Data from: Phytoplankton growth and stoichiometric responses to warming, nutrient addition and grazing depend on lake productivity and cell size

Global change involves shifts in multiple environmental factors that act
in concert to shape ecological systems in ways that depend on local biotic
and abiotic conditions. Little is known about the effects of combined
global change stressors on phytoplankton communities, and particularly how
these are mediated by distinct community properties such as productivity,
grazing pressure and size distribution. Here, we tested for the effects of
warming and eutrophication on phytoplankton net growth rate and C:N:P
stoichiometry in two phytoplankton cell size fractions (<30 μm and
>30 μm) in the presence and absence of grazing in microcosm
experiments. Because effects may also depend on lake productivity, we used
phytoplankton communities from three Dutch lakes spanning a trophic
gradient. We measured the response of each community to multifactorial
combinations of temperature, nutrient, and grazing treatments and found
that nutrients elevated net growth rates and reduced carbon:nutrient
ratios of all three phytoplankton communities. Warming effects on growth
and stoichiometry depended on nutrient supply and lake productivity, with
enhanced growth in the most productive community dominated by
cyanobacteria, and strongest stoichiometric responses in the most
oligotrophic community at ambient nutrient levels. Grazing effects were
also most evident in the most oligotrophic community, with reduced net
growth rates and phytoplankton C:P stoichiometry that suggests
consumer‐driven nutrient recycling. Our experiments indicate that
stoichiometric responses to warming and interactions with nutrient
addition and grazing are not universal but depend on lake productivity and
cell size distribution.