Anthropogenic microparticles presence in Holothuria sanctori from the Macaronesian region

Holothurians play an important ecological role as agents of bioturbation (bottom mixing), sediment aeration and nutrient recycling. These species ingest and excrete larges amount of sediment annually (9-82 kg per individual) [1]. That fact facilitates the mobilization and mixing of sediments. Microplastics potentially buried within these sediments can be incidentally ingested and/or resuspended back into the water column, increasing their bioavailability to other organisms [2]. This study investigates the occurrence of anthropogenic microparticles in Holothuria sanctori collected in intertidal pools from the islands of Faial (Azores, Portugal) and Tenerife (Canary Islands, Spain). Sea cucumbers were collected by snorkelling in randomly intertidal pools more than one meter deep. Once at the laboratory, from each sea cucumber, gastrointestinal tracts (GIT) and Cuvier's tubules were removed and digested. Only for GIT, the sample underwent density separation with saturated NaCl due to the large amount of sediment inside. After filtration of the digests, each filter was observed under a trinocular light stereomicroscope. Analysis of 27 individuals (Azores: 8 and Canary Islands: 18) resulted in 127 anthropogenic particles being detected, with an average abundance of 5.2 ± 3.6 items per sea cucumber and 3.7 ± 2.1 items per sea cucumber, respectively. Microfibers were the most common shape, mainly blue and transparent. MicroFourier transform infrared spectroscopy (µFTIR) analysis showed that the majority had a cellulosic composition (natural and semisynthetic) although 100 Also see: https://micro2024.sciencesconf.org/559638/document