title: Temperature-nutrient interactions exacerbate sensitivity to warming in phytoplankton.
abstract: Temperature and nutrients are fundamental, highly nonlinear drivers of biological processes, but we know little about how they interact to influence growth. This has hampered attempts to model population growth and competition in dynamic environments, which is critical in forecasting species distributions, as well as the diversity and productivity of communities. To address this, we propose a model of population growth that includes a new formulation of the temperature-nutrient interaction and test a novel prediction: that a species' optimum temperature for growth, Topt, is a saturating function of nutrient concentration. We find strong support for this prediction in experiments with a marine diatom, Thalassiosira pseudonana: Toptdecreases by 3-6 °C at low nitrogen and phosphorus concentrations. This interaction implies that species are more vulnerable to hot, low-nutrient conditions than previous models accounted for. Consequently the interaction dramatically alters species' range limits in the ocean, projected based on current temperature and nitrate levels as well as those forecast for the future. Ranges are smaller not only than projections based on the individual variables, but also than those using a simpler model of temperature-nutrient interactions. Nutrient deprivation is therefore likely to exacerbate environmental warming's effects on communities.
authors.affiliation: W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, 49060, USA.|Department of Integrative Biology, Michigan State University, East Lansing, MI, 48824, USA.|Program in Ecology, Evolutionary Biology & Behavior, Michigan State University, East Lansing, MI, 48824, USA.
authors.forename: Mridul K
authors.identifier: 0000-0002-5089-5610
authors.initials: MK
authors.lastname: Thomas
authors.affiliation: W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, 49060, USA.|Department of Animal Ecology and Biology, University of Vigo, Vigo, 36310, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Aranguren-Gassis
authors.affiliation: Department of Ecology and Evolutionary Biology, Yale University, PO Box 208106, New Haven, CT, 06520, USA.|Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, NJ, USA.
authors.forename: Colin T
authors.initials: CT
authors.lastname: Kremer
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA.
authors.forename: Marilyn R
authors.initials: MR
authors.lastname: Gould
authors.affiliation: Department of Biological Sciences, University of Illinois at Chicago, 845 West Taylor Street (MC 066), Chicago, IL, 60607, USA.
authors.forename: Krista
authors.initials: K
authors.lastname: Anderson
authors.affiliation: W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, 49060, USA.|Program in Ecology, Evolutionary Biology & Behavior, Michigan State University, East Lansing, MI, 48824, USA.|Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Klausmeier
authors.affiliation: W. K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, 49060, USA.|Department of Integrative Biology, Michigan State University, East Lansing, MI, 48824, USA.|Program in Ecology, Evolutionary Biology & Behavior, Michigan State University, East Lansing, MI, 48824, USA.
authors.forename: Elena
authors.initials: E
authors.lastname: Litchman
mesh_terms: D017377:Diatoms / Q000254:growth & development*; D008962:Models, Theoretical; D009584:Nitrogen; D010758:Phosphorus; D010839:Phytoplankton; D011157:Population Dynamics; D013696:Temperature
chemical_list: D010758:Phosphorus; D009584:Nitrogen
keywords: R*; mechanistic species distribution model; nutrients; phytoplankton; population growth rate; resources; temperature; zero net growth isocline (ZNGI)