Organisms can grow on microplastics in freshwater ecosystems. The findings of a recent study undertaken by researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) and the Leibniz Institute for Baltic Sea Research, Warnemünde (IOW) show that the potentially toxin-producing plankton species Pfiesteria piscicida prefers to colonise plastic particles, where they are found in 50 times higher densities than in the surrounding water of the Baltic Sea and densities about two to three times higher than on comparable wood particles floating in the water.
A plastic item weighing one gram, floating in the sea, can harbour more living organisms than a thousand litres of surrounding seawater. To date, little research has been conducted to determine the extent to which microorganisms colonise microplastics in brackish ecosystems, and which species dominate such populations. A team of limnologists have investigated the natural colonisation of polyethylene (PE) and polystyrene (PS) microplastics by eukaryotic microorganisms. Examples of eukaryotic microorganisms include plankton species that – unlike bacteria and viruses – are single-celled.
The 15-day experiment involved incubating PE and PS particles, a few millimetres in size, with natural microfauna at different stations in the Baltic Sea, the river Warnow and a wastewater treatment plant. The scientists then used sequence analysis to investigate the complex communities on the microplastics. Around 500 different species of eukaryotes were present on the tiny particles.
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