Microplastic accumulation and biomagnification in a coastal marine reserve situated in a sparsely populated area

Toxic chemicals within and adsorbed to microplastics (0.05-5 mm) have the potential to biomagnify in food webs. However, microplastic concentrations in highly productive, coastal habitats are not well understood. Therefore, we quantified the presence of microplastics in a benthic community and surrounding environment of a remote marine reserve on the open coast of California, USA. Concentrations of microplastic particles in seawater were 36.59 plastics/L and in sediments were 0.227 ± 0.135 plastics/g. Densities of microplastics on the surfaces of two morphologically distinct species of macroalgae were 2.34 ± 2.19 plastics/g (Pelvetiopsis limitata) and 8.65 ± 6.44 plastics/g (Endocladia muricata). Densities were highest in the herbivorous snail, Tegula funebralis, at 9.91 ± 6.31 plastics/g, potentially due to bioaccumulation. This study highlights the need for further investigations of the prevalence and potential harm of microplastics in benthic communities at remote locations as well as human population centers.