Dataset DOI: 10.5061/dryad.fn2z34v6f

Description of the data and file structure

These data were collected as part of a field study investigating whether the invasive aquatic plant Eurasian watermilfoil (Myriophyllum spicatum) exerts allelopathic effects on cyanobacterial assemblages in natural lake systems. The dataset includes:

• Quantification of specific allelochemicals (fatty acids and polyphenols) in water samples
• Cyanobacterial cell abundance and assemblage data (to genus level) from water samples collected at sites with and without M. spicatum beds;
• Associated physicochemical parameters (e.g., total nitrogen, total phosphorus, nitrite–nitrate, water temperature, dissolved oxygen) from the same sampling locations and periods.

Files and variables

Bergeron_Data.csv

METADATA:

Name (Unit): Description

Date: Date of the sampling

Outing: Field outing number

Lake: Name of the lake

Replicate: Replicate

Site: Name of the site

Sample number: Number of the sample

Id: Id of the sample

Precipitation: Qualitative description of precipitation conditions prior to the sampling event.

Sky condition: Visual observation of sky conditions at the time of sampling.

Wave type: Visual assessment of surface water conditions based on wave activity during sampling.

Wind direction: Cardinal direction from which the wind is blowing at the time of sampling.

Water level (m): Water level at the lake outlet, at the Cyrille-Delage dam

Precipitation (mm): Daily precipitation on the sampling day.

Cumulative precipitation (mm): Total cumulative precipitation since January 1st

Cumulative degree-days (°C): Cumulative degree-days (above 0°C) since January 1st

Start time: Sampling start time.

End time: Sampling end time.

Average wind speed (m/s): Average wind speed at sampling site

Maximum wind speed (m/s): Maximum wind speed at sampling site

Maximum depth (m): Maximum depth at sampling site

Atmospheric pressure (mmHg): Atmospheric pressure at sampling site

Air temperature (°C): Air temperature at sampling site

Water transparency (m): Water transparency at sampling site

0 m Water temperature (°C): Water temperature at the surface

0 m pH: pH at the surface

0 m ORP (mV): Redox potential at the surface

0 m Conductivity (ms/cm): Conductivity at the surface

0 m Dissolved oxygen (%): Dissolved oxygen percentage at the surface

1 m Water temperature (°C): Water temperature at a depth of one meter

1 m pH: pH at a depth of one meter

1 m ORP (mV): Redox potential at a depth of one meter

1 m Conductivity (ms/cm): Conductivity at a depth of one meter

1 m Dissolved oxygen (%): Dissolved oxygen percentage at a depth of one meter

2 m Water temperature (°C): Water temperature at a depth of two meters

2 m pH: pH at a depth of two meters

2 m ORP (mV): Redox potential at a depth of two meters

2 m Conductivity (ms/cm): Conductivity at a depth of two meters

2 m Dissolved oxygen (%): Dissolved oxygen percentage at a depth of two meters

3 m Water temperature (°C): Water temperature at a depth of three meters

3 m pH: pH at a depth of three meters

3 m ORP (mV): Redox potential at a depth of three meters

3 m Conductivity (ms/cm): Conductivity at a depth of three meters

3 m Dissolved oxygen (%): Dissolved oxygen percentage at a depth of three meters

Ammoniacal nitrogen (µg N/l): Concentration of ammoniacal nitrogen in the water column

Nitrites and nitrates (mg N/l): Concentration of nitrites and nitrates in the water column

Total phosphorus (µg P/l): Concentration of total phosphorus in the water column

Total nitrogen (mg N/l): Concentration of total nitrogen in the water column

Dissolved orthophosphates (µg P/l): Concentration of dissolved orthophosphates in the water column; NULL means no dissolved orthophosphates were detected

Nonanoic acid (µg/l): Concentration of nonanoic acid in the water column LOD:Limite of detection

Oleic acid (µg/l): Concentration of oleic acid in the water column LOQ: Limit of Quantification

Octadecenoic acid (µg/l): Concentration of octadecenoic acid in the water column

Gallic acid (µg/l): Concentration of gallic acid in the water column

Pyrogallol (µg/l): Concentration of pyrogallol in the water column

Catechine (µg/l): Concentration of catechine in the water column

Eugeniine (µg/l): Concentration of eugeniine in the water column

Ellagic acid (µg/l): Concentration of ellagic acid in the water column

Cyanobacteria (cell/ml): Concentration of cyanobacteria in the water column

Anabeanopsis (cell/ml): Concentration of Anabeanopsis in the water column

Aphanizomenon sp. (cell/ml): Concentration of Aphanizomenon sp in the water column

Aphanocapsa sp. (cell/ml): Concentration of Aphanocapsa sp in the water column

Aphanothece sp. (cell/ml): Concentration of Aphanothece sp in the water column

Borzia sp. (cell/ml): Concentration of Borzia sp in the water column

Chroococcus sp. (cell/ml): Concentration of Chroococcus sp in the water column

Coelomoron sp. (cell/ml): Concentration of Coelomoron sp in the water column

Coelosphaerium sp. (cell/ml): Concentration of Coelosphaerium sp in the water column

