Coarsening coasts: quantifying sensitivity of benthic communities to sandification - data and code Version 1

Sea level rise, increased storminess, and changes in sediment supply due to nourishments are all expected to drive coarsening (i.e., ‘sandification’) of muddy coastal sediments in the decades to come. Since the composition of soft-bottom benthic communities is associated with the sediment grain-size and mud content, this may result in habitats becoming less suitable for some species, leading to species shifts. Species-sediment relations can help to predict how this foreseen sandification may affect benthic fauna. We explore and quantify the sandification-sensitivity of benthic communities, with a tidal basin in the Dutch Wadden Sea as a model system. We identify the species’ sediment optima and tolerance ranges using non-linear quantile regression models, summarise preference and sensitivity at the community level, and determine the difference between optimal and realised sediment habitat. Here, we present the underlying data and the R-scripts used for spatial resampling, quantile regression analysis and obtaining and displaying taxon- and community sediment sensitivity parameters. Benthos and sediment samples were collected as part of the intertidal and subtidal benthic surveys performed by the Royal Netherlands Institute of Sea Research (NIOZ). Intertidal data was obtained through the synoptic intertidal benthic survey (SIBES) [1, 2]. This dataset covers 639 sampling stations in the Borndiep tidal basin, of which 525 are located on a regular 500x500m grid and 114 are randomly placed [3]. For details on the sampling procedure, we refer to Bijleveld et al. [1] and Compton et al. [4]. Subtidal samples were collected as part of NIOZ subtidal sampling campaigns and within the projects TRAILS and WaddenMozaïek. From the 186 subtidal stations in the Ameland inlet and at the ebb-tidal delta, 145 were placed on a 1000x1000 m grid and 41 were randomly placed. For more details on the subtidal sampling, we refer to Franken et al. (in prep) [5]. The combined dataset consists of a total of 2991 samples, collected over the period 2015-2020. The compiled data tables, with abundance (individuals m-2) or biomass (g ash-free dry weight m-2) summarised per taxon, are provided here.

REFERENCES [1] Bijleveld, A. I., de la Barra, P., Danielson-Owczynsky, H., Brunner, L., Dekinga, A., Holthuijsen, S., Ten Horn, J., de Jong, A., Kleine Schaars, L., Kooij, A., Koolhaas, A., Kressin, H., van Leersum, F., Miguel, S., de Monte, L. G. G., Mosk, D., Niamir, A., Oude Luttikhuis, D., Peck, M. A., … Bom, R. A. (2025). SIBES: Long-term and large-scale monitoring of intertidal macrozoobenthos and sediment in the Dutch Wadden Sea. Scientific Data, 12(1), 239. https://doi.org/10.1038/s41597-025-04540-9 [2] Bijleveld, A. I., Tacoma, M., & Koolhaas, A. (2024). SIBES dataset. NIOZ. https://doi.org/https://doi.org/10.25850/nioz/7b.b.ug [3] Bijleveld, A. I., van Gils, J. A., van der Meer, J., Dekinga, A., Kraan, C., van der Veer, H. W., & Piersma, T. (2012). Designing a benthic monitoring programme with multiple conflicting objectives. Methods in Ecology and Evolution, 3(3), 526–536. https://doi.org/10.1111/j.2041-210X.2012.00192.x [4] Compton, T. J., Holthuijsen, S., Koolhaas, A., Dekinga, A., Smith, J., Galama, Y., Brugge, M., Wal, D. Van Der, & Meer, J. Van Der. (2013). Distinctly variable mudscapes: Distribution gradients of intertidal macrofauna across the Dutch Wadden Sea. Journal of Sea Research, 82, 103–116. https://doi.org/10.1016/j.seares.2013.02.002 [5] Franken, O., Holthuijsen, S. J., Meijer, K. J., Kleine Schaars, L., Rasch, B., Kooijman, J., van Weerlee, E., Miguel, S., Koolhaas, A., Witte, S., Rehlmeyer, K., Dickson, J., Smeele, Q., Bijleveld, A. I., Olff, H., van der Heide, T., & Govers, L. L. (n.d.). Below murky waters: Subtidal benthic species and sediment distributions in the Dutch Wadden Sea. In Prep.