Balancing biomonitoring and conservation: A non-lethal method to extract microplastics from the sea anemone Bunodosoma cangicum

The sea anemone Bunodosoma cangicum is a potential biomonitor species of microplastic (MP) contamination. However, current MP extraction methods for this species, and most organisms, are lethal to the specimens. This poses the risk of negatively impact on local populations, which are already under considerable anthropogenic pressures. Therefore, this study aimed to evaluate a non-lethal method to extract MPs from the gastrovascular cavity of B. cangicum. The method consists of inducing egestion by pressing the anemone's central column with the aid of a stainless-steel instrument. The proposed technique was applied to 40 anemones sampled in the intertidal zone of a marine beach on the Brazilian Amazon coast. The recovered particles were characterized by Focal Plane Array Fourier Transform Infrared (FPA-FTIR) microscopy. The MP content obtained by the non-lethal method was then compared with that obtained by the lethal techniques applied previously at the same site. An additional 30 anemones from the same area were used in laboratory experiments to evaluate the method's effects on growth, survival, and predatory performance. The non-lethal method retrieved quantities, sizes and shapes of MPs similar to those recovered by dissection techniques. Furthermore, the exposure to the method had no significant effects on the organism's growth, survival and predatory performance. Therefore, the non-lethal method proved to be efficient in extracting MPs from the gastrovascular cavity of B. cangicum without causing deleterious effects. Thus, the proposed method enhances the species' potential as a biomonitor, as it easily allows numerous organisms to be adequately sampled without sacrificing them. Capsule: The non-lethal method proved to be efficient in extracting MPs from the gastrovascular cavity of B. cangicum without causing deleterious effects.