Microplastics – good for marine bacteria, bad for marine ecosystem functioning?

 Plastic pollution in our oceans is an ever looming threat to biodiversity within marine environments. Not only this but it has been found with increasing frequency in shellfish and so it is also becoming an issue for human health. Because of the abundance of plastic in the oceans it is important to understand how plastic interacts with the marine environment.

A study conducted by Galgani et al. in 2018 aimed to look at how polystyrene microplastics interacted with the marine environment and in particular with dissolved organic matter (DOM). Microcosms were set up containing DOM, bacteria and half contained polystyrene microplastics. Dom was measured along with the absorption of chromophoric dissolved organic matter (CDOM) which is a photo-reactive form of DOM; CDOM is produced naturally by marine bacteria by altering pre-existing DOM substrates.

It was found that in the presence of polystyrene microplastics, more CDOM was produced. This may be because the polystyrene acted as a good substrate for the formation of biofilms which would lead to an increase in bacterial activity. However, an increase in CDOM may have negative effects on the upper layers of the water column in oceans as CDOM absorbs light so it may change light conditions. In order to really assess the impacts of marine microplastic pollution pertaining to polystyrene, the effects of increased CDOM should be measured on photosynthetic marine organisms.

 

Galgani, L., Engel, A., Rossi, C., Donati, A., & Loiselle, S. A. (2018). Polystyrene microplastics increase microbial release of marine Chromophoric Dissolved Organic Matter in microcosm experiments. Scientific Reports, 8(1)