CLS and The SeaCleaners: locating floating marine litter to better tackle plastic pollution in Indonesia


While a picture is worth a thousand words, it can also lead to hasty and misleading conclusions.

When it comes to plastic pollution, the reality is always more complex than it seems. Floating litter of rubbish covering hundreds of square metres of ocean surface, rivers carrying so much rubbish that you can’t even see the water, beaches littered with debris…: these images have travelled around the world and have helped alert global public opinion to the major threat posed by plastic pollution. But they also gave the false impression that identifying the areas where large amounts of waste need to be cleaned up was child’s play. After all, all you have to do is open your eyes!

Is that so ?

Knowing where to look, so you can act

Research shows that ocean plastic pollution is a land-based problem. According to the most recent studies, plastic accounts for 85% of all marine plastic waste and up to 80% comes from land. While there is a consensus on these data, scientific research is still far from unanimous in explaining how this plastic moves from the terrestrial to the marine environment and then ends up in the oceans: how fast? By which routes? By what mechanisms?

And, once in the sea, how does the waste drift? Where does it go? How does it disperse? How fast? In which direction? How can we predict the influence of sea currents, wind, seasonality, etc. on the dispersal of this waste?

So many enigmas to be solved for those who want to act effectively against marine pollution. Fortunately, studies are progressing in understanding where plastics accumulate and concentrate in the river and marine environment, as are predictive models for the release of plastic into the ocean.

Field observation over long periods of time (several years) can partially answer these questions. But there is also an arsenal of technological answers today, which are becoming increasingly sophisticated to complement our knowledge on the subject: satellite data.

Defining MANTA’s scope of action

And in this field, the world champion is French and has become a partner of The SeaCleaners! It is CLS (Collecte Localisation Satellites), a subsidiary of CNES and CNP. CLS is an international company that has been a pioneer in providing Earth observation and monitoring solutions since 1986. Its vision is to imagine and deploy innovative solutions to understand and protect our planet and manage its resources sustainably.

As part of its partnership with The SeaCleaners, CLS will make available the results of studies (1) on the monitoring and modelling of marine plastic waste drift in Indonesian waters, as well as its expertise in locating polluted marine areas in Indonesia, in order to prepare future MANTA intervention zones.

The data comes from 70 satellite beacons connected to the Argos constellation, deployed by CLS at the mouths of three Indonesian rivers: the Cisadane in Jakarta, the Bengawan in Solo on Central Java and the Musi River in Palembang on Sumatra Island. These beacons make it possible to really track down the plastic litter. The aim is to understand the mechanisms of stranding and accumulation and their impact on ecosystems in order to prioritise and optimise collection and cleaning in rivers, on the coast and at sea.

The recovery of the beacons’ positions every hour makes it possible to define precisely the trajectory of each beacon once it is at sea.

For The SeaCleaners, access to the results of these studies is a major challenge: it means knowing exactly which routes the giant cleaner of the seas will have to take to be as efficient as possible in its mission to collect river and marine debris, while having a minimal environmental footprint. In a word: how to optimise MANTA’s movements, and at what time of year to intervene, in order to have a visible impact in areas of high waste concentration.

The subject of satellite data and waste drift modelling is fascinating. To explain the stakes of these technologies, in the service of ocean protection and the fight against plastic pollution, we met Marc LUCAS, Project Manager and Senior Oceanographer at CLS and newcomer to the International Scientific Advisory Board of The SeaCleaners.

“We work on two types of satellite data:

  • Earth observation satellites, which provide a better understanding of the marine environment by providing an environmental inventory of marine plastic drift. They allow us to see the major dynamic structures that organise marine circulation.
  • Satellite telecommunication, which is done using beacons that are placed on subjects (animals, plastic waste, etc.), to be able to follow their trajectory in real time, and allow us to see the accumulation zones… These are relatively new activities that began in the 1980s. CLS is a pioneer in this field thanks to the Argos system, which was used to track feeding buoys for weather networks, or marine animals such as turtles, to understand their behaviour, the places where these species reproduce, their migration…

Today, CLS works a lot with Indonesia. Firstly because it is a historical partnership: we have been working for years with the Indonesian government on the management of fisheries resources. But also because Indonesia is the second largest contributor to marine pollution in the world, after China. With them, we work as a support to train them, to bring them new skills so that they can in the long run be able to manage this plastic pollution.

The work we are doing with The SeaCleaners will essentially be to understand the movement of plastics, to see where they accumulate so that the missions of the clean-up boats (the MANTA and the MOBULAs) are as effective as possible. We are also studying the routes of waste coming from rivers, to find out where it accumulates, both at sea and on land, on beaches, etc. Tracking waste upstream, before it reaches the sea, will allow us to measure the effectiveness of activities such as those of The SeaCleaners, and to be able to react quickly in difficult areas, such as Indonesia.”


(1) Studies carried out by CLS as part of its services for the World Bank (“Indonesia Marine Debris Monitoring and Modeling Initiative to Support the Protection of the Marine Environment” study) and for the Institute for Research and Development (IRD), as part of the AFD-IRD-MMAF FEXTE Indonesia project (“Collection of oceanographic data and implementation of a platform for the modelling and simulation of marine plastic debris in the Indonesian seas”)