Cuspidothrix sp. (cell/ml): Concentration of Cuspidothrix sp in the water column

Cyanodictyon sp. (cell/ml): Concentration of Cyanodictyon sp in the water column

Cyanogranis sp. (cell/ml): Concentration of Cyanogranis sp in the water column

Cylindrospermopsis sp. (cell/ml): Concentration of Cylindrospermopsis sp in the water column

Cylindrospermum sp. (cell/ml): Concentration of Cylindrospermum sp in the water column

Dolichospermum sp. (Anabena sp.) (cell/ml): Concentration of Dolichospermum sp Anabena sp in the water column

Eucapsis sp. (cell/ml): Concentration of Eucapsis sp in the water column

Geitlerinema sp. (cell/ml): Concentration of Geitlerinema sp in the water column

Gloeocapsa sp. (cell/ml): Concentration of Gloeocapsa sp in the water column

Gomphospheria sp. (cell/ml): Concentration of Gomphospheria sp in the water column

Jaaginema sp. (cell/ml): Concentration of Jaaginema sp in the water column

Komvophoron sp. (cell/ml): Concentration of Komvophoron sp in the water column

Lemmermaniella sp. (cell/ml): Concentration of Lemmermaniella sp in the water column

Leptolyngbya sp. (cell/ml): Concentration of Leptolyngbya sp in the water column

Limnothrix sp. (cell/ml): Concentration of Limnothrix sp in the water column

Lyngbya sp. (cell/ml): Concentration of Lyngbya sp in the water column

Merismopedia sp. (cell/ml): Concentration of Merismopedia sp in the water column

Microcystis sp. (cell/ml): Concentration of Microcystis sp in the water column

Oscillatoria sp. (cell/ml): Concentration of Oscillatoria sp in the water column

Phormidium sp. (cell/ml): Concentration of Phormidium sp in the water column

Planktolyngbya sp. (cell/ml): Concentration of Planktolyngbya sp in the water column

Planktothrix sp. (cell/ml): Concentration of Planktothrix sp in the water column

Pseudanabaena sp. (cell/ml): Concentration of Pseudanabaena sp in the water column

Rhabdoderma sp. (cell/ml): Concentration of Rhabdoderma sp in the water column

Rhabdogloea sp. (Dactylococcopsis sp.) (cell/ml): Concentration of Rhabdogloea sp in the water column

Radiocystis sp. (cell/ml): Concentration of Radiocystis sp in the water column

Raphidiopsis sp. (cell/ml): Concentration of Raphidiopsis sp in the water column

Snowella sp. (cell/ml): Concentration of Snowella sp in the water column

Spirulina sp. (cell/ml): Concentration of Spirulina sp in the water column

Synechococcus sp. (cell/ml): Concentration of Synechococcus sp in the water column

Synechocystis sp. (cell/ml): Concentration of Synechocystis sp in the water column

Woronichinia sp. (cell/ml): Concentration of Woronichinia sp in the water column

Other blue-green algae (cell/ml): Concentration of other blue-green algae in the water column

Code/software

Data analyses were conducted using two main software environments:

1. Stata version 16.0 (StataCorp, 2019)
   • Used for the multiple regression and panel data analyses.
   • Included procedures for random effects models with spatial fixed effects, Breusch–Pagan and Pesaran tests for cross-sectional dependence, heteroscedasticity testing (Breusch–Pagan), normality testing of residuals (Shapiro–Wilk and histogram inspection), and multicollinearity assessment using the Variance Inflation Factor (VIF).
   • Based on the VIF results, two variables (cumulative degree-days and air temperature) were removed from the final model.
2. R version 2023.06.2 (The R Project for Statistical Computing, 2023)
   • Used for the analysis of variance (two-way ANOVA, model 1) to compare cyanobacterial concentrations between sampling dates and sites with vs. without Myriophyllum spicatum.
   • Implemented functions:
     • aov() for ANOVA
     • shapiro.test() for residual normality (Shapiro–Wilk test)
     • leveneTest() (from the car package) for homogeneity of variances.
   • A canonical correspondence analysis (CCA) was also performed using the function cca() from the vegan package (version 2.6-4; Oksanen et al., 2022) to explore relationships between cyanobacterial assemblages and environmental variables.

All analyses used freely available or licensed software as noted above. No custom scripts were developed; only standard functions and statistical packages were used.

Access information

Other publicly accessible locations of the data:

• Gouvernement du Québec. (2023b). Niveau d’eau et débit. Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs du Québec. https://www.cehq.gouv.qc.ca/hydrometrie/
• Environnement Canada. (2023). Données historiques. Gouvernement du Canada.  https://climat.meteo.gc.ca/historical_data/search_historic_data_f.html