DOI: 10.5061/dryad.08kprr5h3
title: Long-term monitoring reveals biomass loss and concurrent dominance changes in coastal zooplankton community

description: Time series dataset from Tvärminne Storfjärden. Data includes Zooplankton
 biomass, physical and chemical parameters collected between 1993 and 2021.
 All information about taxa is biomass in mg/m³. Biomass was calculated
 from standard values considering the species (if available) and sex of
 each individual (HELCOM monitoring guidelines, Hernroth 1985).
description: # Long-term monitoring reveals biomass loss and concurrent dominance
 changes in coastal zooplankton community Dataset DOI:
 [10.5061/dryad.08kprr5h3](https://doi.org/10.5061/dryad.08kprr5h3) ##
 Description of the data and file structure Zooplankton samples were
 generally collected once a month throughout the year, including the winter
 season. Samples (vertical net tows) were taken during the day using a 150
 μm Hensen hand-net with a 0.35 m diameter from a depth of 25 m to the
 surface (depth of the sampling site is approx. 32 m). If the sea surface
 was frozen, a hole was drilled or cut into the ice. The samples were
 stored in 4% buffered formalin and analysed microscopically. Prior to the
 analysis, the samples were divided using a Folsom splitter (max 10 times
 which equals a 1/1024 sample) and subsamples were counted to 300 – 500
 individuals of adult copepods, copepodites, cladocerans or polychaete
 larvae. Temperature and salinity were measured every 10 days in the
 vertical profile using a CTD (SIS CTD, FSI CTD and Mini CTD) and values
 were averaged over the upper 25 m. Secchi depth was measured using a
 Secchi disc according to the HELCOM guidelines for monitoring of water
 transparency (HELCOM, 2019). Monthly pH and CHLa data were obtained from
 the Finnish Environment Institute’s VESLA database. CHLa was extracted
 from water samples using ethanol (HELCOM, 2025) and pH was measured using
 a glass electrode. Both pH and CHLa were measured at discrete depths of 1,
 5, 10, 15 and 20 m and the averages were used for further analysis. ###
 Files and variables #### File: final_new_revisions_script.R
 **Description:** R script of the time series analysis conducted for the
 associated manuscript. ### #### File: storfjarden_time_series.csv
 **Description:** Time Series Data from Tvärminne Storfjärden #####
 Variables * Date: Sampling Date * Acartia_AD: Combined biomass of adult
 specimen * Acartia_COP: Combined biomass of undefined copepodite stages *
 Acartia_COP_1-3: Combined biomass of copepodite stages 1-3 *
 Acartia_COP_4-5: Combined biomass of copepodite stages 4-5 *
 Acartia_NA: Combined biomass of specimen of undefined life stage *
 Acartia_NP: Combined biomass of nauplii * Acartia_Total: Combined biomass
 of all life stages * Branchiopoda_NA: Combined biomass of specimen of
 undefined life stage * Branchiopoda_Filter_AD: Combined biomass of adult
 specimen * Branchiopoda_Filter_JUV: Combined biomass of juvenile stages *
 Branchiopoda_Filter_NA: Combined biomass of specimen of undefined life
 stage * Branchiopoda_Filter_NS: Combined biomass of specimen of undefined
 life stage * Branchiopoda_Filter_Total: Combined biomass of all life
 stages * Branchiopoda_Predatory_AD: Combined biomass of adult specimen *
 Branchiopoda_Predatory_JUV: Combined biomass of juvenile stages *
 Branchiopoda_Predatory_NA: Combined biomass of specimen of undefined life
 stage * Branchiopoda_Predatory_NS: Combined biomass of specimen of
 undefined life stage * Branchiopoda_Pred_Total: Combined biomass of all
 life stages * Eurytemora_AD: Combined biomass of adult specimen *
 Eurytemora_COP_1-3: Combined biomass of copepodite stages 1-3 *
 Eurytemora_COP_4-5: Combined biomass of copepodite stages 4-5 *
 Eurytemora_NP: Combined biomass of nauplii * Eurytemora_Total: Combined
 biomass of all life stages * Keratella_NA: Combined biomass of specimen of
 undefined life stage * Keratella: Combined biomass of specimen *
 Keratella_Total: Combined biomass of all life stages *
 Synchaeta_NA: Combined biomass of specimen of undefined life stage *
 Synchaeta: Combined biomass of specimen * Synchaeta_Total: Combined
 biomass of all life stages * Temora_AD: Combined biomass of adult specimen
 * Temora_COP_1-3: Combined biomass of copepodite stages 1-3 *
 Temora_COP_4-5: Combined biomass of copepodite stages 4-5 *
 Temora_NA: Combined biomass of specimen of undefined life stage *
 Temora_NP: Combined biomass of nauplii * Temora_NS: Combined biomass of
 specimen of undefined life stage * Temora_Total: Combined biomass of all
 life stages * Mean_Temp: average temperature in °C over the top 25 m *
 Mean_Salinity: average salinity over the top 25 m * mean_NH4: average NH4
 in µg/L over the top 25 m * mean_NO2: average NO2 in µg/L over the top 25
 m * mean_NO3: average NO3 in µg/L over the top 25 m * mean_PO4: average
 PO4 in µg/L over the top 25 m * mean_Si: average Si in mg/L over the top
 25 m * mean_TP: average TP in µg/L over the top 25 m * mean_TN: average TN
 in µg/L over the top 25 m * mean_pH: average pH over the top 25 m *
 mean_CHL: average CHLa in µg/L over the top 25 m * mean_Oxygen: average O2
 in mg/L over the top 25 m * Secchi: Secchi depth in m  * doy: Day of year
 * year: year * month: month * year,cont: year as continuous variable *
 bio_tot: total combined zooplankton biomass * Copepoda_Total: combined
 biomass of all genera/feeding modes * Branchiopoda_Total: combined biomass
 of all genera/feeding modes * Rotifera_Total: combined biomass of all
 genera/feeding modes * mean_sal_resid: residual values of salinity after
 applying a generalized additive model * mean_temp_resid: residual values
 of temperature after applying a generalized additive model *
 mean_chl_resid: residual values of CHLa after applying a generalized
 additive model * mean_ph_resid: residual values of ph after applying a
 generalized additive model * mean_secchi_resid: residual values of secchi
 depth after applying a generalized additive model ## Code/software
 Microsoft Excel, Rstudio