Data from: Maintained functional diversity in benthic communities in spite of diverging functional identities

Ecological studies based on time-series often investigate community
changes centered on species abundance or biomass but rarely expose the
consequential functional aspects underlying such changes. Functional
diversity measures have proven to be more accurate predictors for
ecosystem functioning than traditional taxonomic approaches and hence
gained much attention. There are only limited studies available that
analyse the functional implications behind decadal changes of entire
communities. We studied zoobenthic communities of two habitats, sheltered
and exposed, of a coastal system subject to contrasting changes in
community composition over the past four decades. Besides eutrophication
and climate-related impacts, the system has been invaded by a non-native
polycheate Marenzelleria spp., adding altered functional properties to the
communities. The functional dispersion (FDis) metric was used as a measure
for comparing the functional diversity of the contrasting habitats, with
special focus on the role of Marenzelleria for the entire communities. We
highlight changes in the functional identity of the communities, expressed
as community-weighted means of trait expression (CWM), using multivariate
techniques, and investigate the relationship between taxonomic and
functional changes. Despite contrasting community developments in the two
habitats, with characteristics traditionally suggesting different
environmental quality, we found that the FDis in both habitats remained
similar and increased with the introduction of Marenzelleria. Although
showing maintained functional diversity across time and space, the
functional identity (CWM) of communities changed irrespective of
taxonomical differences. Examples include inter alia alterations in
palatability proxies, feeding position and sediment transportation types,
indicating changed functionality of zoobenthos in coastal systems. We
show, when focussing on qualitative functional changes of communities, it
is important to evaluate the underlying functional identity, and not only
rely on measures of the diversity of functions per se, as the quality
indication of expressed functional traits can be concealed when using
multi-functionality approaches.

Species_x_TraitsThis file contains the species by trait matrix for all
observed species included in the study. The trait scoring follows the
fuzzy coding procedure as described in the manuscript. Species names are
abbreviated by the first three letters of their genus. The functional
traits are sorted by number (1-9) and followed by their trait-categories.
See the "Abbreviations species and traits. csv" file below and
the manuscript for details.Station_x_SpeciesThis file contains the station
by species abundance matrix. Stations are labeled by their exposure
classification (E = exposed, S = sheltered), their station ID, and their
collection year. Species abundances are the mean abundance of five
Ekman-Birge grab samples per site. Species names are abbreviated by the
first three letters of their genus. See manuscript for
details.CWM_PERMANOVAThis file contains the matrix of community weighted
means of trait category expression (CWM) for all included sampling
stations and years. CWM values were calculated from the species by trait
matrix and station by species matrix and used for the CWM PERMANOVA. See
manuscript for details.Abbreviations species and traitsThis file contains
details to the abbreviations of included species and traits