Algal lipid distributions and hydrogen isotope ratios reflect phytoplankton community dynamics in Rotsee (Switzerland)
Data files
Sep 17, 2024 version files 73.39 KB
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d2H_H2O_ROT19.csv
1.90 KB
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d2H_lipids_ROT19.csv
5.28 KB
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epsilon_lipid1_lipid2_ROT19.csv
2.08 KB
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eukaryotic_algae_microzooplankton_rel_biovolume_ROT19.csv
4.16 KB
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eukaryotic_algal_rel_biovolume_ROT19.csv
3.22 KB
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Lipid_conc_watercolumn_ROT19.csv
9.02 KB
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phyto_microzooplankton_biovolume_ROT19.csv
3.97 KB
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phyto_microzooplankton_rel_biovolume_ROT19.csv
4.67 KB
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phyto_microzooplankton_species_rel_biovolume_ROT19.csv
22.12 KB
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phytoplankton_rel_biovolume_ROT19.csv
3.74 KB
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README.md
11.48 KB
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TN_TP_Temp_ROT19.csv
1.76 KB
Abstract
Reconstructions of past changes in algal community composition provide important context for future alterations in biogeochemical cycling. However, many existing phytoplankton proxies are indicative of individual algal groups and are not fully representative of the whole community. Here, we evaluated hydrogen isotope ratios of algal lipids (δ2Hlipid) as a potential proxy for phytoplankton community composition. We sampled the water column of Rotsee, a small eutrophic lake in Switzerland, every second week from January 2019 to February 2020 and analyzed distributions and the relative offsets between δ2Hlipid values (ε2Lipid1/Lipid2) from short-chain fatty acids, phytosterols and phytol. Comparing these data with phytoplankton cell counts, we found ε2C16:0/sterol and ε2sterol/phytol values reflect shifts in the eukaryotic algal community. To assess whether the selected phytoplankton groups were the main sources of the selected lipids, we further modeled algal ε2Lipid1/Lipid2 values based on δ2HC16:0, δ2Hsterol and δ2Hphytol values from batch cultures of individual algal groups and their biovolume in Rotsee and evaluated the role of heterotrophy on ε2Lipid1/Lipid2 values using a model incorporating δ2HC16:0 and δ2Hsterol values from microzooplankton. Annually-integrated and amount-weighted ε2Lipid1/Lipid2 values measured in Rotsee were within 6 to 17 ‰ of the mean of modeled algal ε2Lipid1/Lipid2 values, demonstrating a strong link with the phytoplankton community composition, while ε2Lipid1/Lipid2 values including microzooplankton lipids had a larger offset. Additionally, cyanobacterial biovolume was positively correlated with the ratio of phytol and phytosterols (phytol:sterol ratio) as well as the ratio of unsaturated C18 and C16:0 fatty acids (C18:C16 ratio). Our results support the application of sedimentary ε2Lipid1/Lipid2 values in eutrophic lakes as a proxy for past phytoplankton community assemblages. Moreover, the calculation of sedimentary phytol:sterol and C18:C16 ratios provides an additional proxy for reconstructing cyanobacterial blooms.
README: Algal lipid distributions and hydrogen isotope ratios reflect phytoplankton community dynamics in Rotsee (Switzerland)
https://doi.org/10.5061/dryad.9s4mw6mrm
Description of the data and file structure
This dataset comprises different parameters measured biweekly in the water column of Rotsee during a one-year sampling period.
Measurements occurred at 1 m depth (A) and the chlorophyll maximum depth at the respective sampling date (B). Sample names include the lake name (ROT), the date (yy-mm-dd), and the sampling depth (A or B). Different specifications were made for biovolume data, i.e., all phytoplankton including cyanobacteria, eukaryotic algae excluding cyanobacteria, and biovolume with and without microzooplankton contribution.
