Plastic pollution : a scientist’s opinion
Interview with Linda Amaral-Zettler, senior scientist at the Royal Netherlands Institute for Sea Research (NIOZ).
Before you joined the NIOZ in July 2017, you worked full-time at the Marine Biological Laboratory in the US. There you coined the term ‘plastisphere’, to mark a new kind of ecosystem that microbiologists like you focus on. What do you know already?
We know that the plastisphere is a diverse, active community of microbial biofilms in what is the equivalent of an ocean desert (in the so-called ‘garbage patches’). These films are attractive for some organisms to selectively feed on, because they ‘smell and taste good’. This is understood to be the result of signal chemicals that the attached micro-organisms produce. We are still actively trying to understand microbial interactions within the plastisphere, and the contribution of microbes to the degradation or breakdown of plastic in the ocean.
What is the precise danger of microplastics in the (deep) ocean?
The biggest issue is the creation of a new habitat where there was none before. The open ocean gyres are the equivalent of deserts (on the nutrient level), so adding a substrate with a nice nutrient-rich biofilm changes this deeply. We do not understand what the domino effect will be. In the deep sea, microplastics become a food source for organisms large enough to ingest it. And so the same issues regarding microplastics biomagnifying up the food chain apply here as elsewhere in the water column.
How important is the role of micro-organisms, like the shelly diatoms, in the sinking of microplastics?
We are actively pursuing this question in my research group using cultured diatoms from the plastisphere. It seems that the size and shape of the plastic substrate also plays a big role in this as well. We are hoping to publish these results soon.
Can we develop a way (a new technology, perhaps?) to remove microplastics from marine environments?
Sadly, there is not a silver bullet to the plastic pollution problem. Most of the garbage patch plastic consists of microplastics that are very difficult (labour intensive and expensive) to collect. We know this very well, as we do this by ourselves for research purposes. The best solutions lie in changing public behaviour at the sources (both on land and at sea) and improving waste management on land. Increasing the value of plastic and rethinking the use of single-use plastics will help change public behaviour.
Bio-express : Linda Amaral-Zettler, senior scientist at the Royal Netherlands Institute for Sea Research (NIOZ), investigates the interplay between microplastics (plastic particles smaller than 5 mm) and micro-organisms like bacteria and (micro)algae.