Geoscience Reference
In-Depth Information
Table 1 (continued)
Traits
Modalities
Maximum size of organism
(cm)
<1
1
10
11
-
20
20+
-
(Oksanen et al.
2013
) for the open-source R software, version 3.0.1 (R Develop-
ment Core Team
2009
). Similarity in
-diversity (i.e. the variability in species
composition among sampling sites for a given area at a given spatial scale) among
the sampling sites were tested using a test for homogeneity of multivariate dis-
persions (PERMDISP routine, Permanova+ add-on in Primer 6; Anderson et al.
2008
). The test was conducted on the basis of species composition (presence/
absence) data in conjunction with compositional dissimilarity (i.e., Sorensen
resemblance measures). Functional diversity was compared among sampling sites
by means of a Monte-Carlo random permutation test (999 permutations). For each
trait, the distribution of modalities was compared among the four sampling sites
using contingency tables (Chi square tests).
β
3 Results
For each trait, the distribution of modalities differed signi
cantly between the four
sampling sites (each p < 0.001; Fig.
2
). All benthic assemblages were dominated by
infaunal organisms (Fig.
2
a) with small to medium body size (1
10 cm; Fig.
2
b).
Small individuals (<1 cm) occurred mainly at stations Slt and WB. Most individuals
were burrowers while sessile species were rare in all assemblages (Fig.
2
c).
Omnivorous organisms dominated the benthos whereas the proportion of purely
herbivorous individuals was generally low (Fig.
2
d). The reproductive mode was
mainly gonochoric with development through a planktotrophic larval stage (Fig.
2
e,
f). The majority of the animals reached maturity within 2 years (Fig.
2
g) and only
few species had a life expectancy of more than 10 years (Fig.
2
h). Only the
assemblage at station WB had a higher proportion of individuals with a longevity
>10 years. Feeding types were more heterogeneously distributed (Fig.
2
i). Deposite
feeders and interface feeders were generally the most common feeding types.
However, predators/scavengers were also common at all sites. Fecundity mainly
ranged between 10 and 10
6
ind. fem.
−
1
(Fig.
2
j). Only at station Slt a considerable
proportion of the infaunal assemblage produced more than 10
6
ind. fem.
−
1
while
only few individuals produced less than 100 ind. fem.
−
1
at all sites.
The average functional diversity of the benthic assemblages ranged from
FD
RAO
= 1.66
-
±
0.16 at site Slt to FD
RAO
= 2.01
±
0.06 at site SSd. The functional
diversity was signi
cantly lower at site Slt than at all other sites (p < 0.001; Fig.
3
).
At site WB, the functional diversity was lower than at sites FSD and SSd (p < 0.01)
which were not signi
cantly different (p > 0.05).
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