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Water samples will have been carefully stored and transported from the field site to the laboratory. Scientists need accurate measurement as to the amount of plastic particles in each sample. This is something that is impossible to judge with the naked eye.

Each sample is filtered, leaving just the solid particles to analyse. Each of the samples is numbered to keep track of where each sample came from.

Once the water sample has been filtered, the remaining particles can be examined under a microscope. As well as microscopy, an infrared beam can be fired at each particle to assess whether it is made from plastic or another material. This spectroscopy technique measures the absorption of different wavelengths of light revealing the chemical signature of the particle.

To test the hypothesis ‘zooplankton eat microplastics’, copepods are fed solutions of algae and microplastics in different concentrations. In this photo, the microplastic has been marked with a fluorescent dye so that it can be tracked clearly through the copepod’s digestive tract.

Other plankton, such as this crab larva are also tested. It is clear that microplastics were indeed ingested when they were present in the experimental batch. Plastic particles have been found in numerous marine invertebrates in the wild, including amphipods, lugworms, barnacles and mussels.