The following files contain (1) phytoplankton and microzooplankton biovolume (absolute values), (2) nutrient concentrations and temperature, (3) concentrations of different algal lipids (fatty acids, sterols and phytol), hydrogen isotope ratios of (4) algal lipids, and (5) lake water, expressed as d2H values, (6) the relative offset between d2H values of different lipids, expressed as epsilon values (ε2Lipid1/Lipid2 = (d2H Lipid1+1)/(d2HLipid2+1) – 1)), (7) the relative contribution of individual algal and microzooplankton groups to total eukaryotic biovolume, (8) the relative contribution of individual algal groups to eukaryotic algal biovolume, (9) the relative contribution of individual algal and microzooplankton groups to total biovolume, (10) the relative contribution of individual algal groups to phytoplankton biovolume, and (11) the relative contribution of single species to the biovolume of the phytoplankton and microzooplankton group they belong to.
Files and variables
File: phyto_microzooplankton_biovolume_ROT19.csv
Variables
- cyanobacteria_um3L: summed biovolume of algal species belonging to the genus Cyanophyceae in µm^3/L
- green.algae_um3L: summed biovolume of algal species belonging to the genus Chloro- and Zygnemophyceae in µm^3/L
- Chrysophyta_um3L: summed biovolume of algal species belonging to the genus Chrysophyceae in µm^3/L
- Diatoms_um3L: summed biovolume of algal species belonging to the genus Bacillariophyceae in µm^3/L
- Dinoflagellates_um3L: summed biovolume of photosynthetic algal species belonging to the genus Dinophyceae in µm^3/L
- Cryptophyceae_um3L: summed biovolume of algal species belonging to the genus Cryptophyceae in µm^3/L
- Ciliata_um3L: summed biovolume of Ciliata species in µm^3/L
- Rotifera_um3L: summed biovolume of Rotifera species in µm^3/L
- Gymnodinium_helveticum_um3L: biovolume of Gymnodinium helveticum (a phagocytotic, non-photosynthetic dinoflagellate species) in µm^3/L
File: TN_TP_Temp_ROT19.csv
Variables
- Total_Nitrogen_mgL: summed concentrations of nitrate, ammonia and nitrite in mg/L
- Total_Phosphor_ugL: summed concentrations of phosphate and dissolved phosphorus in µg/L
- Temp_C: temperature in Celsius
File: Lipid_conc_watercolumn_ROT19.csv
Variables
- C14:0_ugL: concentration of C14:0 fatty acid (myristic acid) in µg/L
- C16:1_ugL: concentration of C16:1 fatty acid (palmitoleic acid) in µg/L
- C16:0_ugL: concentration of C16:0 fatty acid (palmitic acid) in µg/L
- C18:3nx_ugL: summed concentrations of C18:3n3 (linolenic acid) co-eluting with C18:3n6 (γ-linolenic) fatty acid in µg/L
- C18:2_ugL: concentration of C18:2 fatty acid (linoleic acid) in µg/L
- C18:x_ugL: summed concentrations of C18:1n9c (oleic acid) co-eluting with C18:2n6t (linolelacidic acid) fatty acid in µg/L
- C18:1_ugL: concentration of C18:1 fatty acid (elaidic acid) in µg/L
- C18:0_ugL: concentration of C18:0 fatty acid (stearic acid) in µg/L
- C20:3nx_ugL: summed concentrations of C20:3n3 (cis-11,14,17-eicosatrienoic acid) co-eluting with C20:3n6 (cis-8,11,14-eicosatrienoic acid) fatty acid in µg/L
- C20:4_ugL: concentration of C20:4 fatty acid (arachidonic acid) in µg/L
- C22:6_ugL: concentration of C22:6 fatty acid (docosahexaenoic acid) in µg/L
- C22:2_ugL: concentration of C22:2 fatty acid (docosadienoic acid) in µg/L
- brassicasterol_ugL: concentration of brassicasterol (24-methylcholesta-5,22-dien-3β-ol) in µg/L
- cholesterol_ugL: concentration of cholesterol (cholest-5-en-3β-ol) in µg/L
- diplopterol_ugL: concentration of diplopterol (hopan-22-ol) in µg/L
- ergosterol_ugL: concentration of ergosterol (methylcholesta-5,7,22-trien-3β-ol) in µg/L
- sitosterol_ugL: concentration of sitosterol (24-ethylcholest-5-en-3β-ol) in µg/L
- stigmasterol_ugL: concentration of stigmasterol (24-ethylcholesta-5,22-dien-3β-ol) in µg/L
- phytol_ugL: concentration of phytol (((2E,7R,11R)-3,7,11,15-Tetramethyl-2-hexadecen-1-ol) in µg/L
