DOI: 10.5061/dryad.q83bk3jqc
title: Heatwave-mediated decreases in phytoplankton quality negatively affect zooplankton productivity

description: Climate change is expected to increase the frequency of extreme
 temperature events. The effect of heatwaves on phytoplankton is of
 particular concern because they are a key source of C, N, P, and essential
 fatty acids to aquatic ecosystems. Laboratory studies have demonstrated
 that phytoplankton grown at warmer temperatures are a lower-quality food
 source, but how heatwaves affect phytoplankton quality at the community
 scale is currently unclear. Here we address this knowledge gap by growing
 natural assemblages of freshwater phytoplankton at ‘ambient’, ‘constant
 warming’, or ‘heatwave’ conditions. We next fed these phytoplankton
 communities to natural assemblages of zooplankton to test the prediction
 that zooplankton that consume heatwave-exposed phytoplankton will exhibit
 reductions in biomass. Our experiment demonstrated that zooplankton that
 consumed ‘heatwave’ phytoplankton attained lower community biomass than
 those fed ‘constant warming’ or ‘ambient’ phytoplankton. Additionally,
 despite receiving similar total heat input, phytoplankton exposed to
 ‘heatwave’ conditions contained lower C, N, P, and fatty acid
 concentrations compare to phytoplankton grown in ‘constant warming’
 conditions. Correlations between zooplankton biomass and all measured
 phytoplankton traits revealed that decreases in zooplankton biomass were
 best explained by low quantities of C, N, and monounsaturated fatty acids
 in ‘heatwave’ phytoplankton. Our study demonstrates that the effects of
 heatwaves on phytoplankton quality are clearly distinct from those caused
 by constant warming temperatures, and that heatwave-mediated decreases in
 resource quality have immediate effects on consumer
 productivity. 
description: The study was a laboratory experiment using wild-caught
 phytoplankton and zooplankton communities. All data were collected and
 analyzed by the authors except that phytoplankton were identified by
 Biologica Environmental Services in Victoria British Columbia, Canada.
 Phytoplankton taxonomy data were analyzed by the authors. 
description: # Heatwave-mediated decreases in phytoplankton quality negatively affect
 zooplankton productivity 
 **Data file: Kim-et-al-func-ecol-heatwave-zoop-algae-data-dryad.csv**
 Associated figures from the manuscript: Figures 2-4, 5a, 6-8, S2a,b, S4-S7
 Column Name descriptions: * bucket  - unit of replication * sampling_event
 – phytoplankton were sampled three times (1, 2, 3). A subsample of
 zooplankton was counted and identified at each sampling event but other
 zooplankton traits were taken on sampling event 3. Phytoplankton
 phosphorus was sampled once (3).    * period - same as sampling_event
 except describes approximately when during the experiment the samples were
 taken * treatment – three algal temperature treatments were used:
 Heatwave, Warm, and Ambient * total.zoop – total number of zooplankton in
 the subsample * zoop.dry.sample.weight.mg – total dry mass of all of the
 zooplankton in the bucket at the end of the experiment *
 phyto.dry.mass.mg.per.mL – dry mass of the phytoplankton sub-sample *
 zoop.shannon.diversity – zooplankton Shannon diversity (H’), calculated
 using the data in the data file
 “Kim-et-al-func-ecol-heatwave-zoop-taxonomy-data-dryad.csv”. Shannon
 diversity was calculated in R. * phyto.C.ug.per.ml – phytoplankton carbon
 concentration; units are µg per mL algae * phyto.N.ug.per.ml –
 phytoplankton nitrogen concentration; units are µg per mL algae *
 phyto.P.ug.per.ml – phytoplankton phosphorus concentration; units are µg
 per mL algae     * zoop.SFA – zooplankton percent saturated fatty acids
 (see Methods for details)  * zoop.MUFA – zooplankton percent
 monounsaturated fatty acids (see Methods for details) * zoop.PUFA –
 zooplankton percent polyunsaturated fatty acids (see Methods for details)
 * zoop.n3 – zooplankton percent omega-3 fatty acids (see Methods for
 details) * zoop.n6 – zooplankton percent omega-6 fatty acids (see Methods
 for details) * zoop.n3.n6 – zooplankton ratio of omega-3 to omega-6 fatty
 acids (see Methods for details) * pufa.ug.per.mg.algae  - phytoplankton
 polyunsaturated fatty acid concentration; units are µg per mg algae *
 mufa.ug.per.mg.algae - phytoplankton monounsaturated fatty acid
 concentration; units are µg per mg algae * sfa.ug.per.mg.algae -
 phytoplankton saturated fatty acid concentration; units are µg per mg
 algae * n6.ug.per.mg.algae - phytoplankton omega-6 fatty acid
 concentration; units are µg per mg algae * n3.ug.per.mg.algae -
 phytoplankton omega-3 fatty acid concentration; units are µg per mg algae
 * n3-n6-ug-ratio - phytoplankton ratio of omega-3 to omega-6 fatty acids
 na - denotes no data either due to the prescribed sampling method or from
 losing the sample during processing   **Data file:
 Kim-et-al-func-ecol-heatwave-algae-taxonomy-data-dryad.csv** Associated
 figures from the manuscript: Figure 5b, S3 Column Name descriptions: *
 bucket – unit of replication * sampling_event – phytoplankton were sampled
 three times (1, 2, 3). * period – same as sampling_event except describes
 approximately when during the experiment the samples were taken *
 treatment – three algal temperature treatments were used: Heatwave, Warm,
 and Ambient * major_group – broad classification of phytoplankton used
 here * taxon – scientific naming of the major_group classification *
 unit_code – whether the phytoplankton grew as a filament, colony, or
 single cell * units_counted cells.per.unit – how many units were counted
 in the sub-sample * colony.size – grouping of colonies, filaments, or
 cells into size classes (see Methods for details)     * unit.size.together
 – joined classification of unit type and size class     *
 morpho.species.name – joined classification of the taxonomic group, unit
 type, and size class       * morpho.species.name.abbreviated –
 abbreviation of the morpho.species.name  * units.per.mL – extrapolation of
 number of units per mL * cells.per.mL – extrapolation of number of cells
 per mL   **Data file:
 Kim-et-al-func-ecol-heatwave-zoop-taxonomy-data-dryad.csv** Associated
 figure from the manuscript: Figure S2 Column Name descriptions: * bucket –
 unit of replication * sampling_event – phytoplankton were sampled three
 times (1, 2, 3). * period – same as sampling_event except describes
 approximately when during the experiment the samples were taken *
 treatment – three algal temperature treatments were used: Heatwave, Warm,
 and Ambient; zooplankton were then fed algae grown in one of these
 treatment types          * zooplankton.taxa – broad classification of
 zooplankton * counts – number of individuals of each type that were
 counted in the subsample