Microplastics may be responsible for a loss of oxygen in the ocean, according to a new study published in the journal Nature Communications.
Plastic debris in the ocean is a widely known problem for large marine mammals, fish and seabirds.
But on a smaller scale, tiny zooplankton can also mistake very small plastic particles for food and ingest them either accidentally or by chance. The direct effects of such microplastic ingestion are poorly understood, but for the first time, researchers at the GEOMAR Helmholz Centre for Ocean Research used an Earth system model to simulate how zooplankton that ingests microplastics could affect the base of the ocean food web and nutrient cycling.
The research revealed that even low concentrations of microplastics can have a strong impact on ecosystems.
The researchers found that the resulting changes in the ecosystems may be responsible for a loss of oxygen in the ocean beyond that caused by global warming.
Dr Karvin Kvale, lead author of the study said: ‘These findings are significant because there has long been scepticism in the scientific community that microplastic concentrations in the ocean are high enough to have any impact on nutrient cycling.
‘Our study shows that even at levels present in the ocean today, it may already be the case if zooplankton replace some of their natural food with microplastics. If zooplankton eat the microplastics and thus take up less food, this can have far-reaching ecological effects that can, for example, lead to increased algal blooms via a reduction in feeding pressure that affect the oxygen content of the oceans almost as much as climate change.
‘These findings point to a new potential driver of human-induced ocean change that has not been considered before. However, these results are very preliminary because little is yet known about how the base of the food web interacts with microplastic pollution. Further work on this topic is needed, but the study provides strong motivation to expand the capacity of Earth system models to include pollution effects as a new driver of ocean change.’
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