Chapter 32 - Sea cucumber response to microplastic pollution

Abstract

Microplastics (MPs) are tiny plastic particles with sizes ranging from 0.001 to 5mm, which have become ubiquitous in oceans worldwide, from the sea surface to deep sediment and from the equator to the poles. MPs become more available to aquatic organisms as their size decreases. Additionally, organic and inorganic contaminants can be adsorbed onto MPs from the surrounding environment. Sea cucumbers are endo- or epibenthic echinoderms that can be exposed to MPs present in the sediment and/or water column. MP ingestion by sea cucumbers through ingestion of sediment is documented in the wild, farms, deep sea, and in vitro. It has been recently discovered that MPs can be transferred into the coelomic fluid of sea cucumbers along with water through the respiratory tree and that MPs can remain in the body walls even after processing as beche-de-mer sold for human consumption. Various studies have reported that the intake of MPs by sea cucumbers through deposit feeding has little or no effect on their growth performance. However, enzymatic disruption was observed in the coelomic fluid. In addition, MP transfer from the water into the coelomic fluid during respiration could disrupt the global transcriptomic profiling of the respiratory tree. This chapter discusses how sea cucumbers interact with MPs in their environment, MP ingestion rate in various holothuroid species, MP uptake pathways, and the toxicity mechanism of MPs in sea cucumbers. We also provide recommendations for future investigations concerning MP ingestion by sea cucumbers.