DOI: 10.5061/dryad.573n5tbjb
title: Data from: What doesn’t kill you makes you stronger: Fear of predation widens the thermal niche of the harmful algal bloom species Phaeocystis globosa

description: Study Description: This study investigates how predation risk modulates
 the thermal tolerance of Phaeocystis globosa, a harmful algae
 genus. We demonstrate that grazing cues (from ciliates and copepods)
 enhance P. globosa colony formation and expand its thermal niche,
 enabling survival at higher temperatures (up to 30°C) and explaining its
 bloom persistence in tropical summers. Thermal performance curve (TPC)
 modeling revealed that predation cues increase the critical thermal
 maximum from &lt;30°C to 35°C, highlighting the role of "fear
 effects" in mitigating climate-driven vulnerability.
description: <em><strong>Study organisms:</strong> P.
 globosa</em> was cultured in f/2 medium in the exponential stage.
 Ciliates and copepods were fed the green alga <em>Dunaliella
 tertiolecta</em> every 3–4 days
 <strong><em>Grazing risk
 experiment:</em></strong><em><strong>
 </strong>P. globosa</em> grew alone and exposed to grazing
 risks from the ciliate <em>Euplotes vannus, </em>and the
 copepod <em>Apocyclops royi</em><em> </em>were
 maintained at temperatures of 13, 15, 17, 21, 25, 28, and 30°C.
 <strong><em>Solitary cell
 concentrations:</em></strong> Solitary cell concentrations
 were measured using Sedawick-Rafter chambers. Cells were counted in
 randomly selected fields of view until 300 cells were counted per
 replicate. <strong><em>Colony
 abundances</em></strong>: Colony abundances, colony diameters,
 and the number of cells per colony were measured in 24-well plates using
 an Olympus inverted microscope. At least 30 colonies from each replicate
 were randomly chosen to measure colony diameters and cell numbers per
 colony. <em><strong>Growth
 rates</strong>:</em> 2 ml<em> P.
 glo</em><em>bosa</em> samples from beakers were
 collected daily to measure <em>in vivo</em> chlorophyll
 fluorescence with a Turner Designs Trilogy fluorometer.
 <em><strong>Nutrient concentrations</strong>:
 </em>Nitrate, nitrite, phosphate, and ammonium were determined
 following standard colorimetric methods using a Hitachi 722-S instrument
 (Grasshoff et al. 1999).
 <strong><em>pH:</em></strong> pH values
 were measured using a Sentron pH meter (ArgusX, Cole-Parmer,
 USA).
description: # Data from: What doesn’t kill you makes you stronger: Fear of predation
 widens the thermal niche of the harmful algal bloom species Phaeocystis
 globosa
 [https://doi.org/10.5061/dryad.573n5tbjb](https://doi.org/10.5061/dryad.573n5tbjb) ## Description of the data and file structure To evaluate whether non-consumptive effects alter thermal responses, *P. globosa* grown alone and those exposed to grazing cues associated with ciliates and copepods were maintained at temperatures ranging from 13°C to 30°C.  The incubations lasted for seven days. Solitary cell abundances, colony numbers, colony diameters, and cells per colony of *P. globosa* grown alone and exposed to grazing cues at different temperatures were determined. We also quantified TPCss using the equation by Thomas et al. 2012. ### Files and variables #### File: Data\_\_Fear\_Phaecystis\_Warming\_Ye.xlsx **Description:** This dataset contains six sets of data on predation risk on thermal traits of *Phaeocystis globosa*. We provided data on solitary cell abundance, colony numbers, growth rate, colony size, and cell per colony of *P. globosa* grown alone and exposed to grazing risk associated with ciliates and copepods at 13, 15, 17, 21, 25, 28, and 30℃.  * Solitary cell abundance (cells per ml): This dataset contains 168 data points. 84 data points exhibited solitary cell abundance of *P. globosa* grown alone and exposed to grazing risk associated with ciliates and copepods (position: outside cage) at different temperatures. 84 data points exhibited solitary cell abundance of *P. globosa* grown alone and exposed to ciliates and copepods (position: inside cage) at different temperatures. * Colony numbers (colonies per ml): We provided 168 data points to determine the interactive effects of temperature and grazing risk on colony formation in *P. globosa*. 84 data points exhibited colony numbers of *P. globosa* grown alone and exposed to grazing risk associated with ciliates and copepods (position: outside cage) at different temperatures. Another half of the dataset exhibited solitary cell abundance of *P. globosa* grown alone and exposed to ciliates and copepods (position: inside cage) at different temperatures. * Rel\_ size\_ cell:  In the present experiment, we measured 1393 data points of colony sizes and cells per colony . We compared the slopes of log (colony diameters) and log (cells per colony) between grazing treatment (P. globosa exposed to grazing risk) and controls (P. globosa grown alone) to assess whether grazing risk combined with temperature influenced colony architecture.  * Growth rate: This dataset contains 95 data points showing the maximum growth rates of *P. globosa *when grown alone and exposed to grazing cues released from ciliates and copepods at different temperatures.  * pH_25℃: We measured pH values in culture at 25℃ to assess whether pH influence growth and colony formation. * Nutrient_25℃: To assess whether nutrient concentrate affects growth and colony formation, nitrate, ammonium and phosphate concentration were determined. ## Code/software file:"Predation*Temperature*Cod_2503" contains Plotting and statistical analyses were conducted with R (version 4.0.4, R development Core Team) for "solitary cell abundance"、"Colony abundance" 、"colony size", "relationship between colony diameter and colonial cell abundance" and analysis the difference between treatments and controls at different temperature. ## Access information Other publicly accessible locations of the data: * none Data was derived from the following sources: * none ## Version changes Mar 27, 2025: We have expanded this deposit to include all statistical analysis and plotting code used in the study, supplementing the original dataset. **Newly added code includes:** 1. **Statistical analyses:** * Tests for homogeneity of variance and normality distribution * Two-way ANOVA with post-hoc Tukey tests * Regression analysis * Mixed-effects modeling 2. **Visualization scripts:** * All point-line graphs * Regression analysis plots * Code for generating figures showing: * The relationship between algal bloom timing * Multi-year monthly temperature patterns in the South China Sea ## Data & Code Availability: We provide: 1. Raw experimental data on *P. globosa* colony abundance, diameter, and cell counts across temperatures (13–30°C) under grazing-cue vs. control conditions. 2. Statistical analysis scripts (R code) for modeling thermal performance curves (TPCs) and testing treatment effects. 3. Plotting scripts (R code) for generating figures in the study. All data and code are structured to ensure reproducibility.