DOI: 10.5061/dryad.nvx0k6f0v
title: Data from: Taxon-specific hydrogen isotope signals in cultures and mesocosms facilitate ecosystem and hydroclimate reconstruction

description: Phytoplankton play a key role in biogeochemical cycles, impacting
 atmospheric and aquatic chemistry, food webs, and water quality. However,
 it remains challenging to reconstruct changes in algal community
 composition throughout the geologic past, as existing proxies are suitable
 only for a subset of taxa and/or influenced by degradation. Here, we
 investigate if compound-specific hydrogen isotope ratios (δ2H values) of
 common algal lipids can serve as (paleo)ecological indicators. First, we
 grew 20 species of algae – representing cyanobacteria, diatoms,
 dinoflagellates, green algae, and cryptomonads – in batch cultures under
 identical conditions and measured δ2H values of their lipids. Despite
 identical source water δ2H values, lipid δ2H values ranged from -455 ‰ to
 -52 ‰, and clustered according to taxonomic groups and chemical compound
 classes. In particular, green algae synthesized fatty acids with higher
 δ2H values than other taxa, cyanobacteria synthesized phytol with
 relatively low δ2H values, and diatoms synthesized sterols with higher δ2H
 values than other eukaryotes. Second, we assessed how changes in algal
 community composition can affect net δ2H values of common algal lipids in
 20 experimental outdoor ponds, which were manipulated via nutrient
 loading, and the addition of macrophytes and mussels. High algal biomass
 in the ponds, which was mainly caused by cyanobacterial and green algal
 blooms, was associated with higher δ2H values for generic fatty acids,
 relatively stable δ2H values for phytol and the dinoflagellate biomarker
 dinostanol, and lower δ2H values for the more cosmopolitan sterol
 stigmasterol. These results are consistent with expectations from our
 culture-based analyses, suggesting that measuring δ2H values of multiple
 lipids from sediment and calculating 2H-offsets between them can resolve
 changes in algal community composition from changes in source water
 isotopes. With an appropriate availability of sedimentary lipids, this
 approach could permit the reconstruction of both taxonomic variability and
 hydroclimate from diverse sedimentary systems.
description: 20 species of phytoplankton were cultured under identical
 conditions in batch cultures. Biomass was filtered from cultured water.
 Mesocosm experiments were conducted in large-volume experimental ponds.
 Algal biomass was filtered from the water at three time points from each
 of the 20 experimental ponds. From both sample sets, lipids were extracted
 and purified, derivatized (methylated or acetylated) and compound-specific
 hydrogen isotope ratios of fatty acids, phytol, and sterols were measured
 by gas chromatography - isotope ratio mass spectrometry (GC-IRMS).
 Resulted lipid δ2H values are corrected for hydrogen added during
 derivatization. The isotopic composition of filtered water was determined
 by cavity ring-down spectroscopy.
description: # Data from: Taxon-specific hydrogen isotope signals in cultures and
 mesocosms facilitate ecosystem and hydroclimate reconstruction
 [https://doi.org/10.5061/dryad.nvx0k6f0v
 ](https://doi.org/10.5061/dryad.nvx0k6f0v) This data set contains hydrogen
 isotope ratios, expressed as d2H values, of algal lipids from two
 experiments: (1) batch cultures of different algal species under identical
 laboratory conditions and (2) large-volume mesocosms. ## Description of
 the data and file structure File list:  1. Algal_Culture_d2H.csv (results
 from batch cultures) 2. Pond_d2H.csv (results from large volume mesocosms)
 Variable list: * Species: Genus and species of cultured algae * Group:
 Algal taxonomic group used for classifying and plotting data * Class:
 Taxonomic class * Number Replicate Cultures: Total number of replicate
 batch cultures * d2H C16:0 FA: d2H value of C16:0 fatty acid (hexadecanoic
 acid; palmitic acid), expressed in per mil relative to Vienna Standard
 Mean Ocean Water (VSMOW). * d2H Phytol: d2H value of Phytol, expressed per
 mil relative to VSMOW. * d2H Sterol 1: d2H value of the first sterol that
 eluted on the GC-IRMS, if present, expressed in per mil relative to VSMOW.
