Perceived and demonstrated impacts of marine debris

Marine debris is a global conservation issue, raising concerns regarding ecological impacts. We examined the evidence regarding impacts of marine debris via a systematic review of the literature across 13 levels of biological organization (subatomic particle, atom, small molecule, macromolecule, molecular assemblage, organelle, cell, tissue, organ, organ system, organism, population and assemblage) to determine the perceived and demonstrated impacts. There were 347 perceived impacts across all levels of biological organization. Many were hypothesis-driven studies, wherein > 80% were demonstrated impacts largely due to plastic debris. Overall, impacts were largely demonstrated at suborganismal levels of biological organization due to microdebris (<1 mm), while impacts at higher levels of organization (i.e. organism and above) were largely due to macrodebris (> 1 mm). Decision-makers globally are requesting evidence of ecological harm to build effective policies. While we agree that further information is needed to fill research gaps and provide assessments of ecological risk, there are several lines of evidence that marine debris causes impacts across multiple levels of organization, including ecological. Moreover, current work shows that some debris is persistent, bioaccumulative and toxic. Thus, we think that there is enough evidence to take a precautionary approach by beginning to mitigate now before there is irreversible harm.