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Data from: Ecotonal gradients shape biodiversity of multiple estuarine taxa

Oester, Rebecca1; Brannoff, Benjamin2; Biederbick, Johanna13; Grüterich, Luise1; Koll, Raphael1; Lexmond, Fay14; Martens, Nele1; Mittmann-Goetsch, Julian1; Neiske, Friederike51; Putri, Widhi1; Remmers, Sina1; Richter, Diana1; Ruhrus, Lia1; Russnak, Vanessa3; Saadaoui, Youssef1; Theilen, Jesse1; Tobias-Hünefeldt, Sven P.167; Wilson, Monica1; Becker, Joscha N.1; Eschenbach, Annette1; Grossart, Hans-Peter78; Fründ, Jochen1; Kutzbach, Lars1; Meier, Ina C.1; Porada, Philipp1; Schaum, C.-Elisa1; Streit, Wolfgang R.1; Woodhouse, Jason N.17; Jensen, Kai1

Published Jun 16, 2026 on Dryad. https://doi.org/10.5061/dryad.8cz8w9h6c

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Jun 16, 2026 version files 1.89 GB

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Abstract

Estuaries are dynamic transition zones linking terrestrial, freshwater, and marine environments. Their steep environmental gradients govern the distribution and diversity of multiple taxonomic groups. Yet, how these gradients jointly shape biodiversity across terrestrial-aquatic interfaces remains underexplored. Here we analyzed α- and β-diversity across twelve taxonomic groups of microbiota, plants, and animals spanning marsh and riverine habitats along the Elbe Estuary (Germany). Principal component analyses identified salinity as a major axis of environmental variation across land and water, while flooding frequency in marshes and suspended particulate matter in the river were important environmental factors in the marshes and the river, respectively. Different taxa showed distinct associations with these gradients: α-diversity of mainly for small-bodied groups correlated with environmental gradients, whereas community composition varied strongly along estuarine gradients across most taxa. Salinity-related gradients explained the largest share of compositional variation, indicating characteristic halophilic taxa near the river mouth, for example Spartina anglica. This multi-taxon assessment captures parallel yet differing biodiversity patterns across the terrestrial-aquatic boundary, with salinity emerging as the most consistent organizing axis for both spatial turnover and nestedness of community composition. Together, these findings demonstrate how steep ecotonal gradients shape biodiversity across multiple taxonomic groups and habitat boundaries. In transitional ecosystems shaped by freshwater inflow and salinity regimes, such gradients are especially consequential as global change is projected to shift habitat boundaries. Considering these responses is essential for informing adaptive management and conservation in estuarine systems.