IMIS

The presence of a microbial biofilm on marine plastic was described in the pages of Science Magazine over 45 years ago in one of the very first publications reporting plastic in the ocean (Carpenter and Smith, Science 175:1240–1241, 1972). After these early reports, the microbial communities associated with plastic lost attention until about 7 years ago when modern DNA sequencing began revealing the details of this “invisible” world in finer detail. The Plastisphere, or thin layer of microbial life that surrounds plastic in aquatic environments, occurs on every one of the trillions of small pieces of plastic in the ocean. This miniature ecosystem includes primary producers using sunlight and inorganic chemicals to grow, grazers feeding on these “fields” of primary producers, predators killing and eating other cells, parasites, symbionts living together with their hosts, and degraders recycling biomass and chemicals for reuse in the system. Despite the quantities of plastic documented in the ocean, the actual impact of plastic on marine ecosystems is largely unknown. The Plastisphere could play a role in the fate and impact of plastic in our environment, including increasing the productivity of open ocean environments (Bryant et al., mSystems 1:1, 2016 ), generating greenhouse gases (Royer et al., Plos One 13:e0200574, 2018), influencing ingestion and settling by animals (Hadfield, Ann Rev Mar Sci 3:453, 2011; Savoca et al., Sci Adv 2:e1600395, 2016), determining how long plastic takes to break down and sink (Ye and Andrady, Mar Pollut Bull 22:608–613, 1991), and transporting invasive species including potentially harmful microbes (Zettler et al. 2013 . Environ Sci Technol 47:7137–7146, 2013).