov/1X64mAs
http://go.nasa.gov/1HUVKuI
http://bit.ly/1SmOneQ
http://bit.ly/1C1GpAA
http://bit.ly/1r3VCOk
http://ocean.si.edu/ocean-news/ocean-trash-plaguing-our-sea
http://edu.stemjobs.com/the-great-pacific-garbage-patch/
http://bit.ly/1HZobb3
http://bit.ly/1n5Mojv
Garbage patches and gyres
The Earth’s Ocean Basins turn in giant currents called Gyres, driven by surface winds such as the strong equatorial Trade winds. Water circulates rapidly near the ocean coastlines but in the middle of each basin there is a pool of calmer, slower-moving water.
When floating trash gets into the ocean, it rapidly is swept out of the areas with strong currents but it can basically get stuck in the areas with weak currents. This process has led to the formation of “Garbage patches” in the centers of each ocean basin.
It’s important to understand that a garbage patch isn’t a single island of trash, it’s a concentration of trash. It’s an area where there are lots of floating bottles and other debris, not necessarily touching each other, but enough to significantly alter the ecosystem. Plastic debris in particular is really bad because when it is exposed to the sun it hardens and becomes brittle. Sun exposure breaks plastic down into shards that are then eaten by birds and fish in these areas, clogging their digestive system.
This video shows a simulation of the formation of garbage patches based on data collected by NASA. In the process of studying the oceans, NOAA and NASA have released tracking buoys that move along the surface with the currents. This simulation was created by placing thousands of “virtual buoys” into a simulated ocean with currents as measured by the real buoys. The real buoy paths are shown in white, the virtual buoys in blue. You can see how areas with strong currents are rapidly swept clean, while the virtual buoys form garbage patches in the quiet water areas of the central basins.
-JBB
Video Credit: NASA Visualization http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4174
This is simply a gorgeous data visualization. These flow paths show currents in the Mediterranean Sea and the northeastern Atlantic Ocean over an 11 month period. Darker lines are flow at depth, brighter lines are flow near the surface. So many different eddies and flow paths, in addition to the major currents that carry water into and out of the Sea.
Gyres and Eddies
I recently stumbled on a really amazing visualisation by NOAA, which was in honor of National Doughnut Day in the US. The short video was showing a view of what was described as "doughnuts" in the ocean (original link at the bottom of the post). I had a quick read of the article which clarified that I was right in my thinking, that these “doughnuts” were visualisations of Gyres and Eddies. So I wanted to share with you this awesomeness and give you a little run down on what they are.
Modern ocean maps can show huge swirls called ‘gyres’, which turn clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere. A complete rotation within each ocean basin takes years. Along the north and south edges of the gyres there are currents about 150 m (492 feet) deep with a speed of 3-5 km/day, though ‘boundary currents’ on the east and (especially) the west edges of the oceans are appreciably faster and deeper. For instance, the part of the South Pacific gyre against Australia (called the East Australian Current) flows south and constantly impeded the northward progress of James Cook on his voyage of discovery in 1770.
Embedded within the boundary currents are transient eddies, especially at the western edge of the ocean. These can be discerned on a snapshot map of sea-surface heights over a short period. The eddies form when a boundary current meanders so widely that a loop becomes short-circuited, and they are about 30-300km in diameter, drifting polewards. They stir a warm current into the surrounding colder water, and so contribute to the transport of heat (and momentum) towards the pole in the same way that midlatitude frontal systems in the atmosphere mix warm and cold air masses. Clockwise eddies in the southern hemisphere have a cold centre and a slightly depressed ocean surface, while the anti-clockwise eddies have a warm core and a slightly elevated ocean surface.
The oceanic gyres explain why east coasts (where the gyres come from the equator) are usually warm and wet, while west coasts are cool and dry because of (i) the advection of coldness from the poles, and (ii) upwelling. For instance, places in subtropical latitudes (i.e. 20-35˚S) along the east coast of South Africa are 3-8 K warmer than those on the west coast. An exception is Australia’s west coast, where I live, where the southwards Leeuin current along the coast brings warmth towards Perth and suppresses any upwelling. We have plant species that grow here and nowhere else on Earth due to this current. However, there is no exception to the rule that continental east coasts in the subtropics are humid, and west coasts arid. This rule is due mainly to the predominant easterly winds around the Tropic. Gyres transport heat polewards in amounts comparable to those in warm winds.
