Physical Impacts of Microplastics on Marine Species

Abstract

While the physical impact of meso- and macrodebris on biota is broadly documented, microplastics (MPs) are also known to induce various detrimental effects on organisms but their physical impacts are still under debate. Scientific reports indicate that our knowledge of the physical impact of MPs on biota is very limited. The most frequent effects observed have been obtained from laboratory experiments and shown perturbations of behavior and growth, revealing that the most adverse impacts are not mechanical. Data from field observations generally concern the occurrence of debris but not specifically plastics, while size categories of debris are often omitted or do not follow a standard categorization. While laboratory experiments enable the evaluation of various negative acute/chronic effects through dose/response relationships, they may not adequately reflect natural conditions. However, these tools may provide original and comparable data on the various impacts in relation to the sizes, types, and shapes of MPs. Given current knowledge, technical gaps, and the constraints involved in monitoring the mechanical effects of MPs, no standard methods for assessing the physical impact of MPs on biota have been proposed until now for regular and long-term monitoring. This remains a challenge before policy-makers can fully appreciate the factors involved.