Dataset DOI: 10.5061/dryad.m63xsj4fs

Description of the data and file structure

Seasonal water quality and zooplankton data for Portage Lake, Hubbard County, MN, USA (2023-2024)

Files and variables

File:

Portage_CTD.csv

Description: Complete water column measurements of dissolved oxygen, chlorophyll a, and temperature in Portage Lake, Hubbard County, MN, USA (2023-2024)

Variables:

• "Oxygen_perc_sat" : dissolved oxygen in percent saturation
• "Chlorophyll_a_ug_L" : chlorophyll a in micrograms per liter, μg/L
• "Temperature_C " : temperature in degrees Celcius, °C

Portage_discrete_chlorophyll.csv

Description: Discrete chlorophyll a measurements from 2 depths at lake center (surface: 0.5 m below surface; bottom: 3-4 m below surface).

Methodology: Whole water, not sieved, filtered through 0.22 cellulose nitrate filters, folded, stored in 15 ml falcon tubes, wrapped in foil, frozen. All filters were soaked in 10 ml of 90% acetone for 18 hours, vortexed, and read via flourometry in the dark. Triplicate.

Variables:

• "Lake": Lake name
• "Date": Date, month, and year sample collected
• "Year": Year sample collected
• "Depth_m": Depth at which sample was collected in meters
• "Replicate" : replicate
• "Chl_mls_filtered" : milliliters water filtered

• "Chl_raw_ug_L" : raw fluorometer value in μg/L
• "Extracted_vol_mls" : extracted volume in milliliters
• "Adjusted_fluorometer_value" : adjusted fluorometer value in μg/L
• "Chl_ug_L" : final chlorophyll a value in in μg/L

Portage_zooplankton.csv

Description: Zooplankton species data from tows taken at lake center from 1 m above lake bottom to surface. 

Methodology: Triplicate samples for identification were preserved in 70% ethanol. Each replicate consisted of three pooled net tows. Subsamples of each replicate were counted and identified under an Olympus SZH10 stereoscope following Balcer et al. (1984). Adults were classified to species for copepods and cladocerans, while copepodites were grouped as cyclopoids or calanoids. Nauplii were counted without further classification. Individuals carrying egg sacs or brood pouches were also recorded. At least 300 individuals were identified per sample, and abundance was reported as individuals per liter (Ind. L⁻¹). If a sample showed a noticeably different abundance, it was recounted. Only one replicate for Jan 2023.

Variables:

• "Replicate" : replicate. If a sample contained a noticeably different abundance than the other replicates, the sample was recounted. Recounted samples are noted as "recount" under "Replicate."
• "Tow_number" : number of pooled tows per sample replicate

• "Sample_depth_m" : sample depth in meters
• "Area_net_opening_cm" : area of net opening in centimeters
• "Total_volume_ml" : total volume of sample in milliliters
• "Volume_sorted_ml" : total volume sorted in milliliters
• "Total_individuals_counted": total individuals counted per sample
• "Total_Ind_L": total individuals per liter per sample
• Abundance of major zooplankton taxa are included as individuals per liter: Daphnia_mendotae_Ind_L, Daphnia_pulicaria_Ind_L, Daphnia_parvula_Ind_L, Daphnia_birgei_Ind_L, Daphnia_retrocurva_Ind_L, Daphnia_longiremis_Ind_L, Ceriodaphnia_dubia_Ind_L, Bosmina_longirostris_Ind_L, Chydous_sphaericus_Ind_L, Alona_Ind_L, Skidiaptomis_oregonensis_Ind_L, Leptodiaptomus_sicilis_Ind_L, Leptodiaptomus_minutus_Ind_L, Diacyclops_thomasi_Ind_L, Tropocyclops_prasinus_mexicanus_Ind_L, Acanthocyclops_vernalis_Ind_L, Eucyclops_agilis_Ind_L, Mesocyclops_edax_Ind_L, Copepodite_cyclopods_Ind_L, Copepodite_calanoids_Ind_L, Nauplii_Ind_L

Code/software

Software: R

• Name: R (The R Project for Statistical Computing)
• Version Used: R 4.3.1
• License: GNU General Public License
• Website: https://cran.r-project.org