Functional Diversity and Traits Assembly Patterns of Benthic Macrofaunal Communities in the Southern North Sea - Towards an Interdisciplinary Approach in Earth System Science - page 172

matrix) was generated from
10 different traits covering life history, behavioral characteristics, morphological
attributes and environmental preferences of benthic species. Traits were selected
either for their importance for the structure and functioning of the benthic system or
for their sensitivity to changes in environmental variables. Each trait comprised
qualitative or quantitative modalities, which allow for a functional characterization
of individual taxa (Table 1 ). Speci

An autecological database (i.e. “ trait by species ”

c trait modalities were assigned to individual

taxa (i.e. species or genus) using a “ fuzzy coding ” procedure (Chevene et al. 1994 )

with a scoring range for af nity score of zero indicates

no association of a taxon with a modality, whereas a score of three indicates highest
af

nities of zero to three. An af

nity. For example, the polychaete Pisione remota mostly feeds as predator/
scavenger but may also feed occasionally as deposit feeder. Accordingly, the

species was coded 1 for “ surface/subsurface deposit feeder ” and 2 for “ predator/

scavenger . Information on biological traits of

taxa was compiled from peer-reviewed literature, species identi

” for the trait variable ' feeding habit '

cation guides,
online databases (e.g. BIOTIC 2012) and from personal expert consultations.
Missing data were supplemented by using information referring to closely related
species. To give the same weight to each taxon and trait, the scores were stan-
dardized by scaling the sum of all scores for each trait of a taxon equal to 100. The
standardized modality scores for each taxon were multiplied by the average species
abundance at each station and summed up over all taxa. The results are a “ trait by
station matrix

providing the frequencies of occurrence of modalities in each year
and at each station.
The complete trait dataset contained 10 traits subdivided into 43 modalities. The
amount of information available differed markedly among traits. Information on
feeding habit, environmental position and adult motility was abundant, whereas data
on morphological traits (e.g. fragility) and fertilization type were not that readily
available. The full data gathered on the species traits with an attributed reference list
are available as SupplementaryMaterial at PANGAEA

”

Network for Geological and
Environmental Data ( http://doi.pangaea.de/10.1594/PANGAEA.813419 ).
Functional diversity of an assemblage was calculated using the Quadratic
entropy index (Rao 1982 ):

—

X

s

X

s

FD RAO ¼ d ij p i p j

i ¼ 1 j ¼ 1

where s is the number of taxa in the community and pi i and p j are the proportion of
the ith and jth taxon in the community, respectively. d ij is the trait dissimilarity
between each pair of taxa i and j measured as Euclidean distance. Accordingly,
FD RAO is the sum of the trait dissimilarities among all possible pairings of taxa,
weighted by the relative abundance of the taxa (de Bello et al. 2009 ). FD RAO was
calculated separately for each of the 11 biological traits and summed up for the
entire assemblage of a site (Darr et al. 2014 ; van der Molen et al. 2013 ). FD RAO was
calculated using the

' ADE-4 ' (Thioulouse et al. 1997 ) and ' VEGAN ' libraries