Presence of microplastics and antimicrobial-resistant bacteria in sea cucumbers under different anthropogenic influences in Gran Canaria (Canary Islands, Spain)

Microplastics and antimicrobial-resistant bacteria are a matter of concern, especially in aquatic environments. In this study, we compared the presence of microplastics and antibiotic-resistant bacteria in the intestine of the sea cucumber Holothuria sanctori at sites under different levels of pollution in Gran Canaria Island (Canary Islands, Spain, eastern Atlantic). We sampled animals at two offshore sites (controls) under low organic pollution and at a site under high organic pollution, i.e. directly affected by sewage water. From a total of 79 collected animals, 133 Gram-negative bacteria were isolated; 20 were Enterobacteriaceae, and the rest Non-Fermenting Bacilli (NFB). We detected Enterobacteriaceae resistant to critically important antimicrobials, such as ceftazidime or fluoroquinolones, particularly at the polluted site. In addition, we observed a significantly higher number (□2 orders of magnitude) of microplastics in the gut of sea cucumbers sampled at the polluted site, relative to the two controls. Our preliminary results point towards integrating microbiological and ecological approaches to analyse the mutual influence of both pollutants in aquatic ecosystems.