Although they are a rather recent human invention, microplastics have managed to make their way to almost every ecosystem on Earth. Scientists have discovered them in soils, rivers, food and bottled water, and even in the human body. Now, a team of researchers from the University of Prešov in Slovakia has found, for the first time, microplastics in plant leaf axils.
The researchers set out to Eastern Slovakia to study the microorganisms that live in the small water puddles formed in teasel leaf axils. Teasels of the genus Dipsacus have opposite leaves growing on their stems in several levels, forming cup-like structures – known as telmata – that collect water. To their amazement, the scientists discovered differently colored fragments and fibers in the telmata that they later on identified as microplastics.
“Teasel phytotelmata are a relatively common but overlooked aquatic microcosm with a very short-term occurrence of only three to four months,” the authors wrote. “These phytotelmata are very small and have a short lifespan. The question is, therefore, how were they polluted with microplastics?”
Since no other sources of contaminants were found in the surrounding environment, the microplastics most likely came from the polluted atmosphere, although the researchers argue that a different explanation could be that snails might have transported them from the soil or other plants, in or on their bodies.
“The first finding of microplastics in small short-term water reservoirs created by plants is further evidence that contamination of this kind spreads through various pathways and probably no environment on Earth is safe, which of course makes our discovery quite disheartening,” the scientists explained.
“On the other hand, the results of our research of teasel phytotelmata, as a very unusual and highly specific natural environment, offer many possibilities for use in researching the spatio-temporal characteristics of the spread of microplastic pollution and its potential impact on the plants themselves, as well as organisms bound to them by ecological relations.”
Thus, due to their abundance and ability to capture microplastics from the environment, teasel phytotelmata may be used by scientists as reliable bioindicators of the presence of microplastics, which would help identify possible sources and pathways of these pollutants’ spread throughout nature.
The study is published in the journal BioRisk.