Plastic marine pollution as a physical support to spread Ostreopsis blooms

Abstract

Over the past 50 years, polymer manufacturing has been increasing at a very fast pace, from 15 million tons in 1964 to 311 million tons in 2014 and is expected to double again over the next 20 years, as development of new polymer composites increases and as plastics come to serve increasingly many applications. The amount of plastic debris that is being disposed of in the ocean is now estimated to a minimum of 4.8 to 12.7 million metric tons entering the ocean per year. The vast effects of these plastic pieces on the marine environment are deleterious; they include entanglement and ingestion by wildlife, the modification of habitats and the transport of alien species, ultimately toxic and harmful ones, given that marine debris have no boundaries and can travel across oceans during several decades.

The toxic microalga Ostreopsis is largely distributed from tropical to temperate marine areas worldwide, and it has been blooming recurrently forming mats that recovers the benthos of certain Mediterranean beaches over the last 20 years. Some Ostreopsis outbreaks, associated with irritative symptoms in humans and massive macrofauna mortalities, have stimulated studies to assess the role of biotic and abiotic factors on its dynamics and biogeographical distribution. Previous studies suggested the potential effect of plastic on the dispersion of this and other harmful species. Ostreopsis produces sticky mucus to attach to different surfaces such as macroalgae, rock, sand and also plastic, through unknown chemical interactions. Thus, it is likely that some plastic substrates will act as better physical support than others and help to spread further. As of today, no study has looked at the susceptibility of the types of plastic marine debris as a physical support by the harmful alga Ostreopsis. Here, we propose to look at the types of plastic in which Ostreopsis is found in the semi-enclosed Mediterranean Sea, one of the most affected oceanic regions by plastic pollution