In the last decade, marine pollution by plastics and the effects they have on organisms has received much attention. In this aspect, the effects of plastics and their constituent substances have been less studied in the cnidarian group compared to other animal groups such as fish or mollusks. The common jellyfish (Aurelia aurita) is a cosmopolitan species found in waters all over the world while the inverted jellyfish (Cassiopea xamachana) is a species widely distributed in tropical and shallow subtropical marine habitats. Despite being considered invasive and exotic in many coastal habitats such as the Hawaiian Islands and the Mediterranean Sea, it is a key organism in many reef habitats such as the Caribbean Sea or the Gulf of Mexico. Unlike other scyphozoans, Cassiopea spp. are epibenthic, and incorporate the photosynthetic zooxanthella Symbiodinium within their mesoglea during the polyp stage. The aim of the study was to characterize the esterase enzymes of these two species using different substrates and to quantify the degree of inhibition of these enzymes in the presence of model inhibitors and substances used in the manufacture of plastics. The results obtained are discussed on the basis of the characteristics of each species and the presence or absence of endosymbionts in their mesoglea

9º Congresso Ibero-Americano de Contaminação e Toxicologia Ambiental (CICTA) - 9th Ibero-American Congress on Contamination and Environmental Toxicology, 29 November - 2 December 2021, Blumenau, SC, Brazil