Proceedings of the Second Mediterranean Symposium on Marine

On Fig. 4 each <strong>of</strong> <strong>the</strong> five stations contains four samples from four different months.
Dashed lines indicate <strong>the</strong> simulated mean from a 5000 random selections from a master
list <strong>of</strong> 513 species <strong>of</strong> <strong>the</strong> Greek seas. Continuous lines represent <strong>the</strong> 95% confidence
intervals and define <strong>the</strong> area where any ∆ + or Λ + value, for a given number <strong>of</strong> species,
lies within <strong>the</strong> “expected” range.
Figure 4: Average taxonomic distinctness ∆+, and Variance in Taxonomic Distinctness Λ+ values, plotted
against <strong>the</strong> observed number <strong>of</strong> species for two cases: using all groups <strong>of</strong> algae and excluding <strong>the</strong> red algae
group.
DISCUSSION AND CONCLUSIONS
The EEI has adequate resolving power to discriminate between disturbed sites. From <strong>the</strong>
results in <strong>the</strong> specific area <strong>the</strong> EEI seemed to perform better when relative abundance
data were used. Relative abundance intensifies <strong>the</strong> difference <strong>of</strong> percentages <strong>of</strong> <strong>the</strong> two
Ecological State Groups <strong>of</strong> species proposed by Orfanidis et al., (2001).
Taxonomic diversity indices can be very useful, as <strong>the</strong>y can perform on qualitative data,
and <strong>the</strong>ir independence <strong>of</strong> sample size makes <strong>the</strong>m suitable for comparisons <strong>of</strong> different
regions, studies etc. Overall <strong>the</strong> two taxonomic distinctness indices performed better
when <strong>the</strong> red algae group was excluded from <strong>the</strong> analysis. This could be due to <strong>the</strong> fact
that <strong>the</strong> number <strong>of</strong> red algae species is three times greater than <strong>the</strong> number <strong>of</strong> <strong>the</strong> green
and brown algae species. This is affecting <strong>the</strong> balance <strong>of</strong> <strong>the</strong> taxonomic tree and needs
fur<strong>the</strong>r examination.
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