File: d2H_lipids_ROT19.csv
Variables
- C16.0_Avg.d2H_VSMOW: d2H value of C16:0 fatty acid (palmitic acid), expressed in permil relative to Vienna Standard Mean Ocean Water (VSMOW)
- brassicasterol_Avg.d2H_VSMOW: d2H value of brassicasterol (24-methylcholesta-5,22-dien-3β-ol), expressed in permil relative to Vienna Standard Mean Ocean Water (VSMOW)
- ergosterol_Avg.d2H_VSMOW: d2H value of ergosterol (methylcholesta-5,7,22-trien-3β-ol), expressed in permil relative to Vienna Standard Mean Ocean Water (VSMOW)
- sitosterol_Avg.d2H_VSMOW: d2H value of sitosterol (24-ethylcholest-5-en-3β-ol), expressed in permil relative to Vienna Standard Mean Ocean Water (VSMOW)
- stigmasterol_Avg.d2H_VSMOW: d2H value of stigmasterol (24-ethylcholesta-5,22-dien-3β-ol), expressed in permil relative to Vienna Standard Mean Ocean Water (VSMOW)
- phytol_Avg.d2H_VSMOW: d2H value of phytol (((2E,7R,11R)-3,7,11,15-Tetramethyl-2-hexadecen-1-ol), expressed in permil relative to Vienna Standard Mean Ocean Water (VSMOW)
File: d2H_H2O_ROT19.csv
Variables
- H2O_Avg.d2H_VSMOW : d2H value of lake water (H2O), expressed in permil relative to Vienna Standard Mean Ocean Water (VSMOW)
'Avg' in d2H variable names refers to 'average' as the mean d2H value of replicate measurements. Standard deviations of d2H measurements (SD) are listed in the column directly following each variable. These values represent 1 standard deviation of replicate measurements.
File: epsilon_lipid1_lipid2_ROT19.csv
Variables
- epsilon_C16.0_phytol: relative offset between d2H values of C16:0 fatty acid and phytol ((d2H C16:0+1)/(d2H phytol+1) – 1)), expressed in permil
- epsilon_C16.0_sterol: relative offset between d2H values of C16:0 fatty acid and sterols ((d2H C16:0+1)/(d2H sterol+1) – 1)), expressed in permil
- epsilon_sterol_phytol: relative offset between d2H values of sterols and phytol ((d2H sterols+1)/(d2H phytol+1) – 1)), expressed in permil
File: eukaryotic_algae_microzooplankton_rel_biovolume_ROT19.csv
Variables
- green.algae_%: relative contribution of green algae to the summed biovolume of eukaryotes in percent
- Chrysophyta_%: relative contribution of Chrysophyceae to the summed biovolume of eukaryotes in percent
- Diatoms_%: relative contribution of Bacillariophyceae (diatoms) to the summed biovolume of eukaryotes in percent
- Dinoflagellates_%: relative contribution of photosynthetic Dinophyceae (dinoflagellates) to the summed biovolume of eukaryotes in percent
- Gymnodinium_helveticum_%: relative contribution of Gymnodinium helveticum (a phagocytotic, non-photosynthetic dinoflagellate species) to the summed biovolume of eukaryotes in percent
- Cryptophyceae_%: relative contribution of Cryptophyceae to the summed biovolume of eukaryotes in percent
- Ciliata_%: relative contribution of Ciliata to the summed biovolume of eukaryotes in percent
- Rotifera_%: relative contribution of Rotifera to the summed biovolume of eukaryotes in percent
File: eukaryotic_algal_rel_biovolume_ROT19.csv
Variables
- green.algae_%: relative contribution of green algae to the summed biovolume of eukaryotic algae in percent
- Chrysophyta_%: relative contribution of Chrysophyceae to the summed biovolume of eukaryotic algae in percent
- Diatoms_%: relative contribution of Bacillariophyceae (diatoms) to the summed biovolume of eukaryotic algae in percent
- Dinoflagellates_%: relative contribution of photosynthetic Dinophyceae (dinoflagellates) to the summed biovolume of eukaryotic algae in percent
- Cryptophyceae_%: relative contribution of Cryptophyceae to the summed biovolume of eukaryotic algae in percent
File: phyto_microzooplankton_rel_biovolume_ROT19.csv
Variables
- cyanobacteria_%: relative contribution of Cyanophyceae (cyanobacteria) to the summed biovolume of phyto-/ and microzooplankton in percent
- green.algae_%: relative contribution of green algae to the summed biovolume of phyto-/ and microzooplankton in percent
