Gyres and witness islands
to witness the extent of the disaster
Gyres and trash vortexes
Contrary to certain common beliefs, gyres are not areas of compactly accumulated macro-debris, but diffuse pollution zones with stronger concentrations of plastic microparticles than are present in open water. There are currently no technological methods available for locating and mapping them. Floating a few centimeters under the surface of the water, plastic pollution can be almost invisible to the naked eye, and unidentifiable by aerial photography.
Today, it is still impossible to map these vortexes of trash with precision. There are currently five gyres identified around the world: in the North and South Atlantic, the North and South Pacific, and the South Indian Ocean.
It is estimated that 80% of plastic waste in the ocean results from human activity on land, while 20% comes from human activity at sea (marine traffic, fishing, aquaculture, oil rigs, etc.).
Negative impacts on the ecosystem
This waste has a number of negative impacts on the ecosystem and on mankind:
Threat to marine ecosystems
Entanglement, ingestion, intestinal blockage, choking, etc. can lead to animals' deaths. It is estimated that, among others, 86% percent of marine turtles, 44% of marine birds, including 70% to 100% of albatrosses, ingest plastic macro-debris, mistaking it for their prey.
Contamination of the food chain
Plastic matter fragments into plastic microparticles, and releases toxic chemicals (fire retardants, PCBs, bisphenol A, phtalates, etc.) that can easily be ingested by marine animals, and eventually, by humans.
Potential vectors for invasive species that may represent a threat to marine ecosystems and endemic populations
Different types of plastic trash
Plastic trash can be classified into three categories, by size:
- macro-debris, fragments that can be seen by the naked eye (>2.5 cm)
- meso-debris (5mm - 2.5 cm)
- micro-debris, less than 5mm to 1mm. These micro-debris were either dumped into the water as is (polyester fibers, plastic microbeads found in cosmetic products), or come from macro-debris which degrade over time through chemical (UV radiation, oxygenation), physical (wind, waves), or organic (bacteria) processes.
Although until now, no study has led to a global and detailed assessment on this issue, the UNEP's research demonstrated that the study of beaches is an effective means of estimating the quantities and types of plastic present in the oceans.
Witness islands allow better understanding
The odyssey's itinerary is divided into 5 expeditions across the 5 vortexes of trash. The islands under study have been chosen based on their location within trash vortexes. There are 11 of them some of which are far from civilization, and others inhabited. The latter, however, are not home to any significant industrial activity, and are entirely dependent on tourism and local activities like fishing.
Expedition 1 – North Atlantic Vortex
The Azores (Portugal; 2,333 km2; 245,746 inhabitants)
Bermuda (Great Britain; 53 km2; 64,237 inhabitants)
Expedition 2 – South Pacific Vortex
- Easter Island (Chile; 164 km2; 5,761 inhabitants)
Expedition 3 – North Pacific Vortex
- Palmyra Atoll (USA; 12 km2; no permanent population)
- Midway Atoll (USA; 6 km2; 60 inhabitants)
- Wake Atoll (USA; 7 km2; 150 inhabitants)
- The Mariana Islands (USA; 1020 km2; 251,000 inhabitants)
- Koror (Republic of Palau; 380 km2; 11,200 inhabitants)
Expedition 4 – Indian Ocean Vortex
- Chagos (Great-Britain; 56 km2; 3,000 inhabitants)
- Rodrigues (Republic of Mauritius; 108 km2; 38,379 inhabitants)
Expedition 5 – South Atlantic Vortex
- Tristan da Cunha (Great Britain; 207 km2; 300 inhabitants)