title: Photosynthetic efficiency predicts toxic effects of metal nanomaterials in phytoplankton.
abstract: High Throughput Screening (HTS) using in vitro assessments at the subcellular level has great promise for screening new chemicals and emerging contaminants to identify high-risk candidates, but their linkage to ecological impacts has seldom been evaluated. We tested whether a battery of subcellular HTS tests could be used to accurately predict population-level effects of engineered metal nanoparticles (ENPs) on marine phytoplankton, important primary producers that support oceanic food webs. To overcome well-known difficulties of estimating ecologically meaningful toxicity parameters, we used novel Dynamic Energy Budget and Toxicodynamic (DEBtox) modeling techniques to evaluate impacts of ENPs on population growth rates. Our results show that population growth was negatively impacted by all four ENPs tested, but the HTS tests assessing many cell/physiological functions lacked predictive power at the population level. However, declining photosynthetic efficiency, a traditional physiological endpoint for photoautotrophs, was a good predictor of population level effects in phytoplankton. DEBtox techniques provided robust estimates of EC10for population growth rates in exponentially growing batch cultures of phytoplankton, and should be widely useful for ecotoxicological testing. Adoption of HTS approaches for ecotoxicological assessment should carefully evaluate the predictive power of specific assays to minimize the risk that effects at higher levels of biological organization may go undetected.
authors.affiliation: Marine Science Institute, University of California, Santa Barbara, CA, USA. Electronic address: miller@msi.ucsb.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Miller
authors.affiliation: Marine Science Institute, University of California, Santa Barbara, CA, USA.
authors.forename: Erik B
authors.initials: EB
authors.lastname: Muller
authors.affiliation: University of California Davis Bodega Marine Laboratory, University of California Davis, Bodega Bay, CA, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Cole
authors.affiliation: Bren School of Environmental Science and Management, University of California Santa Barbara, CA, USA.
authors.forename: Tyronne
authors.initials: T
authors.lastname: Martin
authors.affiliation: Department of Ecology Evolution and Marine Biology, University of California Santa Barbara, CA, USA.
authors.forename: Roger
authors.initials: R
authors.lastname: Nisbet
authors.affiliation: Jacksonville University, Jacksonville, FL, USA.
authors.forename: Gretchen K
authors.initials: GK
authors.lastname: Bielmyer-Fraser
authors.affiliation: Valdosta State University, Valdosta, GA, USA.
authors.forename: Tayler A
authors.initials: TA
authors.lastname: Jarvis
authors.affiliation: Marine Science Institute, University of California, Santa Barbara, CA, USA.
authors.forename: Arturo A
authors.initials: AA
authors.lastname: Keller
authors.affiliation: University of California Davis Bodega Marine Laboratory, University of California Davis, Bodega Bay, CA, USA; Department of Environmental Toxicology and Nutrition, University of California Davis, Davis, CA, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Cherr
authors.affiliation: Bren School of Environmental Science and Management, University of California Santa Barbara, CA, USA.
authors.forename: Hunter S
authors.initials: HS
authors.lastname: Lenihan
mesh_terms: D057166:High-Throughput Screening Assays; D053768:Metal Nanoparticles / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects*; D010839:Phytoplankton / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical
keywords: Dynamic energy budget modeling; Ecotoxicity; High throughput screening; Marine ecology; Metallic nanoparticles; Plankton