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Deltares | R&D Highlights 2015
CleanSea
The main goal of the European FP7 CleanSea project was to produce guidelines for eliminating litter, and in particular plastics, from the seas. The technical issues included the quantification of plastic debris, determining how the debris migrates horizontally and vertically through the water column and an examination of the effects on marine organisms. Socio-economic aspects were also studied, including the willingness-to-pay of beach visitors for cleaning up the plastic litter, the role that voluntary schemes can play in reducing the amount of plastics in production processes and how policy and other regulatory bodies can provide support through legislation. One of the main achievements of CleanSea was to put the issue of plastics in the marine environment on the political agenda in Brussels. This was done by providing mitigation options for policy-makers in the European Commission in a road map that covered ecological, economical, sociological, and political factors.
The role of Deltares in the project was to obtain new knowledge about the transport of macro- and microplastics from estuaries to the sea, the degradation and fragmentation of plastic litter in laboratory conditions, the effects of plastic particles on microalgae and effects higher up the food chain. Deltares also contributed to the final product, the road map.
Model simulations for the North Sea showed that the lighter microplastic particles tend to stay on the surface and to follow the hydrodynamics towards the north-eastern part of the North Sea. The heavier microplastics tend to sink towards the sea floor and accumulate. The accumulation areas are mainly in the coastal zones and they vary depending on the size and type of plastic.
The breakdown of plastic items into smaller particles was quantified using a mesocosm experiment in which, for example, weight loss over time was quantified. Fragmentation rates proved to vary considerably depending on the type of plastic material. Dynamic Energy Budget modelling was used to learn about the possible effects of plastics on the marine food chain. This technique is based on how an organism acquires and uses energy and how this is affected by environmental variables. Microalgal growth was negatively affected by microplastics, but only when concentrations of particles were high. The effects on primary production at the base of the food chain that were predicted using ecological models with high concentrations of microplastics were negligible. However, the predicted effects on secondary production were apparent since they were a combination of the loss of energy from algae and the direct effect of plastics on zooplankton.
CleanSea was the first interdisciplinary European project to look at marine litter in an integrated way. It involved seventeen partners in a consortium of universities, research institutes, SMEs, NGOs and a network of coastal municipalities. The project has greatly increased our understanding of plastic litter in Europe’s seas but, most importantly, it has resulted in new options for making and keeping our seas clean.
myra.vandermeulen@deltares.nl T +31(0)88 335 8463
dick.vethaak@deltares.nl T +31(0)88 335 8059
Relative impact of microplastics on annual mean secondary productivity
Marine mesocosm containing an artificial plastic soup where different types of plastics were exposed to a regime of UV light and mechanical stress to simulate field conditions
Model simulation for plastic particles showing that most of the plastic
particles travel to the north-east Further reading:
http://www.cleansea-project.eu
Ecosystems and Environmental Quality
