Mariana Vellosa Capparelli, Michael Martínez-Colón, Oscar Lucas-Solis, Gladys Valencia-Castañeda, Omar Celis-Hernández, Enrique Ávila

Fiddler crabs are known as “eco-engineers” who maintain habitat health through sediment bioturbation, being able to interact with microplastics (MP) due to their daily contact with the sediment. Here, we evaluated MP contamination in mangrove substrates in Isla del Carmen, southern Gulf of Mexico, comparing MP content between burrows and pellets resulting from bioturbation and MP bioaccumulation in the soft tissues of the Minuca rapax. In general, MP was more abundant and diverse in burrow sediment than in pellets, however, in less urbanized sites (< amount of MP), pellets seem to concentrate more MP than burrows. The MP characteristics in the pellet and in the tissues reflected those of the burrows. Bioturbation concentrated MP in pellets and tissues, depending on how urbanized the area is, showing a strong top-down effect of MP in subtropical tidal flats. M. rapax is an important structuring agent of sedimentary MP in subtropical tidal flats.