DOI: 10.5061/dryad.fj6q5744j
title: Data from: Connectivity loss in experimental pond networks leads to biodiversity loss in microbial metacommunities

description: Habitat fragmentation is among the most important global threats to
 biodiversity, however, the direct effects of its components including
 connectivity loss are largely unknown and still mostly inferred based on
 indirect evidence. Our understanding of these drivers is especially
 limited in microbial communities. Here, by conducting a four-month outdoor
 experiment with artificial pond (mesocosm) metacommunities, we studied the
 effects of connectivity loss on planktonic microorganisms, primarily
 focusing on pro- and microeukaryotes. Connectivity loss was simulated by
 stopping the dispersal among local habitats after an initial period with
 dispersal. Keeping the habitat amount constant and the abiotic environment
 homogeneous. allowed us to track the direct effects of the process of
 connectivity loss. We found that connectivity loss led to higher levels of
 extinction and a decrease in both local and regional diversity in
 microeukaryotes. In contrast, diversity patterns of prokaryotes remained
 largely unaffected, with some indications of extinction debt. Connectivity
 loss also led to lower evenness in microeukaryotes, likely through changes
 in biotic interactions with zooplankton grazers. Our results imply that
 connectivity loss can directly translate into species losses in
 communities and highlight the importance of conserving habitat networks
 with sufficient dispersal among local habitats.
description: # Data from: Connectivity loss in experimental pond networks leads to
 biodiversity loss in microbial metacommunities
 [https://doi.org/10.5061/dryad.fj6q5744j](https://doi.org/10.5061/dryad.fj6q5744j) ## Description of the data and file structure The datasets contain the underlying data of the results of Szabó et al. (2024), obtained from a four-month outdoor experiment with artificial pond (mesocosm) metacommunities designed to study the effects of connectivity loss on planktonic microorganisms. The experiment took place between 7th July and 27th October 2020 in Tihany, Hungary. ### Files and variables #### File: environmental\_variables.xlsx **Description:** This dataset includes information on the experimental treatments along with the variables measured at the four sampling events. ##### Variables * Sampling_event - ID of sampling event (Week4:4th week of the experiment, Week8: 8th week of the experiment, Week12: 12th week of the experiment, Week 16: 16th week of the experiment) * Mesocosm - ID of each mesocosm from m1 to m30 * Metacommunity - ID of each metacommunity from M1 to M6 * Treatment - connectivity vs. fragmentation treatment * TN - Total nitrogen concentration (mg L-1) measured with a Multi N/C 3100 TC/TN analyzer (Analytik Jena, Germany) * TP - Total phosphorus concentration (μg L-1) measured with standard spectrophotometric method followed by persulphate acidic digestion (Eaton et al., 2005) * temperature - temperature (°C) recorded in situ using HANNA HI-9142 field device (HANNA Instruments, USA) * pH - pH recorded in situ HANNA HI-98129 field device (HANNA Instruments, USA) * EC - electric conductivity (μS cm-1) recorded in situ HANNA HI-98129 field device (HANNA Instruments, USA) #### File: zooplankton\_density.xlsx **Description:** This dataset contains densities (ind L-1) of zooplankton taxa identified during the mesocosm study. Individuals of rotifers and cladocerans were identified to genus level, while ostracods to class level according to the relevant identification guides (Bancsi, 1986; Gulyás and Forró, 1999). Crustacean groups (Cladocera and Ostracoda) were identified with Olympus SZ51 at 0.8x-4x magnification, while Rotifera with Olympus CX33 upright microscope at 4x-100x magnification. ##### Variables * Sampling_event - ID of sampling event (Week4:4th week of the experiment, Week8: 8th week of the experiment, Week12: 12th week of the experiment, Week 16: 16th week of the experiment) * Mesocosm - ID of each mesocosm from m1 to m30 * Metacommunity - ID of each metacommunity from M1 to M6 * Treatment - connectivity vs. fragmentation treatment #### File: phytoplankton\_density.xlsx **Description:** This dataset contains densities (cells mL-1) of phytoplankton taxa identified at the last sampling event (i.e., Week16). The community composition of phytoplankton was determined with an inverted microscope (Zeiss Axiovert) (Utermöhl, 1958) at 630x magnification using the relevant taxonomic guide (John et al., 2002). ##### Variables * Sampling_event - ID of sampling event (Week 16: 16th week of the experiment) * Mesocosm - ID of each mesocosm from m1 to m30 * Metacommunity - ID of each metacommunity from M1 to M6 * Treatment - connectivity vs. fragmentation treatment #### File: phytoplankton\_groups.xlsx **Description:** This dataset includes the list of phytoplantkon taxa identified at the last sampling event (i.e., Week 16) along with the assigned groups. #### File: 16S\_ASV\_set\_prokaryotes.xlsx **Description:** This dataset contains the 16S ASV set rarefied to 13835 read per sample (referred to as prokaryotic dataset in Szabó et al., 2024). ##### Variables * Sampling_event - ID of sampling event (Week4:4th week of the experiment, Week8: 8th week of the experiment, Week12: 12th week of the experiment, Week 16: 16th week of the experiment) * Mesocosm - ID of each mesocosm from m1 to m30 * Metacommunity - ID of each metacommunity from M1 to M6 * Treatment - connectivity vs. fragmentation treatment #### File: taxon\_list\_16S\_ASV\_prokaryotes.xlsx **Description:** This dataset includes the list of taxa assigned to the 16S ASV set. #### File: 18S\_ASV\_set\_microeukaryotes.xlsx **Description:** This dataset contains the 18S ASV set rarefied to 2224 read per sample (referred to as microeukaryotic dataset in Szabó et al., 2024). ##### Variables * Sampling_event - ID of sampling event (Week4:4th week of the experiment, Week8: 8th week of the experiment, Week12: 12th week of the experiment, Week 16: 16th week of the experiment) * Mesocosm - ID of each mesocosm from m1 to m30 * Metacommunity - ID of each metacommunity from M1 to M6 * Treatment - connectivity vs. fragmentation treatment #### File: taxon\_list\_18S\_ASV\_microeukaryotes.xlsx **Description:** This dataset includes the list of taxa assigned to the 18S ASV set. #### References Bancsi, I. (1986). A kerekesférgek (Rotatoria) kishatározója I. Vizügyi Hidrobiológia 15. Vízgazdálkodási Intézet, Budapest, 1–172. Eaton, A. D., Clesceri, L. S., Rice, E. W., Greenberg, A. E., & Franson, M. A. H. (Eds.) (2005). Standard Methods for the Examination of Water & Wastewater, Centennial Edition (21st ed). American Public Health Association (APHA) Press, Washington, DC. Gulyás, P., & Forró, L. (1999). Az ágascsápú rákok (Cladocera) kishatározója. Vízi természet- és környezetvédelem, 9, 1-237. John, D. M., Whitton, B. A., & Brook, A. J. (Eds.) (2002). The freshwater algal flora of the British Isles: An identification guide to freshwater and terrestrial algae. Cambridge University Press. Utermöhl, H. (1958). Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. Mitteilung Internationale Vereinigung Fuer Theoretische unde Amgewandte Limnologie, 9, 1–38. ## Code/software All statistical analyses were carried out using the R (v. 4.2.1) programming language (R Core Team, 2022). R Core Team (2022). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. [https://www.R-project.org/](https://www.R-project.org/). ## Access information Other publicly accessible locations of the data: * Raw sequence reads are available in the European Nucleotide Archive ([https://www.ebi.ac.uk/ena/browser/view/PRJEB78363](https://www.ebi.ac.uk/ena/browser/view/PRJEB78363)) under reference number PRJEB78363