Processed data on freshwater bivalve communities and environmental variables from the upper Neva Estuary, 2022–2024

This record provides a curated, analysis-ready grab-level input dataset on freshwater bivalve assemblages and associated environmental variables from the upper Neva estuary, Baltic Sea, for the period 2022–2024. The dataset supports the reproducible analysis workflow associated with the study “Turnover, local uniqueness and environmental gradients of freshwater bivalve assemblages in the upper Neva estuary (Baltic Sea)”. Each row of the main workbook represents one grab sample. The table includes sampling metadata, bottom sediment category, near-bottom environmental covariates and species-density columns for freshwater bivalves. Species are encoded as stable columns `Sp1` ... `Sp20`; accepted species names, display labels and family assignments are provided in `species_key.csv`. This record contains the public analytical input dataset and supporting documentation needed to reproduce the analyses reported in the associated manuscript. It does not include primary field sheets, raw instrument files, full laboratory records, intermediate derived matrices, model objects, figures, tables or run logs. These analytical outputs are generated locally by the companion R workflow. Underlying primary records are retained by the data holders and are outside the scope of this public data record. Bivalve samples were collected using a Van Veen grab with a sampling area of 0.025 m^2. Abundances are provided as species-level densities expressed as individuals per square metre (ind. m^-2). The companion workflow uses these density values directly for community-composition analyses. For count-based abundance models, the workflow reconstructs the aggregate number of individuals per grab as `total_count_grab = round(total_density_m2 * 0.025)`. Environmental variables include bottom sediment category (`sand` or `silt`), near-bottom water temperature, specific conductivity standardized to 25 °C (`SC25`) and the PP/Mp ratio. Near-bottom temperature and SC25 represent readings taken approximately 0.3 m above the sediment–water interface. The PP/Mp ratio is the ratio of gross primary production to organic-matter mineralization and is used as an index of autotrophic–heterotrophic balance in the water column, not as a direct measure of organic-matter origin. The data record contains: `neva_bivalves_input.xlsx`, `species_key.csv`, `data_dictionary.md`, `README_DATA.md`, `CITATION.cff`, `CITATION.md` and `checksums.sha256`. Companion analysis code: GitHub: https://github.com/Mikhail-Golubkov/neva-bivalves-analysis Zenodo (software snapshot): https://doi.org/10.5281/zenodo.20530070