Marine microplastics spell big problems for future generations

There are certain human environmental perturbations so major that they are capable of destabilizing the earth’s normal function at a global scale (1). These so-called planetary boundary threats include climate change, ozone depletion, and ocean acidification. Emerging as a novel addition to this list is the vast quantity of discarded plastic waste that is accumulating in the oceans on an unprecedented scale, where it breaks down to form microscopic and nanoscopic fragments, or microplastics. Microplastics (particles with a diameter <1 mm, with no lower limit) derive from progressive fragmentation of larger plastic items, or may be manufactured to be of a small size, for use in personal care products, medicines, and industry (2). They reach the seas through beach littering, road runoff, sewage, and illegal dumping activities. Microplastics are ubiquitous in marine waters, from deep ocean sediments to polar icecaps, a result of the estimated 8 million tons of plastic that enters the oceans each year (3). Despite calls for plastic to be reclassified as hazardous (4), legislation to restrict marine debris accumulation is hindered by a lack of evidence that it causes ecological harm. In PNAS, Sussarellu et al. (5) provide an important starting point for assembling this evidence: Using an integrative approach, they show that ingestion of microplastics during gametogenesis has impacts on feeding and reproduction in oysters, with negative impacts on adult fecundity and offspring quality, both of which are key components of an organism’s individual fitness. The results of Sussarellu et al. (5) are important because they support an emerging paradigm that microplastics can reduce reproductive output and fitness in marine species by altering their food consumption and energy allocation. Marine plastic debris is a global threat because of its abundance, persistence, and mobility across scales, with subsequent widespread distribution and potential geophysical and biological impacts … [↵][1]1To whom correspondence should be addressed. Email: t.s.galloway{at}exeter.ac.uk. [1]: #xref-corresp-1-1