These surface currents are governed by four factors: (i) wind drag (drifts), (ii) the slope of the ocean surface (slope currents), (iii) differences in water density, and also the Coriolis force. The ‘absolute current’ (with respect to the land) is the outcome of all these factors together.
~ JM
Image Credit: NOAA http://1.usa.gov/1eUlTwk sourced 06/06/2015
More Info: Ocean Gyre: http://bit.ly/1Md4M3w Ocean Eddie: http://1.usa.gov/1F0Mn4p Leeuwin Current: http://bit.ly/1Md58a6 Perpetual Ocean: http://1.usa.gov/1G1n6uL Perpetual Ocean Video (one of my favourite videos): http://bit.ly/1G1nbi6 NOAA: http://1.usa.gov/1eUlTwk
A trashy map of Earth’s oceans Here’s an odd question…where does one ocean end and another begin? If you travel East from the Indian Ocean, you’ll eventually reach the Pacific, but when? Can you draw a line on a map? Not exactly the easiest thing is it? Cartographers could probably agree on a line but that’s just a convention. To answer that question, scientists from the University of New South Wales did something interesting. They tracked trash. The Earth’s oceans each have dominant currents that spin in circles around the basins known as gyres. They are driven by a combination of strong winds, upwelling, and weather patterns. Water in one of these gyres, and anything it is carrying, will tend to stay in that gyre for a while. In other words, water in some area is going to technically “be” in one of the oceans. There’s actually a natural dividing line in the oceans; water on one side will go one way, water on the other side will tend to go the other way. Water isn’t easy to track because one particle of water looks a lot like the one next to it, but solid particles can be tracked. There is so much trash in the world’s oceans that tracking the trash allows for tracking of the water flowing around it. That’s the source of this map. This is a map the boundary of Earth’s oceans defined by water flow patterns. It’s not exactly where you’d put the dividing line between the Pacific and Indian Oceans if you were drawing a line yourself, but that’s where the dividing line in the water is. A tongue of water in the Eastern Indian Ocean is being pulled regularly into the southern Pacific Gyre, probably enabled by the currents that encircle Antarctica. -JBB Original paper: http://scitation.aip.org/content/aip/journal/chaos/24/3/10.1063/1.4892530 Read more: http://www.scientificamerican.com/podcast/episode/sea-garbage-shows-ocean-boundaries/
A trashy reminder
For several weeks, literally thousands of people have spent their time scouring satellite images of the Indian Ocean for remnants of Malaysia Air flight MH370. It seems almost daily now that possible debris is cited in the water, but these sightings keep turning out to be a different problem; trash.
Humankind has treated the oceans as our final garbage dump. Sometimes it’s done deliberately; trash or even shipping containers can be dumped in the ocean to get rid of them. Sometimes it’s less deliberate; the discarded plastic bottle on the side of the road gets picked up by water during a storm, carried down a river, and eventually finds its way to the ocean. Sometimes it’s not even on purpose; the tsunami waves hitting Japan in 2011 and the Indian Ocean in 2004 carried enormous amounts of debris into the oceans.
The image on the left is a satellite image showing debris in the Indian Ocean; this concentration of debris caused a search team to head to that area hunting for the plane. The image on the right shows a representation of what it probably actually was; random, floating chunks of something, discarded by man at some point.
The waters of Earth’s oceans turn in circular patterns called gyres driven by winds in the atmosphere. Around the edges of these gyres there are strong currents, but the waters in the center are quieter. Floating objects naturally get trapped in these quiet waters, creating the great oceanic garbage patches. Occasionally, some of those objects find a current and are carried away, heading out to shore, or potentially to one of these search areas.
These garbage patches are a problem every day for the life that lives in these areas, but the unique circumstances of this search have created a situation where they’re once again an active problem for the world as well.
-JBB
Image credits: Kal Schreiber (Creative commons license): https://www.flickr.com/photos/50457550@N00/7030900 Satellite image from GISTDA, shared by AP
Read more: http://www.washingtonpost.com/world/the_americas/ocean-garbage-frustrates-search-for-flight-370/2014/03/31/bf5718de-b8c2-11e3-80de-2ff8801f27af_story.html http://www.salon.com/2014/03/27/one_thing_weve_learned_from_the_search_for_flight_mh370_theres_a_lot_of_trash_in_the_ocean/ http://www.krcrtv.com/news/Ocean-garbage-problem-hampers-plane-search/25090362 http://www.slate.com/blogs/the_slatest/2014/03/31/mh370_debris_australia_says_orange_objects_were_fishing_gear.html
