DOI: 10.5061/dryad.hqbzkh1sj
title: Data from: Effects of advancing treelines and melting glaciers on alpine lake ecosystems: A mesocosm experiment

description: Climate warming promotes the upward advance of mountain treelines, thereby
 increasing allochthonous inputs of terrestrial organic matter into alpine
 lakes. Higher temperatures also accelerate glacial ablation, altering
 inputs of finely eroded rock particles, termed “glacial flour”. Organic
 matter (OM) and glacial flour (GF) both affect aquatic ecosystems;
 however, a knowledge gap exists concerning their combined impact. To test
 for the direct and interactive effects of OM and GF, we conducted a
 crossed two-factor outdoor mesocosm experiment. We hypothesized that GF
 sequesters OM through adsorption, thus reducing its effects on the abiotic
 environment and phytoplankton community. Addition of GF decreased
 underwater attenuation of ultraviolet radiation by the OM amendment (i.e.,
 a GF-OM interaction), but not the pronounced positive effects of OM on
 nutrients and phytoplankton chlorophyll. GF did mediate the effect of OM
 on phytoplankton community composition by suppressing diatoms. These
 findings highlight the potential for future shifts in allochthonous inputs
 away from GF and towards OM to stimulate high-elevation lake ecosystems as
 glaciers ablate and treeline vegetation migrates to higher elevations
 under a warming climate.
description: # Effects of advancing tree lines and melting glaciers on alpine lake
 ecosystems: A mesocosm experiment
 [https://doi.org/10.5061/dryad.hqbzkh1sj](https://doi.org/10.5061/dryad.hqbzkh1sj) ## Description of the data and file structure Data collected for: Effects of advancing treelines and melting glaciers on alpine lake ecosystems: A mesocosm experiment Authors: Colleen Dawson, Janet M. Fischer, Mark H. Olson, Rolf D. Vinebrooke Collection: 07/2023 to 08/2023 at Barrier Lake Field Station in Kananaskis, AB, Canada. ### Files and variables #### File: gfomexp_radiometer.csv **Description:**  Underwater light attenuation data from the start and end of organic matter x glacial flour mesocosm experiment.  Missing values are indicated by n/a. Light attenuation coefficients were not calculated when shading effects resulted in weak fitting log-linear relationships. ##### Variables * tank: Unique numerical identifier assigned to each mesocosm tank. * treatment: Experimental treatment (Control, OM, GF, OM+GF). * OM: Presence/absence of organic matter amendment. * GF: Presence/absence of glacial flour amendment. * day: Time period of experiment sampled (start/end). * Kd305: Light attenuation coefficient of 305 nm calculated as the slope of the log-linear relationship between downwelling irradiance and depth radiometer measurements (m-1). * Kd320: Light attenuation coefficient of 320 nm calculated as the slope of the log-linear relationship between downwelling irradiance and depth radiometer measurements (m-1). * Kd380: Light attenuation coefficient of 380 nm calculated as the slope of the log-linear relationship between downwelling irradiance and depth radiometer measurements (m-1). * KdPAR: Light attenuation coefficient of photosynthetically active radiation (PAR) calculated as the slope of the log-linear relationship between downwelling irradiance and depth radiometer measurements (m-1). #### File: gfomexp_tax.csv **Description:**  Algal taxonomic community data from the final day of organic matter x glacial flour mesocosm experiment. ##### Variables * tank: Unique numerical identifier assigned to each mesocosm tank. * treatment: Experimental treatment (Control, OM, GF, OM+GF). * OM: Presence/absence of organic matter amendment. * GF: Presence/absence of glacial flour amendment. * Cymbella: Final day density of algal taxa *Cymbella* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Fragilaria: Final day density of algal taxa *Fragilaria* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Gomphonema: Final day density of algal taxa *Gomphonema* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Naviculoid: Final day density of algal taxa naviculoid symmetrical biraphid diatoms identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Pennate: Final day density of algal taxa pennate diatoms identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Diatom Sp: Final day density of algal diatoms identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Ankistrodesmus: Final day density of algal taxa *Ankistrodesmus* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Carteria: Final day density of algal taxa *Carteria* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Chlamydomonas: Final day density of algal taxa *Chlamydomonas* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Crucigenia: Final day density of algal taxa *Crucigenia* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Haematococcus: Final day