|Title:||Body size, light intensity, and nutrient supply determine plankton stoichiometry in mixotrophic plankton food webs||Authors:||Ho, P.-C.
|Issue Date:||2020||Journal Volume:||195||Journal Issue:||4||Start page/Pages:||e100-E111||Source:||American Naturalist||Abstract:||
Trophic strategy determines stoichiometry of plankton. In general, heterotrophic zooplankton have lower and more stable C:N and C:P ratios than photoautotrophic phytoplankton, whereas mixotrophic protists, which consume prey and photosynthesize, have stoichiometry between zooplankton and phytoplankton. As trophic strategies change with cell size, body size may be a key trait influencing eukaryotic plankton stoichiometry. However, the relationship between body size and stoichiometry remains unclear. Here we measured plankton size-fractionated C:N ratios under different intensities of light and nutrient supply in subtropical freshwater and marine systems. We found a unimodal body size–C:N ratio pattern, with a maximum C:N ratio at ~50 mm diameter in marine and freshwater systems. Moreover, the variation in C:N ratios is explained mainly by body size, followed by light intensity and nutrient concentration. To investigate the mechanisms behind this unimodal pattern, we constructed a size-based plankton food web model in which the trophic strategy and C:N ratio are an emerging result. Our model simulations reproduce the unimodal pattern with a C:N ratio of photoautotrophs ≤50 mm increasing with body size due to increase of photosynthetic carbon, whereas C:N ratios of organisms >150 μm decrease with size due to decreasing photoautotrophic but increasing heterotrophic uptake. Based on our field observations and simulation, we extend the classic “light-nutrient” theory that determines plankton C:N ratio to include body size and trophic strategy dependency. We conclude that body size and size-dependent uptake of resources (light, nutrients, and prey) determine plankton stoichiometry at various light and nutrient supplies. © 2020 by The University of Chicago.
|DOI:||10.1086/707394||SDG/Keyword:||body size; diameter; food web; freshwater environment; light intensity; mixotrophy; nutrient dynamics; phytoplankton; stoichiometry; zooplankton; Eukaryota; Protista; animal; aquatic species; autotrophy; body size; carbon cycle; food chain; growth, development and aging; heterotrophy; metabolism; nitrogen cycle; photosynthesis; physiology; phytoplankton; plankton; radiation response; sunlight; zooplankton; Animals; Aquatic Organisms; Autotrophic Processes; Body Size; Carbon Cycle; Food Chain; Heterotrophic Processes; Nitrogen Cycle; Nutrients; Photosynthesis; Phytoplankton; Plankton; Sunlight; Zooplankton
|Appears in Collections:||海洋研究所|
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