Taxon-specific hydrogen isotope signals in cultures and mesocosms facilitate ecosystem and hydroclimate reconstruction

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..., 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., , # 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).
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