Data used in the paper: Celewicz S., Gołdyn B. 2025. Shifts in phytoplankton communities in response to water parameters and large branchiopod filter feeders in kettle hole ponds of farmland landscape. Scientific Reports, 15 (1), art. no. 17623. DOI: 10.1038/s41598-025-01060-9
Contects:
Temporary ponds in agricultural landscapes, highly vulnerable to anthropogenic pressure and climatic variation, constitute unique habitats for microalgae and endangered filter feeders (large branchiopods). Such ponds play a crucial role in the functioning of farmland ecosystem, yet they remain largely understudied. Our study is the first to examine changes in phytoplankton communities in temporary kettle hole ponds in relation to rapid shifts in biotic (large branchiopods) and physical and chemical parameters of water. We conducted our research over a three-year cycle (in nine ponds in western Poland), with sampling starting in spring when inundation usually occurs, and continuing until the ponds dried out. Among 406 phytoplankton taxa (mainly euglenoids, but also diatoms and chlorophytes), locally rare species (e.g. Desmatractum indutum) were noted. When branchiopods occurred in the ponds, the phytoplankton communities shifted towards unicellular chlorophytes. Furthermore, nitrogen forms, temperature, conductivity, and pH were the abiotic factors altering the studied communities. Surprisingly, the diversity of phytoplankton species did not decrease with increasing temperature, which is inconsistent with the trend observed in permanent water bodies. The study identified specific drivers of phytoplankton community structure and dynamics, underscoring their ecological significance and management implications. These insights will be valuable for future conservation strategies of temporary ponds, crucial in sustaining biodiversity in farmland areas.
Methods:
Study area: The study covered nine ponds located in postglacial depressions in an agricultural landscape of Western Poland. The studied pools were typical kettle-shaped pond water bodies, fed mainly by water surface runoff during snow melt in early spring (vernal pools), with the duration of the hydroperiod (5–12 months) depending mainly on the thickness of winter snow cover. Their surface area varied from 189 to 1171 m2 and maximum depth from 0.5 to 1.2 m. Two ponds (BRW and IRS) did not dry completely during the research period, changing their area to approximately 30% during the summer months (July, August). Other kettle holes dried at least once at different times, from late spring to early autumn. The ponds remained dry from 2 to 9 months.
Field sampling: Samples for phycological, chemical, and zoological (macroinvertebrates) analyses were collected biweekly from the central area of each pond, beginning at inundation and continuing until the ponds dried. If the ponds didn’t dry, they were sampled until the next spring period. In total, 360 samples were collected for phycological analyzes in from 9 ponds, during 118 weeks (February 2008 to May 2010). The ponds were named using acronyms created basing on the names of closest villages or other topographic features and are also used in our previous papers on ponds from the same region. The number of samples taken from each pond varied depending on the hydroperiod length. For quantitative analyses of phytoplankton, the material was sampled using a calibrated vessel (1 L) and fixed with Lugol solution. For qualitative analyses, samples were collected using a plankton net.
Presence and numbering of two large branchiopod crustaceans: anostracan Eubranchipus grubii and laevicaudatan Lynceus brachyurs was assessed in the field each time after the samples were taken. We used a hand net towed for a length of 1 m, 30 times in random places covering the area of each pond. The animals were counted each time the net was towed and returned to the pond after each catch. Water temperature, pH, dissolved oxygen, and conductivity were measured directly in the field using a portable multiparameter meter.
Laboratory analyses: Phytoplankton samples for quantitative analyzes were sedimented in the laboratory and concentrated to a volume of 5–10 ml. The composition and abundance of microalgae were determined with a light microscope. The number of algae individuals was counted in at least 400 fields of a Fuchs-Rosenthal chamber. Algal single cells, colonies, coenobia and filaments were treated as individual units. For filaments or trichomes a length of 100 μm was set as one individual.
The diversity index H’ was calculated using the PAST program. It was expressed with the Shannon-Wiener Diversity Index formula. This index unites information on species variety as well as on the relative distribution of species abundance.
The dominating species among phytoplankton were calculated as those which exceeded 10% of the total phytoplankton abundance in each pond and with high frequency (occurring in more than 12% of all samples). Phytoplankton species names were given according to classifications used in Algaebase. Chemical analyzes of water were conducted in the laboratory following standard methods in order to determine total phosphorus (TP), soluble reactive phosphorus (SRP), nitrate nitrogen (NO3-N), nitrite nitrogen (NO2-N) and ammonia nitrogen (NH4-N).
Dataset: The dataset contains a table covering data on abundance of dominant phytoplankton taxa in the samples collected for the study - each row corrresponds to one such sample. Additonally, for each sample corresponding data on environmental variables that have been used in the satistical analyses are also presented. The data are stored in two equall versions: original .xlsx file and a .csv file version. All the acronyms used in the table are explained in the 'legend' sheet (.xlsx file) as well as in the 'legend.txt' file.