density of algal taxa *Haematococcus* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Oedogonium: Final day density of algal taxa *Oedogonium* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Oocystis: Final day density of algal taxa *Oocystis* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Pandorina: Final day density of algal taxa *Pandorina* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Aphanocapsa: Final day density of algal taxa *Aphanocapsa* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Gloeocapsa: Final day density of algal taxa *Gloeocapsa* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Oscillatoria: Final day density of algal taxa *Oscillatoria* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Pseudanabaena: Final day density of algal taxa *Pseudanabaena* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Rhabdoderma: Final day density of algal taxa *Rhabdoderma* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Chrysamoeba: Final day density of algal taxa *Chrysamoeba* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Chrysococcus: Final day density of algal taxa *Chrysococcus* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Chrysphearella: Final day density of algal taxa *Chrysphearella* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Mallomonas: Final day density of algal taxa *Mallomonas* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Pseudokephyrion: Final day density of algal taxa *Pseudokephyrion* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * Cryptomonas: Final day density of algal taxa *Cryptomonas* identified using an advanced digitalized flow cytometer and light microscopy (cells/L) * I (colonial green): Final day density of unknown colonial green algal taxa "I" identified using an advanced digitalized flow cytometer and light microscopy (cells/L) #### File: gfomexp_water_pigment.csv **Description:**  Physicochemical and algal pigment data from weekly sampling of organic matter x glacial flour mesocosm experiment. Missing values where data collection was incomplete are indicated by n/a. ##### Variables * ID: Sample ID. Includes treatment, tank number, and day sampled. * tank: Unique numerical identifier assigned to each mesocosm tank. * treatment: Experimental treatment (Control, OM, GF, OM+GF). * OM: Presence/absence of organic matter amendment. * GF: Presence/absence of glacial flour amendment. * day: Day sample was taken of 28-day experimental period. * TP: Total phosphorus concentration sampled from water column of mesocosm tank and analyzed by Biogeochemical Analytical Service Laboratory (µg/L) * TDP: Total dissolved phosphorus concentration sampled from water column of mesocosm tank and analyzed by Biogeochemical Analytical Service Laboratory (µg/L) * NO2NO3: Nitrite + nitrate concentration sampled from water column of mesocosm tank and analyzed by Biogeochemical Analytical Service Laboratory (µg/L) * TN: Total nitrogen concentration sampled from water column of mesocosm tank and analyzed by Biogeochemical Analytical Service Laboratory (µg/L) * TDN: Total dissolved nitrogen concentration sampled from water column of mesocosm tank and analyzed by Biogeochemical Analytical Service Laboratory (µg/L) * DOC: Dissolved organic carbon concentration sampled from water column of mesocosm tank and analyzed by Biogeochemical Analytical Service Laboratory (mg/L) * DO: Dissolved oxygen measured from water column of mesocosm tank using a YSI EXO2 sonde (% saturation) * spcond: Specific conductivity measured from water column of mesocosm tank using a YSI EXO2 sonde (µS/cm) * pH: pH measured from water column of mesocosm tank using a YSI EXO2 sonde * temp: Temperature measured from water column of mesocosm tank using a YSI EXO2 sonde (°C) * turbidity: Turbidity measured from water column of mesocosm tank using a YSI EXO2 sonde (FNU) * a320: Absorption coefficient at 320 nm (m-1) of water sampled from water column of mesocosm tank as a measure of chromophoric dissolved organic matter (CDOM). * fuco: Fucoxanthin concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * neo: Neoxanthin concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * viola: Violaxanthin concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * diadino: Diadinoxanthin concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * myxo: Myxoxanthophyll concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * diato: Diatoxanthin concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * lutzea: Lutein + zeaxanthin concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * cantha: Canthaxanthin concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * chlb: Chlorophyll *b* concentration quantified using high performance liquid chromatography for algal pigments (µg/L). * chla: Chlorophyll *a* concentration quantified using high performance liquid chromatography for algal pigments (µg/L).