- Chrysophyta_%: relative contribution of Chrysophyceae to the summed biovolume of phyto-/ and microzooplankton in percent
- Diatoms_%: relative contribution of Bacillariophyceae (diatoms) to the summed biovolume of phyto-/ and microzooplankton in percent
- Dinoflagellates_%: relative contribution of photosynthetic Dinophyceae (dinoflagellates) to the summed biovolume of phyto-/ and microzooplankton in percent
- Gymnodinium_helveticum_%: relative contribution of Gymnodinium helveticum (a phagocytotic, non-photosynthetic dinoflagellate species) to the summed biovolume of phyto-/ and microzooplankton in percent
- Cryptophyceae_%: relative contribution of Cryptophyceae to the summed biovolume of phyto-/ and microzooplankton in percent
- Ciliata_%: relative contribution of Ciliata to the summed biovolume of phyto-/ and microzooplankton in percent
- Rotifera_%: relative contribution of Rotifera to the summed biovolume of phyto-/ and microzooplankton in percent
File: phytoplankton_rel_biovolume_ROT19.csv
Variables
- cyanobacteria_%: relative contribution of Cyanophyceae (cyanobacteria) to the summed biovolume of phytoplankton in percent
- green.algae_%: relative contribution of green algae to the summed biovolume of phytoplankton in percent
- Chrysophyta_%: relative contribution of Chrysophyceae to the summed biovolume of phytoplankton in percent
- Diatoms_%: relative contribution of Bacillariophyceae (diatoms) to the summed biovolume of phytoplankton in percent
- Dinoflagellates_%: relative contribution of photosynthetic Dinophyceae (dinoflagellates) to the summed biovolume of phytoplankton in percent
- Cryptophyceae_%: relative contribution of Cryptophyceae to the summed biovolume of phytoplankton in percent
File: phyto_microzooplankton_species_rel_biovolume_ROT19.csv
Description: In this datafile, each variable is indicating the relative contribution of individual species to the phytoplankton or microzooplankton group they belong to, e.g., the relative contribution of Asterionella formosa to Bacillariophyceae (diatoms) in percent.
If no species level could be determined, cells were summarized to the next taxonomic classification.
General: Missing values in each file are indicated as '#NV'.
Access information
Other publicly accessible locations of some the data:
Methods
Water and biomass samples were taken biweekly from the water column of Rotsee at 1 m depth and the chlorophyll maximum depth over a one-year period. For biomass samples, lake water was filtered through glass fiber filters. The chlorophyll maximum depth on each sampling date was determined based on the turbidity maximum measured by a multi-parameter CTD probe. The temperature at the two different sampling depths was estimated by the mean of temperatures measured by the CTD probe from 0.5 m above to 0.5 m below the respective depth. Cell counts of phytoplankton and microzooplankton species were conducted from water samples and the biovolume of individual taxonomic groups was calculated based on cell densities and the mean per-cell biovolume. δ2Hwater values of filtered water samples were measured by a high-temperature conversion/elemental analyzer (TC/EA) coupled with isotope ratio mass spectrometry (IRMS). Nutrient concentrations of filtered water samples were measured via spectrophotometry (total phosphorus) and by a Total Organic Carbon Analyzer with Total Nitrogen Unit (total nitrogen). Lipids were extracted from biomass filter samples, purified, derivatized (methylated or acetylated) and quantified by gas chromatography–flame ionization detection (GC-FID). Compound-specific δ2Hlipid values of short-chain fatty acids, sterols and phytol were measured by GC-IRMS. δ2Hlipid values were corrected for hydrogen added during derivatization and δ2Hsterol values were further corrected for biases related to peak dimensions.