Multiple dimensions of light shape phytoplankton trait diversity

Light is an essential and often limiting resource for photoautotrophs, especially phytoplankton, composed of different quantities (irradiance) and qualities (wavelengths). Its availability varies on timescales from seconds to decennia, intensified by human-induced perturbations such as increased terrestrial run-off or eutrophication. Phytoplankton possess a comprehensive inventory and diversity of pigments to exploit distinct niches along the vertical light gradient underwater. These light-associated traits add an extra layer of complexity to the already high morphological and biochemical diversity of phytoplankton. The amplitude and frequency of light fluctuations vary predictably by season and day, augmented by stochastic variation on shorter time scales. In combination with the wavelength-specific attenuation underwater, light becomes a complex, multidimensional and highly variable resource. Light fluctuations trigger functional responses in individual organisms and numerical responses in populations and communities, which propagate through the planktonic food web via the link between functional diversity and productivity. This dataset explored phytoplankton absorption properties and applied wavelet analysis on a timeseries of underwater irradiance measurements to explore dominant rhythmic, deterministic fluctuations in underwater light and the temporal scales at which they predominate.