Impact of plastic pollution on benthic foraminifera

Plastics are ubiquitous contaminants that currently affects worldwide oceans and marine biota, with about 5 billion tons of waste accumulated in the natural environment. The ubiquitous nature of microplastics means that marine biota can interact with them. While the fate of microplastics is well known, the biochemical effects of synthetic molecules especially on marine unicellular eukaryotic organisms is poorly investigated. To understand the fate of plastic in oceans and in marine organisms, we investigated the incorporation of (bio)polymers and microplastics in benthic foraminiferal species by applying FTIR (Fourier Transform Infrared) microscopy. Benthic foraminifera are an important component of marine communities, playing a key role in ecosystem functioning and biogeochemical cycling. Their sensibility and rapid response to environmental stress make them an efficient environmental proxy of past and present climate and environmental changes. We applied the infrared spectroscopy analysis to selected benthic foraminifera species: Rosalina globularis grew in laboratory experiments and to Cibicidoides lobatulus, Rosalina bradyi and Textularia bocki collected in a plastic remain found buried into sandy-silty sediment in the Mediterranean seabed. Foraminifera from laboratory experiments were also treated with bis-(2-ethylhexyl) phthalate (DEHP) molecule that incorporates in cytoplasm. The analyses reveal that: 1) microplastic debris can be found in the cytoplasm and inside the agglutinated test of T. bocki; 2) C. lobatulus, R. bradyi and T. bocki, grown on plastic remains, show signals of oxidative stress and protein aggregation; 3) DEHP can be incorporated in the cytoplasm of the commonly calcareous foraminifera R. globularis, thus entering biogeochemical cycles. This study confirmed that foraminifera are good proxy of on-going plastic pollution and the associated molecules can be found in their text.