Changes in spectral quality of underwater light alter phytoplankton community composition

Abstract

Light is a fundamental resource for phytoplankton. To utilize the available light, most phytoplankton species possess pigments in taxon-specific combinations and quantities, which in turn result in a specific use of certain wavelengths. This optimizes the light use efficiency, allows for a complementary use of light, and may be an additional driver for community structure. While the effects of light intensity on phytoplankton biomass production and community composition have been intensively studied, here we focused on the effects of specific light spectrum quality (thus light color) on a natural phytoplankton community. In a controlled mesocosm experiment we reduced the supplied wavelength range to its blue, green, or red part of the light spectrum and compared the responses of each treatment to a full spectrum control over 28 d. Highest community growth rates were observed under blue, lowest under red light. Light absorption by the communities showed adaptation toward the supplied wavelength range. Community composition was significantly affected by light quality treatments, driven by Bacillariophyta and Chlorophyta, whereas pigment composition was not. Furthermore, lower species richness but higher evenness occurred when communities were exposed to red light compared to the full spectrum. We expected the response of phytoplankton communities to changes in the light spectrum to be driven by a combination of species sorting and pigment acclimation; however, the effect of species sorting turned out to be stronger. Our study showed that, even if species might acclimate, changes in the available light spectrum affect primary production and phytoplankton community composition.

Ecological impacts of photosynthetic light harvesting in changing aquatic environments: A systematic literature map

“…changes in the light spectrum can change species growth rates (Luimstra et al, 2019) and alter the phytoplankton community composition (Hintz et al, 2021).…”

“…Overall, rapid changes in light‐climate are favoring fast acclimating or good endowed species over those who cannot acclimate and efficiently harvest the “new” light‐climate. As a consequence, changes in the light spectrum can change species growth rates (Luimstra et al, 2019 ) and alter the phytoplankton community composition (Hintz et al, 2021 ).…”

Sensing the rainbow: genetic and physiological responses to light quality in Ostreococcus, an ecologically important photosynthetic picoeukaryote

“…There is mounting evidence that they do, however. Light quality-dependent changes in photopigments were observed in diatoms, suggesting a form of chromatic adaptation (Brunet et al, 2014;Hintz et al, 2021;Xu et al, 2021). Light quality was found to affect the (which was not certified by peer review) is the author/funder.…”

“…There is mounting evidence that they do, however. Light quality-dependent changes in photopigments were observed in diatoms, suggesting a form of chromatic adaptation (Brunet et al ., 2014; Hintz et al ., 2021; Xu et al ., 2021). Light quality was found to affect the protein content of the red alga Porphyra leucosticte [28], the diatom Cyclotella nana and the green alga Dunaliella tertiolecta [29], and the accumulation of lipids in the chlorophyte Chlorella sp.…”

Environmental niches and seasonal succession of phytoplankton assemblages in a subarctic coastal bay: Applications to remote sensing estimates

“…This approach may include diverse strategies of nutrient utilization (Litchman et al, 2007) that are modulated by temperature and light constraints (Edwards et al, 2016). Specifically, because various phytoplankton assemblages have different light requirements, the spectral quality of the light environment (or optical niches) will have consequences on shaping their composition (Stomp et al, 2007;Hintz et al, 2021).…”