Gaby Gorsky, © Y.Chavance/Tara Expéditions

Gaby Gorsky - Tara Méditerranée’s plastic hunter

Posted on 18 September 2014.

A researcher and plankton specialist, he has been working with Tara Expeditions since 2009 and is the Scientific Director on the current expedition in the Mediterranean.

“Pollution of the sea by plastic can be reversed.”

He is also the Director of the Observatoire Océanologique in Villefranche-sur-Mer/UPMC-CNRS. #LivingCircular was able to interview him before he returned to the schooner Tara to supervise sampling.

#LivingCircular: What does your role as Scientific Director on the Tara Méditerranée expedition consist of?

Gaby Gorsky: I was the driving force behind the expedition, the idea being to make good use of the stop overs Tara had planned in the Mediterranean. Tara Expeditions and its representatives approved the idea, so we set off on a hunt for floating plastic that is lasting from May to November 2014. I am the Scientific Director and one of the coordinators along with Maria-Luiza Pedrotti (CNRS) and Melissa Duhaime (Michigan University).

How do you track down these fragments of floating plastic?

We don’t just take samples of plastic, we also study its physical and chemical environment, and so analyze all kinds of data. First, we establish a roadmap. Using satellite maps, we can see the areas where the plastic is most prevalent, often near urban areas or the mouths of rivers or where there are swirling currents. We also take the weather and currents into account. Using this information, I establish a sampling plan for the week ahead. Together with the ship's captain, Samuel Audrain, and Roman Troublé, the Secretary General of Tara Expéditions, I make adjustments every night depending on the height and direction of the waves, wind and currents,.

Can you describe a typical day for the scientific team on board the Tara?

We take several kinds of samples and measurements in order to get a comprehensive picture of the health of the Mediterranean Sea.

At each sampling station, we take three samples using the special "Manta" nets. The first sample goes for microscopic analysis and to examine the colonization of the plastic. By taking a sample of both plastic and seawater, we can compare the free bacteria with those bound to the plastic. The second sample is taken to the laboratory in Villefranche-sur-Mer which will look at the interaction between the zooplankton and plastic. The third sample will be used to study the nature of persistent pollutants bound to the plastic.

At the same time, we analyze the phytoplankton in the Mediterranean. Throughout the expedition, we also measure the temperature, salinity and turbidity of the water using submerged sensors. Finally, through the special holes in the hull, we can analyze the marine optical data – meaning we observe the photosynthesis conditions as the ship sails through the Mediterranean basin.

And we don’t only work during day, but at night too.

Why is it important to take samples at night?

Plastic floats day and night. But zooplankton migrates every night. From relatively great depths of 1000 meters and more, the zooplankton rises to the surface to feed on phytoplankton. A vertical movement therefore takes place every night. Zooplankton reaches the surface of the sea in the middle of the night, when it is completely dark. It is a special time when we can take samples of the entire marine ecosystem and floating plastic at the same time.

Station de nuit – Tara Méditerranée 2014
Copyright : Yann Chavance © Tara Expéditions

What is currently known about the impact of plastic pollution on plankton and indirectly on people?

The aim of the Tara Méditerranée expedition is exactly that – to find out more about it. The work conducted by a number of researchers has demonstrated bioaccumulation: particular organisms swallow or filter these small fragments of plastic, which then pass throughout the food chain. This is proved by chemical analysis. As they are at the top of the chain, the larger fish amass more pollutants from plastic. With Tara and in collaboration with Italian researchers, we will soon be taking whale skin samples to verify this bioaccumulation because whales feed on phytoplankton and zooplankton.

As for its impact on man, it is proven. Government circulars advise pregnant women in particular not to eat more than a certain amount of fish because it may contain pollutants that have adverse health effects.

How is plastic a “pollutant sponge"?

Pollutants, such as pesticide and chemical fertilizer runoffs, readily adhere to plastic. Plastic is porous which means good adsorption of the molecules known as persistent organic pollutants (POPs). Tara will carefully analyze the POPs present on microplastics and plankton in the Mediterranean, along with their quantity and composition. But that's not all, bacteria also attach themselves to the plastic and become a virus vector, with consequences for humans. Plastic can also carry the larvae of some species. Under the effect of the wind and currents, these organisms can move miles away from their native ecosystems.

You believe plastic pollution can be halted. How can it be done?

There are 3 possible ways. The first, and perhaps the best, is to change what we do and stop using long life, non-degradable plastic and start using natural products. We need to transform industry and change how certain products are manufactured – in particular those where the use of petrochemicals is not essential. We should manufacture paper bags and glass bottles, and replace plastic with natural resin, hemp, etc.

The second way is to break the plastic down. Currently, plastic deteriorates and fragments. The pieces get smaller and eventually are invisible, but are certainly no less harmful. In fact, the smaller the particle, the smaller the organism that is able to ingest it. Plastic therefore passes readily through the food chain. Several laboratories around the world are researching techniques that will offer an alternative. Tara is cooperating with the laboratory in Bagnouls that has isolated bacterial strains capable of breaking down plastic.

The last method makes use of solutions proposed by Boyan Slat, who has invented a system for recovering the plastic floating in the oceans. It would solve the problem of plastic collecting in certain places in the world, but not the cause of the problem. As long as we continue to produce plastic, it will end up in the sea.

Come and see us next year. We start analyzing our samples in November and will have the first results sometime in January 2015.

The schooner Tara, supported by the Veolia Foundation, is continuing its mission in the Mediterranean, before returning to its home port of Lorient on December 7.

For more information:

- The Veolia Foundation supports Tara