title: Aquatic polymers can drive pathogen transmission in coastal ecosystems.
abstract: Gelatinous polymers including extracellular polymeric substances (EPSs) are fundamental to biophysical processes in aquatic habitats, including mediating aggregation processes and functioning as the matrix of biofilms. Yet insight into the impact of these sticky molecules on the environmental transmission of pathogens in the ocean is limited. We used the zoonotic parasite Toxoplasma gondii as a model to evaluate polymer-mediated mechanisms that promote transmission of terrestrially derived pathogens to marine fauna and humans. We show that transparent exopolymer particles, a particulate form of EPS, enhance T. gondii association with marine aggregates, material consumed by organisms otherwise unable to access micrometre-sized particles. Adhesion to EPS biofilms on macroalgae also captures T. gondii from the water, enabling uptake of pathogens by invertebrates that feed on kelp surfaces. We demonstrate the acquisition, concentration and retention of T. gondii by kelp-grazing snails, which can transmit T. gondii to threatened California sea otters. Results highlight novel mechanisms whereby aquatic polymers facilitate incorporation of pathogens into food webs via association with particle aggregates and biofilms. Identifying the critical role of invisible polymers in transmission of pathogens in the ocean represents a fundamental advance in understanding and mitigating the health impacts of coastal habitat pollution with contaminated runoff.
authors.affiliation: One Health Institute, School of Veterinary Medicine, University of California, Davis, CA 95616, USA Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA kshapiro@ucdavis.edu.
authors.forename: Karen
authors.initials: K
authors.lastname: Shapiro
authors.affiliation: Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Colin
authors.initials: C
authors.lastname: Krusor
authors.affiliation: Department of Ocean Sciences, University of California, Santa Cruz, CA 95064, USA.
authors.forename: Fernanda F M
authors.initials: FF
authors.lastname: Mazzillo
authors.affiliation: One Health Institute, School of Veterinary Medicine, University of California, Davis, CA 95616, USA Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Conrad
authors.affiliation: Bodega Marine Laboratory and Department of Environmental Science and Policy, University of California, Davis, CA 95616, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Largier
authors.affiliation: One Health Institute, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Jonna A K
authors.initials: JA
authors.lastname: Mazet
authors.affiliation: Department of Ocean Sciences, University of California, Santa Cruz, CA 95064, USA.
authors.forename: Mary W
authors.initials: MW
authors.lastname: Silver
mesh_terms: D000818:Animals; D002140:California; D020387:Food Chain; D044423:Kelp / Q000502:physiology; D010041:Otters; D052638:Particulate Matter / Q000032:analysis; D011108:Polymers / Q000032:analysis*; D012908:Snails / Q000469:parasitology; D014122:Toxoplasma / Q000502:physiology*; D014124:Toxoplasmosis, Animal / Q000469:parasitology / Q000635:transmission*
chemical_list: D052638:Particulate Matter; D011108:Polymers
keywords: Toxoplasma gondii; extracellular polymeric substances; marine transmission; sea otter; transparent exopolymer particles; zoonotic pathogen