DOI: 10.5061/dryad.02v6wwq7s
title: Data from: Unexpected shift from cyanobacterial to dinoflagellate dominance due to a summer drought

description: The ruling paradigm is that future climate change scenarios will lead to
 an increase in the frequency, intensity, and duration of cyanobacterial
 blooms across the globe. It was therefore unexpected when, during an
 unusually warm and dry summer in southern Sweden in 2018, cyanobacteria
 did not dominate the phytoplankton community of the temperate Lake
 Vombsjön known for toxic cyanobacterial blooms. Instead, a potentially
 toxic dinoflagellate, Naiadinium polonicum, formed a large bloom
 and was dominant for the entire season. Dinoflagellates share important
 functional traits with cyanobacteria, but few studies have considered
 competition between dinoflagellates and cyanobacteria under future climate
 change scenarios. In order to understand the underlying factors leading to
 the N. polonicum bloom in 2018, we designed a study of
 Lake Vombsjön for an additional two years. When compared with subsequent
 years, 2018 was defined by an extended period of thermal stratification
 and hypoxia near the sediment surface. A significant positive relationship
 was also identified between N. polonicum biomass and
 both surface water temperature and soluble reactive phosphorus. We,
 therefore, suggest that the combination of higher temperatures and higher
 water column stability benefitted N. polonicum more so than
 cyanobacteria. Given that these factors are generally associated with
 cyanobacterial success, we conclude that freshwater phytoplankton
 community composition in temperate lakes can take different pathways in a
 warmer world.
description: # Data from: Unexpected shift from cyanobacterial to dinoflagellate
 dominance due to a summer drought #### Description of the data and file
 structure Data in file ‘EW_Data_All’ is presented in the order it appears
 in the manuscript, see below for more information. Data for Table 3 falls
 under the license CC BY and can therefore only be found in the following
 repository:
 [https://github.com/SJean99/Plankton-LakeVombsjon-Scania/tree/main](https://github.com/SJean99/Plankton-LakeVombsjon-Scania/tree/main). Sheets in excel file ‘EW_Data_All: Table1: Combined surface water temperature from our own sampling and from Sydvatten Table2: Temperature (surface and bottom), DO (bottom) and RWCS from Sydvatten Table3: Monthly average outflow and cumulative precipitation from SMHI (available at [https://github.com/SJean99/Plankton-LakeVombsjon-Scania/tree/main](https://github.com/SJean99/Plankton-LakeVombsjon-Scania/tree/main)) Table4: Nutrient data Table5: Chlorophyll-a (fluorometry) and phytoplankton community composition (AlgaeLabAnalyser) Table6: Cyanobacteria and dinoflagellate biomass Table7: Zooplankton biomass Table8: Results from principal component analysis with environmental variables Table9: Results from principal component analysis with zooplankton variables Table10: AUC (Area under the curve) calculations Table11: Results from Multiple Linear Regression analysis with model averaging Relevant abbreviations: (C): degrees celsius mg ww/L: milligrams wet weight per litre (see manuscript for description) mg dw/L: milligrams dry weight per litre (see manuscript for description) AUC: area under the curve RWCS: Relative water column stability DO: dissolved oxygen SRP: soluble reactive phosphorus NA: Not available. Both NA and empty cells indicate that corresponding data was not collected and/or analysed for that specific sampling occasion. Some data used in statistical analyses (precipitation, outflow and radiation) have the licence CC BY and are therefore being housed, together with the associated R-scripts used for the statistical analyses, at [https://github.com/SJean99/Plankton-LakeVombsjon-Scania/tree/main](https://github.com/SJean99/Plankton-LakeVombsjon-Scania/tree/main).