Baseline study Fish, fry and commercial fishery Nysted Offshore ...

Bio/consult as Page 13
Month: 11
Month: 9 Month: 10
Month: 5 Month: 6
Reference
Windfarm
Figure 5. MDS-map of Bray-Curtis distances between all stations calculated as square root
transformed data. The differences between the areas have been illustrated with different
colours. Data from each month have been placed in each their sub plot but they
originate from the same graph. The areas have been tested significant different in month
5 and 9 using permutation test.
To illustrate a significance test of the interaction effect of the BACI-model two sets of
artificial data, which could have come from a baseline survey, were constructed. The
sampling periods May and June were chosen and the number of individuals for
stationary fish species in the wind farm area were increased with a factor 2 and 4
respectively but only in the month of June. This could have been two data sets from a
before and after situation where a change have occurred in the impact area and not in
the reference area.
The analysis was made using Bray-Curtis distances between all samples calculated on
square root transformed data to reduce the effect of abundant species and to secure a
uniform distribution of distances between the replicates from each sampling occasion. A
NPMANOVA-test of significance was made using the same data set.
Figure 6 show the three nMDS plots from each their data set. Note that the points in the
dense swarm moves away with an increase in number of individuals of the stationary
species.