DOI: 10.5061/dryad.2rh61qk
title: Data from: Variation in species light acquisition traits under fluctuating light regimes: implications for non‐equilibrium coexistence

description: Resource distribution heterogeneity offers niche opportunities for species
 with different functional traits to develop and potentially coexist.
 Available light (photosynthetically active radiation or PAR) for suspended
 algae (phytoplankton) may fluctuate greatly over time and space.
 Species-specific light acquisition traits capture important aspects of the
 ecophysiology of phytoplankton and characterize species growth at either
 limiting or saturating daily PAR supply. Efforts have been made to explain
 phytoplankton coexistence using species-specific light acquisition traits
 under constant light conditions, but not under fluctuating light regimes
 that should facilitate non-equilibrium coexistence. In the well-mixed,
 hypertrophic Lake TaiHu (China), we incubated the phytoplankton community
 in bottles placed either at fixed depths or moved vertically through the
 water column to mimic vertical mixing. Incubations at constant depths
 received only the diurnal changes in light, while the moving bottles
 received rapidly fluctuating light. Species-specific light acquisition
 traits of dominant cyanobacteria (Anabaena flos-aquae, Microcystis spp.)
 and diatom (Aulacoseira granulata, Cyclotella pseudostelligera) species
 were characterized from their growth-light relationships that could
 explain relative biomasses along the daily PAR gradient under both
 constant and fluctuating light. Our study demonstrates the importance of
 interspecific differences in affinities to limiting and saturating light
 for the coexistence of phytoplankton species in spatially heterogeneous
 light conditions. Furthermore, we observed strong intraspecific
 differences in light acquisition traits between incubation under constant
 and fluctuating light – leading to the reversal of light utilization
 strategies of species. This increased the niche space for acclimated
 species, precluding competitive exclusion. These observations could
 enhance our understanding of the mechanisms behind the Paradox of the
 Plankton.
description: 1_Species-specific
 growth ratesSpecies-specific light
 dependency of growth of the two dominant cyanobacteria (Anabaena,
 Microcystis) under constant and fluctuating light; and the two dominant
 diatoms (Cyclotella, Aulacoseira) under constant and fluctuating light. -
 "Subject": "F" stands for Fixed incubation bottles
 (constant light; "mode"=fix) at 0, 20, 40 and 80 cms depth.
 "L" stands for Lifted incubation bottles (fluctuating light;
 mode="lift") from the surface to 50, 100 and 180 cms deep. -
 "PAR" is the Photosynthetically Active Radiation (E/m2d). -
 "growth" is expressed per day.2_Species relative
 biovolumesLight-dependency of the
 relative biovolumes of Anabaena and Microcystis to the cyanobacteria
 biovolume and of Cyclotella and Aulacoseira to the biovolume of diatoms
 under constant and fluctuating light. Only relative biovolumes after 2
 days of experiment are depicted. - "Subject": "F"
 stands for Fixed incubation bottles (constant light; "mode"=fix)
 at 0, 20, 40 and 80 cms depth. "L" stands for Lifted incubation
 bottles (fluctuating light; mode="lift") from the surface to 50,
 100 and 180 cms deep. - "PAR" is the Photosynthetically Active
 Radiation (E/m2d).3_Species realized light
 nichesRealized niches of the
 cyanobacteria and diatoms after 2 days and at the end of the experiments
 over gradients of daily PAR exposure (E/m2d) and mixing depth (m). -
 "Subject": "F" stands for Fixed incubation bottles
 (constant light; "mode"=fix) at 0, 20, 40 and 80 cms depth.
 "L" stands for Lifted incubation bottles (fluctuating light;
 mode="lift") from the surface to 50, 100 and 180 cms deep. -
 "PAR" is the Photosynthetically Active Radiation
 (E/m2d).4_Algae groups relative
 biovolumesLight-dependency of the
 relative biovolumes of diatoms, cyanobacteria and chlorophyceae to the
 total biovolume, under fluctuating and constant light. -
 "Subject": "F" stands for Fixed incubation bottles
 (constant light; "mode"=fix) at 0, 20, 40 and 80 cms depth.
 "L" stands for Lifted incubation bottles (fluctuating light;
 mode="lift") from the surface to 50, 100 and 180 cms deep. -
 "PAR" is the Photosynthetically Active Radiation
 (E/m2d).