An estimated 5 trillion pieces of plastic currently float in the world's oceans, up from none in 1950 and posing a question about their potential impact on a food supply chain that stretches from plankton - which have been filmed eating plastic pellets - up through shellfish, salmon, tuna and eventually humans, not to mention whales.
Laboratory tests have shown that fish fed such plastics suffer poisoned livers and consequent metabolic problems. Yet little is known about just how much rubbish is being eaten in wild marine ecosystems, nor whether toxic chemicals remain in plastics after long exposure to sea water and pounding waves.
A research vessel operated by the Norwegian Institute of Marine Research (IMR) in collaboration with FAO, the R/V Dr. Fridtjof Nansen, has since 1975 plied the world's oceans to collect information on marine resources and the health of the marine ecosystems and to help train scientists from around the world.
Some 18 scientists from eight countries and crew are aboard now, in the second of two seasonal missions. Researchers typically measure ocean temperatures, oxygen levels, chlorophyll and biological processes like plankton production and fish distribution, but there are two particular additional goals this year: to assess the scale and nature of industrial rubbish in remote parts of the southern Indian Ocean, and to study how the local Gyre, a cyclical vortex of currents, operates to spread plankton and tiny fish.
"We have found some plastic particles in almost all the stations we sampled," said Reidar Toresen of IMR, cruise leader of the first leg. IMR is providing scientific services to the FAO EAF-Nansen Project financed by the Norwegian Agency for Development Cooperation (Norad).
Huge floating islands of trash twice the size of Texas have recently been located in both the Atlantic and Pacific Oceans, but the southern Indian Ocean is relatively unexplored. The Trans-Indian Ocean Survey will yield critical information to scientists concerned about the extent and impact of so-called plastic beads in the ocean.
Promoting sustainable oceans and fishing practices is a priority for FAO as capture fishery production is the source of 80 million tonnes of nutritious food each year. Together with aquaculture, the world's capture fisheries provide nearly 3 billion people with 20 percent of their protein intake, as well as almost 60 million jobs.
Let them eat resin pellets?
Ocean-borne plastic trash can be ingested by wildlife- some sea creatures have even been seen to prefer beads of a particular color - causing harm. Even tiny plankton have also been observed consuming plastic beads. Such menu choices can have tragic outcomes; sea turtles that eat plastic bags, for example, often die of dehydration and sunburn as their digestion is paralyzed and decomposing food turns into gas that forces the animals to float.
Myctophid fish that spend their daytime in the ocean depths but come close to the surface at night to feed, are prone to ingesting such pellets, but the extent to which they do this will require more work analyzing the samples, said Melody Puckridge of the Commonwealth Scientific and Industrial Research Organisation of Australia, who led the search for plastics. More and bigger pieces of plastic tend to be found nearer coastlines - where fish stocks are greatest - but little is known about how the Gyre transports them and the kind of harbour it offers the smallest particles, she said.
Microplastics - beads less than five millimeters in diameter - are of particular interest as they may be entering the human food chain.
Microplastics are used in human products such as cosmetics and shower gels and are also used in resin pellet form by manufacturers. Virtually non-existent in 1950, more than 250 million tonnes are now produced each year, and some of that finds its way eventually to the sea,. The lion's share of their degradation occurs on beaches, aided by pounding waves and ultraviolet rays, while the process virtually halts for beads that sink to the bottom of the sea.
While the possible chemical and toxicological impact of the beads can be studied in laboratories, information on the location and quantity of microplastics, as well as how they move - fish themselves can be a biological vector and so can the Indian Ocean Gyre moving between Australia and Madagascar --, has to be obtained as it is on the survey with the R/V Dr Fridtjof Nansen. That means releasing and hauling in special nets several times a day, and poring over their contents.
Not just trash
The crew is also launching new, high-technology sinking sensors to measure levels of a range of deepwater biological elements. Provided by Australia with help from India, these robotic sensors are a step beyond the floating robots already in use to monitor ocean temperatures and salinity, as they are programmed to dive down as deep as 2,000 meters to sample oceanic health indicators.
When they resurface, these diving devices gather data at various depths, then resurface and transmit the data to scientists by satellite. The sensors will collect data on levels of chlorophyll, an indicator both of trends in the ocean's carbon storage capacity as well as in the basic food supply that plankton and the fish that eat them can rely on.
A new research vessel on the way
A new Dr Fridtjof Nansen research vessel will be launched in 2016, the latest in a series of Norad-owned ships of the same name that began the collaboration with FAO in the 1970s. The new ship, replete with seven scientific laboratories and an auditorium, will be equipped with modern sonar sensors able to map fish distribution quickly as well as a remote-control submersible vehicle able to take photos of life on the ocean floor.
Mapping the ocean floor is another key part of the EAF-Nansen Project's long-term work, of which FAO is the executive agency and Norad the principal funder. It helps expand understanding of fish demographics, allowing more informed fishery management measures to be set. The FAO-hosted EAF-Nansen Project has helped 16 coastal African countries develop sustainable marine resource management plans and in September will hold a marine taxonomy workshop in Mozambique.
Past efforts have shown that the ocean floor is often deeper than existing maps suggest, especially around so-called sea mounts, which are underwater mountains often formed by volcanos that create a series of unique maringe habitats and whose role in fostering biodiversity has been recognized by the United Nations.