 The specific compound differs among eukaryotic algae. Cyanobacteria did
 not produce any sterols. * d2H Sterol 2: d2H value of the second sterol
 that eluted on the GC-IRMS, if present, expressed in per mil relative to
 VSMOW. The specific compound differs among eukaryotic algae. Cyanobacteria
 did not produce any sterols. * d2H Sterol 3: d2H value of the third sterol
 that eluted on the GC-IRMS, if present, expressed in per mil relative to
 VSMOW. The specific compound differs among eukaryotic algae. Cyanobacteria
 did not produce any sterols. * d2H Sterol 4: d2H value of the fourth
 sterol that eluted on the GC-IRMS, if present, expressed in per mil
 relative to VSMOW. The specific compound differs among eukaryotic algae.
 Cyanobacteria did not produce any sterols. * d2H Sterol 5: d2H value of
 the fifth sterol that eluted on the GC-IRMS, if present, expressed in per
 mil relative to VSMOW. The specific compound differs among eukaryotic
 algae. Cyanobacteria did not produce any sterols. * Pond: Unique ID of the
 experimental pond used in the mesocosm experiment * Treatment: Mesocosm
 treatment. Ponds had either Mussels, Macrophytes, or Both, Neither with
 nutrient additions (Nutrient controls), or Neither without nutrient
 additions (oligotrophic controls) * Sampling date: Date when samples were
 collected, in YYMMDD format * Water d2H: d2H value of filtered pond water,
 expressed in per mil relative to VSMOW * d2H C14:0 FA: d2H value of C14:0
 fatty acid (tetradecanoic acid, myristic acid), expressed in per mil
 relative to VSMOW. * d2H C16:1 FA: d2H value of C16:1 fatty acid
 ((9Z)-hexadecenoic acid, palmitoleic acid), expressed in per mil relative
 to VSMOW. * d2H C18:0 FA: d2H value of C18:0 fatty acid (octadecanoic
 acid, stearic acid), expressed in per mil relative to VSMOW. * d2H C18:x
 FA: d2H value of chromatographically unresolved unsaturated C18 fatty
 acids (cis-9-octadecanoic acid, trans-9-octadecanoic acid, and
 linolelaidic acid), expressed in per mil relative to VSMOW * d2H C18:2 FA:
 d2H value of C18:2 fatty acid (linoleic acid, cis-9,12-octadecanoic
 acid), expressed in per mil relative to VSMOW. * d2H C20:4n6 FA: d2H value
 of C20:4n6 fatty acid (arachidonic
 acid, (5*Z*,8*Z*,11*Z*,14*Z*)-Icosa-5,8,11,14-tetraenoic acid), expressed
 in per mil relative to VSMOW. * d2H C20:5 FA: d2H value of C20:5n3 fatty
 acid (eicosapentaenoic
 acid; (5*Z*,8*Z*,11*Z*,14*Z*,17*Z*)-Icosa-5,8,11,14,17-pentaenoic
 acid), expressed in per mil relative to VSMOW. * d2H C22:6 FA: d2H value
 of C22:6n3 fatty acid (docosahexaenoic
 acid; (4*Z*,7*Z*,10*Z*,13*Z*,16*Z*,19*Z*)-Docosa-4,7,10,13,16,19-hexaenoic
 acid, expressed in per mil relative to VSMOW. * d2H Campesterol: d2H value
 of campesterol (Campest-5-en-3β-ol), expressed in per mil relative to
 VSMOW. * d2H Dinostanol: d2H value of dinostanol
 (4a,23,24-trimethyl-5a-cholestan-3b-ol), expressed in per mil relative to
 VSMOW. * d2H Brassicasterol: d2H value of brassicasterol
 (Ergosta-5,22-dien-3β-ol), expressed in per mil relative to VSMOW. * d2H
 Cholesterol: d2H value of cholesterol (Cholest-5-en-3β-ol), expressed in
 per mil relative to VSMOW. * d2H Stigmasterol: d2H value of stigmasterol
 (Stigmasta-5,22-dien-3β-ol), expressed in per mil relative to VSMOW.
 Standard deviations are reported in the column directly following each
 variable and denoted as st dev variable name. These values represent 1
 standard deviation of replicate measurements, or the long-term precision
 of the quality control standard, whichever value was larger. Values for
 which no data were obtained are left blank.